US2652784A - Drop pit apparatus - Google Patents

Description

Sept. 22, 1953 Filed Jan. 14. 1950 L. D. HOLMES ET AL DROP PIT APPARATUS 5 Sheets-Sheet l INVENTOR. LOUIS DHolmes &

Roberf 8. Hammond W7 ATTORNEY Sept. 22, 1953 Filed Jan. 14, 1950 l D. HOLMES ET AL,

DROP PIT APPARATUS 5 Sheets-Sheet 2 INVENTOR. Louis D. Holmes &

Ro'ber! $.H0mmond Sept. 22, 1953 Filed Jan. 14, 1950 l... D. HOLMES ET AL DROP PIT APPARATUS 5 Sheets-Sheet 3 INVENTOR.

Louis D. Holmes 81 Robert S. Hammond ATTORNEY P W I Sept. 22, 1953 D. HOLMES ET AL 2,652,784

DROP PIT APPARATUS Filed Jan. 14, 1950 5 Sheets-Sheet 4 JNVENTOR. Louis D. Holmes a BY Robert 8. Hammond F 8 ATTORNEY I 23w il 5 Sept. 22, 1953 Filed Jan. 14, 1950 5 Sheets-Sheet 5 H 1| W" "m l I "In W l 43 13 24 T '1' ll "W I! W L DJI'Y'VEINTOR. a ouls mes F l G- 7 BY Robert 5. Hammond ATTOR N Y Patented Sept. 22, 1953 "I TED S E NT iiO FiFlC E "DROP PIT APPARATUS 1Lom's D.-.Ho1mes;"B1ue Islandgeandsltohert SrHammolidi'winnetka; 111.; assignors to Whiting Cor- ?poration; a;- corporation of Illinois Application-January 14, 1950;"Serial No. 138;!378

9;.Glm'ms.

-;Qnr inventiomisflireeted to pimp. :table: appa- ,.'ratus,r.partioularlyzof thetype employed inapit extending transverselyvbeneathla series. ofc-r'alilroad tracks and utilized'f'or raising ancl' -lowering tops which bridge the pit.

ZDrop xtableiinstallationsx areuwid'ely employed :in; rai1road::shops wherecit is frequently necesrsary:to-exchanige'trueks, axle assemb1ies,-or= the :like railway 'svehioles. .tThese installations usually include: onewor more. service traokaexi-tending laterallyavzithrespect to a transverse pit and1bridged.zbya'suitable. service tra'clrfltops: re- :rleasably anchored'ittos'the--pit walls. In instances of: .this' type; arzdrop table is mountedfor movement upon-:railsextending longitudinally along tthapit'bottomand issprovidedwith a lifting platf'iOEIXlIJIIIOVZtblB upwardly into engagement with 'nthevvarions'stopsispanningtherpit. When a :vehieleistto;beservricemeas:by removaliofsa truck,

ritzisrmovedialonga the servieetrackrails until the tnunkito ;be::removedx:is-; disposedxon the service rtraokutop. The :dropztable apparatus is then :usuallyi;bronghtiintoxeposition belowzthe ztop; the

topudisengagedzl romzthe pit'awalls, and the top and vehicle raised-slightly byi therdrop table; apz.-.paratus,- =whioh permits engagement :of .the body of the vehiclezby suitable :body:supportsfdisposed ::near thertop. The table: .andztop-rarel: then 10W- :eredgso thatthe truck orwwheelwassembly can-be ridisengaged sandesubsequentlyeloweredawhile. in :po'sitionaonthe top into the pit by thEldI'Op table. :The. tables. is'zthenemoved laterally along: the: pit aan'dysubsequeri tlytelevatednuntilta the rails .on'. the atop tare alignment/with: the: rails of; a suitable release track or storage pit on to which the wheels C01. tru'cksiare to be discharged. r si-m ilar usage is :made 50f the ;.apparatus. 01,10,ther.2punp0seS, S1ICh :iasrrepa-inon replacement ofzspringsaoroither run- .nning *g'earlassociated; .With the; vehicle.

5 considerable'lperiodrof time.

A third expedient sometimes employediistto "hinge therelease track' top at one end soethat its oppos'lte-endemay be:raisedewithssuitahlemoisv ing equipment. Whi le zt'hisipermits: elevation of 0 ma service tra'okltoprto theialevetofithe' releaseltraek rails, travel is: blo'okedzvmznne'rdireetion onzthe release track and .alltmaterial"fonmerlyirdisposed aoniithe: release traemtop mustnbetremoved sp rior ntoura-ising! the top. l Fztil-urez-ofiropesandzlhoisting 1 equipment: makes such an woperation.hazardous to the workmen anot'in addition.consumeseappreoiable time.

"In other installations, four'heavy rposts are I manually plaoecl suitableso'ckets idisposedzon I the liftingplatform or thee-r01 table? impo "to engage' the'prider side of the rel-ease'etraoktop.

the platform is 'raised: 'earrying with it the service track top; the release 'traek-top iscarried v upwardly on the osts-thuspermitting the1service'track'top-to reach release traeklevel. 'I'I hese "posts -must,i'-however,i be remove'clfi from the drop table before the release track top ean loe lowered F below release traelc level -or before the clrop table --*oarilbe movecld'ongitudinally aiong'rlthespit. flit is L10 th'erefore: necessary to repeatthe operation frequently. l Several-workmen areof 'course required =to perform this: operation, Whieh *eonsumesi considerable time and ispeooming increasingly more dihloult -as' the size and weight of table tops ing5 crease. F'urthermore; the posts, =whioh are usually' earried- -on the-"drop table-apparatus may interfere with *the *movement' of --tru'oks= or= axle assemblies on to and off of the table.

'Gne-Of 'the 'most important objects of our iniiihelpasty; cmlsidelalble y s been to vention is to overcome"the above-men'tiond and other'disadvantages-'ofprior art devices through the provision of a. drop" table installation Which Will automatically elevate 1 a "release traek top when the lifting* platform of 'the cl-rop table is raised from 'below the release'traok top.

Another primary objeot of our invention is e to provide a drop table installation in -xv-hich the upward movement of the lifti-ng platform of a -droptable beneath the release track topyiill-"elevate the top onlywhena' service track topisucan- -=ried on the lifting platform.

Otherimportant objects inblu'de the provision -'of a drop table apparatus-which requires'only a relatively shallow pit, whiizh-mayabe'operated :by

i thepit by an overhead crane; thuspermitting single workman-located eitherat arr-emote point or at the table, and which inherently prevents the unintentional nesting of tops upon the lifting platform of the drop table.

Further objects of our invention, as well as the details of construction or our preferred embodiment and its many advantages, will be disclosed in the following description of our invention and the appended drawings, in which;

Fig. l is a diagrammatic plan view of a typical drop table installation;

Fig. 2 is a diagrammatic elevation of the arrangement shown in Fig. 1;

Fig. 3 is a diagrammatic partial elevation of a drop table in position below a release track p;

Fig. 4 is a partial diagrammatic elevation of a drop table operating without a top on a lifting platform;

Fig. 5 is a partial cross section through one of our vertical posts;

Fig. 6 is a partial diagrammatic elevation of our device in operation with a top in position on a lifting platform;

Fig. 7 is a partial diagrammatic elevation showing our apparatus as illustrated in Fig. 6 in a partially raised position; and

Fig. 8 is a partial diagrammatic elevation illustrating the position of our device with a release track top in position on the lifting platform.

Briefly, we accomplish the objects of our invention by providing four upright posts mounted for vertical reciprocation in the pit walls below the release track top. Means are provided for connecting the release track top to the posts, either permanently or releasably as required by circumstances. Our drop table includes a lifting platform carrying four laterally projecting stirrups spaced apart a distance equal to the spacing of the posts, whereby the stirrups can be aligned by movement of the drop. table with laterally projecting lugs secured to the lower portions of the posts. Thus the drop table may be racked into position below the release track top and as the platform is raised the stirrups will engage the lugs on the posts, thus causing the posts to move upwardly carrying the release track top.

In some installations, particularly where remote control is to be employed, we provide means for preventing accidental nesting of the release track top on a service track top. This apparatus includes a lever arrangement carried by the platform and including an arm which actuates a lower limit switch, the latter being utilized to limit the downward movement of the lifting platform. If a service track top is in position on the lifting platform, the lever mechanism is actuated to raise the switch-engaging arm of the mechanism, thus permitting the platform to travel downwardly a greater distance than would be permitted if the lever were in unactuated position. When the lifting platform is permitted to fall to this position, the stirrups will be at a level below the lugs on the posts, whereby upward movement of the platform will elevate both the posts and the release track top. If, however, the service track top is not in position on the lifting platform, the switch-actuating arm of the lever system will be in a depressed position and therefore actuate the low level limit switch to stop the platform at an intermediate position wherein the stirrups on the lifting platform are above the level of the lugs on the posts. Elevation of the platform under such conditions will not actuate the posts and will permit the lifting platform to engage the release tracl; top, which may thereafter be lowered on the platform.

Automatic operation from a remote point is attained by suitably positioning limit switches which fix the position of the drop table on the track, and which limit upward and downward movement of the drop table lifting platform. When thus installed it is not necessary to assign one or more workmen to duty in the thus effecting a substantial saving in labor. In addition, speed of operation is substantially increased over that possible by manual operation, and the number of mistakes occurring is substantially reduced, since improper operation is made virtually impossible.

In Figs. 1 and 2 we have illustrated a typical drop table installation, wherein a plurality of service tracks in extend over a drop table pit H, the gap being bridged by service track tops l2 releasably held in position by engagement with the pit wall. Pit I extends transversely beneath the level of the tracks it and includes longitudinal walls i3 normally of concrete. P ils it extend along the bottom of the pit i l carry a drop table, generally designated 95. Preferably, body sup-port members II are mounted at floor level near the service tracks ill and are utilized to support the body of a railway vehicle while the trucks or axle assemblies are being lowered on one of the service tracks top 12. A release track !8 also extends across the pit H, being bridged by a release track top l9. Frequently a tunnel 2i is formed below the release track and opens into the pit ii, serving as storage for re conditioned truck and axle assemblies.

The drop table It is basically conventional in design and includes a frame 22 to which rail wheels 23 are journaled. The frame 22 also carries four upwardly extending screw members 24 suitably interconnected by gears, and driven by a reversible motor 25 for raising and lowering a lifting platform 2?, which engages the threads on the screws 24. The lifting platform 2! usually consists of beams 28 secured together to form a square or rectangular outline, and of such length and width to receive and support the release track top l9, and the service track tops I 2.

The service track tops l2 are usually of greater depth than the release track top is. For convenience we therefore provide legs 29 extending downwardly from the bottom of the release track in registry with the beams 28 a distance sufiicient to make the overall depth of the release track [9 equal to the overall depth of the service track tops l2.

In the longitudinal walls [3 of the pit H, immediately below the release track I3, we provide four channel-shaped, upwardly extending members SI, in which we mount a plurality of rollers 32 carried by opposed shafts 33 secured to the members 3!. Posts 34, preferably in the form of H or I-beams, are fitted within the channelshaped member in such manner as to be supported for sliding vertical movement by the rollers 32 and by engagement with the inner walls of the member 3 i. If desired, bearing blocks 3% may be secured to one or more of the faces of the posts 34 for engagement with the members 3i. One of the surfaces of the posts 34 is approximately flush with the surface of the longitudinal walls l3.

Lugs 31 are fixed to the lower portions of the posts 34 and project outwardly into the pit at a predetermined level above the rails 14. Lips 3e are formed on the upper portions of the posts 34 for engagement with retractable bars 4| reeciproca-lly mounted zontthei release trackztop l9 i"be*TpBITmll'/lid tQil-QWEI ;or'rlyitoitsaintermedi'ate and actuated by rods 42. Stirrups 4:3;areerfixed epos'ition .in;which..the; level;of:therstirrups: 43* is 3110 the 'ilirtingtplatformsz'l ofithetdropa-table l6 :la' bovextherlevelsofilihe lugs;l3l., .Upvvard movesarrdtrpnojecuJateraillyzbeyond:therliftingw platform ment of the lifting platform beneath ztherelease :towardsthellcingitudinalawva'lls t3tof2the5pitg5be- 5 itraclntop 29:;maythereforebeaccomplishedwithling: spacedrsapartva xdistancecequal to. the longiout-movement of. theposts and the lifting platitirdinalLdistancerbetweentthezzposts :34 ;lin;such "form broughtf intoengagement withathe :release :manner:lthatttheyzzmayirbe-vertically alignedifor top 59. iUnintentional nesting of xthe :release .zeirgagem'ent :with .the lugs 13-! \bylimovementj of tUaCki'llOp OnL the service "track: top .155 thus- Y-ren- Ether dropl'table lSi-alongtth tracks M. 'tdered virtually: impossible, and r the: necessity of ThEidEOPi table 2 i6 .is :provided withsan supper mai u y nl cin r vy POStSlin position t e :limit switchiddzirrthepatheofithelifting platform :zliiting platform is-eliminated. ;:2.1';-for;:1imiting upward;'fmovementandga lower As previously indicated, i, there are: manyiin- 11 13; t m jh lattgr being;.disp0sed;;ln..l3h stallationswvhere nit-is :ldesired to alsoraise the .pathztofztancarmz41;:of anb'ell crank lever'5.0;piv- 15 traektopi NYWIIBII :p iof the ojyaflyr mqunted ggn theflifting platform 21, A :CiI Qp table ii isuactuatedfrom position beneath vweightzfizi ay :be esecure'drto .the arm z41,:the thereleasettrack'top, regardless of whetherzor gmovement; fi i hyi jlitflitedflbyjstops 49, The 15131011 thererisraservice track top imposition on the :zotherzarmM-S :of thecbell crankzEOrnormally prop m il. iUnder such circum'stancesa itlisob- :jeets laterally.upwardlyiabove;the uppensurface 2 *Vi0us'that. the "bell; crank: leverfEO may :be .elimif t JQ f th p1gtform; 2'l; landis deiznatedmndentheccorrventionalistopmemberrpro- @pressed-;byfingagementwithVa stop g -.-v-. t ,vided for actuationiof the low level. limit-switch 'itop:;-isi-irL-. osi'tion on.the .rplatform 21. =Wherr so 516. The;stopr:m.ember will:.0f course beadjusted cdepressed the endriof thesarm-ufltisvraised,lthus 130181101? dOll/nWardiImm/ementthe platform??? pemittingthe platform- 2"- t t downwardly -:and at-apointwherethelevel' of thestirrupslllii zlaetgreaterizdistanoebefore the end: of the'arm 4'! the platform 27 s be10w=:the.ievel ofithelu s t t v g lm t t -.45 w in this; J31 onthe posts-3'2. It is also possible. under such asitinmutheslevela ofzllthe-stirnups43 carried-by the m ncesto; pe m n ly secure thezrelease .aliiting platfonmrzlrzisibelow'the-levelror the lugs ek posts, althou h this is seldom desirable. 5:3"! :onithapostsrfl l;ewithrthe result that the drop 3,0 -n mplianee with R. S. 4888, werhave ide- -1 ;p1 t get engage t u --not"\v-ish to limit ourselves specifically totthe, form maaiwith m q aj ca usingvthe t gq to =herein descr1bed-except in so far as definedtitby upwardly. Since the releasettrack top lflris-supappel'ldedi Claims- :rportedtbyzthecposts i3tlathruughr'the bars 4|, it fl :lma'yibe'seenithattherreleasetrack top will :be car- 1 "Apparatus i017use"il'l'connefitioniwithla p ilfid'lllpwa'llfilyilby? thei posts; permittingrthetservi :pltwf: t hav g .an-eloneatedpit extending ceitrackztopt2-. to:ber-raised toitheslevel .of the 40=-- r n verse1y ':beneath a plurality of railway r lea tra' klig, itraeksz land v bridg d by a servicev track atop and Whenthereisrno service traekl'top onltheslift- 'fl'eleaselmck 0D vertica'lly for-use' in :matform Hit-the weightymjforces the-arm, vservioing railway avehicle trucks and. the like 'iupwardlyihus lowering.thezfreaendrof thearm i p sl' ig a drop table having'a-frame movable it. When: irr*such-:position,;the limitzswitch 46 ng-rails:.onathe:bottomofxxthe'p tmafi fi willtbes-actuatd: to .=stop: .the lifting. platform;- 2'! oplfli'iform iilhe me, power means on the zatsana'intermediatei level somewhat-above'the low fi engaging gj'p t orm forrdriving i -level previously! described; thelifting plat- 'l downbetween a111711131391" :form filmisiin its.intermediatecposition;ltheustir- 1911 a d a-l0wer position, upright p t d srrupsi43oaretdisposedeatadevelabove the level. of 50 1 in p f release' tracki'top ztherlugsiltl. L'IlhfliidIGPjlifliblBf l6.may therefore andzengageab th t lifting Ithe p, :betmovedjnto position :below .therelease track G l Y-Suppo ting the posts for ii-too" i 9;-

platform Z'Irraisdewithoutmoxreiinovement'llpivlafdly and d wnwardly, anclyspaced iml'lll bf ullhe116517534. xTheslegssZflEon the-:release -QPl r d thfl liftingvplatform 't gk enggg ithegplatform521 bhu pgrmitting ;:and projecting laterally therefrom towardsrthe *1 the release: track: top i he toi-"beedis n a 1 \postsl forengagement therewith as the lifting tthe posts;il lnloy actuationcofithe;loekingzbars 'fl raisedirom lower p ition--136- loweredzmththe;'liftingrplatform. 'Theiarm at ck pwgzthowever, 'willnotr-bezaotuated; sincethasposts Apparaws e v C ctwn W th adrop 29;i1o1d the:body ofitheirelease track-top, i9.v in cot-t f a tim v n an e dp extending 3113elevatedfposifiOn"WhBre: it can"nottengage;the Ltransverselyebeneath a plurality of railway tracks and bridged by aservioe track top and release iarm w.

{Fl-011113113 foregoing it may 1 t h tracktop'inovable' vertically for use in servicing s-everaa serviceztraek topz'isrcarried by the'tliifting w y v trucks and l p i n a :platform, the..arm- Mewill -be -:actuated :inw such-'-65"drop"tab=le'having'a frame m bl along-r3115 rmanneras t0.:-permit theL-lifting platform to. drop "'OIT'lihG"bOlltOlllOf' the pit, a liftingplatform on ;taritsrlowest'position. When :irr this position the the"'frame,-power means on th frame engaging devel.OfHtheTstirrupsH-M is; below; .-the;=1evel of the the' ting platformfor driving the platform up alugslil'l: on the :posts34,-- With theresultthatany and dowribetweenan upper position andaiower upward movement of the lifting platform z 2'li7o 'xpo'sition, upright :po'sts disposed in the pit be- --when:-itisr-below: the 'release track top l9 W fifiiillfiherelfiasetrack p de eageable there- -zcause the-posts:-34--and the release tra'ekltop l9 "W lihIiOl; lifting: thetop,11rneans for" r i u ?=to:. ber1ifited with 1 the lifting platform. v'If,f=.in saupporting thezposts, an inward iplojecting 1 :uether iwords lthe lifting platform 21 :doesanot xecl,Ltoqthexlower-portion: ofieach of the posts 1 earryla: servicetrackrtop, the liftingvplatformmilli 7521811016 a: plura y u w y p s cti e I stirrups fixed to the lifting platform and disposed thereon for registry beneath said lugs when the lifting platform is in its lower position below the release track top.

3. Apparatus for use in connection with a drop pit of the type having an elongated pit extending transversely beneath a plurality of railway tracks and bridged by a service track top and a release track top movable vertically for use in servicing railway vehicle trucks and the like comprising a drop table having a frame movable along rails on the bottom of the pit, a lifting platform on the frame, power means on the frame engaging the lifting platform for driving the platform up and down between an upper and lower position, spaced upright posts in the pit beneath the release track top, means for detachably securing the release track top to the upper portions of the posts, supports fixed to the pit wall and slidably engaging the posts, an inwardly projecting lug fixed to the lower portion of each of the posts and a plurality of outwardly projecting stirrups fixed to the lifting platform and disposed for registry beneath said lugs when the lifting platform is in its lower position below the release track top.

l. Apparatus for use in connection with a drop pit of the type having an elongated pit extending transversely benath a plurality of railroad tracks and bridged by a service track top and a release track top movable vertically for use in servicing railway vehicle trucks and the like comprising a drop table having a frame movable along rails on the bottom of the pit, a lifting platform on the frame, power means on the fram engaging the lifting platform for driving the platform up and down between an upper, an intermediate and a lower position, upright posts disposed in the pit beneath the release track top and engageable therewith for lifting the top, means for reciprocally supporting the posts, and members secured to the lifting platform for lifting engagement with said posts, said members being so disposed and arranged as to prevent engagement with the posts except when the lifting platform is beneath the release track top and in its lower position.

5. Apparatus for use in connection with a drop pit of the type having an elongated pit extending transversely beneath a plurality of railway tracks and bridged by a service track top and a release track top movable vertically for use in servicing railway vehicle trucks and the like comprising a drop table having a fram movable along rails on the bottom of the pit, a lifting platform on the frame, power means on the frame engaging the lifting platform for driving the platform up and down between an upper and lower position, a limit switch for stopping downward movement of the table, a lever on the lifting platform having an arm in the path of the limit switch and movable from a first position to a second position only by a, service track top on the platfrom, thereby positioning th platform in an intermediate position in the absence of a service track top and in its lower position when the service track top is carried by the platform, a plurality of upright posts supported below the release track top for lifting engagement therewith, each of said posts having an inwardly projecting lug near the lower end and a plurality of outwardly projecting stirrups fixed to the lifting platform for lifting engagement with the lugs only when the platform is raised from said lower position beneath the release track top.

6. Apparatus for use in connection with a drop pit of the type having an elongated pit extending transversely beneath a plurality of railway tracks and bridged by a service track top and a release track top movable vertically for use in servicing railway vehicle trucks and the like comprising a drop table having a frame movable along rails on the bottom of the pit, a lifting platform on the frame, power means on the frame engaging the lifting platform for driving the platform up and down between an upper and lower position, a plurality of upright supports in the pit walls below the release track top, a post slidably mounted in each of the supports, means for detachably fastening the release track top on the posts, an inwardly projecting lug fixed to the lower portion of each of the posts, outwardly projecting stirrups fixed to the lifting platform and spaced for vertical registry with said lugs when the platform is positioned below the release track top, a low limit switch on the frame and a lever mechanism on the platform for actuating the limit switch and thereby restricting downward movement of the platform to an intermediate level or to said lower level of the platform, said levels being selected to dispose th stirrups above the lugs when the platform is at its intermediate level and below the lugs when the platform is at its lowest position, the lever mechanism being normally in position to permit movement of the platform to said intermediate position, said lever being moveable from such position by engagement of a service track top only on the platform.

i. Apparatus for use in connection with a drop pit of the type having an elongated pit extending transversely beneath a plurality of railway tracks and bridged by a service track top and a release track top movable vertically for use in servicing railway vehicle trucks and the like comprising a drop table having a frame movable along rails on the bottom of the pit, a lifting platform on the frame, power means on the frame and engaging the lifting platform for driving the platform up and down between an upper and lower position, a plurailty of hollow upright supports in the pit walls below the release track top, a post slidably mounted in each of the supports, means for detachably fastening the release track top on the posts, an inwardly projecting lug fixed to the lower portion of each of the posts, outwardly projecting stirrups fixed to the lifting platform and spaced for vertical registry with said lugs when the platform is positioned below the release track top, a low limit switch on the frame and a lever mechanism on the platform for actuating the limit switch and thereby restricting downward movement of the platform at an intermediate level or at the lower level of said platform, said lever mechanism including a first arm pivotally secured to the platform and movable between two positions, both of said positions being in the path of the limit switch, and a second arm connected to the first arm and projecting upwardly beyond the surface of the platform for engagement with a service track top only carried thereby.

8. Apparatus for use in connection with a drop pit of a type having an elongated pit extending transversely beneath a plurality of railway tracks and bridged by a service track top and a release track top moveable vertically for use in servicing railway vehicle trucks and the like comprising a drop table having a frame moveable along rails extending along the bottom of the pit, a

lifting platform on the frame, power means on the frame engaging the lifting platform fordriving the platform up and down between an upper position and a lower position, upright posts disposed in the pit beneath the release track top for engagement therewith for lifting said top, means for reciprocally supporting the posts and interengageable means on the lifting platform and on the posts for coupling the posts to the platform as the platform is raised from its lower position beneath the release track top.

9. Apparatus for use in connection with a drop pit of a type having an elongated pit extending transversely beneath a plurality of railway tracks and bridged by a service track top and a release track top moveable vertically for use in servicing railway vehicle trucks and the like comprising a drop table having a frame moveable along rails extending along the bottom of the pit, a

lifting platform on the frame, power means for driving the platform up and down between an upper position and a lower position, upright posts disposed in the pit beneath the release track top for engagement therewith for lifting said top, means for reciprocally supporting the posts and interengageable means on the lifting platform and on the posts for coupling the posts to the platform as the platform is raised from its lower position beneath the release track top.

LOUIS D. HOLMES.

ROBERT S. HAMMOND.

References Cited in the file of this patent UNITED STATES-PATENTS Number

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