US2520968A - Drop pit apparatus - Google Patents

Description

Sept. 5, 1950 c. H. scHRAMM Er AL yDROP PIT APPARATUS Filed June v'21, 194e 2 SheetLs-Sheet l amm man Chrlsophev H Schr Boqd OHGHold@ c. H. scHRAMM E1- AL l 2,520,968

Sept; 5, 1950 DROP PIT APPARATUS l P. sheets-sheet 2 Filed June 2l, 1946 Patented Sept. 5, 1950 DROP PIT APPARATUSV Christopher-.IL Schramm and Lloyd H. Holdeman, Muskegon, Mich., assignors to Manning, Max* Well & Moore, Inc., Muskegon, Mich., a corporation of New Jersey Application June 21, 1946,- Serial No'. 678,348

(Cl. ft-32) 17 Claims.

1 The invention relates to drop pit apparatus of the type commonly used in railroad shops for removing and replacing the trucks or Wheels of locomotives and other vehicles and for transporting the trucks and Wheels between the vari- `level and transporting positions and a heavy duty elevator mechanism for raising the table above track level to lift a vehicle or to compress the springs thereof preparatory to removing or replacing the trucks or wheels whereby each elevator mechanism may be designed and constructed for the most eflicient performance of its duties so as to provide maximum ypower when required with high operatingspeeds when'such are desirable, greater accuracy in the control of the mechanism of table movements, and a material reduction in the overall cost of the apparatus.

A more specific object is to provide-heavy duty table elevator mechanism for drop pit apparatus which is operati-ve to provide the powerful'thrust required for raising a heavy vehicle-or for compressing the springs to permit removal of a set of'wheels, thereby permitting use of a lighter weight and higher speed elevator mechanism for raising and loweringv the table from the track level to the transporting position.

Another object is to providek hydraulically oper'- ated table elevator mechanism for drop pit'apparatus adapted to supplement the main elevator mechanism and to supply the powerful thrust required for certain types of work, thus leaving the main elevator mechanism tothe performance of its normal function of raising and'lowering the table between track level and transporting positions.

Other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment illustrated in the accompanying drawings in which:

Figure l s'an end elevational view of drop pit apparatus embodying the features of the invention.

Fig. 2 is a side elevatinoal view o`f the apparatus.

Fig. .3 is a detail view of the means for connesting and disconnecting the Ytable and the auxiliary elevator mechanism.

Figs. 4 and 5 are fragmentary side elevational views showing the different positions of the heavy duty auxiliary elevator mechanism.

Fig. 6 is a fragmentary side elevational view showing the table in course of being lowered by the light duty elevator mechanism.

Fig. '7 is a diagrammatic view showing the hydraulic circuit for the heavy duty auxiliary elevator mechanism.

While the invention is susceptibleY of various modifications and alternative constructions', we have shown in the drawings and will herein describe'in detail the preferred embodiment, but it is to be understood that We do not thereby intend to limit Vthe invention to the specic form disclosed, butintendto cover all modifications and alternativev constructionsf'alhng within the spirit and scope ofl the Vinvention as'expressed in the appended claims.

For purposes of illustrationthe inventionha's been shown' as incorporatedin apparatus for' use in a pit i0 which intersectsand extends beneath one or more railroad tracks'T, commonly called service orrepair tracks. In order to permit locomotives orvother vehicles to berun kover the pit, drop tables Il are provided for bridging the "pit at the various service and repair tracks. The

ytables Hy may be off the vgeneral type shown in the Minty Patent No. 2,111,917, granted March 22,1938, each comprising a generally rectangular 'frame adapted to bereleasably supported in pit bridging position by retractable latch barsv l2 engaging `ledges |13 in the side Walls of the pit. Rails Ui .carried by the table are aimed-with the rails of. the service track T thus forming 'an exten-sion .of such vtrack: whenthetableis latched in place across the pit.

Means is vprovided forraising and lowering fthe drop table Il and fortransp'orting it alongtlie pit i@ for association'with. any of the various service and. repair tracks :in the' shop. Such meansl comprises acarriage ihaving .elevator table l5 supported and guided thereon for vertical movement by upright columns i1 extend-ing upwardly from the carriage to a point closely adjacent the top of the pit. The carriage is fitted with flanged wheel-s i8 adapted to'run on rails lrforming a track at the bottom oirthe pit. .Suitable vmeans such as-v anelectricmotor M is provided for driving the carriage and its load-along the track.

When asetof wheels is to be removed: froma vehicle, as tor exampleL the drivers of a locomoitive, the drop table H is latched in pit bridging position atv one of the .service tracks T and the locomotive is runover the pit-so as to spotthe drivers on thevtable track section Hl. To facilitate. the disconnectionof the: drivers from` the 3 locomotive it is usually necessary to compress their springs and thus relieve the pressure on the retaining bolts. This is done by raising the table VIl and the drivers spotted thereon a short distance above track level. A relatively small vertical movement is sulicient for this operation but it will be evident that a relatively heavy thrust is required to produce it.

Upon their disconnection from the locomotive, the drivers are supported by the table Il and may be lowered with it until they clearv the running gear of the locomotive and any drop tables bridging the pit at other service tracks. With the table in such lowered br transporting position the carriage l5 is traversed along the pit to another service track and the drop table raised to track level to permit the drivers to be rolled off for repairs or other attention. To replace a set of drivers the sequence of operations above described is simply reversed.

, In accordance with the invention, separate elevator mechanisms are provided for traversing the elevator table IE in each of the two ranges of travel above referred to, each such mechanism being designed and constructed to most efficiently meetthe operating requirements of its particular range. Thus for raising and lowering the table between a transporting position within the pit and the track level position, in which range only the weight of the table and its load is involved, we provide a light duty elevator mechanism capable of traversing the table at high speed through a relatively long range of travel. For traversing the ,table in the range for lifting vehicles or for compressing their springs, we provide heavy duty elevator mechanism constructed and arranged to exert the heavy thrust required for that purpose. Moreover, provision is made for rendering each mechanism effective automatically in its own range of travel thus whereby simple, safe and foolproof control of the operation is insured.

The light duty elevator mechanism may be of any preferred type such, for example, as that disclosed in the Blake Patent No. 1,849,972, granted March 15, 1932, which has been found particularly suitable where high operating speeds and a long range of travel is required. As shown in Fig. 2 `of the drawings, the mechanism comprises generally a series of flexible cables 20, preferably in `the form of at wire ropes, by which the table I6 is suspended from the upper ends vof thecolumns Il. One of the cables 20 is anchored to each column and is extended over a rounded guide member 2l adjacent the upper end of the column to a drum 22 rotatably mounted on the table I6. Thus by winding the cables 20 on or unwinding vthem from the drums 22 the table may be raised or lowered asrequired. Power actuated means herein shown as an electric motor MI is provided for driving the drums 22.

' The heavy duty elevator mechanism comprises generally a plurality of actuator members, herein shown as push rods 25, each supported'on one of the columns Il for vertical movement toward 'and from the table I3. While any suitable power actuated means may be utilized for actuating the push rods, hydraulically operated actuators are preferred. In the exemplary apparatus, the push .rods 25`are accordingly provided with pistons 26 working in cylinders 21v as shown in Fig. 7. One such cylinder 21 is rigidly secured -to each column Il adjacent the lower end ofV the column and the associated push rod 25 extends upwardly along the side of the column through suitable guides 28 secured thereto.

Means is provided for operatively connecting the push rods 25 and the table I6 as the latter approaches its upper or track level position and for automatically interrupting the connection when the table is lowered from such position by the main elevator mechanism. The yconnecting means as herein shown comprises a series of abutment members 30 carried by the table I6 and adapted to be interposed between the framework of the table and the upper ends of the respective push rods.

. Referring to Figs. 1 and 3 of the drawings, the members 39, herein shown as elongated flat steel bars, are suspended from the table IS to swing into or out of the path of movement of the push rods. For this purpose each member is provided with two laterally projecting arms 3i spaced apart longitudinally of the member to straddle one of the beams 'constituting the ,framework of the table. At theirV outer endsv the arms 3| are formed Vwith elongated apertures 32'for the reception of pivot pins 33 carried by thetable to provide for limited verticalmovements of the abutment member in addition to swinging movement about the pins .33 as an axis.

Mounted on Vthe underside of the table I6 above each of the abutment members Stare a pair of guide blocks 34 having downwardly facing rectangular notches 35 dimensioned for the reception ofthe member and substantially alined with the axis of the push rod 25. As will be seen by reference to Fig. 3, the upperrend portions of the arms 3l are inclined so as to overlie the abutment member 3G and the apertures 32 are alined in a common vertical plane with the notches 35, the central axis vof the abutment mem-ber and the associated push rod V25. VAccordingly, when unrestrained, the abutment members automatically swing between the guide blocks and the adjacent endsof their associated push rods in alinement -with the notches 35.

By reason of the lost motion connection provided by the slots 32, theabutment members are free to move upwardly when engaged by the -push `rods in their upward movement. When the members engage the guide blocks as shown in Fig. .4 the thrust of the rods is transmitted to the table to raise the same above track levelwposition as Vshown in Fig. 5. The abutment members, of course, engage in the notches 35 in the blocks and are thus eifectually held against displacement .from operative positionl while the table is supported by the push rods. Y

Provision is made for swinging the abutment members 30 into or out of operative position in accordance with the position of the elevator table i6 whereby to'render the heavy duty elevator mechanism operative for raising the table above the track level position and to render the mechanism inoperative in the travel range of the main elevator mechanism. As herein shown, the means provided for controlling the operativeness of the abutment members comprises a series of cams, one for leachrabutment member, adapted for cooperation with follower rollers 2i? (Fig. 3) mounted on the outer supporting arm slof each member.

Y The cams may be conveniently formed on one ofthe side webs of each of the columns Il and, as herein shown, eachcomprises an upper vertical section 38 (Figs. 2, 3 and 6) disposed so as to allow the abutment member to swing into operative position as the ,table le is raised to the track level position. At the lowerendofY the cam secthe, latches l2.

tion 38. is, an inclined section '3.9 adapted. to swing the abutment member outwardly to the inactive potion shown in Fig. 6 as the table is lowered lfrom the track level position and .a vertically diS- leosool intermediate .Seotien lil for holding the member in such position during the lowering of the ta'ole. A t its lov/e1 end the intermediate @am section is connected by a second inclined section 4 I with a vertically disposed section ft2 offset further to the right (as viewed in Fig, 6) for swinging the abutment member outwardly to clear the cylinder 2l' as the table approaches the carriage.

1n order to maintain the table level while being raised or lowered by the heavy duty elevator `n.i,elrianisrri the actuators for the push rods 25 are, .constructed and arranged for operation at .the .game rate of speed. Thus, -when hydrauliy oally leperated actuators are used as in the exemplary-apparatus, pressure uid is supplied to each ofi-the cylinders 21 so as to exert equal pressures on the pistons 26 and thereby generate an equal through each of the rods 25. For this .purpose the cylinders are connected in multiple -ehown in Fig, 7 to receive pressure fluid from a cemmon pump P under control of a suitable manually operable valve V. The control valve V arranged to connect the cylinders 2l simultaneously with the Dump for raising the table or -tyiutlfi a drain 45 for returning the pressure fluid fr In the cylinders to a sump or reservoir P.. from vglgneh it may be withdrawn by the pump for reuse. When the cylinders are connected to the drain, the tables IlY and lr6 descend by gravity. The rate of such descent is regulated by adjust- :nent of the control valve. The pump P, which vmay be of any preferred type, together with a motor M2- for driving it and the reservoir R are suitably supported on the carriage l5.

In the operation of the improved drop pit apparatus a vehicle is run over the pit It so as toy spotthe wheels to be serviced on the table track section lll, the drop table il being supported in pit, bridging position by the latches. I2 atsuch time. The carriage l 5 is traversed along the pittrack i9 to locate it below the drop table and the light duty elevator mechanism is operated to raise the elevator table I6 into close proximity to the drop table. When the vehicle wheels can be disconnected without compression oir their springs the heavy duty elevator mechamism is, used only to raise the table sufficiently to, relieve the latches l2. Upon disconnection of the wheels the drop table is released from the pit byfwithdrawal of the latches l2 and may then be lowered. into the pit by thev light duty elevator mechanism. The wheels may be transported along, the. pit and transferred to another service track` in'. accordance with the usual practice.

Where it is necessary to compress thevehlcle springs to permit removal or replacement of a set of wheels, the elevator table i6 is raised into engagement with the drop table H as above described to support the latter upon withdrawal of As the table approaches the track.V level position in which it is shown in Fig.

the. abutment members 3i) swing into alinement with the piston rods 25 and thus condition the heavy duty elevator mechanism4 for operation. Suitable control means such as a limit savitchA (not shown) may be provided for inter.- Iiupting the operation of the light duty elevator mechanismy vwhen the table reaches track level position and for preventing further'operation of thatfmechanism .in .zt-table. raisingv direction.

Operation of: the heavy.Y duty. elevator mecha.,-

'nism is ,initiated by -manually setting the control valve V to ,direct pressure fluid from the pump P .to the lower ends of the cylinders 21. It will llee appreciated that the valve V may be adjusted so as. to control the rate ofnuid'flo-w to the cylinders thus providing for accurate regulation of the rate of table movement. The delivery of pressure fluid to the cylinders 2l forces the pistons 26 and their associated push rods 25 upwardly. iftslight movement of the push rods carries them into engagement with the abutment members 3U which move upwardly with the rods to engage the vguide blocks 34 and thus transfer the thrust of the rods to the elevato rtable I6. Continued up ward movement of the push rods raises the elevator table I6 ltogether with the drop table l0 and the vehicle wheels spotted thereon thus com- Dling the vehicle springs so that the wheels may bedigsconnected from the vehicle. Engagement of the abutment members. 3l) in the notches 35 of theA guide blocks effectually prevents. accidental displacement of the abutment members while the drop table is supported by the. heavy duty elevator mechanism.

, After disconnection of the wheels from the vehicle the control valve V is operated to connect the cylinders 21 to the drain 'l5 thereby permitting the pistons 26 and the. associatedv appa.- ratus including the drop table to descend, by gravity. When the slack is taken upin the cables 211 substantially as the table reaches track level position, the. load is transferred. to the cables of tlllight duty elevator mechanism, which may then be, operated in the usual manner to lower the drop table into the pit. rThe heavy duty ele'- vator mechanism is automatically rendered ineffective. during such lowering action. After the support of the table is transferred to the cables 2,0, the push rods 25 are withdrawn to theirretractedor idle positions as shown in Fig. 3. Upon such withdrawal the abutment'members 3l! drop out of thenotches 35 and hang freely from the p ins33; As the table is lowered by the light duty lelevator mechanism the cam surfaces 39 and 40 swingtheabutment members outwardly clear of the push rods-Z-li'- as shown in Fig. 6 and maintain them in such positions until the table is again raised to track level.

It will'be apparent from the foregoing that-the inventionV provides drop pit apparatus capable of performing the various operations commonly required of; such apparatus with a high degree of efficiency. Heavyduty elevator mechanism sup'- plies` the powerful thrust required for raising a vehicle or for conipressingl the springs thereof, thus permitting the use of' high speed light duty elevatormechanism for raising and lowering the `elevatortab1ewithin the pit; Control of the ape paratus for the different operations is simple and foolproof and anypossibilityof interference between the two elevator mechanisms is precluded bythe-provisionof means for conditioning each mechanism for operation only in itsproper range of travel;

We claim as our invention:

1. In a--drop vpit apparatus, a .carriage adapted to traverse a. pit extending beneath a servicetrack, a: table supported on saidcarriage,v light duty elevator mechanism mounted on said table forraising-and lowering the tabler through a pre;- deterrnined range of travel, and heavy duty ele.- vatori mechanism mounted on said carriage for raisingthe. table independently of said light duty mechanism g through` aV different. range of travel.

2. ,Inga drop :pitgapparatus;. a carriage adapted to "traverse a' pit extending beneath aser-vice track, a table supported on said carriage,-light duty elevator mechanism mounted on said table for raising and lowering the table through apre'- determined range of travel, separate independent heavy duty elevator mechanism mounted on said carriage for raising the table through a different range of travel, and means operative at a selected point in the predetermined range of travel of the table for rendering said heavy duty mechanism effective.

3. In a drop pit apparatus, a carriage adapted to traverse a pit extending beneath a service track, a table supported on said carriage, light duty velevator mechanism mounted on said table for raising and lowering the table through a predetermined range of travel, heavy duty elevator mechanism mounted on said carriage ior raising the table through a diierent range of travel, and cam controlled means on said carriage for rendering said heavy duty mechanism effective at a selected point in the predetermined range of travel of the table.

4. Drop pit apparatus comprising, in combination, a carriage adapted to traverse a pitlocated below a service tra-ck, a table supported on said carriage, elevator mechanism mounted on said table for raising and lowering Vthe table through a predetermined range of travel, independent auxiliary elevator mechanism mounted on said carriage for raising and lowering the vtable through a different range of travel, and members carried by said table providing a disengageable connection between the table and said auxiliary Y elevator mechanism.

5. Drop pit apparatus comprising, in combinacarriage for lifting the table above said tra-ck level position.

6. In drop pit apparatus, a carriage, a plurality of upright columns mounted on said carriage, a table supported on said columns, elevator mechanism mounted on said table coacting with means on said carriage for raising and lowering the same between lower and upper limit positions, and other elevator mechanism mounted on Said columns for raising and lowering the table above said upper limit position.

7. In drop pit apparatus, in combination, a carriage, a table, means supporting said table on the carriage, said supporting means being operable to raise and lower the table through a predetermined range of travel, and means including a plurality of hydraulically actuated push rods mounted on said carriage for raising and lowering the table through a different range of travel.

8. Drop pit apparatus comprising, in combination, a carriage, upright columns mounted on said carriage, a table, flexible cables connected to the upper ends of said columns, winding drums `mounted cn said table, said cables being connected to said drums to support the table on said columns, power operated means mounted on said table for driving said drums to wind up and unwind the cables and thus raise and lower the table, and heavy duty elevator mechanism carried by the carriage and adapted to raise and 8` lower said table independently of said cable and drum means.

9. In drop pit apparatus of the character described, in combination, a carriage, a table, means supporting said table on said carriage operable to raise and lower the table through a predetermined range of travel, lifting devices mounted on said carriage, and means carried by said table adapted to provide an operative connection between the table and said lifting devices asthe table approaches the upper end of its predetermined range of travel.

10. In drop pit apparatusof the character described, in combination, a carriage, a table, means'including a vertically movable actuator member supported on the carriage, means supporting said table on said carriage forV movement vertically relative to said actuator member through a predetermined range of travel, a plurality of vertically shiftable hydraulicallyr actuated push rods mounted on saidcarriage, and means operable as the table approaches the upper end of said predetermined range of travel for rendering said'push rods eective for raising vand lowering the table through a range of travel above said predetermined range.

1l. In drop pit Vapparatus of the character described, in combination, a carriage, a table, means supporting said table on said carriage operable to raise and lower the table through a predetermined range of travel, power Vactuated lifting devices mounted on said carriage, members on said table adapted to provide an operative connection between the table and said lifting devices, said members being movable to inactive positions to interrupt said connection, and means for shifting said members to their inactive positions in response to the downward movement of the table. Y

12. In drop pit apparatus of the character described, in combination, a carriage having a plurality of upright columns mounted thereonr an elevator table, means supporting said table on: said columns, said supporting-means being operable to raise and lower the table through a predetermined range of travel, auxiliary table elevating means for raising and lowering the table through a different range of travel including push rods supported on the carriage for movement vertically toward and from the table, said table being operative to clear said push rods when within said predetermined range of travel, and members pivotally supported on said table to swing between the table and the adjacent ends of said push rods whereby to establish an operative connection therebetween, said push rods being nor- `mally spaced from said members to permit the swinging of the members between active and inactive positions.

13. In drop pit apparatus of the character described, in combination, a carriage, an elevator table, means supporting Ysaid table on said carria'ge, said supporting means being operable to raise and lower the table through a predetermined range of travel, auxiliary means for raising and lowering the table through a different range of travel including push rods supported on said carriage for movement vertically toward and from the table, a pressure fluid operated actuator for each push rod, a source of uid underV pressure, and a single valve for controlling the delivery of pressure iluid from said source to each of said actuators. Y

14.,In drop pit apparatus of the character described, in combination, a carriage, a plurality of upright columns on said carriage, a table, means supporting said table on said columns, said means being operable to raise and lower the table through a predetermined range of travel, auxiliary elevator means including a cylinder rigidly secured to each column, a piston in each cylinder, a push rod extending upwardly from each piston along one side of the associated column, means for supplying pressure fluid to the cylinder to shift the piston and associated push rod upwardly, a plurality of abutment members mounted on said table for movement into or out of operative relation to said push rods, and cam means on said columns controlling the movements of said members.

15. In drop pit apparatus of the character described, in combination, a carriage, a plurality of upright columns on said carriage, a table, means supporting said table on said columns, said means being operable to raise and lower the table between lower and upper limit positions, auxiliary table elevating means inclufding an actuator rigidly secured to each column, a push rod extending upwardly from each actuator along one side of the associated column, a plu rality of abutment members pivotally supported on the table and adapted to swing into the paths of the push rods as the table approaches its upper limit position, said push rods being operable through said members to raise the table above said upper limit position, and cam means on said columns operative to swing the members out of the paths of the push rods when the table is lowered from said upper limit position.

16. In drop pit apparatus of the character described, in combination, a carriage, elevator mechanism mounted on said carriage including a plurality of vertically movable push rods, a table movable longitudinally of said push rods and having openings providing clearance for the rods, guide blocks secured to the underside of the table on opposite sides of the openings, said guide blocks having downwardly opening notches CII in their lower faces, and pivotally supported abutment members adapted to swing between the upper ends of the push rods and the associated guide blocks when the table is raised above the push rods, said members having a lost motion connection with the table to permit movement of the members into the notches in said guide blocks upon engagement of the members by the push rods in their upward movement.

17. In drop pit apparatus of the character described, in combination, a carriage, elevator mechanism mounted on said carriage including a plurality of vertically movable push rods, a table movable longitudinally of said push rods and having openings providing clearance for the rods, guide 'blocks secured to the underside of the table on opposite sides of the openings, said guide blocks having downwardly opening notches in their lower faces, abutment members movable between the upper ends of the push rods and the associated guideblocks when the table is raised above the push rods, and means providing a lost motion connection between the table and said members to permit the members to move upwardly with the push rods and engage in said notches, said notches preventing withdrawal of the abutment members while said elevator mechanism is in operation.

CHRISTOPHER H. SCHRAMM. LLOYD H. HOLDEMAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date Re. 16,989 Waters June 5, 1928 1,706,211 Coiey Mar. 19, 1929 1,813,022 Burner July 7, 1931 1,849,972 Blake Mar. 15, 1932 2,111,917 Minty Mar. 22, 1938 2,301,579 Plant Nov. 10, 1942

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