GB2125003A - Forklift truck - Google Patents

Abstract

A forklift truck (10) for use in narrow aisle situations has the load engaging tines (18) mounted on a frame which is adapted to be turned laterally left or right about a vertical axis to displace a load into or out of storage tracks on one or other side of the aisle, with an extender linkage (24) for moving the forks rectilinearly. <IMAGE>

Description

SPECIFICATION Forklift truck This invention relates to forklift trucks which are herein defined as comprising a mobile chassis, usually mounted on wheels or rollers, a mast, and a carriage with fork tines or the like supported on the mast and movable in a substantially vertical direction so that a load engaged by the tines can be raised and lowered.

The invention is particularly concerned with such trucks for use in narrow or confined spaces and for inserting loads into (or removing them from) storage racks. There is a particular problem when the racks are separated by narrow aisles where it is not sufficient to make the truck of small dimensions, because if the fork tines extend in the normal direction of movement of the truck, there is insufficient space for the truck to approach a face of the stack (in a direction at right angles to the length of the aisle) for engaging the tines with the load or disengaging them therefrom.

Many different designs of special purpose vehicles have been proposed for these purposes, and the object of the present invention is to provide an improved arrangement for these purposes.

According to the invention a forklift truck is characterised in that a frame is interposed between the fork and the chassis, such frame surrounding the forks except at a position in front of the forks, an extender linkage is disposed between the fork and frame for displacing the fork forwardly and out of the frame, and the frame is mounted for pivotal movement about a substantially vertical axis.

Various embodiments of the invention are now more particularly described with reference to the accompanying drawings wherein Figure 1 is a diagrammatic plan view of a first proposal, in a first position; Figure 2 is a fragmentary plan view of the same arrangement, but in a second position; Figure 3 is a view similar to Fig. 1 but showing a second embodiment in a first position; Figure 4 is a view similar to Fig. 1 but showing a third embodiment; Figure 5 is a view similar to Fig. 1 but showing a fourth embodiment in a first position; and Figures 6 and 7 show the embodiment of Fig. 5 in two different positions.

Like reference numerals are used for like parts in all of the Figures.

In all of these cases, the illustrated forklift truck comprises a chassis 10 provided with wheels or rollers 12, a mast 14, a carriage 16, and fork tines 1 8 for engagement with the load.

In the arrangements of Figs. 1 and 2, a guide 20 is fixed to the chassis 10 and supports a frame 22 which can be turned from the position in which the frame and guide are aligned as shown in Fig. 1, to either left or right. The mast is mounted on the frame so as to turn with the latter and the carriage is mounted on the mast. Means 24 are provided for extending the forks out of the frame. In the lowest possible position the forks, frame and guides can be substantially co-planar.

When the frame is turned on the guide, the mast can be used to elevate the forks slightly so that they can extend out over the guide as shown in Fig. 2 to engage a load.

In the embodiment of Fig. 3, which otherwise is generally similar to Fig. 1, the mast 14 is interposed between the chassis and the guide so that effectively the guide is displaced vertically with the carriage upon the mast. In this case the forks may be located at a slightly higher level than the frame so that they project across the frame when turned to a position analogous with that of Fig. 2, or alternatively a sub-mast 26 may be provided for the purpose of lifting the forks slightly when the mechanism 24 is to be actuated to extend the forks laterally.

In the arrangement of Fig. 4, the carriage 30 is generally L-shaped and is movable vertically on the mast. The carriage supports a frame 32 pivoted to the carriage about axis 34 and the forks are connected to the frame 32 via the mechanism 24 so that the forks can be extended out from the frame 32 as shown in chain dot line in the Figure. The arrangement of Fig. 4 has the limitation that the load can only be projected in one direction relative to the normal forward direction of the vehicle and this means that the vehicle (the truck) has to enter a narrow aisle from an appropriate direction according to the side of the aisle concerned in a particular load transferring operation.

The arrangements shown in Figs. 5 to 7 overcome the disadvantages of the Fig. 4 arrangement, and in a generally similar fashion. In these views, a carriage 30 is mounted on the mast and pivotally connected at 34 to a frame 36 which in turn is pivotally connected at 38 to an inner frame 40 which carries the extender linkage 24 carrying the forks 1 8. As shown in Fig. 5, the frame 40 may carry small ground-engaging wheels 42 for load support when the forks are in their lowermost position. Fig. 6 shows the arrangement of Fig. 5 with the load carrying forks extended laterally to the left, and Fig. 7 when the load is to be extended to the right.

Latches (not shown) are provided to hold the frames together and the frames to the chassis via the carriage at times when the parts are in the Fig. 5 relationship.

In a modification of the Fig. 5 arrangement (not shown) the carriage 30 is fixed directly to the chassis and the mast is interposed between the innermost frame 40 and the extender linkage 24, so that the mast will be turned to left or right in the Figs. 6 and 7 positions respectively.

The extender linkage may require to have a relatively large travel compared to the size of the vehicle, and it is therefore preferred to use a pantograph linkage for this purpose. The linkage may be required to transmit load as well as providing the extending force, that is to enable the fork engaged load to be safely carried even at the top of the mast and at the fully extended position.

The frame may be pivoted by a hydraulic ram, for example.

Claims (8)

1. A forklift truck comprising a mobile chassis mounted on wheels or rollers, a mast, and a carriage with fork tines or the like supported on the mast and movable in a substantially vertical direction so that the load engaged by the tines can be raised or lowered, in which a frame is interposed between the fork and the chassis, such frame surrounding the forks except at at a position in front of the forks, an extender linkage is disposed between the fork and frame for displacing the fork forwardly and out of the frame, and the frame is mounted for pivotal movement about a substantially vertical axis.

2. A forklift truck as claimed in Claim 1 wherein the frame is part-circular and mounted in a complementary guide so that the frame can be turned in both directions from the ordinary forward position.

3. A truck as claimed in Claim 2 wherein the mast is located between the frame and the forks so that the frame is at constant height and the forks can be raised out of the plane of the frame before the extender linkages operate.

4. A truck as claimed in Claim 2 wherein the mast is provided between the guide and the chassis so that the guide is displaced up and down the mast with the carriage, and the forks are arranged at a different height from the frame so that they can extend across the guide.

5. A truck as claimed in Claim 2 wherein the mast is provided between the guide and the chassis so that the guide is moved up and down the mast with the carriage and carries with it the frame and forks, and in which a sub-mast is provided for displacing the forks slightly relative to the frame and guide in a vertical direction.

6. A truck as claimed in Claim 1 wherein the carriage comprises a generally L-shaped frame pivotally connected to a second frame mounting the forks via the extender linkage.

7. A truck as claimed in Claim 6 wherein two generally U-shaped frames are pivotally connected together at one lateral position and the outer of the frames is pivotally connected to the carriage at an opposite lateral position.

8. A forklift truck substantially as described with reference to Figs. 1 and 2, or Fig. 3, or Fig. 4, or Figs. 5 to 7 of the accompanying drawings.