GB2038284A - Mounting a lifting mast on a vehicle - Google Patents

Abstract

A tractor is provided with a mounting mechanism 10 for use in mounting a lifting mast 30 on and dismounting the mast from the tractor. When not in use, the lifting mast 30 can be stored on a stand 40 which is vertically adjustable to facilitate loading of the lifting mast onto the mechanism 10 of the tractor. To counterbalance the weight of the lifting mast especially when the latter is used for handling loads, the forward end of the tractor is provided with a counterweight mounting unit 60 for mounting a counterweight 90 on the tractor and dismounting it from the tractor. To ensure that the lifting mast cannot be used while the counterweight is not present on the tractor, operation of the lifting mast is governed by a valve 100 which puts the hydraulic circuitry of the lifting mast out of operation until the counterweight is in the properly mounted position. <IMAGE>

Description

SPECIFICATION Lifting mast and assembly for use in mounting the mast on and dismounting it from a vehicle This invention relates to a lifting mast and assembly for use in mounting the mast on and dismounting it from a vehicle such as a tractor.

It is well known to use a forklift mast in conjunction with a tractor but, in the past, it has been a laborious task to mount and dismount the mast from the tractor. For example in one widely used prior art construction, the mast and its associated tilting mechanism are mounted, as an integral unit, on or dismounted from the three point linkage of a tractor.

This has inevitably made handling of the mast and assembly difficult during mounting or dismounting.

One object of the present invention is to provide an improved assembly for use in mounting the mast on and dismounting it from a vehicle, especially a tractor, whereby such operations can be readily effected by a single person.

According to the present invention we provide, in combination, a lifting mast and assembly for use in mounting the mast on and dismounting it from a vehicle, said assembly including a tilting mechanism adapted to be connected to the vehicle, characterised in that the mast and the tilting mechanism are releasably connectible whereby the tilting mechanism can be permanently secured to the vehicle and the mast can be connected to or disconnected from the tilting mechanism.

Thus, instead of mounting the mast and tilting mechanism as an integral unit on the tractor, the operation is simplified by permanently securing the tilting mechanism to the vehicle and arranging for the mast to be releasablyconnectibletothetilting mechanism.

According to a further development of the invention designed to further simplify mounting and dismounting, said combination is further characterised by a ground-engaging stand having a vertically adjustable section for supporting the mast when not in use, the mast and said stand section having cooperable formations by means of which the mast can be supported from the stand in general vertical disposition.

Preferably the releasable connection means between the mast and the tilting mechanism includes at least one hook formation provided on the mast, the mouth on the hook being presented downwardly for cooperation with a supporting element provided on the tilting mechanism. In the preferred embodiment, two such hook formations are provided at laterally spaced points on the mast and are cooperable with a bar carried by tilting arms of the tilting mechanism.

The releasable connection means may further comprise apertures on the mast and on the tilting mechanism which are capable of being brought into registry when the hookformations engage with supporting elements of the tilting mechanism whereby the mast can be stably mounted on the tilting mechanism by insertion of a pin or the like through the registering apertures.

When a tractor is provided with a lift mast as aforesaid, it is desirable if not essential to mount counterweights on the upper end of the tractor in order to counteract the weight of the lift mast and loads being handled thereby. in the past, such counterweights have been loaded manually onto the tractor and secured by bolts and usually they consist of a number of plates or the like to facilitate handling. Inevitably, loading and securing of the counterweights has tended to be a time consuming and laborious task.

Thus, whilst the invention as defined above reduces the time spent in mounting and dismounting the mast, there is still the problem of loading and unloading the appropriate counterweight for use with the mast. Moreover, there is the risk that an attempt might be made to use the mast without the possibility of toppling of the tractor when the mast is carrying a load.

Another object of the present invention is to overcome the above drawbacks.

According to this aspect of the invention, the combination as defined above is characterised further by a counterweight lowering and raising mechanism adapted to be mounted on the tractor at the end opposite to said mast tilting mechanism, means being provided for disabling operation of said lift mast until the counterweight has been mounted on the tractor by means of said lowering and raising mechanism.

The disabling mens may comprise a hydraulic valve which controls the oil supply to the lift mast, the valve being arranged to be closed except when the counterweight has been loaded onto the tractor.

Thus, for example, the valve may be mechanically operable by a counterweight so that raising of the counterweight into the mounted position on the tractor by said lowering and raising mechanism actuates the valve to allow oil supply to the lift mast control cylinders. In this way, any control cylinders associated with the lift mast (and any accessories) mounted thereon) are rendered inoperable until the counterweight is in position.

The raising and lowering mechanism conveniently comprises at least one arm, preferably a pair of arms, pivotal by means of one or more fluid powered rams between a generally horizontal pickup position and a generally vertical mounting position and the counterweight may be provided with a hook formation or formations for automatic engage mentwith cross members (e.g. cross pins or lugs) on the arms as the latter are raised from the pick-up position.

Preferably the hook formations on the counterweight are located at a level such that when the base of the counterweight lies on the same level as the contact points between the tractor wheels and the ground, the cross-members of said arms are below and clear of the hook formations when the arms are in the pick-up position. Thus, the tractor can be driven up to the counterweight with the arms in the pick-up position until the cross-members are located immediately below the hook formations and then by raising the arms, the counterweight is automatically raised.

The counterweight may be provided with apertured lugs below the formations for registry with corresponding apertures on the framework of the raising and lowering mechanism when the counterweight has been raised to the mounted position so that quick-release fasteners can be inserted through the registering apertures to connect the counterweight securely to the tractor.

The invention will now be described further with reference to the accompanying drawings, in which Figure l is a side view of a tractor provided with a lifting mast mounting assembly at its rear end and a counterweight mounting arrangement at its forward end; Figures 2 and 3 are enlarged fragmentary side views showing the counterweight mounting arrangement; and Figure 4 is a view similar to that of Figure 1 but showing the lifting mast and counterweight mounted on the tractor.

Referring firstly to Figures 1 and 4, the tilting mechanism comprises a back plate 10 which is adapted to be permanently secured to the rear of the tractor. From each end of the back plate 10, there projects a pair of mounting plates 12 between which a hydraulic ram 14 and tilting lever 16 are pivoted at 18 and 20 respectively. Each ram 14 is coupled to the respective lever 16 at 22. The upper ends of the lever 16 are connected by a horizontal mounting bar (not shown), which may be coaxial with pivots 22, and their lower ends are formed with coaxial apertures 26. When the rams 14 are fully retracted (or only partially retracted) as shown in Figure 1,the lever 16 extends generally vertically and the apertures 26 lie in substantially the same vertical plane as the mounting bar.By adjusting the extension of the rams 14, the lever 16 can be tilted about the pivot 20.

The mast comprises a pair of lateral channel section columns 30 (one only of which is shown) connected by cross pieces (not shown) in conventional manner. A forklift carriage or the like (not shown) is mounted on the mast for raising and lowering motion again in conventional manner, e.g.

by means of one or more hydraulic rams. The mast is provided with a pair of laterally spaced forwardly projecting hook formations 32 for cooperation with the mounting bar extending between the levers 16 and pairs of apertures 34 for registry with the apertures 26. Thus, the mast can be supported from the tractor by engaging the hook formations 32 on the mounting bar and inserting quick release pins through the apertures 26 and registered lugs 34. The hydraulic rams 14 enable the mast to be tilted in conventional manner. The hook formations 32 and apertures 34 may, as shown, be embodied in a pair of plates 35, there being one hook 32 and one aperture 34 in each plate and the plates 35 being spaced transversely of the mast.

The stand comprises a ground engaging base 40 from which a pair of vertical uprights 42 extend. The uprights 42 mount a frame 44 which can be raised or lowered by suitable gear, e.g. a double acting hydraulic ram or rams 45. The frame 44 is provided with a pair of transversely spaced forwardly project ing plates 47 in each of which a pair of vertically spaced formations 46 are formed comprising recesses which open forwardly and includes seating portons 48 for reception of pairs of laterally projecting studs 50 provided on the outer faces ofthe lifting mast columns whereby the mast is supported by the stand in generally vertical disposition when the studs 50 are seated within the seating portions 48.

The frame 44 includes, at its lower end, an angle piece 49 on which the lower end of the mast can rest.

The stand is used to store the mast when the mast is not in use. When it is desired to mount the mast on the tractor, the latter is driven rearwardly into close proximity with the stand and the rams 14 are manipulated until the mounting bar extending between the levers 16 thereof is engaged beneath the hook formations 32 and the apertures 26 register with the lugs 34. To facilitate this, the frame 44 may be (or already be) adjusted by rams 45 to a suitable height. Quick release pins are then inserted through the apertures 26 and lugs 34to complete the coupling between the mast and the tractor. The frame 44 can then be lowered by rams 45 to clear the seating portions 48 from the studs 50 so that the tractor can then be advanced forwardly to completely remove the mast from the stand.

To dismount the mast, the tractor is reversed to bring the studs 50 into recesses 46, the frame 44 is raised by rams 45 so that the studs 50 enter the seating portions 48 whereby the mast is supported by the stand, the quick release pins are removed from lugs 34 and apertures 26 and the frame is raised further to provide clearance between the horizontal mounting bar extending between the levers 16 and the hook formations 32. The final vertical setting of the frame 44 (as governed by rams 45) may be such that the mast is in the correct position for subsequent collection, i.e. allowing for the fact that the position of the tractor chassis will be higher with the mast dismounted.

From the foregoing, it will be seen that mounting and dismounting the mast is greatly simplified and can be readily carried out by one person.

Referring now more particularly to Figures 2 and 3, the counterweight mounting unit 60 comprises a framework which is securely bolted to the front of the tractor by means of brackets 68. The framework includes fixed generally upright portions 80, each of which pivotally mounts an arm portion 82 which pivots about the axis 84 between a pickup position as shown in Figure 1 and a mounting position as shown in Figure 3. At their free ends, the arms 82 are provided with cross members which may, for exam ple, be in the form of cross pins 86, intended for engagement with hook formations 88 provided at the top of the counterweight 90 which is also provided with apertured lugs 92 adjacent its base.

As will be seen from Figure 1, when the counterweight 90 stands with its base on the ground and when the arms 82 of the unit 60 are in the pickup position, the tractor can be driven forwardly until the cross pins 86 lie immediately beneath the hook formations 88. The unit 60 also includes one or more hydraulic rams 62 for moving the arms 82 between the pickup and mounting positions, the rams 62 being connected pivotally at points 64 and 66 to the portions 80 and arms 82 respectively.Thus, by actuating these rams, the counterweight may be raised from the position shown in Figure 1 through the intermediate position shown in Figure 2 to the mounted position shown in Figures 3 and 4 and, when the counterweight is in the latter position, the apertures in the lugs 92 register with apertures 94 provided in the arms 82 so that quick release fasteners can be inserted through the registering apertures to securely hold the counterweight in position.

The hydraulic circuitry for controlling operation of the counterweight mounting unit 60, the mast mounting unit 10 and/or the lifting mast 30 includes a mechanically operable valve 100 which is so arranged that it is actuated only when the counterweight 90 is in the mounted position shown in Figure 3. In this way, it is possible to prevent operation of the unit 10 andiorthe lifting mast 30 until the counterweight has been mounted on the tractor, e.g.

by arranging the valve 100 in such a way that oil supply to the hydraulic rams of the unit 10 and/or the lifting mast 30 is only possible when the valve has been actuated by raising of the counterweight 90 to the mounted position. The valve 100 may for example be arranged in the hyraulic circuitry in such a way that operation of the lifting mast is disabled until the counterweight is in position but operation of the tilting mechanism 10 is possible. Thus, it will be possible in this event to mount the lifting mast on the tractor even when the counterweight has not been mounted on the tractor but load handling operations of the lifting mast will not be possible until the counterweight is in position.

To effect operation of the valve 100, the counter weight may be provided with an abutment 102 which engages and operates the valve actuator 104 when the counterweight has been raised into the mounted position. The abutment 102 may be adjust able in the fore-and-aft direction (as seen in Figure 1) and may be in the form of a screwthreaded bolt whose head is engageable with the valve actuator.

Although the unit 60 has been designed specifical lyfor use in conjunction with a dismountable lifting mast, it will be appreciated that the counterweight loading unit can be used in circumstances other than when the load handling means at the other end of the tractor is constituted by a lifting mast.

Claims (14)

1. In combination a lifting mast and an assembly for use in mounting the mast on and dismounting it from a vehicle, said assembly including a tilting mechanism adapted to be connected to the vehicle, characterised in that the mast and the tilting mechanism are releasably connectable whereby the tilting mechanism can be permanently secured to the vehicle and the mast can be connected to or disconnected from the tilting mechanism.

2. The combination as claimed in Claim 1 char acterised further by a ground-engaging stand having a vertically adjustable section for supporting the mast when not in use, the mast and said stand section having co-operable formations by means of which the mast can be supported from the stand in generally vertical disposition.

3. The combination claimed in Claim 1 or 2 characterised in that the releasable connection means between the mast and the tilting mechanism includes at least one hook formation provided on the mast, the mouth of the hook being presented downwardly for cooperation with a supporting element provided on the tilting mechanism.

4. The combination claimed in Claim 3 characterised in that two such hook formations are provided at laterally spaced points on the mast and are cooperablewith a bar carried by tilting arms of the tilting mechanism.

5. The combination claimed in Claim 3 or 4 characterised in that the releasable connection means further comprises apertures on the mast and on the tilting mechanism which are capable of being brought into registry when the hook formations engage with the supporting elements of the tilting mechanism whereby the mast can be stably mounted on the tilting mechanism by insertion of a pin or the like through the registering apertures.

6. The combination claimed in Claim 2 or any one of Claims 3 to 5 when appendentto Claim 2 characterised in that said stand comprises a base section and a mast mounting section which is vertically adjustable relative to the base section by means of fluid-powered rams.

7. The combination claimed in Claim 6 characterised in that the mast is provided on each side thereof with a pair of vertically spaced lateral projections and the stand comprises a pair of uprights between which the mast can be received, said uprights each being provided with a pair of inverted L-shaped slots for reception of said lateral projections on the mast, said slots being open at one end to enable said projections to enter into the slots as the tractor approaches the stand.

8. A combination as claimed in any one of Claims 1 to 7 characterised further by a counterweight lowering and raising mechanism adapted to be mounted on the tractor at the end opposite to said mast tilting mechanism, means being provided for disabling operation of the lifting mast until the counterweight has been mounted on the tractor by means of said lowering and raising mechanism.

9. A vehicle provided with first and second hydraulically operable units at or adjacent respective ends thereof, the first unit forming part of or being adapted to mount load handling means (such as a lifting mast) and the second unit being adapted to raise a counterweight and mount the same on the vehicle, means being provided for disabling operation of said first unit and/or the load handling means associated therewith until the counterweight has been mounted by means of said second unit.

10. The combination claimed in Claim 8 or 9 in which said disabling means comprises a hydraulic valve which controls the oil supply to the lift mast, the valve being arranged to be closed except when the counterweight is present.

11. The combination as claimed in Claim 9 characterised in that the valve is mechanically operable by the cunterweight such that raising of the counterweight into a mounting position on the tractor actuates the valve to allow oil supply to fluid-powered rams associated with the mast.

12. The combination claimed in any one of Claims 8 to 11 characterised in that the lowering and raising mechanism comprises at least one arm pivotal by means of one or more fluid-powered rams between a generally horizontal pick-up position and a generallyvertical mounting position and the counterweight is provided with a hook formation or formations for automatic engagement with cross members on the arm or arms as the latter are raised from the pick-up position.

13. The combination as claimed in Claim 12 characterised in that the hook formations on the counterweight are located at a level such that, when the base of the counterweight lies on the same level as the contact points between the tractor wheels and the ground, the cross-members on said arm or arms are below and clear of the hook formations when the arms are in the pick-up position.

14. The combination as claimed in any one of the preceding claims, substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.