GB2251593A

GB2251593A - A platform for a boom conveyor

Info

Publication number: GB2251593A
Application number: GB9125752A
Authority: GB
Inventors: John Jenkins
Original assignee: Linvar Ltd
Current assignee: Linvar Ltd
Priority date: 1990-12-04
Filing date: 1991-12-03
Publication date: 1992-07-15
Also published as: GB9125752D0; GB9026352D0

Abstract

A platform 5 is connected to the free end of a boom conveyor, the platform including two laterally spaced hydraulic devices each comprising a cylinder 10 having two chambers 12, 13 separated and defined by a movable piston 11 in the cylinder. The piston 11 has a connecting rod 14, one end of which is connected to a suspension linkage 17 which engages the ground. The cylinder 10 is secured to the platform through a trunnion 9 for movement therewith. The said two chambers comprise an upper chamber (12 Fig 3, not shown) and a lower chamber (13), the upper chamber (12) of each device being in fluid communication through a pipe (20) with the lower chamber (13) of the other device. <IMAGE>

Description

A PLATFORM FOR A BOOM CONVEYOR This invention relates to improvements in platforms for boom conveyors and particularly, relates to a platform on which an operator can stand and which is adapted to be connected to the free end of the boom conveyor.

One particular application for a boom conveyor, that is a conveyor cantilevered out from a base, is the stacking of components into vehicles such as container trucks. The boom conveyor, which may be telescopic, is located at the loading bay of a warehouse and is designed to project into a vehicle to be loaded with components or packages. An operator stands in the vehicle and takes packages from the conveyor and stacks them in the vehicle. As the vehicle is loaded, the conveyor is gradually withdrawn from the vehicle until the vehicle is fully loaded.

To assist the operator in retrieving packages from the conveyor surface, a man rider platform is usually secured to the end of the conveyor so that when an operator stands on the platform, he is at the right height to lift a package from the conveyor.

A disadvantage of such boom conveyors is that the ends of the conveyor tend to move about, particularly as the operator jumps on and off the platform, because of the lack of rigidity in the boom conveyor. This is a particular problem with telescopic boom conveyors. The movement of the end of the conveyor may be up and down due to variations in the weight of packages thereon, laterally from side to side, and also axial stability, that is pivotal movement of the conveyor about its longitudinal axis. The present invention seeks to provide an improved supporting system for a platform to reduce or eliminate the lack of stability.

According to the present invention there is provided a platform adapted to be connected to the free end of a boom conveyor, the platform including laterally spaced hydraulic devices each comprising a cylinder having two chambers separated and defined by a movable piston in the cylinder, one of the piston or cylinder being adapted to engage the ground and the other of the cylinder or piston, as the case may be, being secured to the platform for movement therewith, the said two chambers comprising an upper chamber and a lower chamber, the upper chamber of each device being in fluid communication with the lower chamber of the other device.

Preferably, the pistons of the devices are connected to ground engaging members through a suspension linkage. Resilient means may be provided to bias the suspension linkages to the fully extended position.

A preferred embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows, schematically, a side view of a telescopic boom conveyor in the loading bay of a warehouse, Figure 2 shows an end view of the conveyor showing the loading platform, and, Figure 3 shows a sketch of the hydraulic arrangement of the present invention.

Referring now to Figure 1, there is shown a loading bay 1, typically of a warehouse, which has a telescopic boom conveyor 2 mounted on the loading bay deck and adapted to extend out over the loading platform 3 of a vehicle. The vehicle 3 is backed up to the conveyor 2 so that the free end of the conveyor extends right into the vehicle. At its free end 4, the conveyor has a man rider platform 5 having a platform surface 6, on which the operator stands and which can be folded up to lie flush with upright members 7 of the platform.

Referring now to Figure 2 also, the platform 5 has at each of its lateral sides, a hydraulic piston and cylinder device 8 which is connected to the upright members 7 by a trunnion 9.

Essentially, the two hydraulic piston cylinder devices are identical and so only one will be described in detail. Reference should also be made to Figure 3 which shows a schematic view of the devices including the fluid communications therebetween.

Each device 8 includes a cylinder 10 containing a piston 11 which divides the cylinder 10 into two chambers, an upper chamber 12 and lower chamber 13.

The piston 11 is connected to a connecting rod 14 which extends right through the cylinder 10. At its upper end 14a the connecting rod 14 abuts a spring 15 which biases the piston 11 towards the lower end of the cylinder 10. At its lower end 14b, the connecting rod 14 is connected by means of a pin joint 16 to a swing link 17 of a suspension system, which link 17 is pivot connected by a pin joint 18 to the platform 5 and carries a platform supporting wheel 19 at its lower end.

As shown schematically in Figure 3, the upper chambers 12 of the two hydraulic devices 8, are, in each case, connected to the lower chamber 13 of the other device so that fluid can flow from chambers 12 to the opposite chambers 13 and vice versa.

In operation, the boom conveyor illustrated in Figure 1 is extended into the back of a vehicle and packages or components to be stacked in the vehicle are loaded onto the conveyor from the warehouse (not shown) where they are carried to the free end 4 of the conveyor. A stacker, or operator, stands on the platform 6 and removes the packages as they arrive and stacks them in the vehicle. As the vehicle is filled, the conveyor is gradually retracted, either by the operator working from controls adjacent the platform 6 or by an operator in the warehouse.

It will be appreciated that, as the conveyor 2 is of a relatively light construction, the free end tends to move quite a lot, and particularly is prone to a lateral yawing motion in which the free end of the conveyor pivots about the longitudinal axis thereof. This is a particular problem when two operators are removing packages from the conveyor, as their movements, as they jump on and off the platform, can become magnified with a consequent risk of danger or damage to the conveyor. During its extension and retraction movement, the free end of the conveyor 2 is supported by the wheels 19 of the suspension system. If the operator stands on one side of the platform, thus giving rise to lateral instability, the platform on that side tends to go down carrying the cylinder 10 with it.This action serves to increase the volume of the chamber 13 and decrease the volume of the chamber 12 by the displacement of hydraulic fluid. However, the fluid displaced from the chamber 12 flows through a fluid connection 20 to the lower chamber 13 of the cylinder 10 of the other device. This transfer of fluid to the lower chamber 13 of the other device from the upper chamber 12 of the first device serves to push the cylinder 10 on the other device downwardly so that its movement matches that of the cylinder on the other side.

In this way, the movement of the platform surface 6 is maintained substantially horizontal and the incidence of accidents and damage to the operators and packages is reduced.

The hydraulic fluid tends to damp the movements of the platform and throttles may be provided in the fluid communications 20 to provide the required degree of damping. The required degree of damping may alternatively be provided by the use of appropriately sized pipes in the fluid communications.

Means (not shown), which may be hydraulic or screw thread arrangement, may be provided for adjusting the normal working height of the platform, whilst the platform may also be foldable or retractable to a storage position. Although the embodiment described has the cylinder mounted on the platform and the piston connected to the ground, it will be understood that these could be reversed, with the piston connected to the platform.

Claims

1. A platform adapted to be connected to the free end of a boom conveyor, the platform including laterally spaced hydraulic devices each comprising a cylinder having two chambers separated and defined by a movable piston in the cylinder, one of the piston or cylinder being adapted to engage the ground and the other of the cylinder or piston, as the case may be, being secured to the platform for movement therewith, the said two chambers comprising an upper chamber and a lower chamber, the upper chamber of each device being in fluid communication with the lower chamber of the other device.

2. A platform according to claim 1, wherein the pistons of the devices are connected to ground engaging members through a suspension linkage.

3. A platform according to claim 2, wherein resilient means is provided to bias the suspension linkages to the fully extended position.

4. A platform according to claim 1, 2 or 3, wherein the piston is connected to a connecting rod intermediate the length thereof, the ends of the connecting rod extending out of the ends of the cylinder, the lowermost end being connected to the suspension linkage and the uppermost to resilient means which serves to bias the piston downwardly.

5. A platform according to any one of the preceding claims, wherein the cylinders are connected to a main frame of the platform through respective trunnions.

6. A platform according to any one of the preceding claims, wherein means is provided in the fluid communications between the respective upper and lower chambers to control the rate of fluid flow therethrough.

7. A platform adapted to be connected to the free end of a boom conveyor, substantially as decribed herein with reference to and as illustrated in the accompanying drawings.

8. A boom conveyor including a platform as claimed in any one of the preceding claims.