US2520969A - Drop pit apparatus - Google Patents

Description

L H HOLDEMAN 2,520,969

DROP PIT APPARATUS 2 Sheets-Sheet 1 NVENTO Ioqol Q-LQ-(Oidemowy J ff, J.LM;J wM A Qfirrorameaas Sept. 5, 1950 Filed June 21; 1946 2 Sheets-Sheet 2 L. H. HOLDEMAN DROP PIT APPARATUS Sept. 5, 1950 Filed June 21, 1946 Patented Sept. 5, 1950 DROP PIT APPARATUS Lloyd H. Holdeman, Muskegon, Mich., assignor to Manning, Maxwell & Moore, Inc., Muskegon, Mich, a corporation/of New Jersey Application June 21, 1946, Serial No. 678,349

14 Claims.

The invention relates to drop pit apparatus of the type disclosed in my joint application with Christopher H. Schramm, Serial No. 687,348, filed June 21, 1946, and is more particularly concerned with auxiliary elevator mechanism for such apparatus.

One object of the invention is to provide improved drop pit apparatus of the type having separate heavy duty and light duty elevator mechanisms in which the framework of the apparatus is relieved of the thrust and strains resulting from the operation of the heavy duty elevator mechanism.

A more specific object is to provide a dual elevator drop pit apparatus in which the heavy duty elevator mechanism is mounted in-a novel manner adapted to transfer the thrust and strains generated in its operation directly to the foundation structure of the pit, thus permitting the apparatus, particularly the carriage portion thereof, to be made of lightweight construction.

Another object is to provide improved carriage supported elevator mechanism for drop pit apparatus operative to transfer the weight of a supported load directly to the rails of the track upon which the carriage'runs.

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 1 is an end elevational view of drop pit apparatus embodying the features of the invention.

Fig. 2 is a side elevational view of the apparatus.

Fig. 3 is a perspective view of one of the abutment members for providing an operative connection between the elevator table and the auxiliary or heavy duty elevator mechanism.

Fig. 4 is a fragmentary side elevational view showing the elevator table in various positions within the range of the main or light duty elevator mechanism.

Figs. 5, 6 and '7 are fragmentary side elevational views showing the positions of the auxiliary or heavy duty elevator mechanism at different stages of its operation.

While the invention is susceptible of various" modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intendto limit the invention to the specific form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

For purposes of illustration the invention has been shown as incorporated in apparatus for use in a pit l0 which intersects and extends beneath one or more railroad tracks T, commonly called service or repair tracks. To permit a vehicle to be run over the pit for servicing the wheels or trucks, the pit is bridged by one or more drop tables I l provided with track sections Tl adapted to aline with the tracks T as shown in Fig. l. The drop table shown by way of illustration is of the same general type as that disclosed in the Minty Patent No. 2,111,917, granted March 22, 1938, and comprises a rigid generally rectangular frame i2 adapted to be releasably supported in pit bridging position by retractable latch bars l3 engaging ledges I 4 in the side walls of the pit. Suitable mechanism indicated generally at I5 is provided for retracting the latch bars l3 to release the table for raising it or lowering it,

Means is provided for raising and lowering the drop table I! and for transporting it along the pit It? for association with any of the various service and repair tracks in the shop. Such means comprises a carriage l6 having an elevator table i1 supported and guided thereon for move ment vertically. In the exemplary apparatus, the elevator table I? is supported and guided by up right columns 18, preferably in the form of I- beams, extending from a point adjacent the bottom of the pit Hi to a point adjacent the top of the pit. The carriage is fitted with flanged, Wheels i 9 adapted to run on rails 20 forming a track at the bottom of the pit. Suitable means suchas an electric motor M is provided for driv ing the carriage and its load along the rails 20.

For raising and lowering the table l1, two separate elevator mechanisms are provided, each operating in a different range of travel. Thus one elevator mechanism is provided for raising and lowering the table between the track level position shown in Fig. l and the transporting position shown in broken lines in Fig. 4. As this mechanism is only required to handle the weight of the table l1 and its load, the mechanism may be of the light duty high speed type. The other or auxiliary elevator mechanism is arranged for raising and lowering the table through a range of travel above the track level position and in practice is utilized mainly for lifting the end of a vehicle or for compressing the springs of the vehicle to facilitate removal or replacement of a herein shown is of the same general type as that disclosed in the Blake Patent No. 1,849,972 granted March 15, 1932. The mechanism comprises generally a series of flexible cables 2|, preferably in the form of flat wire ropes, by which the table I! is suspended from the upper ends of the columns l8. One of the cables 2! is anchored to each column and is extended over a rounded guide member 22 adjacent the upper end of the column to a drum 23 rotatably mounted on the table ll. Thus by winding the cables 2! on or unwinding them from their respective drums 23, the table may be raised or lowered relative to the carriage 16. Power actuated means including an electric motor Ml isprovided for driving the drums 23.

The heavy duty elevator mechanism preferably includes a plurality of vertically movable actuator members herein shown as push rods 25 supported and guided for movement vertically relative to the carriage It. In the exemplary apparatus four such push rods are provided, one adjacent each of the columns l8 and within the area defined by the table II. Guide members 26 rigid-with the columns l8 confine the push rods and guide them in their vertical movements. Suitable openings in the table provide clearance fOr the push rods when the table is being traversed by the light duty elevator mechanism so that the table may descend below the upper ends of the push rods. Thus the auxiliary or heavy duty elevator mechanism is normally inefiective for raising'or lowering the table but suitable means is provided for operatively connecting the push rods and'the table to render themechanism effective as will appear presently.

Power driven means of any preferred character may be utilized for actuating the push rods 25 to raise or lower the table l1. As herein shown, each push rod is provided with an individual actuator of the hydraulic type comprising a piston 27 (Fig. 6) working in a cylinder 28 and having a piston rod 29 abutting the lower end of the push rod 25. Pressur fluid from any suitable source is supplied to the lower end of the cylinder through a duct 33 to shift the piston and push rod upwardly, the push rod and elements associated with it descending by gravity when the duct 33 is disconnected from the fluid source and opened to drain the fluid from the cylinder 28.

, In accordance with the present invention, the push rod actuators are mounted on the carriage H in a novel manner so as to transfer the lifting thrust of the push rods directly to the founda tion structure of the pit without interfering with the normal movements of the carriage along the pit tracks. For this purposethe actuator cylinders 28 are mounted substantially in alinement with the rails 20 of the pit tracks and are normally supportedin spaced relation thereto but permitted to move into engagement with the rails when th associated push rods engage the table H. The actuator cylinders are guided in this movement by sleeve members 3| rigidly secured to the columns I8 in axial alinement with the push rods 25, the sleeve members being dimensioned to receive the cylinders with a slidingfit.

.Depending from each actuator cylinder 28 is a plunger 32 carrying at its lower end a channel-shaped shoe 33 adapted for engagement with the face of the rail 20. As herein shown, the cylinder 28 is provided at its lower end with a pair of apertured lugs 34 spaced apart to receive 4 an apertured tongue 35 formed on the upper end of the plunger 32 and the parts are secured together by a pin 36 inserted through the apertures in the lugs and tongue. Cross members 31 and 38 welded or otherwise rigidly secured between th flanges of the columns I8 are apertured for the reception of the plungers 32 and serve to maintain them substantially in axial alinement with their associated cylinders and push rods.

In order to prevent the shoes 33 from dragging on the rails 20 when the carriage is being moved along the pit, the actuator cylinders 28 and associated elements are normally supported with the shoes 33 spaced from the rails, the supporting means being arranged to permit downward movement of the cylinders under the thrust exerted by the rods 25 until such movement is blocked byv engagement of the shoes 33 with the rails. The supporting means may conveniently comprise coiled compression springs 33 encircling the plungers 32 and interposed between the cross members 31 and a collar 4| rigid with each plunger. The springs 40 normally maintain the pushrods 25 and their actuators in a raised position as shown in Fig. 5 with the shoes 33 spaced upwardly from and clear of the rails 23. When a load is imposed on the push rod by operation of the actuator, the spring yields and permits the cylinder 28 and plunger 32 to descend until the shoe 33 rests on the rails 23. Further descent of the actuator is thus blocked and the thrust of the push rod against the table is transmitted directly to the foundation structure of the pit through the rail 20. l

As explained heretofore, the elevator table 11 is construetedand arranged so as to clear the push rods 25. while the table is being raised orlowered by the light duty elevator mechanism and means is provided for disengageably connecting the push rods with the table to render the heavy duty elevator mechanism effective. The connecting means as, herein shown comprises a series of shiftable abutment members 45 carried by the table I! and adapted to be interposed between the framework of the table and the adjacent ends of the push rods. 7

Referring to Figs. 3, 5 and 6 of the drawings, the abutment members 45 preferably comprise elongated flat steel bars supported on the table for-movement into or out of the paths of the push rods 25. In the exemplary apparatus, the members are supported for swinging movement by a pair of laterally projecting arms 36 spaced apart longitudinally of the member to straddle one of the beamsconstituting the framework of the table. At theirouter ends the arms 33 are formed with elongated apertures 31 for the reception of pins 48 carried by the table il.

Mounted on the underside ofthe table i? above each of the abutment members 45 are a pair of guide blocks 50 having downwardly facing rectangular notches 5| (Fig. 4) dimensioned for the reception of the abutment member and substan-.

tially alined with the axis of the push rod 25. As will be seen by reference to Fig. 3 of, the drawings, the upper end portions of the arms 46 are inclined so as to overlie the abutment member 45 and the apertures 41 are alined in a common vertical plane with the notches 5|, the central axis of the abutment member, and the'associ'ated push rod 25. Accordingly. when unrestrained, the abutment'members automatically swing between the guide blocks 50 and the adjacent ends of their associated push rods inalinement with the notches 41.

By reason of the lost motion connection provided by the pins 48 and elongated slots 41, the abutment members are enabled to swing below the guide blocks 56 and over the push rods 25 when the table I'i is supported in track level position and the heavy duty elevator mechanism is inactive. Upon actuation of the push rods, the abutment members move upwardly therewith to enter the notches 51 which prevents any lateral movement of the members and thus precludes accidental disengagement of the connection between the push rods and the table. When the members engage the guide blocks 56 the thrust of the push rods is transmitted to the table to raise it above the track level position as shown in Fig. 7. As explained before, initial engagement of the push rods with the abutment members imposes a load upon the push rods which shifts the actuator cylinders 28 downwardly until blocked by engagement of the shoes 33 with the rails 26. Thus the thrust of the push rods required for raising the table ll is transmitted directly to the rails 26 and through the rails to the foundation structure of the pit.

Upon retraction of the push rods 25 the table I! descends until the slack. is taken up in the cables 2| of the light duty elevator mechanism which then supports the table at track level. As the push rods are further retracted to their idle positions the abutment members as drop out of the notches 5| and hang freely from the pins d8 substantially below the guide blocks Further lowering of the table from the track level is assumed by the light duty elevator as before explained.

Provision is made for swinging the abutment members 45 into or out of operative position automatically in accordance with the position of the table ll. As herein shown, the means provided for that purpose comprises cams 5'2 formed on the flanges of or carried by the columns 18 and positioned for cooperation with follower rollers 53 mounted on the arms 46 supporting the abutment members. The active surfaces of the cams 52 are shaped so as to allow the abutment members to swing into the operative position as the table approaches track level position and to swing the members outwardly to the position shown in Fig. l as the table is lowered from the track level position. The cam surface may also be formed so as to swing the abutment member outwardly a further amount as shown in broken lines in Fig. 4, so as to clear the cylinder 28 when the table I! is lowered to rest on the carriage. Thus the abutment members are shifted into or out of operative position and the heavy duty elevator mechanism is rendered effective or ineffective automatically in response to the movements of the table within the range of travel provided by the light duty elevator mechanism.

It will be apparent from the foregoing that the invention provides drop pit apparatus of a novel and advantageous character capable of performing its varied functions with a high degree of eihciency. Raising and lowering of the elevator table through its normal range of travel is effective by high speed light duty elevator mechanism while the heavy thrust required for raising the end of a vehicle or for compressing the vehicle springs is supplied auxiliary heavy duty elevator mechanism. Moreover, the thrust of the heavy duty mechanism is transmitted directly to the foundation structure of the pit, thus relieving the carriage and its supporting wheels and axles of the heaviest stresses and anism operable to raise and lower the table through a difierent range of travel, said other elevator mechanism being mounted on said carriage for movement into engagement with the tableand; with said rails whereby to transfer the weight of the table and its load directly to the rails.

2. In drop pit apparatus of the character described, in combination, a carriage, rails provid.

ing a track for said carriage, a table, means sup,- porting and guiding said table on said carriage for movement vertically, said supporting means including elevator mechanism operable to raise and lower the table through a predetermined range of travel, other elevator mechanism en.-

gageable with the table and operable to raise and lower it through a different range of travel, means supporting said other elevator mechanism on the carriage for movement toward and from the rails whereby to transfer the weight of the table'and its load directly to the rails, and means for maintaining said other elevator mechanism clear of the rails when the said other mechanism is inactive.

3. In drop pit apparatus of the character described, in combination, a carriage, rails providing a track for said carriage, a table, means sup.- porting and guiding said table on said carriage for movement vertically, said supporting means including elevator mechanism operable to raise and lower the table through a predetermined range of travel, other elevator mechanism operable to raise and lower the table through .a different range of travel, said other elevator 111C011.-

anism including a plurality of members movable vertically into engagement with the table, an actuator for each member, and means for supporting said actuators on said carriage with each substantially in alinement with one of said rails and in spaced relation thereto, said supporting means permitting said actuators to move into engagement with the alined rail when said member engages the table.

4. In drop pit apparatus of the character deescribed, in combination, a carriage, rails providing a track for said carriage, a table, means supporting and guiding said table on said carriage for movement vertically, said supporting .means including elevator mechanism operable to raise. and lower the table through a predetermined range of travel, other elevator mechanism en.- gagea'bl'e with the table and operable to raise and lower it through adifferent range of travel, means supporting said other elevator mechanism on the carriage for movement toward and from the rails,

and spring means urging the mechanism away from said rails, said spring means yielding to per.- mit the mechanism to move into engagement with the rails when operated to raise said table where.- by to transfer the weight of the table directly to the rails.

5. In drop pit apparatus of the character ,d'e-

scribed-in combination, a carriage, rails providing a track for said carriage, a table, means supporting and guiding said table on said carriage for movement vertically, said supporting means including elevator mechanism operable to' raise and lower the table through a predetermined range of travel, other elevator mechanism operable to raise and lower the table through a difierent range of travel, said other elevator mechanism including a plurality of members movable vertically to exert a lifting thrust against the table, an actuator for each member, means supporting each of said actuators on said carriage substantially in alinement with one of said rails for movement toward and from the rail, said supporting means being normally operative to hold said actuators in spaced relation to the rails and to permit movement of the same into engagement with the rails by the thrust exerted by said members against the table. r l

6. In drop pit apparatus of the characterdescribed, in combination, a carriage, rails providing a track for said carriage, an elevator table, means supporting and uiding said table on said carriage for movement vertically, said supporting means being operable to raise and lower the table through a predetermined range of travel, auxiliary table elevating means including a plurality of push rods disposed below said table and movable endwise toward and from the table, means,

for operatively connecting said push rods with the table, an actuator operatively connected with each push rod, a plunger depending from each actuator, means supporting each actuator on said carriage with its associated plunger substantially alined with one of said rails, and spring means yieldably urging said plungers away from said rails, said actuators and said plungers moving downwardly against the action of said spring means upon engagement ofthe push rods with said table whereby to transmit the thrust of the push rods to said rails.

' 7. In drop pit apparatus of the character described, in combination, a carriage, rails providing a track for said carriage, an elevator table, means supporting and guiding said table on said carriage for movement vertically, said supporting means being operable to raise and lower the table through a predetermined range of travel, auxiliary table elevating means including a plurality of push rods disposed below said table and movable endwis-e toward and from the table, means for operatively connecting the push rods with the table, an actuator for each push rod including a cylinder, a piston in each cylinder operatively connected with the associated push rod, means for supplying pressure fluid to said cylinder for shifting said piston and the associated push rod toward said table, a plunger depending from said cylinder, a plurality of guide sleeves on said carriage each supporting and guiding one of said cylinders for movement toward and from one of said rails, spring means acting on each plunger to yieldably urg the same away from the adja cent rail, and a rail engaging shoe carried by each plunger, said actuators and plungers being shifted downwardly against the action of said spring means when said push rods engage the table whereby to transmit the thrust of the rods,

through'said shoes to said rails.

8. In drop pit apparatus of the character described, in combination, a carriage, rails providing atrack for said carriage, a plurality of upright columns on said carriage, an elevator table, means supporting said table on said columns, said supporting means being operable to raise and is lower the table through a predetermined range of travel, auxiliary table elevating means including a plurality of push rods each extending longitudinally of one of the columns and guided thereon for movement vertically toward and from the table, means for operatively connecting the push rods with the table, an actuator for each push rod, means supporting said actuators on said columns substantially in alinement with said rails, a rail engaging shoe secured to each actuator, and spring means normally urging said actuators upwardly to maintain the associated shoes clear of the rails, said sprin means yielding upon engagement of the push rods with the table to permit the actuator shoes to move into engagement with the rails to transmit the thrust of the push rods thereto.

9. In drop pit apparatus of the character described, in combination, a carriage, rails providing a track for said carriage, a plurality of upright columns on said carriage, 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 elevatin means including a plurality of push rods each extending longitudinally of one of the columns and guided thereon for movement vertically toward and from the table, means for operatively connecting the push rods with the table, an actuator for each pushrod, means supporting said actuators on the columns substantially in alinement with said rails for yielding movement upon engagement of the table by the associated push rods, and a shoe operatively associated with each actuator engageable with the alined rail for transferring the thrust of the push rod against the table to the rail.

10. In apparatus for use in a pit intersecting and extending beneath-a service track, rails extending along said pit, a carriage adapted to run on said rails, a table, means supporting said table on said columns including light duty elevator mechanism operable to raise the table from a travelling position in the pit to the level of the service track, heavy duty elevator mechanism carried by said columns and engageable with said 7 table for raising it above the level of the service track, said heavy duty mechanism being engageable directly with said rails and operative to support the weight of the table and its load thereon independently of said carriage and said columns, and means for maintaining said heavy duty mechanism out of engagement with the rails when it is inactive.

11. In apparatus for use in a pit intersecting and extending beneath a service track, rails extending along said pit, a carriage adapted to run on said rails, a table, means supporting said table on said columns including light duty elevator mechanism operable to raise the table from a travelling position in the pit to the level of the service track, and heavy duty elevator mechanism carried by said columns and engageable with said table for raising it above the level of the service track, said heavy duty mechanism being engageable directly with said rails and operative to support the weight of the table and its load thereon independently of said carriage and said columns. 7

12. In apparatus for use in a pit intersecting and extending beneath a service track and having rails providing a track extending transversely of the service track, a table adapted to be releasably latched in position to bridge the pit and to carry a section of tracl alined with the service;

track, means for raising and lowering said table and for transporting it alon said pit including a carriage mounted 0n said transversely extending track, a plurality of vertically movable power operated lifting devices mounted on said carriage and engageable with said table for raising and lowering it, each of said devices having at its lower end a shoe movable relative to the carriage into or out of engagement with the adjacent rail of the transversely extending track and normally supported out of engagement with said adjacent rail to permit free movement of the carriage on the rails of said transversely-extending track, and said lifting devices when operated in a direction to raise the table acting to shift the shoes relative to the carriage into engagement with the adjacent rails of said transversely extending track so that the load on said devices is trans mitted directly to said rails.

13. In apparatus for use in a pit intersecting and extending beneath a service track and having a pair of rails extending along the pit transversely of the service track, a wheeled carriage running on said rails, power operated load lifting devices supported on said carriage for movement 4 into engagement with a load to be lifted, said devices being alined with the respective rails, and a shoe for each device movable relative to said carriage but normally supported in spaced relation to the rails when said lifting devices are idle to permit said carriage to run freely on said rails, said devices when operated in a load raising direction acting to shift said shoes relative to the carriage and into engagement with said rails so as to support the load on said devices directly on the rails.

14. In apparatus for use in a pit intersecting and extending beneath a service track and havin a pair of rails extending along said pit transversely of the service track, load supporting means including a wheeled carriage adapted to run on said rails, a plurality of lifting devices on said wheeled carriage movable into engagement with a load to be lifted, each of said devices having a rail engaging part, said devices when operated in a load raising direction acting to shift said rail engaging parts relative to the carriage and into engagement with the rails to support the load directly on said rails.

LLOYD H. HOLDEMAN.

REFERENCES CITED UNITED STATES PATENTS Name Date Coffey June 1, 1926 Number

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