IE77522B1 - Attachment for a forklift truck - Google Patents

Description

ATTACHMENT FOR A FORKLIFT TRUCK This invention relates to an attachment for a forklift truck, in particular but not exclusively for handling bales of cotton.

At present, when bales of cotton are brought by forklift truck to a laydown area, difficulties arise in positioning the bales accurately as they must be laid down in a pre-determined area marked on the floor.

When carrying two bales, the conventional forklift can position one bale accurately, but the second bale tends to remain between the clamps. To unlodge it requires repeated reversing of the truck causing damage to the floor area and bending of the toes of the clamping arms. To position the second bale accurately requires the forklift operator to either manoeuvre the bale into position with the toes of the fork, or push the bale manually. Using the toes is time consuming and manually pushing the bale may jeopardise the operator.

It is an object of the invention to provide an attachment for a forklift truck which will remove the need for manual handling by using an automated mechanism for removing the bale from the clamping arms of the forklift.

Accordingly, the invention provides an attachment for a forklift truck comprising at least one pair of substantially parallel hydraulically-operable clamping arms which are reciprocable towards and away from one another in a direction substantially perpendicular to their length for respectively clamping and releasing a load between them, and a hydraulically operable pushing mechanism mounted between the arms, the pushing mechanism being extendable in a direction substantially parallel to the arms towards the free ends thereof for pushing a load from between the arms and retractable in the opposite direction for allowing a load to be retained between the arms. -277 52 2 An embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a general perspective view of an attachment for a forklift truck, and Figure 2 is a more detailed exploded view of the attachment.

Referring to the drawings, the attachment comprises upper and lower pairs of substantially parallel horizontal clamping arms 10 and 11 respectively.

The base or root of each upper arm 10 is slidable in horizontal grooves in an upper guide member 12 so that the arms 10 can reciprocate horizontally towards and away from one another in a direction substantially perpendicular to their length, as indicated by the arrow A in figure 1. The lower arms 11 are similarly reciprocable in horizontal grooves in a lower guide member 13. The upper and lower arms 10, 11 on each side of the assembly are tied together by vertical members 14 so that the upper and lower pairs of arms open and close in synchronism.

The clamping arms 10 and 11 are driven to open or close by upper and lower pairs of back-to-back one-stage double-acting hydraulic cylinders 15.

By retracting the cylinders 15 the arms 10 and 11 are drawn together to clamp a load between them, and by extending them the arms 10 and 11 are driven apart to release a load. The clamping cylinders 15 act in an equalising manner, i.e. the cylinders 15 cannot open or close individually.

The guide members 12 and 13 are mounted on a circular back plate 16 which in turn is attachable in a conventional manner (not shown) to a forklift truck for rotation through 360 degrees as indicated by the arrow B in figure 1. Thus the entire clamping arm assembly can be rotated through * 360 degrees from the position shown in figure 1.

Hydraulic power for operating the hydraulic cylinders 15 is provided from the hydraulic system of the forklift truck to which it is attached in use via a non-rotating axial revolving connection 17 (figure 2), and the circular back plate 16 is driven through a rack and pinion by a hydraulically operated -3motor on the forklift truck, all in known manner.

To the extent so far described the forklift attachment is of known design, for example as sold under the name Cascade 35D. However, in accordance with the embodiment of the invention, an automated mechanism for load removal is provided in the form of a pushing mechanism 18.

The pushing mechanism 18 includes a five-stage double-acting hydraulic cylinder 19. The cylinder 19 is bolted onto a substantially vertical mounting plate 20 which is in turn bolted to the back plate 16 via upper and lower mounting blocks 21, the latter ensuring sufficient forward clearance between the plate 16 and the guide members 12 and 13 so as not to interfere with the operation of the clamping arms 10 and 11. The axis of the cylinder 19 is substantially perpendicular to the mounting plate 20 (i.e. parallel to the clamping arms 10 and 11) and is located symmetrically at the centre of the four arms. A substantially vertical pushing plate 22 is bolted to the free front end of the cylinder 19, the plate 22 thus lying in a plane substantially perpendicular to the axis of the cylinder 19 and to the clamping arms 10 and 11.

The cylinder 19 may be retracted and extended by the hydraulic system of the forklift truck via the revolving connection 17. When the cylinder 19 is fully retracted against the mounting plate 20 (the cylinder 19 is shown in its fully retracted state in figure 2) the plate 22 is a sufficient distance behind the free front ends of the clamping arms 10 and 11 to permit a load to be inserted between the arms and retained there by a clamping action of the arms. However, the cylinder can be extended (figure 1) to push a load from between the arms 10 and 11.

Preferably the hydraulic circuit is designed such that the functions of rotating, clamping and pushing are completely independent, i.e. the attachment cannot clamp while rotating or push when clamping.

Claims (5)

1. An attachment for a forklift truck comprising at least one pair of substantially parallel hydraulically-operable clamping arms which are reciprocable towards and away from one another in a direction substantially perpendicular to their length for respectively clamping and releasing a load between them, and a hydraulically operable pushing mechanism mounted between the arms, the pushing mechanism being extendable in a direction substantially parallel to the arms towards the free ends thereof for pushing a load from between the arms and retractable in the opposite direction for allowing a load to be retained between the arms.

2. An attachment as claimed in claim 1, wherein the pushing mechanism comprises a multi-stage double-acting hydraulic cylinder whose axis is substantially parallel to the clamping arms.

3. An attachment as claimed in claim 2, wherein the cylinder carries a plate at its free end, the plate lying in a plane substantially perpendicular to the clamping arms.

4. An attachment as claimed in claim 2 or 3, wherein there are two pairs of clamping arms mounted one above the other and the axis of the cylinder is located centrally between the four arms.

5. An attachment for a forklift truck substantially as described herein with reference to the accompanying drawings.