claim: 1. in a variable pitch propeller, a propeller shaft, E@ cylinder, propeller blades mounted on " said shaft for rotation about the axes of the blades, pitch changing means, means connecting the pitch changing means and the blades, a, piston mo@able in the cylinder, means connected with the piston to actuate the pitch changing 50 means, a fluid.pressure system, a two-way control s@stem In, said fluid pressure system, distributing valves on each way of the said control system for distributing the medium of tlle fluid pressuie to the cylinder for moving tiie piston in C,5 one direction only, one way with moderate, changing speed, and the other way with fast changing speed, yieldable megns for moving the pis ton in the 6pposite direction, stops for. liniiting the maximum displacement of the pision in said directions which correspond to two extreme prede- 60 termined pitches, means in the one way control system of moderate changing speed for establishing acondition of equilibriurn between the action of the fluid medum under pressure and the action of the yieldable means at least in one predetermined intermediate position, which corresponds to an intennediate prede.termined propulsion pitch. 2. In a variable pitch propeller, a. properer 70 ,shaft, a cylinder, propeller blades mounted on the shaft for rotation aboiit -the axes of the blades, a pitch changing means, means connect-ing the pitch changing means and the blades, a piston movable in the cylinder, yieldable means 7r) biasing the piston In one direction, means connected to the pistori to actuate the pitch changing means, a fluid pressure system, a control system In said fluid pressure system, distributing valves for distributing the medium of the fluid pressure system to the cylinder for moving the piston in one direction only while yieldable meglns moves the piston in the opposite direction, a hollow slide valve in the control system coaxial With the cylinder connected to the piston and sliding into a gleeve fixed to:,the cylincter and rotating in a stationary support, said slide valve having ports at different axial positions, said sleeve having ports distributed along the sleeve so as to cooperate with the ports of the valve, and an adimtable distributor ad'apted to bring into operation one set of ports of the sleeve and of the valve in such a manner that the feed which takes plac6 therethrough compels the slide valve to assume the Position corresponding to that in which the reciprocal throttling of the two cooperating ports establishes a condition of equilibrium betweeh the action of the yieldable means and the action of the fluid medium under pressure and a compensation of the iluid losses occurring in the system. 3. In a variable pitch ProPeller as claimed iii claim 2, a slide valve provided with several ports of different lengths in the axial direction distributed around the slide valve and adapted to cooperate with a single port iri the fixed sleeve for the feed of fluid prossure, and means for puttng into action one port of the valve with a port of the sleeve to regulate the-position. to be taken bY the inember actuating th6, blades. 4., In a variable pit ch propeller, a propeller shaft,,-a cylinder, propeller blades mounted on said sbaft for rotation about the axes of the blades, pitch changing means, means connecting the pitch changing means and the blades, a piston movable in the cylinder, yieldable means biasing the Piston in one direction,,meahs connecting the Piston to actuate the pitch changing means, a fluid pressure system, a'control system in said fluid p'ressure system, distributing valves for distributing the medium of the fluid pressure system to the cylinder for moving the piston in, one d4rection while the yieldable means MOVes the Piston in the OPPosite direction, a sleeve secured to the cylinder, a houow slide valve in the control system coaxial with the cylinder connected to the piston and sliding in said sleev'e and rotat-ing in a stationary support, said slide valve having ports at different axial positions, said sleeve having ports distributed therealong so as to cooperate with the ports of the valve, an adjustable distributor adapted to bring into operation one set of ports of the sleeve and of,the valve in such a manner that the feed which takes Place therethrougb. compels the slide valve to assume the position corresponding,to that in which the reciprocal throttling of the two cooperating ports establishes a condition of equilibrium between the action of, the yielda@le means and the action of the fluid zn6diurn under pressure and a compensation 6f the fluid losses oc.,. cu-rring iii the system, and means for introduring into the cylinder a supplehientary feed of fluid under pressure independently of the slide valve for the purpose of producing temporary'variations in the pitch. 5. In a variable Pitch propelleri -,a 'Propeller shaft, a cylinder, ProPeller blades mounted on said shaft for rotation about the axes of the blades, pitch changing means, mean@ connecting

toxi movable in the cylinder, means connected with the piston to actuate the pitch changing means, a fluid pressure syst@em, a control system in said fluid pressure system,, distributing valves for distributing the medium Gf the fluid pressure system to the cylinder for moving the piston in one direction only, yieldable means for moving the piston in the opposite direction, stoos for limiting the maximum displacement of the piston in said directions which correspond to, two extreme predetermined pitches, means in the control system for establishing, a condition of equibbrium between the action of the fluid medium under pressure and the action of the yieldable means at least in one predetermined - intermediate position *1-deh-corresponds o an Intermediate predetermiried pitch, a set of mechanical stop members subjected to the action of the centrifugal force for stopping in one diiection when the medium of thei fluid pressure system becomes inoperative, the movement of the member actuating the blades In an Intermediate position corresponding to a long propulsion pitch, and means iteting bn said stop members iri a direction opposite to the centrifugal force so that the stop members become inoperative when the propeller Is stopped. 12. In a variable pitch propeller, a propeher shaft, a cylinder, propeller blades mounted :on said shaft for rotation about the axes of blades, pitch changing means, means connecting the pitch changing means and the blades, a piston movable in the cylinder, means connected with. the.piston to actuate the pitch changing means,'a fluid pressure systein, a control system in said fluid pressure system, distributing valves for distributing the inedium of the fluid-pressure system -to the cylinder for moving the piston in one direction onln yieldable means for moving th6 piston in the opposite direction, stops for linitting the maximum displacement of the piston in said directions which correspond to. two extreme predeterrained pitches, means, in the control system for establishing a condition of equflibrium between the@ action of the fluid medium under pressure and the action of the yieldible means at least in one predetermined intermediate position which dorresponds to an intermediate propulsion. pitch, two sets of mechanical stop members subjected to the action . of the centrifugal force for stopping lri one direction when the medium of the fluid pressure system becomes inoperative, the movement of the 8. In a variable pitch propeller as claimed in 70 member actuating the blades in two different claim @6, a control nieans for the distribution of positions which correspond to two different preihe fluid medium at high pressure to the cylindetermin ed pitches,. means acting on said stop .der - wlAch controls the pitch ehanging mechamember s In a direction opposite to the centrifunism, a valve, brake actuating means operatint; gal force so that the stop members become inler is stopped, and said valve when moved to one position, and a 75 op@erat ive wherl the propel valve in the control system coaxial with thi cyl@ inder connected to the pistoli and sliding in said sleeve and rotating in a stationary support, said s:@de valve having 'Ports at different axial positions, said sleeve hav'mg ports distribut ' ed therealong so as to cooperate with the ports of the valve, an adjustable distributor adapted to bring into operation one set of @orts of the sleeve and of the valve in such manner that the feed 20 Wliieh takes place tberethrough compels the slide. valve to assume the position corresponding to the@t In which the reciprocal throttnng o;f the two ' cooperating ports establishes a condition of equilibrium between the action of the yieldable means 25 and the action of the fluid medium under pressure and a eompensation of the fluid losses occi@rring in the system, and a cover secured in a movable manner tG the cylinder, for moving the slide valve. 30 6. In a variable pitch- propeller, a propeller shaft, a cylinder, propeller blades biounted on said sliaft for rotation about the axes of the blades, a pitch changing mechanism, means connecting the pitch changing mechanism and the 35 blades a piston movable in the cylinder, yieldable ;@eans biasing the piston in one direction, means connected to the piston to actuate the piston changing tnechanism, a fluid pressure system, a control system with two ways one for 40 moderate and the other for fast changing speed through which the fluid medium is brought to act into the cylinder under' low and high pressure respectively, distributing valves In each way of said control system for distributing the me- 4,5 dium of the fluid piessure to the cylinder for. moving the 'Piston in one direction while the yieldable means moves the piston In the opposfte . direction, means for carrying out the aerodynamic braking of an aeroplane to which the pro- 50 peller is fitted by reversal of the pitch comprising control means for distributing through the fast changing speed way the fliiid medium to the cylinder, a cooperating device which automatidally controls the fuel feed to the engine which r,5 actuates the propeuer for the purpose of automatically coordinating the workhig speed of the ingine during the braking, and safety devices provided between the member actuating thi@ brake and the member normally actuating. the 60 feed of fuel to the engine to prevent wrong manipulations. 7. In a variable pitch propeller as claimed in claim 6. a device operated by the fluid mediiun for coritrolling the feed of fuel to the engine dur- 65 ing the.braking, said device being expandable and contractible under the action of said fluid medium' for c6ntrolling the fuel 'feed to the engine. the pitch changing means and the blades, a pis. discha rge valve controued by the brake actuating ton movable in the cylinder, yieldable means means when it Is moved to another position. biasing the piston in one direction, means,con9. In a l@ariable pitch propeller as claimed in necting the piston to actilte the pitch changing claim 6,'an automatic non-return valve in a means, a fluid @ressurl' system, a control sys5 condui t through which the fluid medium at high tem in said fluid pres@ure system, distributiilg pressure is introduced into the cylinder during v.alves for distributing the medimn of the the braking oi@eration. pressure system to the cylinder ior moving the 10. In a variable pitch propeller as claimed iri piston in one direction only while the yieldable claim 6, means operated by the fluid medium at means moves the piston in the opposite direction, lo high-pressure for the control of the discharge of a sleeve secured to the cylinder, a hollow slide said fluid medium from the cylinder. 11. In a. variable pitch propeller, a propeller shaft, a cylinder, propeller blades mounted,on said shaft for rotation about the axes of the 15, blades, pitch changing means, means connecting the pitch changing means and the blades, a pis-.

10 2,308,228 means for positiveiy aettating the one of said said shaft for rotation about the axes of the sets when the propeuer is running. blades, pitch changing means, means connecting 13. In a variable Pitch propeller, a propeller the pitch changink means and the blades, a pisshaft, a cylinder, propeller blades mounted on ton movable in the cylinder, means connected said shaft for rotation about the axes of the 5 with the piston tG actuate the pitch changing blades, pitch changing means, means connecting means, a fluid pressure system, a control system the pitch changing means and the blades, a pisin said fluid pressure system, distributing valves ton movable in the cylinder, means connected for distributing the medium of the fluid preswith the piston to actuate the pitch changing sure system to the cylinder for moving the pismeans, a flwd pressure system, a control system 10 ton in one direction, yieidable means for moving in said fluid pressure system,_distributing valves the piston in the opposite direction, stops for limfor distributing the medium of the fluid presiting the maximum displacement of the piston sure system to the cylinder for moving the pisirl said directions which correspond to two exton in one direction, yieldable means for moving treme predetermined pitches, means in the conthe pistoii in the opposite direction, stops for lim15 trol system for establishing a condition of equiiting the maximum displacement Gf the piston in librium between the action of the fluid medium said directions which correspond to two ex'treme under pressure and the action of the yieldable predetermined pitches, means in the control sysmeans at least in one predetermined inteimetem for establishing a condition of equilibrium diate position which corresponds to aii lntermebetween the action of the fluid medium under 20 diate predetermined propulsion pitch, a collor pressure and the action of the yieldable means at connected to the means actuating the blades.and lea,st in one predetermined intermediate posiin which one blade Is secured, a lever for regiition which corresponds to an intermediate predelating the a-ninflar position of the blade@ with retermined propulsion pitch, means for introducing spect to the collar pivotally mounted at one end ,fluid into. the cylinder when an engine driving 25 m a radial Position on a face of the collar and -the propeller is inoperative for the p . urpose of engaging at its other end -in a slot in the blade,. reversing the pitch and thus stopping rotation and control bolts engaging the regulating lever. of the propeller due to the wind caused by flight, 16. In a variable pitch propeller, a propeller and means for discharging the fluid from the shaft, a cylinder, propeuer blades mounted on cylinder for mgving the blades to an infinite 30 said shaft for-) iotation about the axes of the pitch. blades, Pitch chanlying means, means coxinecting .14. In a variable.pitch propeller, a propeller the pitch changing means and the blades, a pisshaft, a cylinder,'propeller blades mounted on ton movable in the cylinder, means connected said shaft for rotation about the axes of the with the piston to actuate the pitch changing blades, pitch changing means, means connecting 35 means, a fluid pressure system, a control fiysthe pitch changing -means and the blades, a plstem in said fluid pressure syeitem, distributing ton movable in the cylinder, means connected valves for distributing the medium of the fluid with the piston to actuate the pitch changing pressure system to the cylinder for moving the rileans, a fluid pressure system, a control system piston in one direction, yieldable means for movin said fluid pressure system, distributing valves 40 ing the piiton in the opposite direction, stops for for distributing the medium of the fluid pressure limiting the maximum displacement of the piston system to the cylinder for moving thd piston in in said directions which correspond to two exone direction, yieldable means for moving the treme predetermined.pitches, means in the conpiston in the opposite directionl- stop@ for limit- .trol system for estabiishing a condition of equiing the maximum displacement of the piston in sa@ld directions which correspond to two extreme predetermined pitches, means In the control system for stablishing a condition of equilibrium e between the action of the fluid medium under pressure and the action of the yieldable means at least In one predetermined intermediate position which corresponds to an intermediate predetermined propulsion pitch, said means connected with the piston to actuate the pitch changing means including two telescoping elements capable of being expanded by spring means, a cylinder provided between said elements, and means for Introducing fluid into the last mentioned cylinder for the purpose of modifying the length of said telescoping elem.ents against the action of the spring means. 15. In a variable pitch propeber, a propeller shaft, a cylinder, propeller blades mounted on 45 librium between the action of the fluid mediuin under pressure and the actign of the yieldable means at least in one predetermined Intermediate position which corresponds to an intermediate predetermined propulsion pitch, said means. 50 corinected to the piston to actuate the pitch changing means including a rod guided parallel to the axis of the propeller shaft and cooperating with a slider fixed on the rod, said slider having a seat therein, a member engaging said seat 55 -situated eceentrical.ly relatively to the axis about which the blade Is orientated and secured to the foot of the latter. 17. In a va riable pitcli propeller as claimed tri claiin 2, a member actuating the pitch-changing 60 mechanism and a slide valve of op@n tubular form. RAFFAELE MAT=CCI.

Patented Jan. 12, 1943 2@3089228 UNITED STATES PATENT OFFICE 2,308,229 AIR PROPELLER WITH ADJUSTABLE PITCH DURIING FLI[GEET Raffaele Matteuccl, Turin, Italy, vested in the Anen Property Custodian Application August 20, 1937, Serial No. 160,170 li@ Ualy August 31,1936 17 Chams. (Cl. .170-135.6) The present invention.relates to a propeller, the pitch of which can be varied during flight and which is more particularly intended for use in aviation, the propeuer being such that it is possible to effect the variation in pitch under such 5 conditions as to obtain at will any one of a number of fixed pitches, and in addition, if desired, an infinite series of pitches between two "flxed extreme propulsion pitches, and also a,certain number of auxiliary pitthes capable of being uti- 10 lised under spepial conditions of operation bf the aircraft. In the propeller according to the pie@ent invention the control of the pitch of the blades is effected by the aid of fluid under pressure, the 15 action of which is controlled by the pilot, if desired with the assistance if desired of an auto- , matic regulator controlling the variation of the pitches in the field of the pitches used for the propulsion and which, for the intermediate -pitches 20 between those determined by mechanical stops maintains the blades in conditions of equilibrium in the different -desired positions in opposition to a return member which tends to bring the blades to a deter-mined pitch used normauy for the pro- 25 pulsion. Certain pitches, which due to the effect they exert upon the operation of the aircraft, @must be used only under certain conditions or in certairi predetermined relationship with the operat- '0 ing conditions of the engine driving the propeuer, are made dependent upon a particular control which in its tum is connected to suitable safety devices, with a view tG preventing accidental or dangerous manceuvres. Some embodiments of the present invention ari@ inustratea by way of example in the accompanying drawings. - ngure I represents in diagrammatic cross seetion the propeller shaft-with the .root of a blad4e 40 and the pitch varying'device which in the case inustrated is placed in the propeuer shaft, in combination with a number of controuing safety devices. Mgure 2 is a diagrammatic plan view of the 45 ro6t of a blade with its actuating device, and gives an indication of the various pitches that can be obtained. Figures 3, 4, 5 and 6 illustrate diagrammaticaby the relative conditions of a propeller blade, of 50 the balancing counterweight and of. the controlUng device iihder different pitch conditi,ons. FU-ures 7, 8, 9 and 10 illustrate in part section and oil a large-r scale' the coiiironing distriba@torunder various operating conditions ;)5 Pi - gure'll is an enlarged sectional view of apatt ' of Fig. 1 showing a pawl device applied to the blade actuating member with the object of maintaining it in a fixed position. Figures 12, 13 and 14 illustrate in elevation, in part section and ln'detail, an asseinbly arrangement of the members actuating a propeller blade. , Flgure 15 illustrates diagrammatically an arrangement'for regulating the angular position of a blade relative to its actuating member. Figure 16 illustrates in longitudinal se6tion a @ontrouing device adapted to art upon the conditions of operation of, the carburettors of the engkne and in general upon the supply of fuel to the engine, in a manner which is dependent upon the conditions of operation In which the properer has been placed. Flgures 17 and 18 illustrate resp@ectively a vie* from the left hand erld and a cross section on the line I Bx- 1 8x iii Figure 16. Figure' 19 is a section of an automatic discharge vent employed in the air cotitrol piping. Flgures 20, 21 and 22 illustr-ate a device for obtaining a reciprocal lgcking action between a control for the propeller and the control for the carburettors or for the supply of fuel to ihe engine. i-igures 23 and 24 iuustrate in section along the line, 23x-23.t in Ogure 24 and along the line 24x-24x in Mgure 23, an arrangemlint for regulating the control slide valve. . Mgiire 25 ibustrates diagrammatically a simplifled embodiment of the device for controlling the pitclx of th@-propeller blades. Plgure,26 illustrates a t@@ of propeller according to the invention, pro,@ided with another type of Pawl device, adapw to secure the propeuer in various pitch positions. Figure 27 JJlustrates thE, pr6peUet ac6ording to the invention, constructed iii such a manner as to peMAt firearms to be flred tlirough the propeller shaft. Mgure 28 ibustrates ariother embodiment of the properer. With the propeller according to the present invention it 'is possible to obtain a plu@ality of con. ditions of pitch. Tne various pitch ELrrangementr, are as follows: Three or more fixed propeller pitches and In particular a high pitchla mean pitch and a low pitch, and if desired intermediate pitches between the fixed pitches. Reversal of the pitch combined with the automatic opening of the fuel to the engine wmch driv6s the propeller for the purlbose of exerting

2 2,808 228 a braking of the pinne. This opening is effected in a fixed degree for obtaining the normal braking, or in another fixed degree for obtaining the emergency braking, according to the will of the pilot. 5 I Infinite pitch, so that dur@ng flight with the engine free, the blades of the propeller can be disposed with thelr edge in the direction of the wind caused by flight in order to reduce the resistance offered by the propeller to the forward 10 motion of the aircraft. Before effecting this pitch it Is preferabie to stop the rotation of the propeller caused by the wind of the flight, by means of a reversal of the pitch of the blades. A so-called "Warining-up" pitch, which permits 15 the engine to be warmed up on land before taking off, by preventing the wind of the propeller from cooling the engine. In the embodiment illustrat6d in Mgure 1, the numeral I designates the propeller sbaft which is 20 hollow and is driven by the engine by mefins of a reduction gear formed by a pair of gear wheels indicated diagrammatically at 2, 3. The'shaft I Is supported In the casing 4 of the reduction gear by means of the bearings 5 and 6, while upon the 25 part of the shaft whieh projects from the casing 4 there is mounted the hub 7 upon which the variable pitch propeller blades are mounted, one of - these blades being indicated at B. This assembly is effected ior example by means 50 of a radial pivot 9, rigid with the hub 7 and by means of suitable bearings ID. Each blade Is rigid with 4 collar I I adapted to be adjusted angularly and provided with a centrifugal mass 12 adapted'to balance the c6ntrif35 ugal and aerodynamic actions operating upon the same blade and which tend to modify iti pitch. This collar is controlled as described hereinafter by means of a rod 13 and a cross member 14, by the rod IS of a piston 16 slidably mounted in the 40 hollow shaft I constituting the control cylinder. The outer end of the hollow properer shaft is' . closed by the cover 17 having an annular cavity opening towards its outer face traversed by the rcid 15 of the piston 16 which Is guided by the 45 sleeve'l 7'. Upon the side of the cross member 14 directed towards the.@iead of the shaft f.pawls 18 are Orranged. Each of these pawls is rotatably mounted at 19 by anti-friction means and Is provided with an arm 18' subjedted to the action of rao a compression spring 20 arranged In a cavity of the cross member 14. The main arm of the pawl I 8 is adapted to abut against an annular member 21 arranged in the cavity in the cover 17, or is adapted to penetrate into the annular, cavity 2 I' 55 of the same member according to the conditions of operation as described hereinaftei. This annular member possesses a certain elasticity on account of the provision of cuts f 21 formed therein so as to deaden the impact,4pon the application of the pewls. 60 The rod 15 of the piston. 16 has a should6r 15' adapted to abut against a couar 22 which is rendered moderately elastic by means of cuts 122 lind which is fixed to the cover I 7 and serves to deaden the stopping impact of the rod. The rod 15 is 65 surrounded by the spring 23 which-constitutes the member for returning the biades and which a6ts upon the iiiston 16 by bearing against the cover 17. The piston 16 upon the face which is oppo76, site that upon Which the spring 23 bears is provided with a cavity 16' adapted to engage with clearance upon a fixed annular member 24 so as to form, when the piston 16 returns to the end throttles the flow of the flidd and deadens the stopping motion of the piston I 6 and of the members connected thereto. The piston 16 is proionged by a tubular sude valve 25 provided with ports 26 In proximity to the piston and with parts 27, 28. formed at suitable points near i6 open end. These ports 27, 28 are adapted.to correspond respectively with the holes 29, 30 in a sleeve 31 fixed upon the shaft I and within which the slide valve 25 moves. The sleeve 31 tums with easy friction in a packing support 32 fixed to the casing 4 and in which are form6d grooves $3, 34 which correspond respectivelv with th& holes 29, 30 and to which lead the tubes 35, 36 coming from a control distributor 37 which is adapted to cause the fluid under pressure to act in the desired manner. The extremity of the hollow fixed support 32 Is connected by, means of the tube 38 with a chamber 40 provided with two ports 41, 42 which communicate respectively with a chamber 43 and with a duct 44 leading into the casing 4 and wlilch constitute the seat of the valves 67, 08 described hereinafter. The control distributor 37 receives the fluid under pressiire from a supply pump 43'driven by the engine. In'general engine lubricating oU is utiUsed by drawing it preferably fr6m the duct which delivers it under pressure and'by discharging it, into the casing 4 or into the oil reservqir. A safety valve 47 is arranged In the tube 46 which connects the pump 45 *ith the control distributor 37. This valve is set 9,t a predetermined pressure and discharges the fluid into the casing 4 through -the tube 48.- A tube 49 leads from the tube 46 and communicates diredtly with the chamber 40 and coxisequently with the tube 38 and With the chamber 50 formed by the support 32, while a control valve 51 is inserted in the tube 49 and is actuated in the manner described hereinafter. The tube 49 is connected to thedistributor 37 by means of the tube 52. The chambers 50 and'58 of the cylinder I are connected by means of the tubes 49 and 52 with the distributor 37 by means.of which they can be put into communication with a discharge tube .54 leading into the casing 4 or into the oil reservoir, this being done according to the different combinations either directly, by means of the tiibe 59 or by means of a discharge valve 53 through the tube 56. The tube 49 may also be placed in direct communication with the pump 45 by means of the valve 51 which is normally closed. A stop valve 55 Is arranged in the tube 54 on the dowristream side of the valv& 53 and is con'trolled in. the ma.nner dese.ribed hereiiiafter. Iri combination with the control system described which employs liquid under pressureuse is made of another control s3@stem which employs an au)dliary fluid, in particular compressed air or gas, this second control system being designed for obtaining rapid variations in Pitch under the required conditions of safety. Wheh the iuxiliary fluid is compressed air the system may advantageously be supplied from a tank 60 wliich may be formed by the compressed air tank or other reservoir which is already provided for other purposes on the aircraft. To the tank 60 is connected the chamber 61 the orifices 62, 63 of which constitute the seat for the valires 64 and .65. The tube 66 leads off from the downstream side of its right-hand travel, a Sinuous passage which 75 of the valve 65 and delfvers to the upstream side

2,308,228 3 of the- automatic valve 67 of the chamber 43 while a cylinder 69 is branched on the tube 66, the piston 70 of this cylinder being subjected to the action of a return spring 71 and controlling the stop valve 55 of the discharge duct M. The tube 72 leads away from the downstream side of the valve 64 and'delivers into a small cylinder 13, the piston 74 of which @bontrols the valve 68 against the action of its return spring. The tube 75 also leads from the tube 66 and communicates through a flexible tube 142 with a d6vice 77 which wfll be hereinafter described and which is intended to modify the conditions of openings of the carburettors of the engine or the fuel @umps, while the tube 76 Ieads from the tube 72 and is also connected through the flexible tube 133 to the same device 77. The two tubes 72 and 75 are connected at 78 and 79 to a valve 80 dechar.-ing to the atmosphere and controlled in the manner desdribed hereinafter. Upon the tubes 75 and 76 are branched automatic v6nts 81 of the type illustrated in Fig. 19 and comprising,a ball, 82 arranged with slight clearance in a chamber closed at the upper part by a plug 83 provided with a hole 84 opening to the, atmosphere'. The ball 82 permits any small quantities of air to escape to the atmosphere which under normal conditionsreach the vent on account of leakages through the hole 85 communicating respectively with the tube 75 or 76 so that when a high pressure is set up in the duct 85 the ball is thr6wn against the plug 83 and closes the hole 84 -thus shutting off. the hole 85 and the tube to which it is connected from the atmosphore. The valves 65 and 64 are controlled by means of a rocking lever 86 pivoting at 87 and actuated by means of the lever 88 which is Providled with a member 89 co-operating with the pawl, stop 90 pivoting it 91 and actuated by the spring 57 in order. to separate the three positions which the rooking lever 86 can adopt as described hereinafter. 'The rocking lever 86 is acted upon by, a locking device of known type. comprising as shown in Figs. I' and 20, 21, 22 a quadrant 92 rigid with the rocking lever 86 and provided with a notch 93, a bolt 94 provide ' d with a notch 95, and an Intermediate ball 96. This ball permits the,movement of the cluadrant when the notch 95 in the bolt-94 is sitie@ted opposite to it, and on the contrary-locks the sector when the bolt is moved away from the abov& mentioned position. This same ball permits the movement of the bolt 94 when the notch 93 in the quadrant 92 is situated opposite the ball and prevents this movement when the quadrant 92 is moved away from said position. The bolt 94 is connect6d to the lever 97 which controls the supply of fuel to the engine by means of the rod 98 which also acts upon the arms 99 of the valve 80 which disbharges to the atmosphere. The control of the fuel supply or of the fuel pumps by the lever 97 is effedted by m6ans of the device indicated diagrammatically at 77 in Mg. 1 and described hereinafter with reference to Mgs. 16,'17 and 18, which device permits the levers fOO controlling the supply' of fuel to be acted upon independently of the normal control lever 97 and while the latter is locked. According to the 4zonditidns in which the control member is situated this device permitg the supply of fue.1 to be effected in accoidance with different pre-established conditions a@s described, hereinafter. The actuation of the valve 5 1, the rocking lever 86 and ihe device 77 adapted to act upon the levers I 00 which control the supply of fuel, is preferably effected by means of auxiliary control members fitted upon the lever 101 which controls the aircraft of upon an equivalent member. For this - purpose the valve 51 is controlled against the action of the closing spring 102 bk, the cable 103 which passes over the pulleys; 104, 10@ and is connected to' a lever 106 mounted at 10 the l@ase of the control lever IO 1. In a similar manner the ro eking lever 86 is connected by means of the cable 107 which passes over the pulleys 108 and 1-t5, to the flight lever I IO which is pivotally mounted at I I I upon the 15 control lever IO 1 ; and finally ihe cable - 1 12 which acts upon the device 77 in the mann described hereinafter and which passes' over the pulleys 109 and 105, is conriected t6 a lever 113 placed at the side of the lever I I 0 also pivoting at I I 1. 20 The two levers I I 0, I 1 3 are of different lengths so that it is possible to operate the lever I I 0, which is the longer, without actuating tl-ie other lever wwle by gripping them both near the pivot I I I the two levers I I 0, I 1 3 can be actuated simultaneously by a single opera' ion. The lever I IC is provided with a safety locking device which operates in combination with the device controlling the brakes of the whe6ls of the landing carriage of the aircraft. This lock30 ing device is formed by a pawl 114 pivoted at 115 upon the control rGd and subjected to the action of the piston 116 provided with a return spring 117 and the cylinder 118 which Is connected to a compressed air duct (not shown) 35 which leads to the wheel brakes of the carriage. By means of this arrangement when the brakes 'are'actuated the piston II 6 is raised and the pawl 114, by turnihg in. an anti-clockwise direction aboiit its own pivot I 1 5, disengages the lever I I 0. 40 The control distributor 37 is formed by a multi-! way distributor of suitable type which_permits the various necessary connections to be established at ,@will bet*een the oil supply - (tube 46), the tubes 35 and 36 which lead to the grooves 33 and 45 34, the tubes 59 and 56 which@ by means of the tube 54 return the,oil to the casing 4 or to the reservoir, the first directly and the second through the discharge valve 53, and the tubes 52, 49 which communicate with the chamber 50. The safety valve 47 of the PUMP 45 is set in such a manner as to maintain a pressure slightly greater than that of the air in the tank 60. On the other hand, the discharg6 valve 53 is set for ei pressure which ir, slightly greater than that which it is negessary in the chamber 58 of the c . ylinder in order to maintain the Pollar 15' with certainty in contact with th elastic stop 22, this e pressure being lgwer than that in the tank 60. In the embodiment illustrated the propell@x is adapted to have three normal propelling 60 Pitches (16w, medium and high), zero pitch, inflnite pitch (that is to say, With the median. Plane of the blade located In a plan@e which a@Proximates the axis of rotation of the propeller), an auxiliary low Pitch fGr taking off, and in addition an Inverse pitch op@osite to th@ preceding pitches. This inverse pitch may be employe'd for exerting an.aerodynamic braking action o the n aircraft or for reversitig its motion when movin.g 70 on laiid or. as stated above for warming up the engine ;apidly before taking off, anil EnaUy,for -stopping the rotation 6f the PropHeller due to2'the wind 6aused bY the flight. beforesetting.At to the infinite i3itch. In each of the different proCh in I fl ch 45 pelling pit POS !tiOns and the n nite pit

4 2,308,228 position each propeller blade Is substantially bal. anced about its own pivotal axis by the action of the mass 12. -This wiU be understood from Plgs. 3i 4 and 6 which show the relative positions adopted by the 5 centrifugal mass 12, the blade 8 and the parts of the device which actuate the blades in th@ above mentioned pitch positions, and this will also be, seen in Mg. 12 in which the position of the masses 12 relative to the axis of rotation of 10 the propeller is illustrated. From these figures it will be understood that the action of the centrifugal force developed by the mass 12 upo;i each blade by means of Its lever arm relative to the axis of pivotal movem6nt of 15 the blade compensates substantially the centrifugal force acting on the blade 8 and the aerodynamic stresses@ exerted upon the blade tending to turn the blade about its axis of pivotal movement. 20 It follows that a relatively w6ak action of the .spring 23 or of the fluid acting on the piston 16 will be suffleient to proldude the desired Variations in pitch. In ihe conditioris shown in Fig. 5 (in-, verse pitch) th6se aero-dynamic actions are, on 25 the contrary, not quite compensated and these actions by adding to the action of the spring 23 facilitate the rapid return t6 the propelling piteb positions. In Mg. I the blade Is shown in the high "restlp 30 pitch position which is the position It tends to adopt during flight in the case when the control device is not operative. -The propeller is maintained in this position by the return spring 23 acting upon the piston 16 and by the pawls 18 35 which bear against the elastic member 21 mounted in the cylinder co@er., Under these conditions the control distributor 37 effects a connecti6n between the tube 46 leading from the oil pump 45 and the two tubes 35 and 40 36. The oil thus fllls the chamber 50 and the cavities communicating with the latter and through 38, 40, 49, 52, 37, 59 and 55, and diseba'rged freely at 54 and returns tothe casing 4 or to the oil reservoir. 4r, In order to eff6et the mean pitch position the distributor 37 Is moved into the position for which it establishes a connection between the tubes 46 and 36 while it closes the tubes 35, 52, and 56. The oil then passes through the groove r)o 34, the hole 30 and the port 28 in the hohow slide valve 25, to reach the interior of the latter,'and it leaves the hollow slide valve through the holes 26 so as to act in the chamber 58 of. the cyltnder 1. The piston 16 of this cylinder then moves to55 wards the left against the action of the spring 23 tintil the displacement of the slide valve',25 which throttles the passage th-rough the ports 28 and 30 reaches the Point at which the ofl which passes under pressure exactly compensates for the 60 leakages whicli occur upon the packing rings. of the piston 16 and between the parts of the slide. The flrst of these leakages pass ifito the frolit part of the cylinder and itre discharged into the It this way the device actuating the blades is placed in a,position of eqUilibriUM whieh corresponds to the desired pitch. This position is 11- The excess of oil delivered b the. pump 45 is . y discharged from the distributor 37 through 56 to the discharge valve 53 and to the tube 54. the distrlbutor 37 is placed in 9. cond.itionio establish the connection of the tube 46 with the.tube 35 and with the groove 33 and to operete the closure of 36,.52, and 59. An oi)eration similar to that already described'is theil obtained and the blades reach the position of equirbrium wmeh corresponds to the position of the sude valve in which the passage of the oll uxider pressure between the 6o-opt@rating ports 27 and 29 is thr,ottled to a degree such that the reduced seetion permits a quantity of oil to pass which compensates for leakages (Fig. 8). The excess of oil delivered by the pump isdischarged from the distributor through 56, 53 and 54. By providing In the slide valve 25 and in the sleeve 31 a number of pairs of ports and of cooperating holes such as 27, 29 and 28, 30, and also the relative connections with the supply 46 through the distributor 37, other pitches may be obtained. The pitch may also be reversed with the object of obtairing the wgrming up pitch deflned above by moving the distributor,37 into the position for which it closes the tube 35 and establishes the communication of the tube 46 with the tubes 52, 49 and 38 and ofthe tube 36 by means gf the tube 56 with the discharge valve. 53 through which the excess of oil is discharged.through 54. The "zero" pitch may be obtained starting from the warming up pitch by establishing a direct discharge of oil from the tube 36-@t(i the tube 54. The piston IS and the slide i valve 25 then recoil untfl the free edge 251 of the 6lide valve (Fig. 9) becomes situated approximatply opposite the edge of the hole 30. 'The desired pitch is then established and is maintained by the oil supplied continuously through the tube 38. In order to obtain an infinite pitch, assuming that the pyopeller shaft is at rest and that the pawls I 8 are consequently not subjected to the aetion of centrifugal force,. fluid under pressure may be injected momentarily, into the cylinder so as to separate the pawls 18 from the annular member 2 1. The pawls I 8 under the action of their springs 20 then move towards the axis until they abut against the stop 123 and are thus in a condition to re-enter the annular tecess 211 of the member 21 when the displacement to the right of the piston I 6 under th6 action of the return spring 23 (Mg. 11) has been completed. During the latter part of - the travel 6ffected under the action of the spring'23, the motion is damped as a result ofthe throttling to which the liquid is subjected in@ide of the sinuous passage formed by the bell 24 over which fits, with a certain amount of @lay, the cavity 161 of the piston (Flig. 7, dotted line). A specially adviantageous manner -of bringing the infinite pitch Into operati6n will be herein-. after described. The taking off pitch may be obtained, when the low pitch has Eilready been put In operation, by opening, the valve 51 through -@.he actuation of the lever 106@ 'nie oil und6r pressure then passes, casing 4 throligh the hole 120. The second of 65'through the tubes 46, 49, directly Into the chamt@ese leakages are discharged directly into this . ber 50, thus producing the desired slight discasing. pJAcement to the left of the piston, IS and of the rod 15. After the valve 51 i& closed, the normal pitch is reestabl.4hed as a result of the leakages through which the bil thus -int.,bduced leaves the lustrilted in Flg. 7. 70 cylinder. The conditions of aerodynamic braking of the aeroplitne, which, braking may be of use in cases 6f difecult lafiding and under other conditions Of In order to chazige to the low pitch position 75 flight, are, preferably, obtained with the aid of a

2,808,228 totitrol system oi3orgted by an auxillary fluid, which may be assumed to consist of compressed air, with a view to obtaining an extremely rapid actuation which would not be easy to obtain with the liquid conlrol already described. Instead of 5 compressed air any other fluid pressure may be used provided the particular valve gear that operates the distribution rapidly exhausts the fluid ' into the chamber 58 of the cylinder. To carry out this inanipulation, the handle 88 10 is shifted and moved irito a position to the left of the mean position. The valve S5 is then ,opened and a rapid current of air in the tube 66 causes the valve 67 to open. On reacliing the chambers '50 and 58 the air rapidly moves the 15 piston I 6 to tl@e extreme left so as to produce a reversal of pitch. At'the same time the air acts on the piston 76 of the cylind6r 69 and closes the valve 55 so as to cut off the discharge of oil from the cylinder 1. 20 The closing of the valve 55 causes an increase in pressure of the oil in the system fed by the pump 45 until it reaches the value for wliieh the safety valve 47 has been adjusted or a value that Is Wgher than that of the air supVAy. 25 The rise in oil pressure is transmilted into the, chamber 50 through the tube 35 since the position of the sude valve leaves botii of the ports 29, 30 uncoverea (Flgure 10). The oil then passes into the chamber 30 until the pressure reaches po the adjusted value of the valve 47 with the result that immediately after the injection of air has . been completed the valve 67 again closes. Siinultaneously 'with the operation described, the compressed air passes into the tube 75, closes 35 the automatic vent 8 I in the manner specified and, actuates the device 77 which incteases the feed of fuel necessary to raise the functioning conditions of the engine automatically to the predetermined degree and to ensure rtutomaticauy that 4o .the braking attains the efficiency desir@d. The equipment and arrangements are such that this automatic intensification of the functioning conditlons of the engine is effected during the braking with a sli-.ht lead relatively to the mo- 45 ment in which the blades pass through the "zero" pitch, in such a manner as to obviate@ the propeller being stopped by the flight air-currents when the reversal of the pitch has been attained. effected by means of the handle 88 as already set foith; to facilitatd the manipiilation further, there is provided a secondary colitrol fitted on the control flight lever ID 1 and co;nprising-) the levers I i 0, I I 3. By means of this control, the pilot while actuating the brakes of the carriage wheels in a 55 known manner by means of the button I IO and thus also cutting out even the pawl II 4, operates the lever II 0 aiad causes the aerodynamic braking of the aeroplane.- In aU cases the brake Telesse is effected by 60 means of handle 88, which is thrown over into the right hand position and; the valve 64 then opens ,and the air passes into the cylinder 73 giving rise to the displacement of the pigton 74 and the opening of the valve 68, with the@-result thitt the 65 compressed air, or, generally si3eaking, the atixiliary fluid collected in the axial section of the cylinder, discharges rapidly into the chamber 50 , under the influence of the return spring 23 and 70 the non-compensated aerodyhamic forces exerted on the blades and passes into the casing 4 through the conduit 44. The handle 88 is then restored to its normal position. blade-actuating mechanism in their extreme po-'@ sitions is dampened during the rapid movement of braking and of brake release, by the resilient members 2 i, 22, on which bear respectively the pawls I 8 and the collar 15' of t4e rod i S. The braking mam'pulation described cannot be carried out prematurely, as, for instance, when the bngine Is running at a high speed, owing to the mutual-locking mechanism 92, 96, 94 between the handle 88 and the fuel-feed control. This is so, for the reason that the mechanism just described allows the handle 88 to be manipulated only when the feed control is in its positjon of slow operation or near this.position; furthermore, this same mechanism does not permit the control of the carburettors or equivalent organs, to shift from tWs position so long as the handle 88 is outside of its mean Inoperative position. A further security is offered by the valve 80, which is under the influenee of the carburettor control in the sense that it permits the tubes 72, 75 to discharge into atmosphere wheii the carburettors or equivalent members are in normal working conditions, while it prevents this discharge and reestablishes the communic6tions necessar@, for brakmg wh@n the carburettors are under retarding, conditions. With the air control device des'eribed in the foregoing, the inflnite pitch may also be obt"d, that is to say, the blades may set approximately to the plane passing through the axis of rotation of the propeller. To this end when the propeu-. ing engine has ceased to function, a braking, operation of the nature specifiedis carried out, so as to reduce to a standstill the propeller which, otherwise, @night continue to rotate under the'influence of flight currents, this b@eing done by reversing the pitch and thereafte r effecting the brake-release. As soon as the propeller has stopped and the piston has regained its extreme left position in which the pawls 18 become disengaged from the member 21, these-pawls being no longer subjected to the action of the centrifugal force come together again near the rotation axis of the propeller under the influence of the s' 9 prin @ 20. When the brake j?e lease operation is then carried out, that is, when the cha.mber 50 is put In condition to discharge through the conduit 44, the pawls The manipulation of the brake-system may be so la p6netrate into the recess 21' (Mg. 11) and allow the rod 15'to regain the extreme righi point - in Its travel, its stoppage is damped by the throttling of the current of oil, in the manner already set forth.' The.means intended to establish the fuel feed conditioris necessary for the two degrees of aerodynamic braking may be of any suitable type whatever. As illustrated in the forms of practical c6nstruction shown in Mgs. 16, 17 and 18, the means comprise a cylinder 125, the tubular head 132 of which is c'onnected at 126 to the beu-crank lever 127 (Fig. 1) actuated by means of the rod 128 connected to the handle 07 of the carburettor control. Within thecylinder 125 a piston 130 is arranged to slide against the influence of a spring 129 the hollow rod 131 of which slides witl-Lin the head 132, while its hollow interior communicates through the flexible tube 133 with the tube 76 while the apertiires 134 in the rod 131 establisli communication with the interior of the cylinder 125. The piston 130 is prolonged on the outside of the cylinder. 125 by means of the rod 135, which is connected to th6 levers 100 for the control of the fuel fe d e The stoppage of ihe m6vable meir@rs of the 75 and Is provided with a crbss-piece 136, to wl-Ach

6 2,308,228 are secured two rods 137 parallel tG the cylinder 125 and, in their turn, secured td a couar 138 sliding on the cylinder 125. To the couar., 138 are secured the rods 139 of the two, ,,pistons 140 arranged within the 6y]inders- 141 which are extemally mounted on the cylinder 125 in diametricauy opposite positions and connected to the tube 75 by the flexible tube 142. Upon the cylinder 125 is mounted in a freely rotatable manner a sleeve 143 connected to the cable 112 and provided with a -pair of rods 144 . against which can bear the collar 138, while the latter has also a pair of apertures 138', which allow the rods 144 to pass therethiough when the sleeve 143 that cairries them is In a certain angular position. When the air is pressing within the tube 75- 142 and in the eyhnders 141, the pisthns 140 move to the right, against the action of th@ spring 129, the rods 139, the couar 138 and the rad 135 with piston 130, while the cylinder 125 rezilains motionless since it is secured to the handle 97 which is locked by the system 92, 96, 94. Thus the displacement of the levers 100- is effected in a manner corresponding to the travel 25 .accomplished by the collar 138, which travel in, tum depends on the angular position of the rods 144 and consequently on whether or not, the lever 113 has been manipulated. In the latter case, the collar -138 and the rod 135 are StOPPed 30 as soon as the collar 138 meets the rods 144 while in the former case they are flnauy dispItLced, in consequence of the free passage of the collar 138, over the rods 144, which are in positions opposite the ap6rtures 1381 until the collar 138 35 meets the sleeve 143. Vrhen the conduit 142-75 is put in communication with the exhaust and the compressed air passes into the tubes 76, 133, the rod i35 rapidly resumes its original position 'under the influence 40 of the spring 129 and of the air wl-Ach acts, In cooperation with the spring 129, on the piston 130 of the cylinder 125 thtough 132, 131, ' 4. In Figs. 23 and 24 is shown a system which permits the adjustment of the relative c6nditions 45 of the ports of the slide valve,25 and of the sleeve 31 with which it cooperates and, in consequence, the posiiions which may be imparted to the piston 16 and to the -blades. In this case, the slide valve 25 is provided, tio opposite each of the apertures 29, 30 which communicate with the corresponding feed groove 33, 34, with several ports 27, 27','27", 27111, 28, 281, 2811, 28"1, havink differi@nt lengths measured l.n @ the axial direction and distributed over the periphery of the slide valve. By mounting the slide valve in various angular positi6ns relativ'e to the sleeve 3 1, one or other of the ports 2 7 ... 28 ... may be adjusted so as to coopetate with the apertures 29, 30 of the' sleeve 31. This Is rendered easier by the general arrangement by virtue of which the piston can be drawn -off along with the slide valve 25 of the front part of the propeller'by dismantlin a minimum nuniber of ,9 parts and without it being necessary to disturb the reduction gear that actuates the propeber. In Figs. 12-14 is illustrated a prefeited form of,the connection between each collar I I secured to a propeller blade and the cross-piece 14 Intended to control, thdm. Wilis connection is operated, for each blade, with the aid of the rod 13, which with its guide 150 slides on the lateral slipper-block 151 secured_ on the boss 7 of the propeller and on which it groove 153 so as to withstand the -centrifugal forces. The guide member 150 has a transverse recess 154, In which works a roller 155 Idly mounted on the pin-156 fixed to the collar It by means of the cotter 157. The. exact angular adjustment of the blade 8 relative to the colaar 1 1 may be achieved -with the aid of the device shown in Flg. 15, which comprises.a lever 160 pivoting at 161 on the arm 10 .1 I' of th6 codar and the extremity 1601 of which dngages with precision in the groove 162 of the foot of the blade 8. Two bolts i63, 164 screv@ed into the lateral lugs 16011 of the lever 160, act on a iod 165 fixed- to the arm I I' and pass 15. through a port-hole 1601 in the lever 160. It is obvious that by simultaneously acting on the two bolts 163, 164, the lever 160 may be swung about is pivot 161 and consequently the blade may be angularly displaced relatively, to the colle in which t4e foot of the blade is thus 20 x II$ locked with the aid of the bolt 166 shown in Flg. 2. In Mg. 25 is diagrammq@tically iuustrated a niore simple form of construction of the propeuer described above with the propeller shaft I formIng the cylinder, the piston 16, coiitrols the cros@p@ece 14 that acts on the blades and the distribu-' tion system comprising the shde valve 25, the sleeve 31 and the stationary element 32 constituting the chamber 50. With this form of construction it is possible to obtain, by means of the manipulations already described, the va-rious pitches previously specified with the exception oethe lnflaite pitch. With the propeller descri@ed it is possible to obtain, during flight, a pitch higher than the high normal which is produced when the I)awls I 8 abut against the annul@r member 2 1. This pitch may be of advantage iii the event of prolonged flights at high altitudes. For this purpose, recourse is had to two groups of stop pawls, of the tvpe of the pawls I 8 in Figure 1. The pawls of each grotip have different lengths and are so arraliged that it is ]@ossible, during fught, to cut qut the, longest pawls. . A system of this type is shown in Flgtij@e 26, in which the pawls I 8 correspona to tho8e described above and establishthe high normal.pitch. In a manner siniilar to that of the pawls I 8, the pawls 218 are mounted. The arm Intended to bear on the reSt7member 21 is shorter so. that when the pawls 2-18 are operated to @top the rod 15 and the whold system (if blade control against the action of, the return spring 23, the blades take up a position corresponding to a piieh lilgher than the normal pitch. The pawls 18, whidh correspond to the @high nornial pitch, are, equipped with a device which permits their being cut out'as desired. To this end, there @cts on the' arm 181-, which is influended by the spring 20, a rod 170 actuated by a rocking7@lever 171 pivoted Ett 172 on the crosspiece 14 and controred by a rod 173 that is driven by the piston 174 of a small cylinder 175 mounted (@n the extreniity of the rod 15. When oil -under pressure Is made to pass into the Interior of the cylinder 175 through the tube 177, the rocking lever 171 is mad,e to oscillate and the pawl@ IO are driven Into their Innermost position 55 60 65 7o-and under conditions eriabling them to re-enter, the recess 211. The pawls I 8 thus remain cut out while the shorter pawls 2 i 8 continue to be operative and, as they bear against the member 21, maintain the blades In the -position of the engages, by means of a lug 152, in a longitudinal 75 aiixfliary high pitch.

2,808,228 Inorder to carry out this manipulation, it is, ,of course, necessary to separate the pawls 18 from the member 21 and the propeller is brought Into th6 condition of mean pitch prior to carrying out the manipulation described. With this ob- 5 ject in view, it is preferable that the tube 171', which discharges into the cylinder 175 and wbich is secured to the rod 15 and to the slide valve 25, should commlinicate witl@ the feed of the :ftuid through an aperture 176 of the slide valve 25, 10 whi6h wiU assui4e a position oppositt, the feed aperture when the slide also is in the position of mean pitch. It is, in this case, assumed that the feed of the fluid is derived from a source other than the pump 45 and that ft iscontrolled by the 15 distribut or 37. In order to establish the high pitch for gteat altitudes, the- distributor 37 is then adjusted into the position of mean pitch, the oil under pressure is fed into the cylinder 175 and the distributor 37 20 is thereafter adjusted into the high pitch position. The blades thus take up the position of high pitch fdr great heights, since the stoppage is effected by the shorter pawls which are always subjecte d to the action of the centrifugal force, 25 instead of by the longer ones 18, which have been put out of aqtion in opposition to the centrifugal force by the manner of functioning just described. For the purpose of reverting to the position of 50 high normal pitch, the distributor 37 is restored to the position of mean pitch, with the result that the pawls 18 return to their normal position under the infiuence of tl-ie centrifiigal force. This is possible since the pecwis 18 are no longet sub- 35 jected to the action p.f tht oil in the cylinder 175, since the feed of oil, into this cylinder tak6s place merely for an inst@nt during the manipulation describe d and immediately thereafter, the pressure in the cylinder 175 is relieved ovn'ng to leak- 40 a ges and under the actibn of the spring 170 influencin g the piston 174. The distributor 37 is then adjusted to the position of high pileh lii which the inembers are stopped by the longer pawls IO, which'again abat against the rest-piece 45 .21. In Mg. 27 is . shown a constructional form of the propener described and adapted to permit firing a weapon through the propeller shaft. In thig form of construction, the structural @arrangq- 50 ment and the operation are similar to those already described and the various meinbers are indicated by,the same reference numerals. The rod 15 of the piston and the slide valve 25 are tubular and the members 31 and 32 are so shaped as to r,5 permit the slide valve, without in any degree sacrifici ng the requisite fluid tightness, being elongate d tgwards the rear psA and emerging from the casing towards the mu7,zle of the @ftre@. arm. . T.n the case of propeuers mounted directly on 60 the crank-shaft of the engine or a-Iso on the driven shgft of coaxial teduciion gear, the whole of the propeller shaft passes through tl-ip- stationary sleeve 32 which ensures,,Rutd tightness 6 ri, and with which it cooperates to establish by means of radial apertures, the various communtcations with the'intcrior of the cylinder and with the distribution slide valve 25 that reciprocates within the sleeve 31 mounted In the axial eav'ty 70 of the shaft. The assembly thus constituted gives substanti ally the arrangement iuustrated in Fig. 7 and with the operating conditions previously describe d, are reproduced. The section of the the engine, carries the cranks or is connected With them or else,is connected with the driven member of the coaxial reductidn,geer. In the constructional f orm shown in Fig. 27 the, cylinder is open on the side opposite the boss of the propeller and the dismantling of the internal elements is carried out 'Lrom this side, by removing the cover 180, which is integral'with the sleeve 3 ' I in which slides, in a leakage-proof man@ ner, the slide valve 25. - This cover is secured by a circle of screws i 8 I paranel to the axis of the propeller, screwed into the ring 194, which is threaded, into arL extension of the cyhnder. This form of construction for the cylinder is advantage6us inasmuch as it allows it to be given a diameter greater t ri wo e perm ed the diameter oi the recess by which the propeller boss is incorporated on to the shaft; the manner in which the cover is fixed into the cylinder does not enlarge its outer diameter and renaers it e aster to mount the shaft onto the plain bearings 124, which are particularly preferable in this application by reason of their limited radial size. The collar 182 cooperates with the recess 183 to form a labyrinth intended to deaden -the end of the return stroke of the piston I 6 'under the action of the spring 23. '@he limitation of the left hand stroke of rod 15 for th6 purpose of reversing-the pitch is effected by the couar 158 provided ingide the cylinder as a rest for the piston 16; the collar 159 of this latter cooperates with the collar 158 to form a labyrinth in which the oil that escapes from the piston 16 deadem the shock at the moment Of contilet. In Fig. 28 is illustrated a constructional form of.the propeller in which the displacem6nt of the cross member 94 for obtaining determined auxiliary pitches, such as the infinite pitch is effected by shortening temporarily the length of the piston rod. In this form of construction, th@ tubular shaft I the piston 16, the return spring 23 and. the s 'ii@e valve, 25 are constituted and function as already set forth but the rod 15 is madeiip of t@vo telescoping elements 215 and 216 and maintained by a spring I 85 in the elongated position -in wwch they are locked'by the thrust exerted by. the collar 2161 of the element 216 on the inner gradient 2151 of the other. The element 216 carries the crosspiece 14 to which are seduted the rods coatrolling the blades while 215 is se@. ciired to the piston 16. To the piston 16, and, consequently, to the eleraent 2 1 5 there ig also secured a hollow axial rod 186 whicl-4 at its extremity, carries a piston 187 adjusting itself within a cylinder 118 located at the ektr@mity of the element 216. Between the. piston 187 and the fluid tight packing 189 integral with the element 216 and sliding on the rod 186, Is provided a chamber 190, which communicetes, via the apertures 19 (, and the cavity of the rod ISO, with a tube 192 intended for. t4@ feed of liquid under pressure. When the liquid is idle within thb chamber 190, the two elements 215, 216 occupy the extension l@osition depicted, under the influence of the spring 185. When liquid,under pressure is forod in; this liquid acts, through the tube 192, the hollbw rod 186 and the apertures 19 1, so as t6 set up a pressure within the cylinder I 88 and shifts the eleirient 2 1 6 within the interior of 2 (5 iind over the rod 186, towards the' piston ' 16 in such a way as to produce the displacement of the.propeller blades while the piston 16 teshaft 1, projecting beyond the sleeve 32 towards 75.mains in the position assigned it by its control.

The relative displacement between the two elements 215, 216, may continue until the. corar 216' abuts against the piston 16; under these conditions, the inflnite pitch is obtained. This arrangement may be combined with a .5 system of;pawls acting by centrifugal force and capable of pre-estabmhing another auxiliary pitch such as that for great altitudes. To effect this, there are pivotally mounted at 193 on the - piston 187 the pawls 184 subjected to the in10 fluence of the return spririg 195 and subject to the action of centrifugal force. If the displacement, just described, of the element 216 relatively to 215 takes place while the shaft I is at rest, the pawls 194, under the influence of the spring 195 15 retain, the position indicated in Fig. 28 and allow the element 216 to execute its complete travel relatively to 215.1 if the sha@ft ( is in rotation, the pawls 194 swing outwards under centrifugal force and are 20 brought li@to engagement with the collar on the extremity 196 of the element 216 so as to stop the latter after a certain travel and thus maintain the pawls in the pitch position for high altitudes. 25 With the systein just described It is possible, by means of a hand or self-acting speed governor, to control the admission of fluid through any one of two cooperating ports of the slide valve @o as to effect the necessary throttling and the discharge 50 through the chamber 50i to as to obtain between two extreme propigsion pitches an infinite series of intermediate pitches. . In the foregoing description, it has been assumed that the control means 37-88 are in35 tended for a single engine only but it is obvious that they may act, simultaneously, on several engines. The various control members, indicated diagrammatically by 110, 113, 106, may be of anY 40 ap riate typ6, such as, for instance, electroprop magnetic or pneumatic. I