GB2045209A - Lift trucks - Google Patents

Abstract

With a lift truck of the kind in which an operator's cab (12) is raised with a fork carriage (16) up a mast (10) of the truck, and the forks (18) can be moved laterally of the cab face and rotated to extend either directly away from the cab or laterally of the cab face, the operator may be required to load a stillage on the forks by hand from the cab, taking articles from storage racks alongside. To ease such manual loading, the fork carriage (16) is mounted for lateral movement on two laterally extending parallel guides (36 and 38) which are vertically spaced apart to permit an operator to walk between them from the cab (12) for better access to the stillage on the forks. <IMAGE>

Description

SPECIFICATION Lift trucks This invention is concerned with lift trucks of a kind in which the truck comprises a main mast, an operator's cab, means operative to move the cap up and down the main mast, and a carriage mounted on the cab and arranged for movement of load supporting means both laterally of a face of the cab and rotationally between a first position in which said supporting means extends in a direction extending directly away from said face and a second position in which said supporting means extends in a direction extending laterally of said face. A truck of this kind is hereinafter referred to as being "of the kind defined". Said load supporting means maybe in the form of forks.

There are known fork lift trucks, being lift trucks of the kind defined, which are particularly useful for operating in a narrow aisle between two rows of storage racks. With a truck standing in the aisle it can operate to load or unload a storage rack to the side of the truck by movements of the forks laterally of the face of the cab when the forks are in their second position. After rotation of the forks to their first position, a load can also be picked up or put down in front of the truck.With the forks in their second position, the truck may be employed either for "pallet picking" operations, in which loaded pallets are picked from (or deposited on) storage racks to the side of the truck, or for "order picking" operations in which the operator manually selects articles from the storage racks and loads them on to a receptacle (which may be a pallet, or a stillage or other container) carried by the forks in the aisle opposite the face of the cab.

A difficulty arises in order picking operations with known trucks, in that the operator's reach from the cab is limited and difficulty is accordingly experienced in loading the pallet, stillage, or other receptacle.

It is an object of this invention to provide a lift truck of the kind defined in which an operator in the cab has better access to a load carried opposite the face of the cab.

According to the invention, there is provided in a lift truck of the kind defined a walkway through the face of the cab to permit an operator to walk from the cab to a receptacle carried opposite the face of the cab by load supporting means on said carriage.

In a preferred form of the carriage is mounted, for movement laterally of the face of the cab, on two laterally extending parallel guides on the cab, the two guides being vertically spaced-apart to permit an operator to walk therebetween. A bottom one of the two guides may comprise a cylindrical bar along which the carriage is mounted to slide, and the top guide may be in the form of an inverted channel in which rollers of the carriage are located.

The carriage preferably comprises a secondary mast of the truck, and means operative to move a carrier of the carriage up and down the secondary mast. By this arrangement a load carried by load supporting means on the carrier can be raised and lowered short distances without movement of the cab on the main mast.

Preferably the carriage is arranged for rotational movement of load supporting means through 180 , between its second position and a position in which it extends in the opposite direction. By this means a truck can operate on storage racks on both sides of the truck, when the truck is standing in an aisle between the racks.

There now follows a description, to be read with reference to the accompanying drawings, of an embodiment of the invention.

In the accompanying drawings: Figure 1 is a view in side elevation of the truck; and Figure 2 is a view in front elevation of the truck.

The lift truck shown in the drawings comprises an extensible vertical main mast 10, an operator's cab 12, means comprising a hydraulic cylinder 14 (Figure 2) operative to move the cab 12 up and down the main mast 10, and a fork carriage 16 mounted on the cab. The fork carriage 16 is arranged for movement of load supporting means in the form of forks 18 both laterally of a front face 20 of the cab and rotationally (about a vertical axis) between a first position (not shown) in which they extend in a direction extending directly away from the face 20 (forwardly of the truck) and a second position (shown in the drawings) in which they extend in a direction extending laterally of the face 20.

The truck comprises a rear-engined motorised body 22. The extensible main mast 10 comprises a fixed outer mast portion 24 mounted on the body, and a movable inner mast portion 26 mounted to slide up and down the outer mast portion. The hydraulic cylinder 14 comprises a body portion 28 secured to the trunk body 22 and a piston rod 30 which is secured to the inner mast portion 26. The cab 12 is mounted to slide up and down the inner mast portion 26. A chain (not shown) is connected at one end to the cab 12 and at its other end to the trunk body 22 and passes over a pully on the inner mast portion 26, so that as the inner mast portion 26 is raised a certain distance up the outer mast portion 24 by the cylinder 14, the cab 12 is raised by twice that distance.Accordingly, by means of the cylinder 14 the cab 12 can be raised from a bottom position shown in phantom in Figure 1 to the top position shown. Raising and lowering of the cab is controlled by an operator in the cab.

The fork carriage 16 comprises a vertical secondary mast 32 of the truck, and a fork carrier 34 mounted for movement up and down the secondary mast. The mast 32 is mounted on the cab, for movement of the carriage 16 laterally of the front face 20 of the cab, on two parallel laterally extending guides on the cab. A bottom one of the two guides comprises a horizontal cylindrical bar 36 along which a bottom end portion of the secondary mast 32 is mounted to slide. A top one of the two guides is in the form of a horizontal inverted channel 38 and rollers 40, mounted on the top of the secondary mast 32, are located in the channel for guidance of the top end of the mast.

The front face 20 of the cab 12 is open except for two openable safety-doors 42, and the bar 36 and the channel 38 of the fork carriage guides are vertically spaced apart a sufficient distance to permit an operator to walktherebetween. The bar 36 is substantially at the floor level of the cab.

Means operative to move the fork carriage 34 up and down the secondary mast 32 comprises a hydraulic cylinder 44 standing vertically between uprights 46 of the mast 32 ahd secured to the mast. A piston rod 48 of the cylinder 44 carries a pulley over which a chain 50 passes, one end of the chain 50 being secured to the body of the cylirider 44 and the other end of the chain being secured to the fork carrier 34. Upon operation of the cylinder 44, the pistoh rod 48 (and the pulley thereon) is driven upwards, and by means of the chain 50 the fork carrier 34 is accordingly raised up the mast 32.By this means there is provided e "free iift" faciiity, by which the operator can raise and lower the fork carrier 34 short distances (as indicated in Figure 1) without movement of the cab i2 on the main mast 10.

The fdrk carriage 16 is arranged for rotational movement of the forks 18 through 180 , between their second position and a third position in which they extend in the opposite direction; in moving from their second position to their third position the forks move through their first position, Means whereby the forks 18 are rotatable is of a known construction and will not be described in detail herein, but the fork carrier 34 comprises a slide block 52 mounted on the secondary mast 32, a bracket 54 pivotally mounted on the slide block, and hydraulic means (not shown) for rotating the bracket on the slide block. The forks 18 are mounted on the bracket 54.

The truck is shown, in Figure 2, in the aisle between two storage racks R. The forks 18 are shown in their second position. By movement of the secondary mast 32 (by means not shown) on the guides 36 and 38, a load on the forks 18 can be picked up from, or set down on, the storage rack to the right hand side of the truck, as indicated in phantom. Height adjustments along the secondary mast 32 can be made by the operator as necessary.

Alternatively an "order picking" operation can be undertaken, in which a pallet or stillage, or other receptacle, is carried by the forks 18 in the aisle opposite the front face 20 of the cab (the forks being in the position shown in Figure 2) and the operator manually selects articles from the storage racks and loads them on to the receptacle on the forks. To assist loading of the receptacle, the left hand door 42 (as viewed in Figure 2) can be opened to allow the operator to walk through the front face 20 of the cab to the receptacle, there being a walkway through the face 20 between the guides 36 and 38. An electrical safety interlock prevents operation of the truck whilst either of the doors 42 is open, so that the operator must return to the cab 12 before further operating the truck.

Claims (7)

1. A lift truck of the kind defined in which there is provided a walkway through the face of the cab to permit an operator to walk from the cab to a receptacle carried opposite the face of the cab by load supporting means on said carriage.

2. A lift truck according to Claim 1 in which said carriage is mounted, for movement laterally of the face of the cab, on two laterally extending parallel guides on the cab, the two guides being vertically spaced-apart to permit an operator to walk therebetween.

3. A lift truck according to Claim 2 in which a bottom ohe of the two guides comprises a cylindrical bar along which said carriage is mounted to slide.

4. A lift truck according to either one of Claims 2 and 3 in which the top guide is in the form of an inverted channel in which rollers of the carriage are located.

5. A lift truck according to any one of Claims 1 to 4 in which said carriage comprises a secondary mast of the truck, and means operative to move a carrier of said carriage up and down the secondary mast.

6. A lift truck according to any one of Claims 1 to 5 in which said carriage is arranged for rotational movement of load supporting means through 180 between its second position and a position in which it extends in the opposite direction.

7. A lift truck constructed and arranged substantially as hereinbefore described with reference to the accompanying drawings.