claiin: 1. A hot-box detector circuit, comprising a heat detector, including heatresponsive means producing an eleetrical. signal in response to incident radiant energv, and 70 adapted to be mounted on one side of a length- of railroad track, optical means ima_aing said heat-responsive means on passing railroad journal bo--es wh.,n so mounted, signal hidicatin- means coupled to the output of said detector, wheelresponsive@ means mounted in said section of track 75 and adapted to produce electrical energy in response to

5 wheels separated by a given car-truck ivheel base, gating means interposed bet,,veen said detector and said indicator, said gating means including a first coincidence circuit comprising a first pair of wheel-trip dev-ces spaced a distance equal to said given wheel base, the respective de- 5 vices comprising serially connected nornially open contacts disposed to control the passage of detector signals to said indicator only apon coincident closure thereof, the respective devices each inclilding means for closing said contacts in response to a wheel passin- thereover, whereby 10 the serially connected contacts are closed s imiiltaneously only Nvhen a car of said @iven wheel base passes over said pair of wheel-trip devices, and a second coincidence circuit comprisin.- a second pair of -viheel-trip devices similar to said fi@-st pair and spaced a distance equal to said given 15 wheel base, adjacent trip devices of said first and second pairs being spaced along the track a predetermined distance related to the field of detection of sa;d detector, the distance bein- such that when a wheel passes over the first of said adjacent devices, the associated bearing is entering 20 the field of detection and when said wheel passes over the second of said adjacent devices, the said bearing is leaving the field of detection, and means responsive to the coinc-ident actuation of both wheel-trip devices of said second pair and in closin.- relation w:ith said gating means, where- 25 by said gating means will be operative to open and close only for the d,,iration of passage past sad detector of a truck- having said given wheel base. 2. A hot-box detector circuit according to claim 1, in Nvhich secotid gating means is connected to be operated in opening and closing directions respectively by the first and 30 second of said adjacent devices, said second gating means -b-,ing effectively connected in series in controlling relation with the out@put of said detector to said sig nal-indicating means. , 3. A hot-box detector circuit, comprising a heat detec- -- tor, including heat-responsive means producing an elec,trical signal in response to incident radiant energy and adapted to be mounted on one side of a length of railroad track, optical means imagining said heat-responsive mear@s 40 on passin.- railrdad journal boxes .vhen so mounted, signal-indicating means coupled to the output of said detector, and including gating means determining the passage or not of a signal from said detector to said s ignal-indicating means, first wheel-responsive means mounted in said 4,5 section of track and adapted to produce an electrical si.nal in response to coincident detection of wheels separated by a given car-truck wheel base, said first wheel-responsive means being located along the track at a location prior to detection by said hep-t detector of heat from either of 50 the journals of the particular car truck, second wheelresponsive means mounted in said s.cti6n of track and adapted to produce an electrical signal in response to coincident detection of wheels separated by said given car-truck -Wneel base and located along the track at a loca- r)5 tion beyond the location at which said detector observes journal heat from said car truck, means operative by said 3,079,497 6 first wheel-responsive means for opening said gatin.- circuit, and op-.rative by said second wheel-responsive means for closin,@ said gati-@ia circuit. 4. A hot--box d.-tector circuit comprising a heat detector including heat-r@- sponsive means producing an electrical signal in response to incident radiant ener.-Y and adapted to be mounted on one side of a length of railroad track, optical means imaging said heat-responsive means on passin-, railroad jour-@ial boxes when so mounted, signal-indicating means coupled to the output of said detector, wheelresponsive n-ieans mo-,inted in sa-'@d section of trac'K and adapted to produce electrical ener,-y in response to wheels separated by a given car-truck wheel base, said wheel-responsive means comprising a first pair of wheeltrip devices separated a distance equal to said -iven wheel base, a second pair of wheel-trip devices sepa'rated a distance equal to said wheel base and separated from the @wheel-trip devices of said first pair, and a -ating circuit interposed between the detector output and. said signalindicating means, the respee-tive wheel-trip devices comprisin@- normally open contacts and means for closing each of said contacts in response to a -,vheel passing thereover, control rr-lechanism including a series connection of the contacts associated with said first pair for opening said gating circuit upo-, coincident closure of said contacts associated with said first pair, said control mechanism fiirther inciliding a series connection of the contacts asso-,iated ivith said seco,@id -pair for closing said -ating circuit upon coincident closure of the contacts associated with said second pair, the spac,n- betiveen said pairs bein- such in relation to the tru' @ ck parts imaged by said optical means as to define a gate-open interval embracing the scan of two journal boxes on one side of one truck, whereby said gating circuit is operated only when a car of said given wheel base passes through said length of track. 5. The circuit of claim 4, and including a second gating circuit between the detector output and said signalindicating means, said second gating circuit being operated by those two adjacent wheel-trip devices whch are intermediate the ends of the succession of wheel-trip devices of said pairs, said second gating circuit including a gateopening connection to one of said adjacent wheel-trip devices and a gate-closing connection to the other of said adjacent wheel-trip devices, whereby signals will be passed to said indicator only upon concurrent operation of said @first and second gating circuits. References Cited in the Me of this patent UNITED STATES PATENTS 2,033,645 ParkhiH ---------------- Mar. 10, 1936 2,138,645 Rey ------ ------------ Nov. 29, 193 8 2,630,043 Kolisch ----------------- Mar. 3, 1953 2,781,477 Jenner ----------------- Feb. 12, 1957 2,818,508 Johanson et al - --------- Dec. 31, 1957 2,856,539 Orthuber et al - --------- Oct. 14, 1958 2,963,575 Pelino et al - ----------- Dec. 61960

S-tates "p 3,079,497 HOT-B-OX DETECTOR GATli-@TG C7-RCUIAI-lareld S. Remz, Westbu.-y, @nd AILert W,@iishir-si@y, Pori', V,Iashir-o@ion, iN.Y., assiguors to Servo CO-7POr@lt-.(n Of America, New LFyde Park, N.Y., a corporation of I'lew %7 Ork Filed Nov. 21,1953, Sey. No. 775,453 5 Cla'@ms. (Ci. 246--469) This inv,-ntion relates to a holbox detector circuit, and more particularly to an arrangem@-nt for detectin.- a-@id indicatin.- the inlensity of h-,aL signals @'rom journal bearin.-s of ra'Llroad cars, of a parti-.ular iviieel base. The type of hot-bo,- dete--tor circuit to which this invention relates comprises ap infra-red radiation detectot moiinted trackside, and positicned to focus an image ol' t'no infra-red cell on the successive jo,,irnal boxes as the train moves by the dete-,Lor. The s;-nais develop@-d by th-- d-.tector correspoid to th-- heat i@itens;ty of the journal boxes. Tjie si-.11als are amplifi,3dand the@i applied to an indicator-alarm circuit. If a hot-box condit;on exists, a s,, al of comparatively high amp!,' ude is developed ..n by the d-.te--tor, which when amplified opere,-,es -an alarm circuit. For a rr-ore detailed d'@scuss@.on of th-- -eneral hot-box detector circuit, reference is made -to copending application Serial No. 747,553, filed June 30, 1958, for Hot-Box 1- @@etector, now Paten'L No. 2,880,309. Hot-box detectors are gener@qily util-lzed to detect heat rad:ia'tions from -joi:irnal bearings o@i freight cars. Most other types of cars, su-.'@i as locomotives and passenger ca.-s, use roller bearings -@,ihi--h -,enerally are not sub:cct to ho@-box faillire. However, roller b-.arin-s operate at cop-siderably higher temperatlres than joumal bearings and o@@easionally c@arse false alarm si.-nals. In add,'@lilon, loc@omotives and passen.-er cars have stray heat soil-rces, such as steam leals in the vicinity of the beari-rigs, so that -,@ihen such heat sources are deteeled, they may also cause false alarm si-nals. Stud;es of car conslruelion, jiheel-base, etc. have revealed that, with the excenl,@oti of @only a srnall pereenta.@e, fr@-ight-car trucks haie a common size wheel-base whicia is different from @he truck wheel-base of otner types of cars, sach as passen,@er cars and locomotives. This iiivention takes advantage cf the d;stinctive freight-car truck )@.@eel-base. Accordin,-Iy, it is an obj--ct of the nve.,ltion to provide a bol-box d.-t--ctor circuit co.-nprising a circuit responsive only to ca@-s of a partic,-llar tru--Ic wheel-b,,lsc, for "passiig" si,-Pals -fxcm the d,-t-,ctor to th@- indicator. it is a fur,her object of this ir@vention to provide a unique -P-ting circuit, which may be adadtcd to existing I installia-..ions, for "passi-a" si,-@--.ials only from cars of a givep- trucl@ wheel-base to a si,-nal indicalor. In @accordance viith on aspect ol' the invention, there is T)rovided a hot-box detector circuit ccmpn'sii:@,- a tracl@@s'i@e--.noun'Led heat d,-tec'cr position,-d to detect heat radiations from railroad car bearings as the car moves o,ier a given sectio:i of track. The heat detector produces s; als wh@ch correspond to the heat radiations. The signals are npplied to a s:@gnal indicating rieans, whereby the relat,'.Ve amD!it,,ides of the si.-nals niay b,- observed for ',,ot-box dbtdction. -Lbe inveition is chara--,terized by n-iounling v,,heel-responsive means, in the _viven section of track, ivhich is adapted to produce e'@ectrical energy in respons@- to wheels se-parated by a given wheel-base. A g,,)tin.- circuit is interposed bet,@,i,-en the detector output ,i-@id the indicator, which is opened by the electrical energy, for passin.- si.-nals to th,-- indicator. The above-mentio-@ied ancl other '_eatures and objects of this invention and the manner of a@taining them will become more appar.-nt a-iid 'Lhe inventi4on itself will be best understood by -Teference to the following descrip32079,497 0 ce pal-ented Feb. 26, 1963 2 tion of an embod-'Ment of the invention talen in conj'unction with th-- accom_Danying drawing, wherein: F.,GURE 1 is a block diagrani of the general arrangement of the novel hot-box dc@tecting circuit in relation to a section of railroad track; and R@'IGUPE 2 is a schematic diagram of a multiple coin'den, c., -e gatin- cirellit utilized in the system iflustrated in FIGURE 1. Referring first ito FIGURE 1, there is illustrated a 10 s,-cLion;c:i' track 1, vrherein the trackside-mounted equipment is installed for detectin.@ hot-boxes. 'n-ic equi-or-ie-.it comprses a pair of detectors 2, 3 mc)unt-.d alongside each of the tracks I and positioned to detect infrared radiations from jourral bearings on the 15 TOlliflg fTCi.-ht s@Lock. The deLeeLors are of @a type described in detail in the abo7,re-mentioned appl-ication. Briefiy, eacli heat detectot comprises a pair of heat sensitive ce'lls connected in a balanced bndge circuit. One of the heat ser.,sitive cp-lls is shielded from extemal radi-a20 t;ons aid is, therefore, at ambient 'temperature. The other cell is exposed to heat radiatioils which are focussed on the cell by a stii+able lens arrangement. Thus, as the rolli-ng stoef, passes by the detectors Z, 3, images of the resp--cti@ie c,-Ils ar-, focussed on the successive joutnal 25 boxes. The heat radiations upset the bridae balance a@.id th.- signal output is proportional to the strength of the received radiations. T',-e detectors 2, 3, also comprise electrically operated shutter mechausms S to block u-iiwanted background Ta30 diatic,@n fre-m the heat s-,nsilive cells, and to prevent dixt patticles a,.qd ottier obscurin@@ matter from collecting on the optic lens in the absence of atrain. Shutters S are opened when the first wheel of a t-ain operates wheeltrip 4, a@id they are held open i'Lor the full passage of the 35 train, as 'W@ll be pointed otit. The Yiheel-trip 4, and each of th-@ other wheel-trip devices to be referred to, comprises preferably a m4gnetic circuit molinted close to the tracl@-. The devicp, is designed to d--Iiver an electrical impulse Nvhen a rail40 road wheel passes over it. A detaiied description of a preferred ,vheel-trip device rqiy be found in copending appli--ation Serial No. 670,220, ffled July 5, 1957, for Railroad Wheel Trip. In order that the effective f-.eld of detection of the 45 detector be limited to the journal boxes, after the shiitter mechanism has bc-en opened, a gating system is provided. The gating sy-.tem com-Drises wheel-trip de,,ic,-s -4 and 5 spaced a predetcrmiled dista@nce apart. The d,@tectors 2, 3 are po,--itioned relative to the Nvheel50 trip devices so that as the foi-vpard wheel of a given truckpasses _n over ivheel@trip 4, assumi g the @train to be moving from left to right, the iirst of the t,,vo associated journal boxes of the -truck is just enten-.ig the field of detection, and when t'@ie same wheel passes over wheel-trip 5, the .55 associated journal boxes are passing out of the field of detec-L'@.on. 'ne wheel-trip devices 4, 5 are conn@-cted to a programmin.- eircll;,t P which a,tuates the shut-ter enown diagrammatically at S. The programming circuit is pre' 60 erably a simple stotage @circuit which prevents piilses after the first pulse from operating the sh-atter me@hanism. The first pulse therefore opens the shutter, and the pulse produced by the last wheel, after a given time delay closes tli-. shutter. The shutter th,,is st@ys open 65 1 th@- complete passag-. of a train. The wheel-trip dev.,ces are also coupled to a gating eireiiit, shown for sirpplicity in FIGUR-E- 1 as a polariz-,d relay 6. The si-enal outputs froni the detectors 2, 3 are respecii-,rely ampli4ied at 7 aild 9, and appl,'@ed over relay con70 tacts 9, 10 and 11, 12 to a signal indicator and alarm circuit 13. T'no contacts 9 and 10 are contacts of the polarlzed relay 6. The contacts IIL ;and 12 are contacts

3 of a Telay circuit shown by block diagram 14 in FIGURE 1, and in detail -in F'IGURE 2. In the conventional detector ci-rcuits, no provision was @n-ade for diseriminatiniz against wheel bases of locomotives and passenger cars, and only whe--I-trip devices 4, wprp provided for controlling the signalling circuit. In other wotds, the earlier. signalhng circuit did. not include contacts 11 and IZ. L:e we assume these contacts lo be qlqs,pd, then it is apparent that the signalling circuit is con,tro.Hed by the g4te circint 6. T@hus, when the first wheel of the train passes over the whc@e@-trip, device 4, a pu@l-se@ is, produced which opens t4e. sh.utter mecha,nisms of, detectors 2 and 3; and which energizes the relay 6 to cl@ose contacts 9 and 10@ T@he signals develop.-d. by: det(@ctors 2 and 3, cortesponding to the heat radiati.ons from.,the respective iournal boxes, ar-e amphfied and,. ii contacts 11 and 12 are also clo-sed, a,re applield 'Lo- the signal.indicator circuit 13.. l@be signal i.ndicator circuit,may, iiielude alarm devices of buth@ the vlisual and audible type, devices for recording the heat signal@:from each 4Df the j,ourn.al boxes, etc.. When the ,same. wiiee-I p,@asses ovet ivheel-trip device 51 a pulse i@ ptoduced. which opens thle contacts 9 and. 10, thereby preventing any further signals from passing. to the signal indicator., IA. F6r each succeeding wheel passage, the trips, 4-5 willi, perform. the, function of transiently , open,ing and closin- the ou@tput circuits supplied by detectoramplifiers, 3-7 iand 2-81 respecti@vely. The hot-box detector circuit as just described (and ;assu,tning unbroken lines in place of contacts 11-12) is conventional, and details of the circuit may be l@arned from. the. above-mentioncd copending applications. 1-n accorda,nce. with tlus: invention, the circuit,,is improved -to disctim-inate against Tailroad cars having- wheel bases different fropl the wheel. base of f-reight, cars., Tp@, acr-,omplish, this dis,crinunation.. two additional -whepl-trip, deyicfs, s,imilar to the, devices 4 and 5, are provided. The additional devices, are. shown,..at 15- and 16.- Tbe- wheelrtrip@ device 15 is. separated, @lrom wh.-eltri p. device.,4 by a chst.ance equal to -the track wheel. bas@, of a, freigig ca@r. Sim arly,, wheel-t@rip device, - 16,is spaced fr<)m wheel-trip, device 5 by the distance,of a truck wheel base of a freight car. In effect, therefc-re, the circuit is provided, witIL' dual gating means;,the gates being cont. nected in series so tha@t a I pair ofpredetermined conditions 'must exist before "heat" signals are applied to the signal, ind-icator. Coincident actuation of the viheel-trip devices 15 and 4 op@epates t-o open a first@,gate-circui@t, whic]4 is closed@ by cdincident acttiation of wheel-trip devices 5-16; and.wheel-triDdevices,, 4. and 5. constitilte, respectively, the opening and closing means for the sec!ond. gate c.irlzuit. The purpose of the wheel-trip device 16@ and its, relationship with wheel-trip. device 5 will be more fully d ' escribcd in. connection wi,th, FIGU ' RE 2. T.lie,contacts 11 and 12 are closed by the relay circuit 14 ionl when the wheel-trip devices:15 and 4 are si-Tnul. y t-aneousl.y.iactu,a'Led, thus cert@fying that,.a truckof d@sired wheel base is present for joumal-heat inspection.. This coincidence detection is schematically suggested in FTGURE. I by@ "AND" circuit conneeting the devices 4, and is. since an "AND" circuit produces a pulse only in resppnse@ to@ --oincident. inputs, no signal will. be app@ed to ihe relay 114 unless both wheel-tnps 4 and@ 15. are energized Simultaneous-ly. An "AND" circuit is also shown connected to, the ,Nvhqe 1-trips 5 and@ 16, suggest-ing that coincident applicatior Of PUISES iS Tequired in order for the "AND" circ,uit to,.deliver a signal to the relay 14. The signal produced by the. first "AND" circuit energizes the relay 14 and Closes the. contacts 11, 12, and the si-gnal produced -by the second "A-NU' circuit results is opening the con-tacts II, 12, thus certifying that t]4e trluck of desired wheel base; has just passed the location of journal-heat inspection. It should. now be apparent@ that the gatin circuits. are 9 3,079,497 4 in the na'Ltire of multiple coincidence gating circuits, which are shonvn schematically in greater detail in FIGURE 2. It will be recalle-d tnat the basic function of the improved circuit is to close contacts 11, 12 in response to coincident operation of the ivheel-trips 4, 15 and to open the contacts in respo-nse to coi-.icident op,-ration of the wheel-trips 5 and 16. The element which perfor@ms this function is relay 14, comprising co-il 17 and contacts 11, 12. 10 The energizing circu-it foT the coil 17 comprises@ a battery 18 connected over the coil, through a transistor 19, to ground. The transistor is normally cut off and, therefore, the energizing circuit is normally open. The control circuit, for thett,,ansistor -19 comprises the battery 18, 15 ia dropping resistor 2.01 nor,mary open wheel-trip contacts 21, 22 and capac,itor 23 t<) ground. The control circuit constitutes a charging circuit fo.r the capacilor 23-. When the capacitor 23 is charged, its voltage is sufficient to cause the transistor 19 to conduct and:thereby close 20 the energizing circwlt for the co-il 17. The capaci@tior dis@ chargp circuit comprises resistor 24, base electrode 25, emitter electrode 26, to ground4. The. control, -circuit a@ shunt-,d to gtound by normally -open contact-s 27 and 23. Tof @ ivhe@-1-t@rip devices 5 and 16, 25 TesPectively. Thus, whenthe whi@@,.Ig of a truck of given wheel base, i.e., the wheels of a freight car truck, pass devices 15 and 4, the contacts; 21 and over wheel-trip 22, are. simul-taneously closed and the charging C-ircuit fiom battery, 18, to capacilor 23 is completed. The posi30 ti@,re voltage onL capacitor 23 causes the transistor to conduct, thereby clbsp',ng the coil energizing circuit. Energization o@,L coil 17 clo-ses the contacts 11 and 12, respectively. At the same tiine, the fo-r-ward' Nvheell having iactuated wheeltrip dev@i.ce 4 closes 4he contacts 9 and 35 @10,, thereby completir@a the circuit fiom th-. detector to the, signal indioal@or. The value of the TeSistor 20 is seli@c' ed sa. that the c,harging time is relativfly sho.-t. The value of the resistor 24 is selected so that the discharge t,irne through 40 this, resi@tor and'.,the base-emitter circuit of thetransistor is suffic@iently long so that the coil 17 remains energized for a- period sufficient to per-mit an entire freight truck -moving at a slb,@v speed to piass from. wheel-trip 4 to wheel-trip S. it will be recalled that the contacts 9 45 and 10 are r-los-.d merel by a wheel passing over the y -wheel-trip devi-.e, 4; contacts 9 and 10 are opened- by Lie N@.rheel passing over wheel-trip 5. The contacts 11, 12 a@re opened by t-he simultaneous operation of w.@eel-trip devices 5 and 16. Operation of 50 the wheel@t-rips 5 and 16 closes,the contacts 27" 2&, thereby short-circuiting the capacitor 23 to ground'. A positive and abrupt discharging ci@rcuit is required in order that.the circtiit ma be prepared for the followin- car. 'Y In@ the absence, of such a circuit, the chaxge on capacitor 55 23 ma-y, be c-arried over to the following car which may be another type - Vi car carrying. spurious heat sources. If desired, the, contacts 11, and 12 may be by-passed to a recordi@.- storage device, e.g., a paper recorder, fQr storing the information transmitted by the detectors. 60 Vvlule the fotegoing de'scription sets forlh the p-rinciples rf, the invention in connection with specific apparatus, it is to be clearly undbrstqod that this description is made only by way @of example and not as a limitation of the scope -of the inventio-n as set forth in the objects thereof 65 a-,id in the accompanying claims. We