US1706211A

US1706211A - Mechanism

Info

Publication number: US1706211A
Authority: US
Publication date: 1929-03-19
Anticipated expiration: 1946-03-19

Description

March 19, 1929. o. L. COFFEY DROP PIT MECHANISM 5 Sheets-Sheet Filed Oct. 1, 1928 M Qm March 19, 1929. o. L. COFFEY 06,211

DROP PIT MECHANISM Filed Oct. 1, 1928 5 Sheets-Sheet 2 March 19, 1929.

O. L. COFFEY DROP PIT MECHANISM Filed 001:. 1928 5 Sheets-Sheet WA T Patented Mar. 19, 1929.

mm STATES;

oscnn L, COFFEY; or HARVEY, ,ILLINoI's,

AssIGivo'R .i'ro

HARVEY, ILLINOIS A coRroRA rIoN OF ILLiNQISQ,

" Application fiIed October 1,' 1928.Serial is.

' i Y The invention relates to drop pit mechanismof-the type usedfor removing heavy Wheels from railroad locomotives-on oth'er vehiclesw I The objecfts'o'f the invention'aie"to provide improved-fcontrolling I 'inechanism' in drop pits of the typein which enelectricino tor is used'f o'r driving the geering-wh-ichiis employed to lift and lowerthe droputeble;

in improved controlling mechanism bywhich the table will be=operated tit differential speeds; 1 nzune'ly,"a t --lowspeed during the range of thetable in whiclrthe vehicle wheels are lifted above track level t0 perinit disconnection of tlie'wheel exles fromwthev'ehicle and the connection thereof to.the vehicle,ind athigh speedduring theremainder 0f the range of in'overnent of the 5 table improved controlling mechanism by which :this' speed change will -beautomatically effected nsithe lifting mechanismpasses from one off-said ranges-to the OtllGIl; improved :contrblling inechainism "whichrenders the lifting: inechanism' inoperative-when the table locking de- Vices are" notiproperly: set; improved: controlling mechanisrnfwhich will automatically stop the lifti-ng lmechanisni iwhen? :the' table reaches its high limit' of5 travel ;5 improved highflimit controlling me'chani sin Wliich is controlled by-the'relfitive :position of'the lifting carriage or table 'thereonirelatively to the trolley in the pityand improved controlling mechanism for controlling the-lowJlimit-of 'the lifting mechanism.

features hereinafter set forth and more particularly defined by claims at the conclusion hereof. 1

In the drawings: Fig. 1 is a side elevation of mechanism embodying the invention.

' Fig. 1 is an inverted plan of the speed change and high limit switches and the device for operating them. Fig. 2-is a plan of the trolley and the lifting linxchinism thereon. Fig.

3 is an end elevation, parts being shown in section. Figs.4 and 5 are details of one 'of the automatically operated switches.

6 is a. section through the drop table on line 6-6 of Fig. 3. Fig. 7 is a. diagram ofthe electric controlling means and circuit-connections for the motor which operates the mechanism. A l

The invention is exemplified with an equipment comprising a track 8 interruptedet the margins of a transverse pit 9, -rails 10 on the The invention consists in-theseveral'novel bottom ofthe pit, Qdrop taZbIeMl-I provided 1 with rail' sections 12ft!) bridge the xp'it be tween the rails-of track 8',==' end locking 'bolts 13 Wl 1IQby the ta'ble may 'b'e-locked-'in trticle bridging position. The table 5 is composed of peirs of' I longitudinal girders'Q-I" under lying the rail sections- 12, outsid'e longitndinzil 'girderS ll; and cross girdersfl l ri idly se cured to said longitudinal girders-*to dform a r'1 gi d'su pportin'g structure for rai-l section's 12. Side platforms l lfi 'zire supported on-the longitudinal' girders iP- zin'd ill fl B'olts':s'l3 are operable into recesses 13 to=stationa1 iiy support' the table'; "There are 'four-of. shid bolts underlying thenends 0% the rail seetions -12 respectively; andvguided in blocksi'13 fixed between girder's #11 5 I l'lhese ibolts are? Econ j o ntly operable" :by a lever: 13": which? is fixed to 3;;'Sl1a ft'- 13 wh-ich is:journal led in bearings carried by the table, rockers ilvrs :13,- :and linlts 13 between s aid speetively. Theumechanismiiator 1 raising and lowering the table H5 so :thatealwheel! or load 'm'ay zbe lowered: into lthe? pitufqrltr ansfn to another 5 track i8. iand ppaised v to i thei'ides-ired levers and bolts 13 -reheight; is? mounted: onto: itrolleyl Io-rvwheeled truckl Thistiolley' com'pri'sesla frame ,com- 'posedof longithdinat'girders l t vandi cross girders 14;"; and is providedwitlr wheels; 14 :mounted in bearings oonnectedito -saidiloilgiitudmal-zgirderspand adapted to Erunon 'r'ai-ls '10.; Suitableimechanismli's providedifor prjopellin g-zthe trolley as: :welL-nnderstood: in the The -=lifting. 1 mechanism: com 'ris'e's; four standards 15'having their lower ends rigidly secured in blocks 15 secured to the girders 14 of the trolley, and Worm gears l6'threaded :to standards 15 and adapted, by-their rota.- $1011 in opposite directions,ato raisean d-lower a carriage Gwhich isadapted to separably engage thetable H, so that the.carriage-inay be raised and lowered' independently :of ;the table when desired. The fra-me'of this car .ringe comprises-a. pair of girders :17? int each end of the carriage,'girderslTi isecured tothe Y inner girders :17, and sectional gearicases 17 secured. to'girders:-17 -;;-Said gear cases contain the gears -16,'and worms-26,21ndare adapted to conta'in lubricant for said-Wheels and the screw-threads on standards 15. An electric motor B is mounted Iona framemember 19 fixed to the inner girders 17*. Gearing driven by said imotorforvsimultaneou'sly rotating-worm gears 16. comprises a pinion20 on tlie'mot/bi slla'fit,:a-'gear 21 meshing with said pinion and fixed to a shaft 22 which is mounted in bearings on the carriage G, bevelledpihions23 ontlie' ends of shaft 22, bevelled gears 24 meshing with gears 23 and fixed to shafts 25' respectively, and worm wheels 26 on the ends of shafts 25 res ectivel engaging the worm gears 16. When the motor B is operated in one direction, it will, through the described gearing, simultaneously rotate the worm gears 16 to raise the carriage-G, and when the-motor is operatedin re'versedirection, it will: rotate gears 16- to lower the' carriage G, This exemplifies lifting mechanism for, a drop table which is driven. by ain'otor and) gearing mounted on a lifting-"carriage which separably engages the droptable.

Themeclianism for controlling the'operat'ion otthe electric motor B, which is mounted on: carriage Gr, to raise or lower the drop table and the carriage independently of the table, comprises a manually Operable. switch: device A which comprises a normally open switch-button t0 and contact 41, for controlling the circuit for the lowering movement of: tlie carria-ge,-a nornnrlly closed stopbutton and' a contact 45,. and a normally open switch. button 43 .with a contact 42 for controlling the lifting circuit; a normally closed switch. C w-h-icl'r includes a springpressed arm 0' and a contact- 0 engageable by said spring-pressed. roller carrying arm, for automatically opening the lifting control circuit when the carriage ha sreachedits predetermined high limit, controlled by a connection between the carriage G and the trolley I; a spring-closedswitch D', controlled by the locking mechanismfor. the droptaibie, which will open thelowering-control.circuit when the table-latches 13 are outof either their fully closed or oponp'osit ions, and includes a spring-pressed arm (1' and a contact (Z engageable by the arm; a spring-closed switch E. for controlling the low limit of the movement of the carriage G, which includes a spring-pressed.arme and a contact e st'pa rahie from said contact to open the lowering control circuit when the carriage reaches its low predetermined limityand a speed-cont rol switch F. controlled by the movement of the carriage, to control the. operation of the motor B so the lifting mechanism will be up craied at a relatively slow speed within a prcdetermined range. while the table. is near its track-bridging position and at a. higher speed during the remainder of the lifting and lowering movements of the carriage. Each of the switches G, D, E and F are substantially of the construction shown in Figs. 4 and 5. Each is enclosed in a box 30, and comprises a shaft 31, pivotedin the box. and to which a switch-arm is secured, abridge-pin 32 on the arm. to .engage a pair of spring contacts. a spring 33 for normally shifting the arm to close a circuit at said contacts, a roller 3st adapted to be engaged by the operating element, and a stop 35 to position the arm when the switch is closed;

This controlling mechanism also comprises an elcctro-n'iagnet which includes a helix 0 for operating a pair of connected

switchmembcrs

59, 60, which are insulated from each other, and a. bridging member (51, to control the motor circuit for lifting the carriage, an elcctro-n'iagnet whichcomprises a helix 6 for shifting a pair of switch-

members

62, 63, and a bridge contact 64, to control the motor circuit for the lowering movement ot the carriage, an electro-magnet comprising-a helix 58 for operatinga pair of switch-

members

71, 72 for controlling a control circuit for opcrating the motor to drive the lifting mechanism at high speed; an elcctro-magnet comprising a helix 57 for operating a pair of snitch-members 75, 7G, for controlling the motor-circuit tooperate the-motor B at low speed; and a relay-magnet,controlled by the speed-control switch F, and including a helix 7' for operating a pair of switch-members 7t).

80, and a bridge-member 81. All of said magnets and switches are contained in a box 36 secured tothe carriage G.

The motor 13 is of the two speed, reversible type with separate windings for the two speeds at which it is desired to operate the gearing, in either direction. Currentfor the operation of motor B, which is vertically movable with the'carriage G and the controlling circuits, is supplied by

line conductors

50, 51 and 52. The switclrdevice A is usually suspended from the box 36 by a flexible cord 37. The lift-control switch C is operated by a. cam on an arm 91 which is fixed to a shaft 92 jonrnalled in brackets 93 fixed to the girders 17 of the carriage G (Fig. 1). The switch C is normally closed, and the cam 90 engages the switch arm 0 to separate it from contact a" to open the circuit.- and cause the motor to stop when the carriage has been raised to its high predctermimal limit. Arm Ul is adjustably secured to shaft 92 so the limit may be varied as desired. The speed control switch F is operated by aicam 9 1 on an arm 95 which is also adjustably fixed to the shaft 92. so the point at which the speed change is elieeted may lie varied as desired. Normaliv. switch F is closed to close the circuit for cont rolling the motor B at high speed. \Vhcn cam 94 engages arm f of said switch. it will separate said arm from the contact f to open the high speed control circuit and cause a circuit to be established which will cause the motor to drive the lifting mechanism at low speed. The boxes containing the switches C and F are lixed to a bar 37 secured to girders 17 of the carriage G. Shaft 92,

1 retrac t ed,' the switeh l carriage G. Link 96 has its upper end fixed to shaft 92 and its lower end pivoted at 98 to -the upperend of'link 97,'and the latter has its lower' en'd pivoted, at 99, to lugs 100 I which are'fixed to the trolley I. The lock-controlled switch-D'- is normally closed and operatdby-acam101 on an'arin 102 which is fixed"t'o the-cross-shaft 13 which: controls the positionsan'd movementsof the locking bolts 131for-thef t'able-'H Cam 101 is positioned to swingacross the path of the roller 38 which isifi xed to' a 'girder of carriage G. The 10w limit switch mounted on the carriage G, 'and the" rollrj on its i arnr e is adapted to 'strike anianglefiron lug 106 which is fixed t6 the trolleyafifanie, soft hat the switch will be operated "only *"when the carriage "reaches thelower limit} of-its;mv'ement.

'ation F will be as "follows Assum- Them)? 4 'lng'the ta le-H'to be'int-i' ack-bridg'ing position 'sho'wn =in Figi 3, I andfthe'bolts- 13 fully will be open, because -atfsuchi-time the cam- Qgt WilI be positioned to separate-ariaff from contact 7. 1111111- wheeling =a locomoti-v i's' to"lift the t-able' sufli'ciently' toraise a pair of the l l cqgmorive wheels &to permit them to be disconnected from thelocomotive. For this purpo'se',"'the operator Will ress the-lift- 'control button ofihe ina'nua' ly'controlled swi'tch devie'e A',--" so,it willeng'age contact l2, whereupon the"fo'llowi'ng circuit for control ling the operation of the motor at low speed will be established; line conductor 51, conductor 107, arm "0 and contactc -o'f the liftcontrolswitch ;C, ='conduc tor 108, helix a, conductor lea-contact 42, switch-member 43, conductors 110, 111, conductor 116, and lineconductor'-52.- This will'energize the helix 6 of the lift-control magnet, and operate

switch members

59 and 60 toelose against contacts 53, respectively, and bridge-member 61 to engage contacts 66, 67, and thereupon the following, circuit will be established through the helix 57 of the lowspeed control magnet, viz line conductor 51, contact 53, switclnmember 59, conductor 113, contact 83, bridge-men'iber 81, contact 82, conductor 114, helix 57, conductor 115, conductor 119, switch-member 60, contact 65, conductor 116, and line conductor 52. The energizing of helix 57 will establish the following circuit for the operation of the motor B at low speed; viz line conductor 51, conductor 107, contact 53, sw'itcbmember 59, conductor 113, contact 77, switch-member 75, conductor 117, the low-speed windingof motor B, conductor 118, switch-member 6, contact 78,

conductors

115, 119, switch-member 60, contact 65,

Conductor 116, and line conductor 52. The line conductor 50 leads to the motor 13, as

well understood in the art. This will cause the motorB to operate in one direction and operate the lifting mechanism at low speed until the high limitswitch C is opened, and whenithe. latter occurs,the circuit through helix-.0 will be opened, to release

switchmcmbers

59,60, and open the motor circuit Flast describedat contaetsi53, .65, to stop the operation of-the' motor. lVhen' the wheels have been uncoupledfrom thelocomotive, the operator will -.-press switch-button 40 of device =A.,- so it willen- 'gage contact 41, :whereupon the following 'efl-and arm e of the switch E,'conductor .121, helixeflm'onductor 122, contact 41, switchbutton 40 of device A, conductor 111, and line-conduct'on52. This will, energize helix 22 toshift switch-members 62-, 63, and 64,

to. close the following control circuit; viz line conductor 51, conductor 10?, contact 54,

vswitch-member 62, conductor'119, conductor 115, helix 57,conductor'll4, contact 82,

bridge-member 81, contact.83,0onductor 113, switch-meinber63, contact 68, conductor 116, andiline conductor 52. When the helix 57 is energized, the following circuit will be established for'the operation of the motor;

line-conductor 51, conductor 107, contact 5 1,

switch-member 62,

conductors

119, 115,'eontact/ 78,; switch-member 76, conductor 118, the low spe'e'd-reverse winding otmotor B,

conductor 117, switch-member 7 5,-contact 77 conductor "118, switch-member 63, contact 68, conductor 116, and line conductor 52. The motor-will then lower the carriage and droptable 'at 'low speed until thecam 94, which controls the switch F, releases arm f of said switch after the carriage has been lowered at slow speed the range desired, usually from six to twelve inches. This permits accurate operation of thetable H into the desired positions while the wheel-locking wedges are bein; removed. Stitch-buttons 40, and 4-3 are ot'the spring-pressed, normally open type, so that when the operator releases either of the coactinp members, the circuits controlled thereby will be opened. During these cycles, 7

the operator must hold his finger on one of the push buttons to continue the lifting or lowering operation, and the lifting mechanism will automatically stop when the push button is released by the operator. Assuming that it is desired to continue the lowering movement, the operator will continue to keep his finger on push button 40 to close it against contact 41, and when the cam 94 releases the switch-arm f, as the result of the lowering of the carriage G, the following control circuit will be established'through helix f for causing the motor B to operate in lowering direction and at high speed at all times when switch F is closed, which circuit is as follows: line conductor 51, conductor 107, conductor 124, helix f conductor 125, contact f arm f,,conductor 116, and line-conductor52. W hen the helix f is energizedyit will shift

switchsm'em'bers

79, 80, and 81, to interrupt the circuit at switchmember81, andcontacts 82 and 83',- andestablish the following circuitz line conductor- 51, conductor 107, switch-arm 0., conductor 56, switch-arm d, contact d conductor 120, contact e arm e-,' conducto'r .121,-heliX c of the lowering control magnet, conductor 122, contact 41, push-button 40, conductor 111, and line conductor 52.. .v This circuit will cause helix 6 to be; energized:whiehwill shift bridge-member 64 into engagement with contacts 69, 7 0,? to establish 'a' circuit which will make it possible to continuethelowering operation without the necessity of the 0p erator keeping his fingerlonuthe button 40. The circuitfor; his purpose will-be as follows: line conductor. 51, conductor 1,07, arm 0, conductor 56, armtdf, contact d conductor 120, contact e arm e,- conductor.121-', helix e conductor 122,-c0ntact 69, bridge-member (54, contact 70, a conductor 126,' contact 85, switch-member 80, conductor 127,- push-button 44, and contact .45, which are normally closed, conductor lll andline conductor 52. e

V mencement.oftherange of low speed move- The energizing. of 'helixe' will also close the following circuit to energize helix'58 of the high speed lowering control magnet; .viz line to cause the addit onal upper travel of the conductor n 51, conductor 1 107, contact- 54, switchrmember 62, conductors. 119,-115, helix 58, conductor 129, contaot'84, switch-member 79, conductor 113, switch-member 63, contact 68, conductor 116, and line conductor 52. W hen helix-58' is energized,

switch members

71,72 will be shifted to close the following circuit for the high :speed operation of motor B during the remainder of the lower in; cycle; viz line conductorf51, conductor 107, contact 54, switch-member. 62,

conductors

119, 115, contact 74, switch-member 72, conductor 130, the high speed winding of motor B, conductor 131, switch-member 71, contact 7 3, conductor 113, switch-member 63, cont-act (38, conductor 116, and line conductor 52. The motor B will-thereupon lower the carriage G either until the operator presses the push button 44 to stopthe motor, or until the switch E is opened as the carriagereaches its low limit. When the carriage G, withthe table thereon,'-has been lowered,'and it is desired-to raise the table with the load thereon, to the track leiehtheoperator will press but ton 43, so it will engage contact 42, which will establish the following circuit: line conductor 51, conductor 107, switch arm 0, contactc, conductor 108, helix 0*,conductor 109,

contact 42, push-button 43, conductors 110, 111, and line conductor 52. Simultaneously, a parallel circuit will be established, so that the operation of the motor B may be continued without holding push button 43 closed, which will be as follows: lineconductor 51, conductor 107 arm 0, contact 0 conductor 108, helix 0*, conductor 109, contact 66, bridge-member 61, contact 67, conductor 126, contact 85, switch-member 80, conductor 127, push button 44, contact 45, conductor111, and line conductor 52. When helix 0 is thus energized, it will also establish a circuit for energizing the helix 58 of the high speed lift control magnet, .to close a circuit-for caus- ,ingthe motor to lift the carriage which cir- =-cuit will betas follows: li.ne .conductor-51,

conductor 107, contact 53, switch member 59, conductor v113, switch-member 7 9,, contact 84,

, conductor 129, helix 58,

conductors

11,5, 119,

switch-member 60, contact ,'and conductors 1 116, 52. @Hjelix 58.--will then shift switch- 1ne1nbers71, 72 to establish the circuitthroug-h the motor B to operate the, gearing,int-he proper direction to lift-the carriage, which will be as follows :conductors '51, 107, contact 53, switcltanernber. 59, conductor 113, contact 73, switclrmember 71, conductor 131, the

winding of motor ,.B,-conductor 130, switch member 72, contact 74,

conductors

115, 119,

; switchniember 60, contact 65, andconductors ,"116, 52. This circuit will remain closed until the operator presses the stop,,button 44, or

if the carriage is to be lifted above the comment, until-the switch F is opened by the cam 94,- which 'isoperated by the linkage '96, 97,

carriage to :be effected atlow speed. When the switch F has been opened, helix P will i be deenergized topermit switch members 79,

80 -.to separate from contacts 84, 85, so that the same control circuit will-be established as described in connection with the initial low speed lifting operation, which circuit '101 will shift switch-a rin d to open the circuit at contact (1 and th us interrupt the control circuit to prevent the operation of the'inotor B in .lovieri'ng direction until the bolts have been properly set. The opening ot the circuit at contact d interrupts the circuit through helix e so thatthe motor circuit will be interrupted at contacts 54 and G8. o

The invention exemplifies controlling mechanism for-a drop-table which is operated by a lDOiQl on the lifting carriage, in which provision is madefor lifting and lowering the table at different speeds, so that the table may be accurately positioned within that range of its travel in which the wheels are separated'and attached to the vehicle rl O in which provision is made for automatically withoutthe necessity of the operator l olding the switch in position; and in wliich'the nioye mentsof the speed-control and high-limit switches. are controlled by .a connection between thelifting carriage and the trolley. 11 5;

The invention is not to beunderstoodas re: stricted to the details set. fo tl1,. since .,these may be modifiedwithin the scope of thea'pf pended claims, without departingd-from the spirit and scope of the invention. Having thus described the invention, what I claim as new anddesire to secure by Lettcrs Patent, is:

1. In mechanism of the elass described,-;the combination with a pit, and a drop table adapted to move vertically iii-the; pit,= o;E

ing mechanism mounted to travel laterallyin the pit for shifting-the table, anelectric motor for-driving said I nechanism, and means.;,for controlling the: motor to operate. the lifting mechanism at different speeds during-differ; ent ranges oftravel.

La 2-. In mechanism of theclass deseribed,--the combination with a -.-pit, ,and: a dr'op-table adapted to move'vertically in thepit, Offliitq mechanism mounted to travel laterallyinithe pit for shifting the table, an electric anotor for driving said mCll2l-nlSl11',"3I1d'lllGl-IlSffOl controllingithe n'iotor to operate :thelifting mechanism to'raise and lower the table atflifferent speeds during different ranges (if-travel; 3. In mechanism of the class described, the combination with .a pit, and a drop :table adapted to .n'iove vertically in the. pit, of ,lifting mechanism mounted to travel laterally in the pit for shifting the table, a reversible electric motor for driving said mechanism, and

means for controlling the motor to operate the lifting mechanism to raise and'lower the table at different speeds during different ranges of travel. M.

4. In mechanism of the class described, the combination with a pit, and a drop-table adapted to move vertically in the pit, lifting mechanism mounted to travel laterally in the pit for shiftingthe table, comprising screws, elements on the screws, and an electric motor for driving said elements, and means for controlling the motor to operate said-elements at different speeds duringditferent ranges of travel." 'i j ,5. mechanism 'ofthe class'described, the combination with a'p'itand a d'rqp' table adapt; ed .to move vertically in the pi't Qlifti'ng" mechanism'gmounted to 'trav'e'l laterally inf the pit fonsh'ifting thetable-comp i ing screwgfelemerits thescrew's and an electric mo't'or'for driving said; elements, and 'nialn's for-con walling-sht' inotbr to operate" said elements to raise and lower the table atditferent speeds durinfiditfetent' ranges of'icravei: 6;- 1p mech nism ff-the cl s s-'deseribed ,-the combination"M'ithTa-p ;'an'd"a map-table adaptedto inoveverti'callyiritl e ic-era trol leymo lfmjtetl w trivel lat'erallyin the pit; lift mgmeeh is'iho'ri'tlie trolley,"finshifting'the ....c eirisingwre se her -r g i write operate i'si'nftntf d fferent-speeds dur-" f. 'fi 7. Inmehanisiii'bftlie combination with, a pit, .aiitl tedto "'i'ri' 'eWert" tllyiir' t 61-01 a;

" pit, bf a lek'l ici' n e di e e r e e' illy'ie iri t' in; me'chani. r'onrtlretrollejifor shifting the table, oi i ing; jelectriemo'to ,fan'd ma ns olly, t lli' igithe ii'ioecha is ff di t 9 dperate th .l f-t g. en "Speeds-.q mii sin le lsi d. h i g'ih switch a cdr'inction e tweenflthe l ifting mechiinis nand theti o ey,

. 0.; lnlm bm'is U T the class es'cr'ibed, the eombina t iongwith vapi t, ar' i d a drop stable adapted to. move, vertically. in the pit,'oflifting mechanism molinted tot navel laterally in the pit n: s hifting th e 113519; ielectricmotor for driving said me,chanism,land,'means ,for controlling thejmotor operate the lifting mechanism atv different ,speeds diirin'g differ ie es ii-tr e nd 'fa t m l y stop the, motor: when the E lifting. mechanism Ieaches a: pre e e m ne .'h g1 1.-

.e-i e 11-. In mechanism .of the class described,

w the combination ivith a pit, and a drop-table adaptedto move vertically in the pit, 0" lifting mechanism-mounted to travel latera ly in the pit for shifting thetable, an electric motor for driving said mechanism, and means for controlling the motor to operate. theliftin g m ha is at-slifieli nt spe d dllifing d ent ranges of travel and to antomatically stop the. .motor. at predetermined high and low limits.

12. In mechanism of the class described, the combination. with a pit, a. drop-table adapted to move vertically in the pit, lifting mechanism mounted to travel laterally in the pit for shifting the table, comprising screws, elements on the screws, and an electric motor for driving said elements, and means for controllin 'the motor to operate said elements at difiierent speeds during .difierent ranges of travel, and to antomatically stop the motor when the lifting mechanism reac a predetermined limit. d i w 13. In mechanism of the class described, the combination Wit a pit, and a dro'p-talile adapted to 'ino ve ver ic'ally in the pit, of a trolley moun'ted'to travel laterally in the-spit, lifting mechanism on the t r olley, for-shifting the table, comprising an'elect'ric motor, and means carriedon the trolley, for controlling the motor to operate the lifting mechanism at differentspeeds' lir ng difi'erent'ran'ges of its travel, and to automatically stop the motor when the lifting mechanism reaches a predetermined high limit. I

14. In mechanism'of the class described, the combiiiationivi th a pit and a drop table adapted to'move verticallyin' the pit, of lifting mechanism monnted to travel laterally in the'pitfor shifting the table, comprising an electric motor, andmeans for controlling the motor tooperate the lifting mechanism at low speed during a predetermined upper range of travel of the table and at a higher speed during its lower-range of travel.

l5.'In mechanism of the class described, the combination with a pit, and a drop-table adapted to move vertically in the pit, of lifting mechanism monnted to travel laterally in thepit for shifting the table, an electric motor for driving said mechanism, and means for controlling the motor to operate'the lifting mechanism antomaticallyat different speeds 'dnri'ng different ranges oftraveh'and to aiitoinatically stop the motor when the lifting mechanism reaches a predetermined height. 16(In mechanismbflth'e class described, the combinatitin with a pit 'and a drop table adapted'lto move vertically in'the pit, of a trolley monnted'to travel laterally in the pit, lifting 'meehanism'on the trolley for shifting the'table, comprising an electric motor, and 'means carried on the trolley; for automatical- 1y eontrollingfthe motor to o erate thei'liftin'g meclianism at low speed do-ring a predeterrise-s11 mined upper range of travel of the table and at a higher speed during its lower range of traw I 17. In mechanism of the class described, the combination with a pit and a drop-table adapted to i'nove vertically in the pit, of lifting mechanism mounted to travel laterally in the pit for shifting the table comprising an electric motor, and means for automatically controlling the motor to operate the lifting me'cl ani'sn' at low speed during a predetermined upper range ofthe table and at a higher speeddnrin g the lower range of movement of the table comprising a switch and a connection het'iveen said'inechan'ism and the trolley. Infmecha nism of the class described, t-lje"coml)inati on ivith a it and a difop-table adapted tomove vrtical iy 'inthe pit,'oflifting mechanism moiint'ed to'ti'avcl laterally in the pit 'fdr'sliiftingthetahlc, comprising a'reyeisible electric 'moto'r,jand means for contfidlling the iniotor to operate the lifting mechanism 'atlow speed during a predetermihed 'npper range of the table and at a higher speed dnring the lo'wer range of movement of the table,'comprising 'a high-speed control'magnet and a low speed control magnet. w

' 19. In mechanism of the class described, the combination with a .pit and a "drop-table adapted to move vertically in'thepit, of lifting mechanism'm'onnted'to travel laterally in the pit for-"shifting the table,-comprising a reversible electric motor, and means for controlling the motor to operate the lifting mechanism at low "speed during a predetermined npper range of-the table and at a higher-speed dnri'n g the lower rangeof movement ofthe table, comprising a high-speed control magnet, a low speed control magnet, and'magnets 'foi' eontrolling the direction of operation oft/he motor.

20. In. mechanism of the class described, the combination with a pit and a drop-table adapted to move vertically in the pit. of lifting mechanism mounted to travel laterally in the pit for shifting the table, comprising an electric motor, and a carriage adapted to separably engage the table, switch-means mounted on the carriage for controlling the motor to operate at different speeds during different ranges of "travel of the lifting mechanism, and a connection for shifting said controlling means, operated by the vertical movement of the carriage.

21. In mechanism of the class described, the combination witha 'pit and a drop table adapted to move '-\'ertica liy in the pit, of lifti-nginech-anis'm for'shifting the table, comprising an electric motor, and a carriage adapted to "separably engage the table. switch-means for controlling the motor to operate aili'fi'ernt speeds during different ranges'of trav'e'l of't'he lifting mechanism, and

llU

a'pair of links operated by the vertical movement of the carriage, for operating said switch-means.

22' In mechanism of the class described, the combination with a pit and a drop table adapted to-move vertically in the pit, of a trolley mounted to travel laterally in the pit, lifting mechanism on the trolley, for shifting the table comprising an electric motor and a carriage adapted to separably engage the table,-a switch for controlling the motor to opcrate at differentspeeds, during different ranges of its travel, comprising a switch moiuited on the carriage, and a connection between the carriage and the trolley foreontrolling said switch.

I '23. In mechanism of the class described, the combination with a pit and a drop table adapted to move vertically in the pit, of a trolley, lifting mechanism on the trolley, for shifting the table comprising an electric motor and a carriage adapted to'separably ere gage the table, a switch for controlling the motor to Qperate'at different speeds during differentranges of its travel, comprising a switch mounted on the carriage, and a linkconncction between the carriage and the trolley for 'co'ntrolling said switch.

24-. In mechanism of the class described, the combination with a pit and a drop-table adapted tomove vertically in the pit, ofa trolleymounted to am-91 laterally in the pit, lifting mechanism on the trolley for shifting the table comprising a two-speed electric motor and a carriage adapted to separably engage the table, and means for'antomatically controlling the motorto operate at different speeds during Ldiflerent ranges of its travel, comprisiiig'a switch, a connection between the carriage and the trolley for shifting said switch, and high and low speed relays controlled by said switch.

In mechanism of the. class described, the comhination with a pit and a. droo-tahle adapted to more \'erticall in the pit, of a roller mounted to travel laterally in the. pit, l'ting mechanism on the trolley for shifting (alile comprising a reversible two-speed 'ir motor and a carriage adapter to sepa ably engage. the. table, and means for controlling the motor to operate at dili'erent speeds during di lierent ran 'es of travel, comprising a switch, a connection between the carriage and the trolley for shifting said switch, high and low speed relavs. and relays for cmztrolling the direction rotation of the molor.

28. in mechanism of the. class described, the combination with a pit and a drop-table ad d to move vertically in the pit, of liftleelninism mounted to travel lat "rally in the pit for shifting the table, con'iprising an electric motor, means for locking the table in its raised position, and means for controlling the operation of the motor, comprising a switch, controlled by said "locking means.

In mechanism of the class described, the combination with a pit and-a drop-table adapted to move vertically in'- the pit, of a trolley mounted to travel laterally in th'e pit, lifting mechanism for shifting the table, comprising an electric motor,- means for looking the table in its raised position, and means for controlling the operation of the motor, comprising a switch controlled'by said locking means, and a device mounted onthetable for controlling said switch. I,

28. In mechanism of theIclass, described, the combination with a pit and a; drop-table adapted to I move vertically inthc pit,- of lift. ing mechanism mounted to travel'late'rally in the pitfor shifting the table, comprisingian electric motor, means for :loekingthe table in its raised position, means for-controlling, the operation of the motor, and means, controlled by said locking means, for renderingthermo tor inoperative, comprising-.a- :switchon the lifting mechanism, and means on the-table to control the switch. x z :7; i

29. In mechanism of the class described, the combination with a pit and .adrop ,table adapted to niovc verticallyein the :pit, ofa trolley mountedto travellatcrally in the-pit, liftin mechanism on' the trolley for, shifting the table, comprising a carriage separablyienr gaging the table, and an electric motor? on the carriage, means carried by the t able'iorlocking it in its raisedposition, means for controlling the operation ofathekmotor, Eand means, controlled by said-lockingl-means, for rendering the motor inoperative,comprising a switch mounted on the carriageand adevic on the table, for shifting the switch.

30. In mechanism of the olassydescribed, the combination with a pit-andadrop-table adapted to move vertically in the.pit,-of;'a trolley mounted to travel laterally in the pit, lifting mechanismon the trolley, for shifting the table, comprising an electric motor and. a carriage separably engaging said table, and on which the table is mounted, controlling means for the motor for rendering the motor inoperative when the carriage reaches its high limit comprising a switch on the carriage and a connection between the carriage and the trolley for operating said Switch.

31. In mechanism of the class described, the combination with a pit and a drop-table adapted to move vertically in the pit, of a trolley mounted to travel laterally in the pit, lifting mechanism on the trolley, for shifting the table, comprising an electric motor and a carriage separably engaging said table and on which the table is n'lountcd, controlling means for the motor, and means for rendering the motor inoperative when the carriage reaches its high limit comprising a switch on the carriage and a link connection between the carriage and the trolley for operating said switch.

32. In mechanism of the class described, the combination with a. pit and a drop-table adapted to move vertically in the pit. of a trolley mounted to travel laterally in the pic, liiitin mechanism on the trolley, for shifting the table, comprising a two speed electric niotor,- and a carriage separably engaging said table, means for controlling the motor, auto niatic means for rendering the motor inoperat-ive when the carriage reaches its high limit, comprising aswitch on the carriage, a speed-- control switch mounted on the carriage, and a connection between the carriage and the trolley for controlling said switches.

33. In mechanism of the class described, the combination with a. pit and a drop-table adapted'to move vertically in the pit, of a trolley mounted to travel laterally in the pit, lifting mechanism on'the trolley, fol-shifting the table, comprising a two-speed electric motor, and a carriage separably engaging said table, means fol controlling the motor, automatic means for rendering the motor inoperative when the carriage reaches its high limit, comprising a switch on the carriage, a speed-control switch-mounted on the carriage, and a link connection between the carriage and the trolleyfor controlling said switches.

34. In mechanism of'the class described, the combination with a pit and a drop-table adapted to move vertically in the pit, of a trolley monntedto travel laterally in the pit, liftin mechanism on the trolley for shifting the-ta le, comprising an electric motor and a carriage separablyseng'ag'ing said table, and motor-controlling meanseomprising a switch on the carriage for rendering the motor inoperative when the carriage reaches its high limit, a shaft on the carriage for controlling the switch, aird' a connection between the earriage and the trolley for operating said shaft.

3-5. Inmechanism of the class described,

the combination with a pit and a drop-table adapted to move vertically in the pit, of a trolley, lifting mechanism on the trolley, for shifting the table, comprising an electric motor and a carriage separably engaging said table, and motor controlling means comprising a switch on the carriage for rendering the motor inoperative when the carriage reaches its high limit, a shafton the carriage for controlling the switch, and a link connection between the carriage and the trolley for operating said shaft.

36. In mechanism of the class described, the combination with a pit, and a drop-table adapted to move vertically in the .pit, of lifting mechanism mounted to travel laterally in the pit for shifting the table, comprising an electric motor, and means for con-trolling the operation of the motor comprising a manually operable device, including open switches for controlling the up and down movements of the lifting mechanism, and a stop-switch, and means for continuing the operation of the motor independently of the raising and lowering switches, under control of the stop switch.

37. In mechanism of the class described, the combination with a pit, and a drop. table adapted to move vertically in the pit, of a trolley mounted to travel laterally in the pit, liftin mechanism on the trolley for shifting the table, comprising a reversible electric motor, and means for controlling the operation of the motor, comprising a manually operable deviee,'including normally open switches, for controlling the up and down movements of the lifting mechanism, and a stop-switch, and means for continuing the operation of the motor in either direction, independently of the raising and lowering switches, under control of the sto a-switch.

Signed at hit-ago, Illinois, this 28th day of September, 1928.

OSCAR L. COFFEY.