GB2242670A

GB2242670A - Level indicating means

Info

Publication number: GB2242670A
Application number: GB9007586A
Authority: GB
Inventors: John Paul Servadei
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-04-04
Filing date: 1990-04-04
Publication date: 1991-10-09
Also published as: GB9007586D0

Abstract

A level indicating means is disclosed in operation with a fork-lift truck by way of example. The arrangement comprising an upright frame (2) on a wheeled platform. A lifting portion (4) is provided with two lifting forks. Secured to a side portion of the frame (2) is a guide rail (6) on which are slidingly adjustable a plurality of proximity switches (8). Each switch (8) is connected to an associated connected (10) by a flexible cable. The lifting portion (4) has a metal rod (12) projecting from it so that when the portion (4) is raised or lowered the end of the projection moves past each switch and actuates it. A visual or audible signal is then given that the forks of the device are at a pre-set height, which is determined by the requirements of the job in hand. <IMAGE>

Description

LEVEL INDICATING MEANS The invention is concerned with level indicating means, suitable for use particularly but not exclusively for use in ascertaining the level to which a lifting device is to be or has been moved.

It is not uncommon for operators of lifting machinery to be working in circumstances in which their view of the operating zone of the machinery is obscured. An example of such a circumstance is in the use of a type of lifting device, generally known as a fork-lift truck, in which the free ends of a pair of forwardly projecting lifting arms are inserted into spaces formed by wooden or plastics pal lets or the like on which a load is positioned for carrying. A skilled operator frequently is able to judge by eye alone whether the free ends of the lifting arms are at the correct level as the truck is manoeuvred so that the ends can engage the pallet without either damage to the load or hitting the pallet, but this is not always possible.

The present invention provides a level indicating means for use with lifting devices, said means comprising proximity sensing devices, a supporting frame means for adjustably supporting said proximity sensing devices at selected levels, each said sensing device being operable to initiate a indicating signal, and operating means adapted to be mounted for heightwise movement upon a movable portion of an associated lifting device.

The present invention further provides a lifting device comprising a mobile upright frame and a lifting portion movable heightwise with respect to said frame, a mounting device associated with said frame, a plurality of proximity sensing devices adjustably received on said mounting device for positioning in selected heightwise positions with respect to said frame, operating means provided on said lifting portion to operate said proximity sensing devices and means for emitting an audible or visible indicating signal upon operation of said sensing devices.

In an example to be described below, the lifting device is a fork-lift truck having a mobile upright frame and a lifting portion including two lifting forks. It will be understood that the description, which is to be read with reference to the drawings, is given by way of example only and not by way of limitation.

In the drawings: Figure 1 is a diagrammatic view of a fork-lift truck framework, with forks omitted for clarity; Figure 2 is a similar view showing a lifting portion of the truck in a raised position.

The fork-lift truck shown in the Figures comprises an uprigh-t frame 2 mounted upon a wheeled platform (not shown) and adapted to be driven by a power source such as a battery so that the truck may be manoeuvred into operating positions as required. A lifting portion 4 of the truck comprises a frame which supports two lifting arms in a conventional manner. The arms are not shown as such, for the sake of clarity, but illustrative heightwise operating positions are indicated at L1 and L2 in Figures 1 and 2 respectively.

Secured to a side portion of the frame 2 is a guide rail 6 upon which are slidingly mounted a plurality of proximity switches 8. Two switches 8 are shown in the drawings but it will be understood that as many switches may be provided as necessary for the job in hand as will be explained. Each switch 8 is connected by a cable to an associated electrical connector 10 on the frame 4, a suitable circuit arrangement being provided which links to a series of indicator lights in the cabin of the truck, each switch having its associated light in a console.

Provided upon the lifting portion 4 is a metal projection 12 adapted to extend outwardly so that when the portion 4 is raised or lowered, the end of the projection passes each of the appropriate switches 8 in a manner to actuate it, thus initiating an appropriate signal.

In operation, the procedure is as follows. In circumstances where, for example, an operator must repeatedly carry out a manoeuvre between, say, two predetermined levels, he will set the first level by positioning the unloaded forks at the desired height (L1) and then adjust the position of the nearest switch 8 until it is adjacent to the projection 12. The forks are then raised to the second position (L2) and the second switch 8 is positionally adjusted.

When the operator returns to the truck cabin, he will carry out the necessary raising and lowering of the loaded forks between the set positions L1, L2 in which the projection 12 actuates each switch, actuation causing an indicating light to be illuminated on a console in the cabin. It will be understood that there may be three or four lights, each operated at an adjusted level to suit a set manoeuvre which may be a single-step or a multi-step operation. In any such arrangement however, the operator does not have to rely on his judgement in otherwise difficult situations.

Various modifications may be made within the scope of the invention.

Claims

CLAIMS:

1. A level indicating means for use with lifting devices, said means comprising at least one proximity sensing device, a supporting frame means for adjustable supporting said proximity sensing device(s) between selected levels, the or each said sensing devices being operable to initiate a indicating signal and operating means adapted to be mounted for heightwise movement upon a movable portion of an associated lifting device.

2. Indicating means as claimed in claim 1, wherein the supporting frame means comprises a rail upon which the proximity sensing device(s) are slidably mounted so as to be securable at one of said selected levels.

3. A lifting device comprising a level indicating means as claimed in either one of claims 1 and 2, there being further provided a mobile upright frame and a lifting portion comprising said movable portion, wherein operating means provided on said lifting portion are adapted to operate said proximity sensing device(s) so as to initiate said indicating signal.

4. A device as claimed in claim 3, wherein the lifting portion includes two lifting forks.

5. A device as claimed in either one of claims 3 or 4 wherein the indicating signal comprises an indicating light.

6. A device as claimed in any one of claims 3 to 5, wherein said operating means comprises a projection extending from the lifting portion towards said supporting frame means.

7. A lifting device including a level indicating means, constructed and arranged to operate substantially as hereinbefore described with reference to and as shown in the drawings.