GB2355244A

GB2355244A - Fork-lift truck auto-balancing system

Info

Publication number: GB2355244A
Application number: GB9918355A
Authority: GB
Inventors: Terence Harley
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-08-05
Filing date: 1999-08-05
Publication date: 2001-04-18
Also published as: GB9918355D0

Abstract

A standard fork-lift truck chassis is adapted to accept a movable rear counterweight 1 which is supported by two arms 3 located in slide-rails 9 on the truck chassis in a manner to allow the counterweight to move freely back and forth compensating for the lifting of a load by forks 8, or placement of a load on the truck forks beyond the load centre point specified for the truck. Hydraulic rams 4 are automatically activated by a load-sensor on the rear axle via an electronic logic circuit immediately moving the counterweight backwards to maintain the truck in a state of equilibrium thereby avoiding a dangerous occurrence. An automatic cut-out safety bar is fitted to the rear of the counterweight to avoid danger to personnel behind it.

Description

2355244 Fork Lift Truck AUTO-BALANCING SYSTEM This invention relates to a

Fork Lift Truck A UTO-BALANCING SYSTEM.

Fork lift trucks are well known vehicles used in the handling of goods and materials lifted from delivery vehicles and shuttled into various types of high and low storage systems. They can also be used for moving materials of various types around factory premises. They work by off- setting the load lifted by means of a rear mounted counter-weight. In all fork lift trucks today this counter-weight is secured by large fixings and does not move.

Unfortunately it is common practice for fork lift truck drivers to underestimate the load they are about to lift. This results in the truck over-balancing and tipping up at the rear, at the same time losing the lifted load which crashes to the ground. The rear of the truck then also comes down heavily causing damage to the vehicle and great danger to all concerned. If the truck lands at an angle it can bounce and tip side-ways resulting invariably in the death of the driver who usually tries to jump clear.

According to the present invention there is an over-balancing detector fitted in the rear axle of a standard fork lift truck, an electronic circuit which interprets the information provided by the detector and an hydraulic system which is activated by the said circuit. This pushes the truck's rear counter-weight backwards, secured by two heavy-weight arms fitted into heavy-weight sleeves in the truck, there-by automatically offsetting the over-balance detected. An alarm will be activated to alert all concerned around the vehicle the moment an over-balance is detected and the driver can then safely lower the load to the ground. A safety cut- out bar is fitted to the rear of the counter-weight which will immediately stop the proceedings should the counter-weight come into contact with anyone or anything behind it.

As this Auto-Balancing System is primarily a safety device, it is not envisaged that this will be used to increase the working capacity of any fork lift truck, as that would be a function of all the specified parts working collectively.

2 A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: - Figure I shows in oblique elevation a standard fork lift truck with the counter-weight in the normal position on the main chassis; Figure 2 illustrates the system activated showing the counter-weigbt, supported by its arms in their corresponding slide channels, in its extended position located by hydraulic cylinders fitted to the sides of the truck; Figure 3 shows the over-balance detector fitted in position on the rear axle, with the rear chassis assembly above; Figure 4 illustrates the counter-weight with supporting arms, locating hydraulic cylinders and safety cut-out bar at rear of counter-weight; Figure 5 shows the safety cut-out bar and cut-out switches.

3 Referring to the drawing, the Auto-Balance System would be an integral part of a standard fork lift truck, as shown in Fig. L, fitted to the main chassis 5.

The system activates when a sensor 6 (shown later in Fig3) fitted on the rear axle, detects a reduction in pressure consistant with an overbalance of the truck due to an excessive load being lifted or maximum rated load wrongly placed on forks 8.

As illustrated in Fig. 2, this is interpreted by an electronic circuit, secured inside the truck chassis, which directs hydraulic pressure via a solenoid controlled valve to the hydraulic cylinders 4 causing them to push the counter-weight arms 3 located in sliderails 9 backwards along with the counter-weight 1, to a point where the pressure on the rear axle sensor 6 is equalised. A flashing light I I and audible alarm sounder 12 are also activated by the electronic circuit. When the load being lifted by forks 8 is removed, the pressure on the sensors 6 will activate the hydraulics to re-locate the counter-weight in its normal position.

In Fig.3 is shown the activating pressure sensor 6 fitted to the rear axle of the truck with the rear truck chassis assembly above.

Fig. 4 shows a perspective view of the counter-weight I and arms 3 with hydraulic cylinders 4. Fitted to the rear of the counter-weight I is a system cut-out bar 2.

As illustrated in Fig 5 this bar activates two electric switches 7 which when pushed-in by the cut-out bar 2, causes the system to stop extending the counter-weight I by instructing the electronic circuit to close the solenoid controlled valve to the systems hydraulic cylinders feed pipe..

4

Claims

I A fork lift truck automatic re-balancing system comprising a movable rear counterweight supported by two arms located in slide-rails on the truck chassis adapted to allow the counterweight to slide back and forth. 2 A fork lift truck automatic re-balancing system as claimed in Claim I wherein the counterweight is moved by the action of two hydraulic cylinders fitted to the chassis and connected to the counterweight arms. 3 A fork lift truck automatic re-balancing system as claimed in Claim I or Claim 2 wherein the hydraulic cylinders are activated by means of a pressure-sensor located in the rear axle assembly of the truck through an intermediary electronic logic circuit. 4 A fork lift truck automatic rebalancing system as claimed in Claim 2 or Claim 3 wherin an integral automatic cut-out safety-bar is fitted to the rear of the counterweight acting apon two, system de-activating, cut-out switches which are connected to the electronic logic circuit. 5 A fork lift truck automatic re-balancing system as claimed in Claim 4 wherein a flashing light and audible alarm sounder and are activated by the electronic logic circuit. 6 A fork lift truck automatic re-balancing system substantially as described herein with reference to figures I - 5 of the accompanying drawing.