GB2208583A - Tractor hitch - Google Patents

Abstract

An automatic pick-up hitch comprises a first part (2) by which the hitch can be fitted to a hitch frame (1) of a tractor and by which a hook (4H) of the hitch can be raised and lowered. An elongate second part (4) is movable lengthwise relative to the first part in order to displace said hook (4H) in an adjustable manner latch means (14) is associated with said first (2) and second (4) parts and serves selectively and releasably to secure them at desired overall hitch hook extensions. A hook locking bar (5) is associated with the second part (4) for automatic release and locking relative to said hook (4H) as the first part (2) is lowered and raised, respectively. <IMAGE>

Description

Title: Tractor Hitch DESCRIPTION This invention relates to automatic pick-up hitches of adjustable length and arises from seeking to improve on existing automatic pick-up hitches for trailers, particularly as used by tractors in agriculture.

Existing automatic pick-up hitches are, of course, well known for the speed and safety with which they enable hitching a tractor and trailer. However, those readily available are limited by their short length, which generally makes them unsuitable for pick-up of machines that are powered from power take off (PTO) shafts, also a well-known and very useful provision for tractors. Thus, for use with PTO operated machinery, available automatic pick-up hitches have to be replaced by conventional swinging drawbar or clevis type hitch devices.

According to this invention, an automatic pick-up hitch comprises a first part by which the hitch can be fitted, say pivotally, to a hitch frame of a tractor and by which a hook of the hitch can be raised and lowered, and an elongate second part movable lengthwise relative to the first part, say telescopically, in order to displace said hook in an adjustable manner, latch means associated with said first and second parts and serving selectively and releasably to secure them at desired overall hitch hook extensions, and a hook locking bar associated with the second part for automatic release and locking relative to said hook as the first part is lowered and raised, respectively.

Associating the locking bar, say pivotally, with the second part assures that it will operate automatically regardless of extension of that second part relative to the first part.

The latch means is preferably releasable by a handle that may be operable from the tractor itself, say by reaching behind the driver's normal position.

Practical implementation of one embodiment of this invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figures 1 and 2 show a telescopic pick-up hitch hereof diagramatically in raised and lowered positions, respectively; and Figure 3 is an exploded view showing parts of a specific such hitch in greater detail.

In the drawings, referring first to Figures 1 and 2, the pick-up hitch comprises an outer body part 2 within which an inner part 4 is telescopically movable in order to extend or retract a pick-up hook (shown at 4H integral with the inner part 4). The inner part 4 can be latched in any one of alternative extensions relative to the outer body part 2 by a latch 14 shown co-operating with spaced notches 16 along the inner body part 4.

The outer body part 2 is pivotted (3) to a hitch frame 1 and can be raised or lowered by a suitable linkage operated by tractor hydraulics, say using chains or rods, preferably with hook or catch means to hold it in the raised position until tractor hydraulics are operated, see 40 in Figure 1.

The inner part 4 has a locking bar 5 hinged thereto at 6 to extend along the part 4 and intrude over the space behind the pick-up hook 4H (Figure 1) into which a tractor ring 15 can fit. Lowering of the outer body part 2 allows that ring 15 to be engaged or disengaged due to rotation at hinge 6 under the action of compression spring means 13 then spacing the free end of the locking bar 5 from the pick-up hook 4H (Figure 2). A stop 9 assures that the locking bar 5 goes into its locking position when the outer body part 2 is raised.

The stop 9 further serves to set a maximum extension for the inner part 4 (Figure 1) by abutment with a stop 7 on the locking bar 5. A stop 8 internal of the outer body part 2 serves to limit insertion of the inner part 4 into the outer body part 2. Such action of the stops 7 and 8 preferably corresponds to maximum and minimum latchable extensions of the inner part 4 relative to the outer body part 2, i.e. to endmost ones of the notches 16 being engaged by the latch 14.

Hitching and unhitching of a tractor should be evident from Figures 1 and 2. To hitch-up, the outer body part 2 is released and lowered, which is readily done using tractor hydraulics, at which stage the locking bar 5 spaces from behind the hitch hook 4H.

The tractor concerned is then manoeuvered to position the hook 4H below the tractor ring 15 on trailer bar 12, and the outer body part 2 is raised. The hook 4H will engage the ring 15 and lift the trailer bar 12 until the outer body part 2 reaches its fully raised position, whereat the locking bar 5 is pressed down against the spring means 13 and its free end prevents unlocking of the trailer ring 15. The outer body part 2 should automatically latch in its fully raised position as previously mentioned. Unhitching involves simply releasing and lowering of the outer body part 2.

Figures 1 and 2 also show a convenient mechanism whereby length of the pick-up hitch can be adjusted. A handle 11 is hinged at 17 and has an arm 19, usually two as a fork arrangement, whose end(s) 20 serves to release the latch 14 when the handle is pulled in the direction of the arrow 11A. Then, the inner part 4 can be pulled out of or pushed into the outer body part in order for the latch 14 next to engage another of the notches 16, thereby setting a different length of the hitch. That can be done manually if there is no trailer hitched up. Alternatively, and advantageously, length adjustment can be done with a trailer hitched up. Trailer brakes should be applied if available, or care taken to assure that no problems can arise, say operating using the inertia of the trailer on substantially level ground.Then, release of the latch 14 by moving the handle 4 can be followed by inching the tractor forwards or backwards, preferably with the handle released after the current notch 16 is clear of the latch 14 and the latter then automatically engaging the next notch 16. One of the available lengths for the hitch, i.e. one of the notches 16 engaged by the latch 14, advantageously corresponds to the British standard for drawbar lengths, namely 356mm.

It will, of course, be appreciated that length adjustability of hitches hereof enables the distance between power take off shafts (see 10 in Figures 1 and 2) and hitch hook centre-lines (at 4H in Figures 1 and 2) to be varied, and positions for notches 16 can be chosen to suit various PTO operated machinery to be towed by and operated from a tractor.

Turning to Figure 3, similar references are used where appropriate. The hitch frame 1 is, of course, of a well-known type for affixing by nuts to studs 22 on an equally recognisable tractor axle casing 21 and associated PTO 10. The outer body part has a suitable pivot provision 3 relative to that hitch frame 1, basically via a pivot block on the part 2 to fit between ears of the frame and with associated pivot and linch pins.

The outer body part 2 has a top face slot 24 to accommodate the locking bar 5, the latter shown hinged at 6 by an ear onto a slot at the inner end of the inner body part 4 and an associated pivot pin. Also, the outer body part 2 is shown with a slot 25 for a latch 14 in the form of a shallow U-shaped member movable between guides 26 extended below the slot 25.

Upstands of the latch member 14 are shown with pierced ears 27 tht serve an anchorages for tension springs 28 going to further ancherages 29 on the body part 12. The springs 28 (one only shown) serve to bias the latch member 14 into a slot 16 of the part 4, and the guides 26 serve to retain the latch member 14 when depressed by ends 20 of a forked ended lever 11.

Pivotting 17 for the handle 11 involves a bracket rearwardly of the forks 19, a pivot block on a bracket 31 securable by nuts to studs 32 on the tractor axle casing 21, and a pivot pin shown with associated linch pin. The backet 31 is shown extending downwards to afford the stop 9 at its lowest portion. The handle is cranked to one side so as to be more readily accessible, including from the driver's normal position on a tractor say by reaching behind.

The spring bias 13 for the locking bar 5 relative to the inner part 4 is indicated as a compression spring housed in a hole 33 in the part 4 and engaging on a pip 34 on the bar 5. It could be useful to provide a saddle bracket on the inner part 4 behind the hook 4H to limit upward spacing of the locking bar 5 under the influence of the spring 13, see dashed at 38.

Lastly, concerning Figure 3, the outer body part 2 is indicated with a side bracket 40 extending upwardly therefrom at an angle suited to being engaged by an hydraulically driven linkage for raising and lowering the body part 2, also a retaining hook at the fully raised position (neither shown).

It will be appreciated that, insofar as further detail is shown in Figure 3, there are many alternatives available, some of which could be forced by use of other hitch frames, tractor axle casings, etc. That, of course, applies particularly to the mechanism for raising and lowering the hitch, including retaining hooks, basically by adaption of such provision as is conventionally provided for a raisable/lowerable hitch, for example with hooks pivotted on plates flanking the tractor axle casing, or on extension of the hitch frame, and with a lever linkage for manual release; and/or with chains or telescopic rods also one to each side from arms as indicated at 40 (again to each side of the outer body part 2) to the upper hydraulic lift arms, though other arrangements could be made.

Claims (7)

1. An automatic pick-up hitch comprising a first part by which the hitch can be fitted to a hitch frame of a tractor and by which a hook of the hitch can be raised and lowered, and an elongate second part movable lengthwise relative to the first part in order to displace said hook in an adjustable manner, latch means associated with said first and second parts and serving selectively and releasably to secure them at desired overall hitch hook extensions, and a hook locking bar associated with the second part for automatic release and locking relative to said hook as the first part is lowered and raised, respectively.

2. An automatic pick-up hitch according to claim 1, wherein said hitch is pivotal to said hitch frame.

3. An automatic pick-up hitch according to claim 1 or claim 2. wherein said second part is movable telescopically relative to said first part.

4. An automatic pick-up hitch according to any preceding claim, wherein said locking bar is pivotally associated with said second part to operate automatically regardless of extension of said second part relative to said first part.

5. An automatic pick-up hitch according to any preceding claim, wherein said latch means is releasable by a handle.

6. An automatic pick-up hitch according to claim 5, wherein said handle is within normal reach of a tractor driver's normal position.

7. An automatic pick-up hitch arranged and adapted to operate substantially as herein described with reference to and as shown in the accompanying drawings.