GB2161768A

GB2161768A - Driving trailer wheels from tractor rear wheels

Info

Publication number: GB2161768A
Application number: GB08516292A
Authority: GB
Inventors: Peter Woof
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-06-28
Filing date: 1985-06-27
Publication date: 1986-01-22
Also published as: GB8516292D0

Abstract

A coupling for use between an agricultural tractor and a trailer, the trailer having driven wheels, comprises a frame 62 carrying wheels 33 connected by a differential 30, gear box 85 and output shaft 75 to transmission 29a, 28 and thence the trailer wheels. The frame 62 is carried on lower links 34 of the tractor 3-point linkage, and a ram 40 can move the wheels 33 into engagement with the rear wheels of the tractor to drive the wheels 33 and thus the trailer wheels. The trailer can take the form of an agricultural implement having driven wheels. <IMAGE>

Description

SPECIFICATION Improvements in or relating to trailers and couplings therefor This invention relates to trailers and couplings therefor and is particularly, though not exclusively, concerned with agricultural trailers and couplings therefor.

According to one aspect of the invention a coupling unit for coupling a tractor and a trailer, the trailer having a driven axle, comprises a support adapted to be pivotally connected to lower links of a tractor 3-point linkage, wheels carried by said support and connected to a drive mechanism, a ram pivotally connected to the support and adapted to be pivotally connected to a tractor, so that in use operation of the ram moves the wheels into engagement with wheels of the tractor to drive the trailer wheels through the drive mechanism.

The ram may be pivoted to a bracket adapted to be secured to a lower link of a 3-point linkage.

The drive mechanism may comprise a differential connected to axles carrying the coupling wheels.

There may be means operably connected between the coupling wheels and the lower links for maintaining an output shaft of the drive mechanism in a desired orientation during movement of the coupling wheels into engagement with the tractor wheels.

Said means may comprise a strut pivotally mounted with respect to the axle housings and the lower links.

The differential may have an output shaft in use extending towards the tractor, a gear box connected to the differential output shaft, and a coupling output shaft connected to the gear box and in use extending away from the tractor.

From another aspect of the invention a trailer comprises a body, ground engaging wheels, and means for driving the wheels, said driving means comprising means adapted to be connected to a wheeled tractor device so as to engage the wheels of the tractor device and thus drive the trailer wheels.

The driving means may comprise a frame adapted to be pivotally connected to a tractor, wheels rotatably carried by the frame, means for moving the frame to bring the wheels into contact with wheels of the tractor, and a transmission operably connecting the frame wheels and the trailer wheels.

The moving means may comprise a ram pivoted to the frame and adapted to be pivoted to the tractor.

The ram may be pivoted to a bracket adapted to be attached to a lower link of a tractor 3 point linkage.

The frame wheels may be connected to a differential carried by the frame, said transmission comprising a trailer differential to which the trailer wheels are connected, and said transmission comprising means operatively connecting the differentials. The connecting means may comprise relatively axially movable parts connected to the frame differential and the trailer differential and the trailer differential through universal couplings.

The frame may be pivotally connected to the tractor by links forming lower links of a three-point linkage.

The trailer may have a draw bar connectable to the tractor and rotatable about a vertical axis relative to the trailer body.

The invention also includes a combination of a tractor device and a trailer as above.

The combination may include a hydraulic circuit comprising said ram and a source of liquid under pressure, and a manually operable valve for controlling the energizing of the ram.

The invention includes a tractor connected to a said coupling and also a tractor connected to a said trailer.

The invention includes tractor-trailer combination including a coupling between the tractor and trailer and movable into engagement with wheels of the tractor for driving wheels of the trailer.

The invention may be performed in various ways and some specific embodiments with possible modifications will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a side view of a tractor and trailer with part removed; Figure 2 is a perspective view of part of Figure 1; Figure 3 is a plan view of Figure 1; Figure 4 is a hydraulic circuit; Figure 5 is a perspective view similar to Figure 2 of another embodiment; Figure 6 is a schematic side view of a coupling; Figure 7 is a rearward view of Figure 6; Figures 8 to 11 schematically show use of the coupling of Figures 6 and 7; Figure 12 is a side view of another arrangement; Figure 13 is a plan view of Figure 12; and Figure 14 is a perspective view of part of Figure 12.

Referring to Figures 1 to 3, a trailer arrangement 10 comprises a trailer 11 having rear ground wheels 12 rotatable on half axles 13, 14 connected to a central differential 15. The axles 13, 14 are rotatable in housings connected via a resilient suspension 16 to a body 17 of the trailer. The rear end 18 of a draw-bar 19 is fixed to the trailer body and at the front has an eye 21 for releasable connection to a conventional hitch 22 of a tractor 23, in the case shown an agricultural tractor having rear wheels 43 and front wheels 43a. The rear end of the drawbar could be pivoted at 20 to the body 17 about a vertical axis and in this case the trailer would normally have front wheels also.

A transmission rod 24 is operably connected at its rear end through a universal coupling to the differential 15 and at the front is supported from the trailer body by a yoke 25 and is connected via universal coupling 26 one part 27 of a sliding yoke drive telescopic coupler the other part 28 of which is connected to a universal coupling 29 to which is connected the output of a differential 30. The parts 27, 28 are relatively axially movable and are keyed together so as to rotate together.

The differential 30 is operably connected to half axles in housings 31 supported by yokes 35 in a frame 32. The half axles are connected to wheels 33. Opposite sides of the frame 32 are pivotally connected at 36 to links 34 pivoted to the tractor 37 and forming part of the conventional 3-point linkage of the tractor. The top link of the 3-point linkage is omitted and replaced by a hydraulic ram 40 whose piston is pivoted at 41 to the frame 32 and whose cylinder is pivoted at 42 to the tractor.

The wheels 33 are normally clear of the driven tractor rear wheels 43 and the trailer 11 is pulled in the usual way. However the ram 40 can be energized to pivot the frame 32 clockwise as seen in Figure 1 to bring the wheels 33 into respective engagement with wheels 43 (as shown in Figure 1 in chain-dotted line). In this position the wheels 33 are driven by frictional engagement with the tractor wheels 43 and this in turn drives the trailer wheels 12 via differential 30, coupling 29, parts 27, 28, coupling 26, transmission rod 24, and differential 15.

The ram 40 is in a hydraulic circuit (Figure 4) including a pump 50 driven by the tractor engine and connected via line 51 to drive conventional tractor hydraulics as indicated at 52. The line 51 in this case is connected to a manually operable flow control valve 53 mounted on the dashboard so that opening of valve 53 energizes the ram 40 to drive the trailer wheels 12. The input line 40a to the ram 40 would be coupled to one of the normally available hydraulic couplings on a tractor.

Thus as desired, for example in the case of a heavy load on the trailer and in slippery conditions e.g. a ploughed field, the valve 53 can be opened to drive the trailer wheels.

The diameter of wheels 33 may for example be 18 to 22 inches (46 to 56 cms). The ratio of the diameters of the tractor wheels 43 to wheels 33 may be in the range from 3:1 to 7:1 for example. The relative sizes of wheels 33, 43, 12 are chosen so that the peripheral speed of wheels 12 is the same as the peripheral speed of wheels 43 when moving in a straight line. The ram load may for example be 3 to 4 tonnes.

It will be noted that the trailer wheels are not driven from the power take off (PTO) of the tractor, which is normally rotated at a constant speed.

The invention could be applied to a balanced trailer, that is a trailer having ground wheels both fore and aft of the trailer centre of gravity as shown at 12a Figure 3. The term trailer is to be understood widely as anything pulled behind the tractor. Thus the trailer could be an agricultural tool or implement having a driven axle. The tool could be adapted to disturb or operate in the ground.

In a similar arrangement shown in Figure 5, in which similar parts to Figures 1 to 4 have the same reference numerals, the wheels 33 are cage wheels for improved grip with wheels 43 and are carried on beam axles 60 rotatable in bearings 61 in sides 62 of frame 32. The coupling 29 is encased in a protective bellows 29a. The cage wheels 33 comprise spaced parallel circular discs 63 having bead rims 64 connected by circumferentially spaced helically extending bars 65 lying in a cylindrical surface connecting rims 64.

Referring to the coupling arrangement of Figures 6 to 11, this is generally similar to Figure 5 but with certain modifications. In this case the frame 32 has no upper crosspiece but comprises two side members 70 arranged for pivotal connection on pins 71 to the two lower arms 34 of the 3-point linkage. Straps 35 on the members 70 support the axles 60 for rotation relative to the frame members 70. Cage wheels 33 are carried on the axles. In this case the differential 30 has an output shaft 72 extending in use towards the tractor and connected through gears 73 and chains 74 to drive a shaft 75 adapted to be coupled at 26 to the transmission shaft 24 of the trailer 11 having wheels driven by shaft 24. The gear ratio between shafts 72, and 75 may be 1:1.The ram 40 is in this case pivotally connected at 77 and 78 between a lug 76 on one frame member 70 and a clamp bracket 79 removably secured on a link 34. Thus the coupling can be raised on links 34 using the conventional tractor hydraulics and the ram 40 then energized to pivot the frame members 70 to bring the wheels 33 into contact with the tractor wheels 43. An arm 80 is fixed to a housing of axle 60 and is pivoted at 81 to a strut 82 pivoted at 83 to bracket 79. The strut 82 includes portions threaded together at 84 so as to be adjustable in length. The pivot 81 is close to pivot 77 so that as the ram is powered there will be slight relative movement between the frame (strap 35) and the axle housings, and shaft 75 is kept substantially horizontal (on flat ground). A box 85 may enclose the gears 72, 73.

The coupling of frame members 70, ram 40, strut 82, bracket 79, differential 30, axles 60 and wheels 33 may be assembled as a separate unit 90 which when desired can be connected to the 3-point links 34 (Figure 9) and then coupled to the trailer (Figure 10). In this condition the PTO of the tractor is still available for driving e.g. a slurry agitator if the trailer is in the form of a slurry tanker.

In Figures 8 to 11 the ram 40 is, as shown, optionally connected to the tractor.

Suitable couplings are provided for energizing the ram 40 from the tractor hydraulic power supply. Figure 11 shows use on an incline.

The term trailer is to be understood widely as anything pulled behind the tractor. Thus the trailer could be an agricultural tool or implement having a driven axle. The tool could be adapted to disturb or operate in the ground. In case of different speed of tractor and trailer axles on negotiating a bend, it may be desirable to include a slipping clutch 72a between differential 30 and shaft 75 arranged to slip before there is slip between the tractor wheels and the cage wheels 33.

Figures 12-14 show another, similar, arrangement but in this case there are two rams 40 respectively on either side of the differential 30 and pivoted at one end to the frame 62 and at the other end at 42 to a lug 90 secured to link 34 near pivot 37. The axles 60 having housings which themselves are provided with outer housings 60a fixed to frame 62. The coupling is raised to a waiting position by links 34 (full lines in Figure 12) and, when required, the rams 40 are energized to pivot the coupling on pivots 37, 36 to engage wheels 33 and 43. As above a pivoted strut 82 is provided in this case between gear box housing and link 34 and shaft 75 is kept horizontal during this movement by slight relative movement between the axle housings and the frame 62, the pivots of the struts and rams forming essentially a paralellogram arrangement.

Claims

1. A coupling unit for coupling a tractor and a trailer, the trailer having a driven axle, comprising a support adapted to be pivotally connected to lower links of a tractor 3-point linkage, wheels carried by said support and connected to a drive mechanism, a ram pivotally connected to the support and adapted to be pivotally connected to a tractor, so that in use operation of the ram movs the wheels into engagement with wheels of the tractor to drive the trailer wheels through the drive mechanism.

2. A coupling unit as claimed in Claim 1, in which the ram is pivoted to a bracket adapted to be secured to a lower link of a 3-point linkage.

3. A coupling unit as claimed in Claim 1 or Claim 2, in which the drive mechanism comprises a differential connected to axles carrying the coupling wheels.

4. A coupling unit as claimed in any preceding claim, including means operably connected between the coupling wheels and the lower links for maintaining an output shaft of the drive mechanism in a desired orientation during movement of the coupling wheels into engagement with the tractor wheels.

5. A coupling unit as claimed in Claim 4, in which said means comprises a strut pivotally mounted with respect to the axle housings and the lower links.

6. A coupling unit as claimed in Claim 3, in which the differential has an output shaft in use extending towards the tractor, a gear box connected to the differential output shaft, and a cou piing output shaft connected to the gear box and in use extending away from the tractor.

7. A trailer comprising a body, ground engaging wheels, and means for driving the wheels, said driving means comprising means adapted to be connected to a wheeled tractor device so as to engage the wheels of the tractor device and thus drive the trailer wheels.

8. A trailer as claimed in Claim 7, including a frame adapted to be pivotally connected to a tractor, wheels rotatably carried by the frame, means for moving the frame to bring the wheels into contact with wheels of the tractor, and a transmission operably connecting the frame wheels and the trailer wheels.

9. A trailer as claimed in Claim 8, in which the moving means comprises a ram pivoted to the frame and adapted to be pivoted to the tractor.

10. A trailer as claimed in Claim 8 or Claim 9, including a differential operably connected to the wheels carried by the frame, said transmission comprising a trailer differential to which the trailer wheels are connected, and said transmission comprising means operatively connecting the differentials.

11. A tractor I trailer combination including a coupling between the tractor and trailer and movable into engagement with wheels of the tractor for driving wheels of the trailer.

12. A coupling unit substantially as hereinbefore described with reference to and as shown in Figures 1 to 3, or Figures 6 and 7, or Figures 12 to 14, of the accompanying drawings.

13. A tractor I trailer combination substantially as hereinbefore described with reference to Figures 1 to 3, or Figures 6 to 11, or Figures 12 to 14, of the accompanying drawings.