GB1584032A

GB1584032A - Restraining hook mechanism

Info

Publication number: GB1584032A
Application number: GB1293978A
Authority: GB
Original assignee: VULCAN TRUCKS Ltd
Current assignee: VULCAN TRUCKS Ltd
Priority date: 1978-04-03
Filing date: 1978-04-03
Publication date: 1981-02-04

Description

(54) RESTRAINING HOOK MECHANISM (71) We, VULCAN TRUCKS LIMITED, a British Company of 10 Nuffield Estate, Poole, Dorset, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a restraining hook mechanism, and in particular, but not exclusively, to a restraining hook mechanism provided on a trailer for conveying pallets to and from an aircraft, the restraining hook mechanism being used for holding a pallet on such a trailer during movement of the trailer. Such restraining hooks must be capable of being moved between an operative position in which they engage a pallet and a inoperative position in which they disengage the pallet.

Trailers provided with restraining hook mechanisms are known but the hook mechanism is usually operated through a lever, rod and link system. Such trailers are usually formed of a welded sheet and strip metal construction and as such a construction is not always dimensionally accurate this can lead to problems with the lever, rod and link system and usually bearings of such a system have to have large clearances to enable inaccuracies in the trailer to be compensated.

According to the present invention there is provided a restraining hook mechanism, comprising a pivotable hook member, means for resiliently urging the hook member to an inoperative position, a pivotable arm member engageable with a rear side of the hook member and pivotable between a first position in which it allows the hook member to move to its inoperative position and a second position in which it retains the hook member in its operative position, pivotable movement of the arm member between said first and second positions causing the arm member to engage and move the hook member from its inoperative position to its operative position, a first sprocket in driving engagement with the arm member, a first chain engaged with said first sprocket, a pivotably mounted operating lever, a second sprocket in driving engagement with said operating lever, a second chain engaged with said second sprocket and cables connecting the ends of the first and second chains to form an endless drive transmission between said sprockets.

Preferably the arm member comprises a plate-like member connected at one end to a shaft on which the first sprocket is mounted, said one end being provided with a portion engageable with a first adjustable stop which determines the second position of the arm member, said plate-like member being engageable with a second adjustable stop when in the first position.

In a preferred embodiment the hook member and said arm member are movable between a pair of fixed side plates in which the hook member and arm member are pivotably mounted.

Preferably the hook member is resiliently urged by a coil spring.

The invention also relates to a restraining hook mechanism provided on a trailer for conveying pallets.

An embodiment of the invention will now be described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic side elevation of a trailer provided with restraining hook mechanisms according to the present invention, Figure 2 is a plan view of the trailer, Figure 3 is a plan view of one of the restraining hook mechanisms, and Figure 4 is a section taken along the line 4-4 on Figure 3.

The trailer is indicated generally at 10 and consists of a chassis 11 provided with wheels 12 and a tow bar 13 having a connecting hitch 14. The front wheels 12 can be pivoted by the tow bar 13. Mounted on the chassis 11 is a turntable 15 having rows of rollers 16 and two elongate platforms 17. Also mounted on the chassis 11 at its forward end is a table 18 having rows of rollers 19 and two platforms 20. Connected to the forward end of the chassis 11 are supports 21 for rollers 22 and connected to the rear end of the chassis 11 is a hitch 23 and supports 24 for rollers 25.

Mounted on the turntable 15 are two diametrically opposed restraining hook mechanisms indicated generally at 26. The restraining hook mechanisms 26 are identical and therefore the construction and operation of only one mechanism 26 will be described in detail. The turntable 15 is provided with locking means (not shown) which can lock the turntable 15 in each of two positions, one position being that shown in Figure 2 and a second position in which the turntable 15 has been rotated through 90 degrees from that shown. Foot-operated pedals 27 are provided on the chassis 11 for releasing the locking means.With the turntable 15 in the position shown in Figure 2 and with the rear restraining hook mechanism 26 in an inoperative position and the forward restraining hook mechanism 26 in an operative position a pallet can be moved onto the turntable 15 so that the forward end of the pallet engages the hook of the forward restraining hook mechanism 26 and then the rear restraining hook mechanism 26 is brought to its operative position so that its hook engages the rear end of the pallet. The trailer 10 is then used to convey the pallet. When the trailer 10 reaches its unloading position the turntable 15 is rotated through 90 degrees after releasing the locking means by means of pedals 27 and is locked in its new position by the locking means.The forward hook restraining mechanism 26 is brought to its inoperative position in which its hook disengages the pallet and the pallet can then be moved off the turntable 15. The turntable 15 can then be rotated back to its original position and the rear restraining mechanism 26 brought to its inoperative position and the forward restraining mechanism 26 brought to its operative position so that a pallet on an adjacent connected trailer 10 can be moved from that trailer onto the turntable 15. It will be appreciated that a plurality of trailers 10 can be connected together in a train. Only one trailer of a train of trailers need be provided with a turntable 15.

A restraining hook mechanism 26 is shown more clearly in Figures 3 and 4. Secured to the turntable 15 are two spaced apart parallel plates 28 interconnected at one end by a transverse plate 29. A hook member 30 is received between the plates 28 and carried on a pin 31 rotatably mounted in the plates 28. The hook member 30 has a hook portion 32 and an extension portion 33 to which is connected one end of a coil spring 34 having its other end connected to structure of the turntable 15. Also received between the plates 28 is an arm member 35 in the form of a plate secured to and extending from a bush 36 fixed to a shaft 37 which extends through the plates 28. Extending from the bush 36 is a stop plate 38 which in the position shown in Figure 4 abuts against an adjustable stop screw 39.

Mounted on each end of the shaft 37 is a sprocket 40 and engaged with each sprocket 40 is a chain 41. Fixed to each end of the chain 41 is a cable 42 which is received in a sheath 43 connected to the plate 29. Carried by the plates 28 is a member 44 provided with an adjustable stop screw 45.

Each cable 42 at its other end is connected to one end of a chain 46 which engages a sprocket 47 mounted on a shaft 48. Also mounted on the shaft 48 is an operating lever 49. As will be seen from Figure 2 each lever 49 is movable between two spaced apart wall portions 50 and 51 carried by the turntable 15. The lever 49 is axially slidable on the shaft 48 and resiliently urged by a spring (not shown) so as to lie in the path of a detent (not shown) provided on one of the wall portions 50, 51 so that the lever 49 is prevented by the detent from inadvertently moving beyond the detent due to vibration when the trailer 10 is being moved.

With the hook member 30 in its operative position as shown in Figure 4 the arm member 35 is inclined and contacts the rear face of the hook member 30 thus holding it in its operative position against the force of the spring 34. The arm member 35 will thus prevent the hook member 30 from moving in a clockwise direction, as viewed in Figure 4, if subjected to a rearward force by a pallet. In order to move the hook member 30 to its inoperative position the lever 49 is pivoted anti-clockwise thus rotating the sprocket 47, the lever being moved over the retaining detent against the spring force applied to the lever, and the transmission comprising the chains 46 and 41 and the cable 42 will simultaneously rotate the sprockets 40 in an anti-clockwise direction.

The arm member 35 will then pivot downwardly until it abuts the stop 45 and allow the spring 34 to pivot the hook member 30 in a clockwise direction so that the hook portion 32 lies between the plates 28.

In order to move the hook member 30 back to its operative position the lever 49 is pivoted in a clockwise direction as viewed in Figure 4 and thus the sprocket 40 is rotated clockwise by the chains 41, 46 and cables 42 and the arm member 35 moves in a clockwise direction and pivots the hook member 30 in an anti-clockwise direction against the force of the spring 34.

It will be appreciated that each restraining hook mechanism 26 need only have one operating lever 49 and associated trans

Claims

WHAT WE CLAIM IS:

1. A restraining hook mechanism, comprising a pivotable hook member, means for resiliently urging the hook member to an inoperative position, a pivotable arm member engageable with a rear side of the hook member and pivotable between a first position in which it allows the hook member to move to its inoperative position and a second position in which it retains the hook member in its operative position, pivotable movement of the arm member between said first and second positions causing the arm member to engage and move the hook member from its inoperative position to its operative position, a first sprocket in driving engagement with the arm member, a first chain engaged with said first sprocket, a pivotably mounted operating lever, a second sprocket in driving engagement with said operating lever, a second chain engaged with said second sprocket and cables connecting the ends of the first and second chains to form an endless drive transmission between said sprockets.

2. A restraining hook mechanism as claimed in claim 1, in which the arm member comprises a plate-like member connected at one end to a shaft on which the first sprocket is mounted, said one end being provided with a portion engageable with a first adjustable stop which determines the second position of the arm member, said plate-like member being engageable with a second adjustable stop when in the first position.

3. A restraining hook mechanism as claimed in claim 1 or claim 2, in which said hook member and said arm member are movable between a pair of fixed side plates in which the hook member and arm member are pivotably mounted.

4. A restraining hook mechanism as claimed in any preceding claim, in which the hook member is resiliently urged by a coil spring.

5. A restraining hook mechanism as claimed in any preceding claim, in which the operating lever is movable in a transverse direction against a resilient force which urges the lever to lie in the path of a detent for preventing inadvertent movement of the lever beyond the detent towards a position in which the arm member is caused to be moved by the lever to its first position.

6. A restraining hook mechanism as claimed in any preceding claim, in which the cables are sheathed.

7. A restraining hook mechanism as claimed in any preceding claim, in which there are two first sprockets located one on each side of the lever member, two operating levers each with its own second sprocket and two endless drive transmissions.

8. A restraining hook mechanism as claimed in any preceding claim provided on a trailer for conveying pallets, said hook mechanism being operative to hold a pallet on the trailer.

9. A restraining hook mechanism as claimed in claim 8, in which the mechanism is provided on a turntable of the trailer.

10. A restraining hook mechanism substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.