Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.


  1. Advanced Patent Search
Publication numberUS3434738 A
Publication typeGrant
Publication dateMar 25, 1969
Filing dateJun 1, 1967
Priority dateJun 1, 1967
Also published asDE1630248A1
Publication numberUS 3434738 A, US 3434738A, US-A-3434738, US3434738 A, US3434738A
InventorsCampbell Trevor G, Coogan Lawrence P, Hosoda Yoshimi
Original AssigneeCaterpillar Tractor Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Push-pull coupling for tractor-scraper units
US 3434738 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

March 25, 1969 T. G. CAMPBELL ETAL 3,434,738


N 9E N S N l'l] S I N "fn K L() 4 L v o, Lrm Lf) Y" fr Y@ N (.0 \..-r M W N .m nl @D A INVENTORS. ff) TRENOR (I CAMPBELL Aw RENQE. P Cooq-AN YOSHINH HOSODA March 25, 1969 T. G. CAMPBELL. ETAL 3,434,738

PUSH-PULL COUPLING FOR TRACTOR-SCRAPER UNITS Filed June 1, 1967 sheet ve2 of 2 im E .15.. E

Ol Z ,l 0 2 H 47 Q y l i 1@ ,f 2.5 ,Z/f 3a 45 53 54 j@ L-6 INVENTORS. TREVOR Gr. CAMPBELL LAWRENCE P. CoocTAN Yosn-nwn HOSODA United States Patent O 3,434,733 PUSH-PULL CoUPLING nog: TaACToR-SCRAPER UNIT U.S. Cl. 280-477 Claims ABSTRACT OF THE DISCLOSURE Push-pull coupling for tandem earthmoving scrapers where the coupling may be rapidly connected or disconnected permitting the Scrapers to operate either in unison or separately. A push block and pull hook are mounted on the rear of the forward scraper. A p-ush block and means for engaging the hook are mounted on the front of a rearw-ard scraper. The means for engaging the hook are raised and lowered by a scraper operator through a hydraulic jack for rapid engagement or disengagement with the hook of the forward scraper.

Cross-reference to related patents U.S. Patent No. 3,290,806 entitled Controls for Tandem Operated Earthmoving Scrapers, issued Dec. 13, 1966 to R. A. Peterson and assigned to the assignee of the present invention.

Background of the invention The present invention relates to a push-pull coupling for earthmoving scraper units and more particularly to a coupling having means for rapid connection and disconnection o the coupling whereby the Scrapers may operate intermittently either in tandem or as separate units.

Tractor-Scrapers of a type which do not have elevators but rather are loaded according to their forward motion generally do not have suiiicient power for efficient selfloading. For purposes of an increased loading rate, it is common to employ a pusher tractor to provide additional power during loading of the scraper. However, this method of loading has been at least partly undesirable since it requires the use of additional units during loading and detracts from overall operating efficiency during an earthmoving operation.

A more recent solution to this problem has been the employment of permanently-coupled multiple scraper units which may also include unitized controls to permit operation by a single operator. Such an arrangement is described in U.S. Patent No. 3,290,806 referred to above, and has some disadvantages which are overcome by the present invention.

Summary of the invention The present invention provides a push-pull coupling between selfpowered vehicles wherein the coupling includes means for rapid connection or disconnection such that the vehicles may operate intermittently either in coupled relation or as independent units.

Brief description of the drawings FIG. l is a side view in elevation of the present pushpull coupling employed between two Scrapers;

FIG. 2 is a side view in elevation of the push-pull coupling with the parts illustrated in pulling relation;

FIG. 3 is a side view in elevation of the push-pull coupling with parts in pushing relation; and

FIG. 4 is a plan view of the coupling with parts shown in section.

Description of the preferred embodiment The present invention is described below ith particular reference to a pair of two engine Scrapers wherein the present push-pull coupling may be advantageously utilized. However, it will be apparent from the description that the push-pull coupling may also be employed with single engine Scrapers or with other vehicles which are to be intermittently used individually as well as in a pushpull tandem relation.

A forward scraper 11 and a rearward. scraper 12 are illustrated in FIG. l in an arrangement suitable for tandem operation. A push-pull coupling, generally illustrated at 13, is disposed between the rear of the forward scraper and the front of the rearward scraper. The coupling has a portion 14 disposable at the rear of the forward scraper which comprises a push block 16 and a pulling hook 17. The coupling also has a portion 13 disposed upon the front of the rearward scraper including a push block assembly 19 and a moveable means or bail 21 to engage the pulling hook 17. An operator of one of the tractors, preferably the rear tractor, controls the position of the bail 21 between its engaged and disengaged relation with the pulling hook through suitable means such as the hydraulic jack indicated at 22.

Having particular reference to FIGS. 2, 3 and 4, the coupling portion disposed at the rear of the forward scraper is mounted on its rearwardly extending framework 23 which has a usual push block 24 mounted thereon. The additional push block structure 16, permitting better cooperation with the other coupling components, is aixed to the standard push block 24. The pulling hook 17 is welded to a pair of forwardly diverging braces 27 and a downwardly extending member 28. The braces are pinned to the scraper framework at 29 while the downwardly extending member is bolted to the push block` at 31. The braces have cross-pieces 32 and 331 welded thereto to provide structural reinforcement. Thus, although standard pushers may be employed with the coupling portion 14 if necessary, the pulling hook and its supporting members may be readily removed if the forward scraper is to be employed with, for example, a standard pusher tractor for extended periods of time.

The rear coupling portion 18 is mounted at the forward end of main frame members 34 of the rearward tractor by means of forward extending brackets 36 which are bolted thereto. The bail 21 for engaging the forward pulling hook is preferably angular and is pivotally connected to each of the brackets 36 by means of pins 37. The hydraulic jack 22, which is operable by the rearward tractor operator, is pivotally connected to the rear tractor frame at 38 and has its rod 39 pivotally connected to an offset tab 41 of the bail adjacent one of its pivotal connections with the tractor frame. The triangulated support members 27 of the forward coupling portion cooperate with the angular bail to guide it into engaging relation with the pulling hook 17.

To support the rear push block assembly 19, a support member 42 (FIG. 4) is disposed transversely between the brackets 36 which are bolted to the tractor frame. Two pairs of push block brackets 43 and i4 extend forwardly and generally upwardly from the support member 42. The rear push block comprises a gate assembly i6 which is pivotally secured to each of the bracket pairs by means of a ball joint, one of which is shown at 47. To take up shock due to Contact of the front push block 16 by the rear push block i9, two conventional spring groups 48 comprising a plurality of interconnected resilient pads 49 are pivotally supported as at Sil by brackets 51 which are secured to the rear surface of the push block gate 46. Each spring group extends rearwardly to be bolted to the support member d2 by means of bolts SZ. A bar 53 extends laterally through the push block gate assembly i6 and projects outwardly a short distance on either side thereof. This bar adds strength to the gate assembly and provides a down stop for the bail 2l to prevent it from being nosed into the ground at any time. A resilient stop block Sli is provided on each of the bracket pairs 43 and 44 to provide a positive rearward limit for pivotal motion of the gate assembly 46.

Numerous advantages of the present invention arc readily apparent from a consideration of the operation of a pair of tractor-scrapers employing the present push-pull coupling. As the scrapers enter a borrow pit or other loading area, the rearward tractor approaches the forward scraper with the bail raised by retraction of the hydraulic jack to a position illustrated in FIG. 3 and contact of the front scraper push block 16 is made by the resilient push block t6 of the rear scraper. The rear scraper can approach the forward scraper slightly askew and not appreciably interfere with or atleet the initial pusher operation. Due to the reduction of shock through the use of the resilient push block, the contact can be made with differential speeds of up to approximately four miles per hour with no resulting damage to either of the tractor-Scrapers. lt is to be noted, however, that generally straight alignment of the two tractor-Scrapers is recommended during contact. At this point of the operation, the tractive effort of the front scraper, in combination with the empty rear unit, will quickly and economically load the front scraper bowl.

As the front scraper is loaded and its tractive power thus increased by the added weight, its tractive effort is contributed to the rear unit for loading thereof. To accomplish loading of the rear unit, the bail is lowered, preferably during the prior push operation, into engagement with the pulling hook by the tractor operator causing extension of the hydraulic jack 22 whereupon the bail is lowered over the pulling hook and into contact with the forwardly extending support members 27. Since the coupling portions are in pushing relation as illustrated in FIG. 4, the bail rests upon the support members 27; and as the speed of the forward scraper is increased relative to the rear scraper, the bail rides on the support members 27 and is thus guided into positive engagement with the pulling hook whereupon the coupling portions are in pulling relation as illustrated in FIG. 2. rl`he tractive effort of the front tractor, which has been greatly increased by the added weight in its scraper bowl, can then assist the rear unit in loading of its scraper bowl. This manner of loading, which was described in more detail in US. Patent No. 3,290,806, has been proven by tests to reduce loading time, in some instances, to the point where both Scrapers can be loaded in essentially the same time that each separate unit could be loaded.

Additional advantages of the present invention are provided primarily through the ability of the coupling to be rapidly engaged and disengaged whereby the two scraper units may cooperate in a tandem relation or may be disengaged during normal operation to permit the two units to operate as separate self-contained units. For example, if there is a breakdown in either scraper, the other scraper may simply continue in operation by itself or in combination with still another scraper unitl provided with the present coupling. Also, the ability to separate the two scraper units during operation permits greater maneuverability of the units as they leave the borrow pit or loading area and travel to an unloading site. Still further, since an operator is controlling each scraper unit during its tandem operation with another unit, proper control of each scraper is provided to increase overall operating efficiency.

Although the invention has been described with a single push-pull coupling 13 disposed between a pair of Scrapers, it would be desirable for most efficient operation to have each scraper equipped with a rear coupling portion 14 as well as a forward coupling portion 18 for interchangeability of a plurality of Scrapers to provide tandem pushpull units. Still further, the invention was described with cushioning means provided only in the push block assembly disposed at the front of the rearward tractor. However, to provide for shock occurring in all operating relations of the coupling and to permit better cooperation between the coupling portions and the tandem vehicles, it may also be desirable to provide shock absorbing means in the push block at the rear of the forward tractor as well as in either the pulling hook assembly or the bail which is to be engaged therewith.

What is claimed is:

1. A push-pull coupling for disposition between a tandem combination of self-powered vehicles and providing for selective coupling and uncoupling of the vehicles while traveling at normal operating speeds comprising:

a coupling portion arranged on the front of one vchicle and including a forwardly facing push block, a pivotal bail formed with two elongated members which are mechanically secured to a frame member of the one vehicle and extend forwardly in angularly closing relation, and means for controlling the pivotal position of the bail, the control means being disposed for regulation by an operator of one of the vehicles, and

another coupling portion arranged at the rear of the other vehicle, the other coupling portion including a rearwardly facing push block to generally mate with the forwardly facing push block to permit pushing of the other vehicle by the one vehicle, and hook means for engagement by the bail to permit pulling of the one vehicle by the other vehicle, the hook means being supported by a structure secured to a frame member of the other vehicle, the support structure including a triangular guide member diverging forwardly from the hook and another member arranged to form a vertical extension of the rearwardly facing push block, one of the push blocks including shock absorbing means to absorb shock caused by contact between said coupling portions during travel of the two vehicles.

2. The invention of claim l wherein the vehicles are of the earthmoving type, the support structure for the hook of the other coupling portion being pivoted to the frame of the other vehicle and including means for maintaining the support structure in pivoted relation adjacent the rearwardly facing push block.

3. The invention of claim 1 where the vehicles are earthmoving scrapers and wherein the forwardly facing push block is formed by a gate portion pivotally connected to framework of the rear tractor and the shock absorbing means comprises cushioning means disposed between the pivotal push block gate and the rear tractor framework to absorb shock resulting from Contact between said push blocks.

4. The invention of claim .l wherein said control means is a hydraulic jack interconnected between said rear trac- 5 6 tor and said pivotal bail, said hydraulic jack being op- 2,587,208 2/ 1952 Peterson 280-481 X erable from the rear tractor to control the pivotal posi- 2,674,815 4/1954 Adams 37-126 tion of the bail. 2,788,999 4/ 1957 Fryer 280-481 5. The invention of claim 1 further comprising a me- 2,986,827 6/ 1961 Peterson 37-144 chanical stop disposed in the coupling portion of the one 5 3,079,176 2/ 1963 Duke et al 280--481 vehicle for interaction with the pivotal bail to limit its 3,243,203 3/ 1966 Hermiz et al 280-481 downward motion and prevent it from nosing into the 3,290,806 12/ 1966 Peterson 37-129 ground particularly when the rearward vehicle is operating independently, LEO FRIAGLIA, Primary Examiner.

References Cited 10 US' CL XR' UNITED STATES PATENTS 37 126, 129; 280481, 490 1,807,379 5/1931 Burrows 280-477 2,529,159 11/1950 Hyler 280-479

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US1807379 *Sep 17, 1926May 26, 1931Clark Tructractor CoDraft coupling for tractors and trailers
US2529159 *Oct 24, 1946Nov 7, 1950Plant Choate Mfg Co IncEarth-moving equipment
US2587208 *Oct 13, 1950Feb 26, 1952Louis L PetersonVehicle coupling
US2674815 *Aug 20, 1949Apr 13, 1954Gen Motors CorpBowl and apron control for carry type scrapers
US2788999 *Apr 23, 1952Apr 16, 1957Gen Motors CorpPusher bumper for lever type scraper
US2986827 *Apr 10, 1958Jun 6, 1961Caterpillar Tractor CoBulldozer for tandem push loading
US3079176 *Jan 3, 1961Feb 26, 1963Int Harvester CoPush bumper for vehicles
US3243203 *Aug 29, 1963Mar 29, 1966Int Harvester CoCushion bumper for vehicle
US3290806 *Dec 2, 1964Dec 13, 1966Caterpillar Tractor CoControls for tandem operated earthmoving scrapers
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3740080 *Nov 10, 1971Jun 19, 1973Gen Motors CorpCushioned hook for a push-pull type vehicle coupling
US3847416 *Nov 2, 1973Nov 12, 1974Caterpillar Tractor CoHydraulic control circuit with remotely controlled dual pressure relief valve
US3906613 *Oct 25, 1974Sep 23, 1975Caterpillar Tractor CoMethod of installing a push-pull coupling on a scraper vehicle
US3977699 *Jun 9, 1975Aug 31, 1976Kabushiki Kaisha Komatsu SeisakushoShock-absorbing push-pull coupling for tandem scrapers
US3997275 *Mar 25, 1976Dec 14, 1976Caterpillar Tractor Co.Force transmitting connection
US4025086 *Oct 31, 1975May 24, 1977Caterpillar Tractor Co.Push block assembly with shear load transmitting means
US4078820 *Oct 29, 1976Mar 14, 1978Caterpillar Tractor Co.Bail for push-pull scraper
US4166633 *Jan 30, 1978Sep 4, 1979Fiat-Allis Construction Machinery, Inc.Coupling hook for pulling vehicles
US4266798 *Feb 14, 1979May 12, 1981Caterpillar Tractor Co.Push-pull coupling for power scrapers
US5382042 *Nov 15, 1993Jan 17, 1995Mcphee; Steven J.Towing device support
US7937858Nov 21, 2008May 10, 2011Caterpillar Inc.Hitch assembly and tractor scraper using same
U.S. Classification280/477, 280/481, 280/490.1, 37/418
International ClassificationB60D1/04, B62D49/04, B60D1/00, B62D49/00
Cooperative ClassificationB60D1/04, B62D49/04
European ClassificationB62D49/04, B60D1/04