claim: 1. The coD.-Lbination of: a piston rod; a, mem'i@;er axiz@lly rilovable on tie rod; and meons co- ll,)6 operatively associa;ed wi-th said mo,- @able member ard p-is'Lon rod, and movable @iiith the rod, ,tdaa'4ed to be actuated by fiaid pressure, to move sa-ICt --rnembor axiaily on I@h,- r@od. 2. The combination of- a piston rod; a nien-i- 1 ber fixed relative to the pisto-,i rod; a, member -axially movable on the rod; aiid means cooperat-ively associated -,vith Said fixc-d member and said axially movable -Tnerilber, and movable witl'l the rod, adqpted to be actuated by fluid pressure, to 115 move said axially riovable member relative to the rod. 3. The con,-bination of: a piston rod; a nut screw-threadedl3@ ricuiiled on the pistor rod; ard m'eai-is co6peratively asso6iated -%vith tne nuL 120 and piston rod and inovabi-, with th,:-@ piston rod, adapted to be actuated by fluid pressure, to rotate the nut. 4. The co-mbinatio-Ti of: a piston rod; a nut screw-threadedly moyw-ted on the pistoii rod; a '-12Z@ n-leirber fixed relative to the pi-ston Tod,, and m6ans cooperatively associat-,d with the nut and fixed member, adapted to be actuated by fluid pressure, to rotate the ntit. 5. The coffo,.nation of: a cylinder,, a p4,ston in 130 the cylinder hgving a piston Tod; a retairirg iaember axial' y Movably engagipg the piston rod, adapted to contact with tlie piston, to liniit axial rnovement of the pisto-71 relative to the rod; and means cooperatively associated wiib- tl-ie retain- 13.5 ing w-ember and pisto,@i rod, adapted to be actueued by fluid pressure I wi'4hi,,i the cylinder, to nao-@e the retainipg'member in a direction of iiicreasingly tighter contact with the piston. 6. The combination of: a cylinder; a piston in the . cyliv-ider having a pi@ton rod; a member f-xed felative to the piston rod; a retaini-yig member axially movably engap.,ing the piston rod, adapted to contact with the piston, to lir-ru'l-, axial movem,,3nt of the piston relative to the red; and means coopera@tively associated -gith tne reta@ining riaember and the i-ixed member, adal@ted to? be actuated by 'Lluid pressure wit'--u'n the cylhlm dor, to , (ve the retaining member in a diree-

1,931,900 tion@ of increasingly tighter contact with the in the cylinder having a@piston rod; a iiut screwpiston. 7. The combi-iiatio,-,i of: a cylinder; a pistoy-i in the cyliiader havi-Tig a pis',@bn rod; a n-Lr.', , screwthreadedly mounted on the rod toi e.,.gage tl.,ie pistor-, to liniit ax;--al -- rjaove@@rient of -@,he pistoii re' a.tive to the rod; and @i,.eans cooperat4 vely associated w-iti@7,. the nui, a.--,id -oisilon red, aiid movable uith the pis'Goii rod, ada-pted to be a-.tuated 1( by fuid presl,,ure -,,,j-i@,hin bhe ---y.Linder, to rotate the nut towards ti@ghte-,ai_ng position. 0 .. The coiiabiiiation of:i @, cyliider; a p@is-ton in the cylinder havi,,ig a - D,@S'Lon rod; a i-netn7oar fixed relative 'Lo the pisto@i .-od; a ni-it screiv15 threadedly mo-Lu-ited oi-i 'L-,he rod to engage the p4@Stoii, to lir(iit ax-ial movei-ii--nt of '-,he p!',s+@o.,-i relative to t.-@o red; nie2,.D-s cocrel-'a'c.--;ve'y ass6ciated v,7itl,,i the fix@ad and nu@, riiovable @T.-'th the rod, adabted to be ,ict'Ua+@-d by 20 fi'aid presslre tt-ie cyl-"rdof, '.o Ioto.c- the nu'@ to-,.vards tighte,,--.',---@,g posi.tion. 9. Thc- combiioti-,--;a of: q- piston rod; a ine-Tliber axially i-r@ovab-'@e o--i the rod;, ard r.,i--aps cooperatively associal ,ed @j,,itli- said movable meai25 ber a,-id pisto-ri rc)d, apd riio-@7qble with tl-ic iod, adapted to '--e actuated by --'iuid pres-sur-1, to@ r-n-cve said member or, the -od, qaid means inc"udiiag a pq,@,vi or@d, ral@chet meci'.,lavism. 10. The comb-iia,-4,ion of: a ois'L-oia rod; a 30 ber fixed relaLti-Ve to th-- -oistort rod; a ir-eiii)or axia-@lly movable on the rod; or@-cl @n-cans cooperatively associated v@ith soid iieriber and said axially movabl-c ar-.d inova..tl',e vpth the rod, adap'bcd to be eetualod by fii,,id 13res35 sure, to mo-@,7e s@.ii--' novable relat, ive to the rod, saicl r.,iegns i-nclud-',,-Ig a pa),v,@ and ratchet rnecharisri. 11. The coir-bl@natioT-i of' a pisto-q rod; a n-Liu screw-threadedily mounted on the piston rod; 40 ap-d meaiis cooperativel@ asso@-ieed with the iiut a,-id pl@'bon rod and wi-th the piston rod, adadted to be actuated by --'tlLiid pressure, to rotate the T-iut, said means inclu""Iing a pawl and ratchet meelianisro_. 45 12. The of-: a piston rod; a nut screw-thread-ldly rn-oLi--!ited,o--a thi-, piston rod; a inember fixed re!-ati-Ve to the pistoii -cd" and niea-D-s cooperativel@y a@-- sociated -,Tli'uh the il-ut and fixed irorL.,iber, adcipted to be. ae'tlua('ed by fluid ,50 pressure, 'co ro4.-,-,@@e -tiie iiut, said -r,,i@@aiis including a pa--.,,.Tl ar-C-1 ratchet ii2c-chanisrii. 13. '-The boi-abiiia@@ion 6f.: a ey'lindc-r; a pis'6,ii - n the cyiinder havil'lg a. piston rod; i, retaid@.ng ri,iember ayially r.-iovably el-"ip,,aZiiig pis'lon rod, 55 odapted to contact with ti-i-e pi@.ton, to mover-nent of 'L,b-e P"@,stoii rela-tive to the rod; and me-a-ns coolierat-1vely associated i@i@ith '.-he retoinir@g naeiiiber ao-d - oifton rod, adopt--d to be actuated by fiuid pres..sare vjith,,ii the cyli,-rider, to 60 move the retniiiing member in a dir,,-@-t--;on of increasing',Iy tighter contact the p- ston, said means iiiel-tidiiig a pawl and -ra@.chet r(ieeliaiiism. 14. The coribinatio--i of: @l- cylinder; a p@is-,,@on i-n -@he cyl,@iider havi-qg a piston -r.,)d; a meniber 65 fixc-d relative to the T,)istc,,-P. ro dl- q-, -cetaining r-qei-4iber axially niovably e.-.ga.-in,,;, c,he Tjiston rod, adapted to conta-t v,@,th the pist-or-, to limit ax-ial movei-D-e,n'u of the pis4@- on r-,'lati@le to the rod; ond r,ieans coo-oeratively associated vvith -Lhe retE)i_n70 ing mereiber and the fixe@a meiriuc.-r, adopted to be actuated by fl@uid press,.ice ,v-"Ithin the cyli,-qder, lbo Paove the re@aini-ng memb.,r i-n o, direction of increasing'-y tilgliter coiatac@ @,7ith the piston, 9-qid . -lu meai,is iil@ -di,,ig a pa@vi- aiid iatchet rnechailisir@. 'I 15. The coriibi-11-at@ioii of: a cyli-nder" a pistoii threadedly mounted on the rod to eiigage thd piston, to limi@u axial movement of the pisl@-oli relative to the rod; and ineans cooperatively assocLated with the nut and pistoii rod, and i-hov- 80 able with tha piston rod, ada-oted +lo 'oe a,;tuated by L9-uicf, pressure within 'che cylinder, to rotaLe the towarr' 's tighl@en-iiig position, said vneans including a pav,71 and ratciiet -meciiarism. 16. The coxr-bination of: a cylinder' a piston 85 iia the cylindet hoving a piston rod; a meraber li,-ed relative t6 the piscon rod; a liut screwthreadedly mou-iated on tiir-, rod tG etigage the pisto-,a, to limit axial Eiovernent of th-, piston relgtive to t-he- -,--od; and means cooperati@Te.Ly @go &6soc@ '@ated wich the -fixed ine-mber and iaut, movable tiie rod, adapted to be ac'Lua'bed by f-luid pressuxe within, the cylinder, to rotate the hut tow2,rds tighte-Tiing position, said -,neans inciuding a pawl and ratchet 95 17. The combinati.on of: a@cy.-inder ad.%pted to coii.Li-fe f@uid under -oressore; a loligit-Lid-inaily reciproc ating pis'Lon rod exlu-ending iziuo the cylinder; a piston head carried by '@he pisl@-On rod i@,i slidi-Tip@ conl@-act with 'Lhe cylinder; a r etainiii.- 100 meriiber -.,r@ovably engagi-ng the pistop- rod to seciire '@-h,-- pi.@ton head +@herecia; and means ac'-,Uated by ilu-'@d-pr6ssure @,vithin the cylip-der '@o, i-iove caio, @,7-otginiiig me-ifzer against the piston head. 18. Th,-3 c6-ibiiibAi n o@: a cyli-@ider ada-,ote@@l 5 0 L 10 to coyifine iluld under p@essure; a lo.,).,-itudinal-y reeiprocati,,,g P'@stoii rod extei,,din.- i-Lito.th,-, cylinder; a piston "-,ead -,arried by the piston rod i-ii slid-Ing coii'Lact w-i'cl,, t-@ie cyli,nder.; a iiut screnv threade dly ,i-c-@agiiig the piston rod aiid s ecurir.,& 110 the pisto-,i head@ thereo-,-i; a,-id alitomatic @teans actuated by the fluid pressure within the c,ylindor luo revolve tb-e -nut to-,vards the piston head. 19. The conibinat-,-on of: a cylinder ad@@pted 'uo confine fl-Liids under pressure; a longi tlidinally 115 reciprocating p-iston rod --xtending into the cylind--r; a piston head carri-ed by the piston rod in -,liding cod-tac@u with the cy'-finder; a iiu,t screwthreadedly enpraging the pisto@-,,i rod to secure the piston head tnereon; a rpe--,-nber iigid',y L-ixed to 120 the p;ston rod adjacent the P-tit; and means interactir@g between fhe nii6 and the fixed @ner@,iber to rotatp- the -niit, said mea-Lis being adapted t.o be actuated by fl-uid pressur-- within the cylinder. 20. The coi-nb-il'latior- o-f: a cyli--ader adapted 125 to confine fiuids up-der pressure; a iongitudinally reciprocating piston rod 6xtendiTip, i-nto the cylinder; a piston head carried by the pisuor@ rod in sliding coiitact v@ith the cylinder' a iiut screwthr . eadedly engagip-g the piston rod and securiiig 130 the piston head th,-r-.on; a meriaber rigidly fixed to 'Lhe pisiop- rod; n paa@l and rachet inechanism adadted to exert rotative stress between the f.xed member at-ld the nut; and rp eails actuated by the fluid presstire within the cylinder adapted to 135 operate the pawl and rachet mechanism. 21. The combination of: a cyli@ider adapted to coni'.@-e f-luids under pressure; a lo.q,aitudinally reciprocating pistbn rod extep-ding into the cyliiide,-; 9, pi-.Qton head carri.ed by t'ne piston rod 140 i-n @lidiT-lg coirtact v7ich t'-Yie cylinder; a nut screwthreadediy engaging the piston rod and securing the piston head thereon; a --,,nember rigidly - :qxed to the piston rod, a second mernber ei-igagi-ng the nut to rotate therewi-th; and fiu-id pressure acl'u145 ated r@i-eans actuo,@@ed by the pressure wi-thin the cyli3ader and ada@ot--d to i-nteract between the two members, whereby the second member rotates the iiu@, o-Ti the piston rod to-wards the -Diston head. 22. The com-binatio,@i of: a cyli,nder adapted 15,0

4 1,931,900 to confine fluids under pressure; a longitudinally reciprocating piston rod extending into the cylinder; a piston head carried by the pisto@n rod in sliding contact with the cylinder; a iiut screwthreadedly engaging the piston rod to secure the piston head thereon; a me-r@iber rigidly -.rixed to the piston rod; a socket memb,,@,r e--,,igaging the nut to rotate therev7ith' a pa,7vl and rachet ;r@echanism adapted to 4nteract bet-@7ieen the iixed mem:10 ber and the socket i-ieriier to rotate the socket member and thereby the iiut; a-via' fl-uid pressi-ire actuated meaiis for ope,. @6ing the pawl and rachet mechanism, such -rneans being adapted '6o be actuated by fiuid pressure within the c:@li@ider. 15 23. The combinatioii of: a, -or.-,,!sure cha-alber confining fluid under fli-ictuating pressure; a, rod extendin,g it-lto the chamber; an onnular rachet fixedly mounued cn the rod; a nut scre-@,v-threadedly enga.-ing the rod in the chamber; a, cyl20 i-nder mounted on the ntit; a piston slidiy-igly mounted in the cylinder ay).d ada,oted to reciprocate in response Lo, pressure fli).ctuations in the chamber; aiad a pa-w! operativelly co-,iiiected to the piston and adapted to engage the arinular rachet, thereby rotatiiag the nut. 24. The combin@qtion of: a cyl@@nder confini--(ig fluid under fluctuating pressures; a lon,-i'@-ud5r,.ally reciprocating piston rod e.@tendiilg ir@'co the cylinder; a piston head carr-led by the p4lston rod ,30 in sliding cot-itact ,vith the cylinder; a iiut scre-%vthreadedly engaging the pi.ston rod to secure the piston head thereon; a srnall cylinder mouited on the nut; a small piston slidingly raounted in the small cylinder and ad@@Dted to recipi:ocale 35 in responqe to pressure fluctuations in the slirrounding fiuid; and a pawl and rache'u m,,ch40. 45, -55 60 65 70 75 anism associated with the piston, rod. that carries the nut and with the small piston, where y the small piston intera-.'Us with the pis on ro . 25. The co.@--bination of: a cylinder confining fi'uid under fliictuating pressures; a, longitudinally 80 reciprocating piston rod extendi-lig into the cylinder; a p4ston head carried by the piston rod in sliding co-,itac'u with the cylinder; ,) nuL screwthreodedly engaging the p-iston rod to s--cuvo the T.)is@on head thereor)-; a rachet fixedly mouiited 85 on the piston rod; 9- sriiall cylinder moudted o,@i '@b-e nut; a snliall piston slidingly --rjn-o-aiited in the sr.,iall cylinder and adapted to rec-lprocatb in response to p-,iessure fluctuations, in the surrounding fluid; and a pav@l operatively connected 90 to the smqll p-'--stor. and posit-loned to e-igage the rachet. 26. The co-,mbiiiation of: a piston rod; a 11-ut screw-threadedly mounted on the piston rod; a p,,.wl-and-rotchel'-, mechay-ii--@-n betwe@-n the nut 95 aiid the piston rod; and means associated with the pawl-a-7-d-ratcliet mecha-Til@sm actuated by fluctuating f uid i)ressure associated with recinrocatioiis of the piston rod, vvhereby rotative s@rp@ss ;s e@,e,,,ted. agaiiist the nut upon each move- 100 ment of the piston rod in one direction. 27. The co-@,iibination of: a piston rod; a nut .crei7j-threadedly mounted on the piston rod; a ro,tchet associated with the piston rod; a pawl@ asso-,-Iated with the nut; and means actueed 1,35 by 'i@uctuati-ii,,- -fluid pressure associated with reciprocations of t'-rie piston rod, Arhe,-eby the panvl is pj:c-ssed i.,ito rotative engagemenl, with the ratchet upon each movement of the piston rod iil olie direction. JOHN W. McQUAID. 115 120 126 130 135 140 145 1

Patented Oct. 24, 1933 1 9 9 3 1 9 0 0 UNITED ST@ATES PATENT, OFFICE 1,931,900 AUTOMATIC LOCK NUT John W. McQuaid, T6rrance, Calif. Application June 6,1931. Serial No. 542,571 27 Claims. My invention relates t6 the piston construction of pumps, engin6s and the like, particularly to means for securing a piston head to a piston rod, and rnore particularly refers to automatic,means for insuring a continuously efficieiit attachment of a removable piston head to a piston rod@ iV.y inveiitioil rday be broadly described as comprising a keeper movably carried by the piston rod to engage the piston head and fluid-pres10 sare-actuated mealls for advancing the keeper on the piston rod in the direction of increasingly ei'Acient engagement with the piston head. The actuating means derives its power from the fluid pressure in the cylinder enclosing the piston head, 15 and is constructed without valves to be automatically operated by variations in that fluid pressure occurring as pulsatioiis with the reciprocation of the piston. The total strain from pressure exerted against 20 the face of the piston is concentrated at the joint between the piston head and the piston rod, and, even in low pressure cylinders, the thrust exerted by the piston head against the piston rod is of relatively great magnitude. . In high pressure 25 cylinders, this thrust may amount to several tons. In single-action cylinders, the thrust is exerted as a relatively rapid pulsating force in one direction, and in double-action cyjinders, the thrust is exerted as a @elatively rapid pulsating 30 force alterp-ating in two directionsl- consequently the piston tends to develop "play" between the piston head and the means securing the piston head to the piston rod, and, because of@ the magnitude of the forces involved, the:wear upqn the 35 parts affected increases tapidly even in the case of the hardest metal- My inveriti6n.provides for ti-htening up the joints between thQ piston head and the piston rod as soon as any play tends to develop, in fact, before any play tends to appear, and since my device is actuated by the internal pressure of the cylinder, the greater such internal pressure, and the 9'reater the thrust of the piston head against the piston rod, the more positive the action of my invention. 45 A feature of my invention is that it niay@be applied to a piston w-ithout requiring any 8ubstential alteration, of the piston parts. In my preferred form, I provide a socket member which .merely slips over an 6rdina-rY, hexagonal nut. The fluid50 pressure-actuated means carried by this socket me,nber @-,eacts against a second nut which is suitably adjusted on, the piston rod and then fixed in its position by a set screw engaging the Piston rod. Because of this simple construction, my inv6ntion may be manufactured as an acces(Cl. 309- 4) sory to be quickly adapted to any pu4ip already installed; but it is within the purview of my invention to modify or s-iinplify,this construction for incorporation in,a pump as produced at the factory. 60 The se and other objects and advantages. of my invention will be clear from the fo owing etailed description, considered with the attached drawing, in whichFig. I is a side elevation of a piston head on a 65 piston rod, the piston head being shown in sectioii; Fig. 2 is an end elevation of Fig. 1; Fig. 3 is an enlarged, end elevation.Gf the socket member carrying the fluid pressure actualted 70 means; Fig. 4 is a side elevation of Fig. 3; and Fig. 5 is a vertical section 6f the. fluid pressure actuated mechanism taken in an outward direction as indicated by the lines .5-5 of Fig. 4 7.5 and. showing, in addition, a portibn of the coacting ratchet. A piston rod 20 carrying a piston head 21, reciprocat es within a cylinder 22 indicated by the dotted, lines in Fig. 1. Inasmuch as 'Lhe piston 80 head may be of any of the well-known types and is not itself a feature of this invention,. it w no be described in detail. The means of attachin.@ the piston head 21 to piston rod 20 consists of two opposed retaiiii@ng men-ibers, one an inner 85 annular shoulder 23, preferably integral with the piston rod, and the other,@an outer adjustable a,@inular member, which may be in the form of a nut 24 screw-threadedly engaging the 01).ter threaded portioii 25 of the piston rod. , These two go annular retaining memvers present opposed beveled surfaces 26.and-27, respectively, which engage opposite ends of axial bore 23 of piston head 21. Mie. outer end 29 of nut 24 is hexagonal in cros@- section. 95 The automatic means for urgi-ng nut 24 ;towards piston head, 21 comprises a fixed annular ratchet 30.and a fluid-pressure-actuated mechanisni 31 cooperatin g with ratchet 30 and engaging nut 29 to rotate therewith. Ratchet 30 is in the f6rm IOU of a; nut screw-threadedly engaging the piston rod and has an outer hexagonal flange 32. When this ratchet member is suitably adjiisted on threaded p6rtion 25 of the pisl@on rod, it is loc d against rotatibn by a set screw 33 erigaging a slot 105 34 cut longitudinally in the thi-eaded 13ortion 25 of the jaiston rod. The fluid-pressure-actuated mechanism proper is housed within a laterally positioned cylip-der 35 overhangin g the petiphery of rdtchet 30 and pre I 10

1,931,900 senting a pawl 36 to cooperate thereviith. CYinder 35 is cai:ried by, and is intearal with, a hexagonal cap 37, which is centrally apertured al@38 to loosely fit over the piston i:od and which embraces nut 24, so that niovements of cylinder 35 laterally with respect to piston rod 20 are transmitted to liut 24 as rotary movement thereof. The construction of the fluid-pressure-actuated mechanism is indicated in Figs. 4 and 5. Cyl-in10 der 35 is closed a, one end, open at the oth(-,r end, having a protrudir-ig lip 39 at its open end to, f acili@ate assembly of its internal mechanism, and has a longitudinal slot 40 through -,vhich palvl 36 @extends to engage teeth of ratchet 30. Within cyl15 inder 35 is a reciprocating plunge-r 41 m,@ldhined from round stock. Pawl 36 is pivo,tally attached to plunger 41 within a deep longitudinal slot 42. Slot 42 has a recess 43 seating a helical expansile spring 44 which serves to4 continuously press pawl 20 36towardsretchet3o. Theiimerend45ofplu-ager 41 is reduced to form aiyjaulat @@houlder 46 and Ls terminally threaded to receive nut 45a. A piston head 47, preferably of rubber, shaped wi-th ,annular flanges 47a extending in both directions 25 longitudinally along the inner wall of cylinder 35, has a tubular nietal core 48 by which it is r,,ioui-ited on plunger 41. The core is provided with sllitable packing rings 49 at each end and is held between nut 45a and shoulder 46. It is clear that 30 the piston head is -niounted to serve as a mi ovableflui,d-tight seal, proof against leakage in either direction. Piston head 47 and the closed end of cylinder 35 deflile a closed compression chaniler 50 which is spanned longitudinally by a helical a5 expensile spripg 51 which engages the end 45 of plunger 41 and seats in a recess 52 in the closed end of the cylinder. ,My invention takes advantage of the facl. that Whether the piston is part of an engine or a PumP 40 there is a rhythmical variation of tl,.e pcessure within cyli,@ider 22. The operation of the fluidpressure-actuated mechanism may be understood by considering plun-@er 41 movable with respect t(> cylinder 35 under eaternal fitiid pressure 45 against piston head 47, or by considering cylindor 35 as being movable with respect to pl-aager 41, the thrust of the cylinder towards the plunger being accounted for by 'uhe pressure on the closed end of the cylinder less the pressure on fhe rim 50 of the open end; or the closed chambe27 50 may be considered as tending to contract and expand under variations in pressure external thereto, thereby causing movement of the cylinder 35 aild the plunger 41 relatively to each bther. In any 5.5 case, it is apparent that fluid pressure cam- es the plunger to: rpove towards the closed e-nd of the cylinder and that this movemz,@nt is o:-)Posed both by spring 51 and by the corhpression of air v,7'-(iieh fills chamber 50, aiid that when external pres6iO sure decreases the interal forces act in a direction to separate the plunger from the cylinder. The forces actina on the moving parcs are transmitted by pavil 35 to the fixed rachet 30, movements of '@he plunger and the piston rela.65 tive to each other caus-ing the pavil to in, pi:qge against a Yachet tooth. The effect of th-. pp",v impiriong against the tooth is to cause the fl pressure-act,,iated rne,- '@iar-ism to interaci@tweeli nut 24 and rachet 30; aiid since the ra 70 is -fixed against rotation, pressi:.re exer4-ed by a-,,vl 36 against the ratchet tooth is conveyed to nllt 24 as a force tending to rotate nut 24 iii@to ti.-hter engagement with piston head 21. @xlhen pressure against rachet 30 is withdrawn, ii,,it 2-i does not ,.5 retreat from any advance it has made because the force transmitted by piston head 21 is exerted across the thread of 'che nuL,. Consequently, as plunger 41 and the closed end of cylinder 35 move further apart, the lower end of pa-@vl 36 is dragged up the outer surface of a tooth, -Lnd, if moved 8C, far enough, will engage the rachet at a new point when the plunger and the clrsed end of the cylinder again move towards each other. A great nuraber of successivp rec-IP,:ocations of the pawl -@vill ordinarily be on the surface of one &I tooth, the range of movemen'Ll gradually extending up the tootla until the rachet drops into a ne-vv notch. Pawl 36 impinges upon the ouf-er end of notch 40 to limi'u the outward movemel'it of th-P plunger, and before the plu-nger may be with- 1)0 drawn from cylinder 35, it is ne--essary to press the pawl inward to clear the cylinder wall. In assembling the form of my invention shown in the drawing, it iv, necessary to retract pawl 36 u,@itil rachet 30 is adjusted adjacent socket member 37. The preferred form of my inveiition, deser-ibed for the puxpose of illustration and coriiple@@e disclosure, sLigges'Us a wide range of @nodificatiolis in structure and forrn. I reserve the right to 1,00 all such modifications that pro-oerly come @withi-Ti the@ scop@- of th-- claims appended hereto. Having described i-ry invent@ion, I