GB2195608A - Cask handling platform - Google Patents

Abstract

A platform 10 for mounting on the forks of a lift truck 12 has a loading ramp 14 pivotal between upright and lowered positions by a fluid actuated piston and cylinder 15 on the under-side of the platform 10. A source 23 of fluid pressure communicates with the piston and cylinder 15 and a vertical pressure cylinder 16, the latter being adapted to engage a striker plate 17 as the platform descends towards ground level to control the flow of fluid to the piston and cylinder 16 to cause the ramp to pivot from its raised position to its ramp position. The source of fluid pressure is normally cut off by a check valve 24 which is opened when the cylinder 16 engages the striker plate 17. A spring 22 causes the ramp 14 to raise as the platform ascends from ground level and also expels fluid from the horizontal cylinder 15 prior to the vertical cylinder 16 closing the check valve 24. The source of fluid pressure instantly retains the check valve 24 closed and thereby locks the ramp 14 in its raised position as soon as it reaches that position. Alternatively, the ramp is retained in the raised position by means of a locking bar and shuttle plate. <IMAGE>

Description

SPECIFICATION Cask handling platform This invention relates to a platform which is raised and lowered by a fork lift truck for transporting casks to and from racks in a warehouse.

Such platforms are already known and have a loading ramp at the forward end which automatically rises to an upright position when the platform is raised to form a retaining wall, and also automatically lowers as the downwardly moving platform nears ground level.

One known mechanism for lowering the ramp includes two transversely spaced pivotal arms located under the platform each adapted to engage the ground as the platform descends to actuate an associated spring assisted mechanical linkage carried on the underside of the platform and transversely spaced from each other.

A disadvantage of such an arrangement is its reliance on ground engagement because on an uneven or pitted surface, one pivotal arm may fail to make proper contact, with the result that stress is placed on the linkage associated therewith leading eventually to damage requiring removal of the platform for repair.

Another disadvantage of the known arrangement is the amount of noise made by firstly the pivotal arms then the platform and finally the ramp engaging the ground.

An object of this invention is to provide an improved means of controlling the ramp.

According to the present invention there is provided a platform adapted at one end for attachment to a fork lift truck on which a striker plate is mounted, said platform having a loading ramp at its opposite end pivotal relative to the platform between an upright position in which it forms a retaining wall and a lower downwardly angled ramp position, a longitudinally disposed fluid actuated piston and cylinder carried on the underside of the platform and connected to the ramp to move the ramp between its raised and lowered positions, a source of fluid in communication with the horizontal piston and cylinder and a vertically disposed pressure actuated means mounted on the fork lift end of the platform adapted to engage the striker plate as the platform descends towards ground level to control the flow of fluid to the horizontal piston and cylinder to cause the ramp to pivot from its raised position to its ramp position.

Preferably, the source of fluid in communication with the horizontal piston and cylinder is normally cut off by a check valve which is opened when the pressure actuated means engages the striker plate.

Preferably also, the pressure activated means is a pressure cylinder, the piston of which extends downwards from the cylinder for engagement with the striker plate.

Preferably also, spring means is provided in the horizontal piston and cylinder to cause the ramp to rise from its ramp position to its raised position as the platform ascends from ground level, said spring means also expelling the fluid from the horizontal cylinder prior to the vertical cylinder closing the check valve.

Preferably also, the supply of fluid is stored in a bladder accumulator which provides a pressure to instantly retain the check valve closed and thereby lock the ramp in its raised position as soon as it reaches that position.

Alternatively, the ramp is normally retained in the raised position by means of a locking bar and shuttle plate, the locking bar being disposed horizontally at one side of the platform and connected to the ramp to move rearwardly, as the ramp moves to its lowered position, to extend beyond the fork lift attachment end of the platform, said shuttle plate being provided on said end of the platform to normally prevent rearward movement of the locking bar while the platform is raised, said shuttle plate engaging a stop plate on the fork lift truck as the platform descends towards ground level to hold back the shuttle plate a short distance from the ground so that the locking bar is free to extend beyond the platform only when the ramp is lowered to the ground.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side elevation of a cask handling platform mounted on a fork lift truck; Fig. 2 is a side elevation to a larger scale illustrating the fluid actuated means for operating the ramp which is in its raised retaining wall position; Fig. 3 is a side elevation corresponding to Fig. 2 showing the ramp in its lowered ramp position; Fig. 4 is a diagrammatic illustration of the fluid lines; Figs. 5 and 6 are side elevations illustrating a mechanical means for locking the ramp in its raised position; and Fig. 7 is a diagrammatic view illustrating hand controls on the platform.

Referring firstly to Figs. 1 to 3, the cask handling platform 10 is engaged at one end by the forks 11 of a fork lift truck 12, although it may also be fitted directly to the carriage 11 A of the fork lift mechanism. At the opposite (front) end of the platform 10 there is a pivotal ramp 14 which can be raised to an upright position to form a front retaining wall, or lowered to form a ramp.

The ramp 14 is normally in its raised position except when the platform is descending and is close to ground level. Then a fluid actuated mechanism comes into operation to cause the ramp to lower.

The fluid actuated mechanism is preferably hydraulic and includes a piston and cylinder 15 which is mounted horizontally and centrally on the underside of the platform 10 towards the forward end thereof and a vertical pressure cylinder 16 mounted at the rear end of the platform and engageable with a forwardly extending striker plate 17 mounted on the mast 13 of the fork lift truck.

The piston 20 of the horizontal piston and cylinder 15 is connected to the base of the ramp 14 and can retract into its cylinder 21 under hydraulic fluid pressure to pivot the ramp from its raised position to its lower position as hereinafter described and a compressimon spring 22 is located in the cylinder 21 to urge the piston outwards when the hydraulic pressure is released.

The cylinder 21 is connected to a source 23 of hydraulic fluid which may be a tank or, preferably a bladder accumulator, see-Fig. 4, but the supply of fluid to cylinder 21 is normally cut off by a check valve 24. That check valve can be opened on actuation of a pressure cylinder 16 which comprises a vertical cylinder 25 and a downwardly extending piston 26 which has a compression spring 27 therearound.

In use, as the descending platform nears ground level, the vertical piston 26 engages the striker plate 17 and retracts into its cylinder as the platform continues its descent.

Fluid in the vertical cylinder is carried under pressure into the horizontal cylinder while at the same time the check valve 24 is opened to allow additional fluid from the source 23 to pass to the horizontal cylinder.

When the platform is subsequently raised, the compression spring 27 causes the piston 26 to extend outwardly of its cylinder 25 and fluid from the horizontal cylinder 21 returns to the cylinder 25. Also the compression spring 22 in the horizontal cylinder 25 urges the longitudinal piston 20 outwardly of its cylinder 25 and the remainder of the fluid returns to its source 23 before the check valve 24 is closed by the pressure of the fluid in the source 23. Once the check valve 24 is closed, the horizontal piston 20 cannot be retracted and therefore the ramp 14 is in effect locked in its upright retaining wall position.

If desired an alternative or additional mechanical locking means can be provided as illustrated in Figs. 5 and 6.

A horizontal bar 30 is mounted at one side of the platform and has a length substantially the same as that of the platform. The front end of the rod 30 is connected to the base of the ramp 14 and when the ramp is in its raised position the rear end of the rod 30 terminates substantially level with the rear end of the platform. In this position, the rear end of the rod 30 normally abuts a shuttle plate 31 which is carried by the platform. The rod 30 is however, capable of rearward movement as the ramp is lowered to its ramp position, and that movement extends the rear end of the rod beyond the platform. To permit such movement, a stop plate 32 is mounted on the fork lift mast 13 so that as the descending platform nears ground level, the shuttle plate 31 is held back, thus freeing the rod for movement as the ramp is lowered.When the platform subsequently rises, the rod 30 retracts and the shuttle plate 31 rises with the platform thus preventing rearward movement of the rod 30 and in effect, locking the ramp in its raised position.

Hand controls are provided on the platform so that an operator standing on the platform can control the hydraulic feed of the fork lift apparatus. Separate levers 40, 41 cause the lift mast to ascend or descend and if the platform is lowered too quickly, e.g. by releasing too much fluid from the fork lift hydraulic system, the vertical piston will provide a dampening effect on the platform and prevent sudden impact with the ground.

The platform is provided with side flaps 45 which are normally raised but can be lowered individually for off loading casks from the platform onto racks or vice versa on either side of a passageway along which the platform is transported and raised or lowered to a level with the appropriate rack. The side flaps are each controlled by a hand lever 46, and an interlock 47 is provided which moves relative to the fork lift control levers so that these controls cannot be operated unless both flaps are raised.

In the prefered embodiment, as best shown in Fig. 1, the side flaps 45 each have a central tongue 48 which in the upright position is 18 above the platform and provides a sufficient safety guard in combination with a fixed top rail 49 at 1 metre above the platform for an operator standing on the platform.

In a modification the tongue is omitted and the side flap is only 6" above the platform; in such an arrangement a mid rail (not shown) is provided 18" above the platform and is adapted to swing upwards in a parallel motion to the top rail 49 as the flap is lowered so that casks can be rolled off or onto the platform.

A guard housing 50 is also provided above the controls on the platform for the operator.

As a further safety feature the motive power of the fork lift truck may be cut off while the platform is elevated above, for example 2 feet. This is achieved by providing a limit switch on the fork lift mast to be tripped by the platform as it ascends and descends, the descending trip returning power control to the driver of the truck.

The fork lift truck is provided at the top of its mast with a hydraulic hose reel which carries the hydraulic lines to the platform mounted control levers 40, 41.

The horizontal piston and cylinder may be actuated pneumatically instead of hydraulically.

Further, it may be actuated in a manner other than as described in the preferred embodiment, e.g. as a double acting piston and cylinder, the inlet side being determined by actuation of the vertical pressure activated means which may be a fluid pressure cylinder or an electrical switch to operate a pump.

Claims (7)

1. A platform adapted at one end for attachment to a fork lift truck on which a striker plate is mounted, said platform having a loading ramp at its opposite end pivotal relative to the platform between an upright position in which it forms a retaining wall and a lower downwardly angled ramp position, a longitudinally disposed fluid actuated piston and cylinder carried on the under-side of the platform and connected to the ramp to move the ramp between its raised and lowered positions,a source of fluid in- communication with the horizontal piston and cylinder and a vertically disposed pressure actuated means mounted on the fork lift end of the platform adapted to engage the striker plate as the platform descends towards ground level to control the flow of fluid to the horizontal piston and cylinder to cause the ramp to pivot from its raised position to its ramp position.

2. A platform as claimed in claim 1, in which the source of fluid in communication with the horizontal piston and cylinder is cut off by a check valve which is opened when the pressure actuated means engages the striker plate.

3. A platform as claimed in claim 1 or 2, in which the pressure activated means is a pressure cylinder, the piston of which extends downwards from the cylinder for engagement with the striker plate.

4. A platform as claimed in claim 4, in which spring means is provided in the horizontal piston and cylinder to cause the ramp to rise from its ramp position to its raised position as the platform ascends from ground level, said spring means also expelling the fluid from the horizontal cylinder prior to the vertical cylinder closing the check valve.

5. A platform as claimed in any one of claims 2 to 4 in which the source of fluid is stored in a bladder accumulator which provides a pressure to instantly retain the check valve closed and thereby lock the ramp in its raised position as soon as it reaches that position.

6. A platform as claimed in any one of claims 1 to 4 in which the ramp is retained in the raised position by means of a locking bar and shuttle plate, the locking bar being disposed horizontally at one side of the platform and connected to the ramp to move rearwardly, as the ramp moves to its lowered position, to extend beyond the fork lift attachment end of the plat form, said shuttle plate being provided on said end of theplatform to normally prevent rearward movement of the locking bar while the platform is raised, said shuttle plate engaging a stop plate on the fork lift truck as the platform descends towards ground level to hold back the shuttle plate a short distance from the ground so that the locking bar is free to extend beyond the platform only when the ramp is lowered to the ground.

7. A platform substantially as hereinbefore described with reference to the accompanying drawings.