GB2118140A - Extending mast of fork lift truck - Google Patents

Abstract

A fork lift truck has two spaced apart vertically parallel box-section structural members (23) simultaneously forming the functions of rams. The rams carry a vertical framework (24), guided by the structural members (23) and in turn carrying a traverse frame (16) for a traversing pivotal fork and carriage assembly (13, 14 and 15) arranged forward of the structural members (23), whilst a driving compartment (12) is arranged rearwardly of the structural members (23). <IMAGE>

Description

SPECIFICATION Improvements in materials handling equipment The present invention concerns improvements in materials handling equipment.

It has been found that non-circular, more especially square hollow section lifting members have more resistance to torsional forces when loads are side shifted or traversed laterally on materials handling equipment.

The present invention involves the adaption of such square hollow section structural members to perform also the functions of a ram.

Displacement cylinders have been found to have the particular advantage of being suitable where the cylinders are of considerable length since the conventional piston and piston seals are replaced by a fluted centralising guide of a nonferrous metal or a plastics material. The only sealing required on a displacement cylinder is at the neck of the shell and these can be exchanged in situ when two cylinders each equipped with lock-off valves are fitted.

Most materials handling equipment such as fork lift trucks have structural lifting members and hoist cylinders and in certain cases these members obstruct the operator's view so it is desirable to reduce the number of vertical members to a minimum.

An object of the present invention is to reduce the number of structural members in materials handling equipment whilst maintaining or enhancing load bearing capacity and structural stability and increasing operator visibility.

According to the present invention in materials handling equipment at least one long box section structural member simultaneously forms a ram.

Suitably, the box section is square as this gives maximum rigidity and torsional resistance. This device is particularly suitable to fork lift trucks and can also be used in equipement such as squeeze clamps or cranes. The device can be manufactured from extruded or seam welded rectangular hollow section steel.

The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a fork lift truck with an offset mast incorporating the device of the present invention; and Fig. 2 is a corresponding plan view.

In the drawings it can be seen that an operators seat 11 is positioned in a driving compartment 12 remote from forks 13 of the truck. The forks 13 are attached to a carriage 14 and thence to a pivot 1 5. The provision of the pivot 15 enables the fork and carriage assembly 13, 14 to be rotated through an angle of 180 .

The pivot 1 5 has powered movement on an offset traverse frame 1 6. Thus, loads can be laterally placed on racking either side of a narrow working gangway.

Vertical movement of the whole front end 13, 14, 15, 1 6 is effected by a pair of chains 18 each passing over a pulley 19 secured to an inner moving mast assembly 24. One end of each chain 18 is attached to the traverse frame 1 6 and the other end to a bracket 20 which is fixed to a ram 23.

Movement of the inner mast assembly 24 is effected by the ram 23 which in turn causes the chain 18 movement and thence the front end 13, 14, 15, 16.

Claims (Filed on 5. 4. 83).

1. A materials handling apparatus comprising at least one long box section structural member simultaneously forming a ram.

2. An apparatus as claimed in claim 1, in which the box section is square and forms the outer shell of a hydraulic ram.

3. An apparatus as claimed in claim 1 or 2, in which the structural member is made of extruded or seam welded rectangular hollow metal section.

4. An apparatus as claimed in any preceding claim, in which two structural members are vertically mounted spaced apart on a movable base a driving compartment being secured to the base behind the vertical members, a centrally or offset mounted traverse frame being arranged on the side of the vertical members opposite the driving compartment.

5. An apparatus as claimed in claim 4, in which the traverse frame is mounted on two spaced apart displaceable vertical members joined by upper and lower cross members, each vertical member being juxtaposed inwardly of one of the vertical structural members which are secured at their upper ends to a cross member in turn fixed on the movable parts of the rams.

6. An apparatus as claimed in claim 4 or 5, in which a fork and carriage assembly is pivotally mounted to the traverse frame.

7. An apparatus as claimed in claim 5, in which the traverse frame is secured to chains or wire ropes and vertically moved with the vertical members to which it is secured.

8. A materials handling apparatus constructed and arranged substantially as herein described with reference to and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improvements in materials handling equipment The present invention concerns improvements in materials handling equipment. It has been found that non-circular, more especially square hollow section lifting members have more resistance to torsional forces when loads are side shifted or traversed laterally on materials handling equipment. The present invention involves the adaption of such square hollow section structural members to perform also the functions of a ram. Displacement cylinders have been found to have the particular advantage of being suitable where the cylinders are of considerable length since the conventional piston and piston seals are replaced by a fluted centralising guide of a nonferrous metal or a plastics material. The only sealing required on a displacement cylinder is at the neck of the shell and these can be exchanged in situ when two cylinders each equipped with lock-off valves are fitted. Most materials handling equipment such as fork lift trucks have structural lifting members and hoist cylinders and in certain cases these members obstruct the operator's view so it is desirable to reduce the number of vertical members to a minimum. An object of the present invention is to reduce the number of structural members in materials handling equipment whilst maintaining or enhancing load bearing capacity and structural stability and increasing operator visibility. According to the present invention in materials handling equipment at least one long box section structural member simultaneously forms a ram. Suitably, the box section is square as this gives maximum rigidity and torsional resistance. This device is particularly suitable to fork lift trucks and can also be used in equipement such as squeeze clamps or cranes. The device can be manufactured from extruded or seam welded rectangular hollow section steel. The invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a fork lift truck with an offset mast incorporating the device of the present invention; and Fig. 2 is a corresponding plan view. In the drawings it can be seen that an operators seat 11 is positioned in a driving compartment 12 remote from forks 13 of the truck. The forks 13 are attached to a carriage 14 and thence to a pivot 1 5. The provision of the pivot 15 enables the fork and carriage assembly 13, 14 to be rotated through an angle of 180 . The pivot 1 5 has powered movement on an offset traverse frame 1 6. Thus, loads can be laterally placed on racking either side of a narrow working gangway. Vertical movement of the whole front end 13, 14, 15, 1 6 is effected by a pair of chains 18 each passing over a pulley 19 secured to an inner moving mast assembly 24. One end of each chain 18 is attached to the traverse frame 1 6 and the other end to a bracket 20 which is fixed to a ram 23. Movement of the inner mast assembly 24 is effected by the ram 23 which in turn causes the chain 18 movement and thence the front end 13, 14, 15, 16. Claims (Filed on 5. 4. 83).

1. A materials handling apparatus comprising at least one long box section structural member simultaneously forming a ram.

2. An apparatus as claimed in claim 1, in which the box section is square and forms the outer shell of a hydraulic ram.

3. An apparatus as claimed in claim 1 or 2, in which the structural member is made of extruded or seam welded rectangular hollow metal section.

4. An apparatus as claimed in any preceding claim, in which two structural members are vertically mounted spaced apart on a movable base a driving compartment being secured to the base behind the vertical members, a centrally or offset mounted traverse frame being arranged on the side of the vertical members opposite the driving compartment.

5. An apparatus as claimed in claim 4, in which the traverse frame is mounted on two spaced apart displaceable vertical members joined by upper and lower cross members, each vertical member being juxtaposed inwardly of one of the vertical structural members which are secured at their upper ends to a cross member in turn fixed on the movable parts of the rams.

6. An apparatus as claimed in claim 4 or 5, in which a fork and carriage assembly is pivotally mounted to the traverse frame.

7. An apparatus as claimed in claim 5, in which the traverse frame is secured to chains or wire ropes and vertically moved with the vertical members to which it is secured.

8. A materials handling apparatus constructed and arranged substantially as herein described with reference to and as illustrated in the accompanying drawings.