GB2296486A

GB2296486A - Access Platform Used With Fork Lift Truck

Info

Publication number: GB2296486A
Application number: GB9425995A
Authority: GB
Inventors: Roger Albert Brettell
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-12-22
Filing date: 1994-12-22
Publication date: 1996-07-03
Also published as: GB9425995D0

Abstract

An access platform 6 that is electro-hydraulically powered and is designed to attach to the forks 7 and operate in conjunction with most industrial trucks of the fork lift counterbalanced and reach type. When the platform is attached to the fork of the lift truck it can be lifted vertically by the truck to the full reach of the trucks mast. The platform can be operated independantly of the truck to gain another 3.430 metres of reach above that of the truck it is attached to, it can also adopt a cantilever mode allowing it to also reach forward up to 2.700 metres. <IMAGE>

Description

ELECTRO-HYDRAULIC WORKING PLATFORM FOR USE WITH FORK LIFT TRUCKS.

This invention relates to an electro-hydraulic operated working platform for attachment to standard industrial fork lift trucks of the counterbalanced and reach type.

Working platforms for attachment to fork lift trucks are well known and are commonly used in industry. They fit directly onto the forks of the truck and are used to lift people up and down but these working platforms are incapable of movement independant of the fork lift truck.

This invention has its working platform that is capable of movement independant of the fork lift truck. The complete assembly is linked together in three separate sections, firstly the main frame 1, which is the section that is attached to the forks of truck it also houses the the electro-hydraulic powerpack 2 and the hydraulic cylinder 3. Secondly are the twin-arm boom 4 and the two parallel arms 5 which are attached to the main frame 1 by pivot pins. Then thirdly is the working platform itself item 6 which in turn is attached to the other end of the twin-arm boom 4 and two parallel arms 5, also by means of pivot pins.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings : Drawing 1/4 :- Side View of complete assembly Drawing 2/4 :- Front View of complete assembly Drawing 3/4 :- Plan View of complete assembly Drawing 4/4 :- 3 Extreme Modes (positions) Drawing 1/2 :- Wiring Diagram Drawing 2/2 ::- Hydraulic Diagram The main frame 1 in this invention is the section that is attached directly to the forks of the truck as opposed to the working platform in previous invention6 To secure the main frame 1 to the forks, the forks must be positioned through the rectangular box section base of the main frame and made secure by means of the two snap lock safety pins 7 behind the heel of the forks, additionally the four adjustable pins 8 are to be tightened down onto the top face of the forks The reverse of this proceedure is of course necessary to allow the main frame 1 to be detached from the forks. Also mounted to the base plate of the main frame 1 are the electro-hydraulics (not shown but described later) covered by a hinged box 2 (when 2 is referred to in the text it is the electro-hydraulic power pack to which we refer and not the box which the drawings show).Behind this pivotting from a pair of lugs attached to a tie section of the main frame 1 is the hydraulic cylinder 3, this cylinder 3 is the means of supplying the force to lift and lower the twin-arm boom 4 and the piston of the hydraulic cylinder 3 is attached to a pair of lugs mounted on a tie section of the twinarm boom 4 by means of a pivot pin. The twin-arm boom 4 is attached by pivot pins at one end of both arms to lugs on the two upright posts of the main frame 1 and at the opposite end of both arms to lugs on the working platform 6 also by means of pivot pins. In parallel to the twin-arm boom 4 there are two separate parallel arms 5 which also attach to the main frame uprights at one end the working platform 6 at the other by means of lugs and pivot pins.The working platform 6 has a chequer plate floor mounted on an angle iron frame with a kicking flat welded around to form a well. A safety cage of square box section steel to a height of one metre has been welded to the base. Within the safety cage frame an inward opening gate has been incorporated, which is spring loaded to close automatically and is latched when closed. Also the floor plate has been drilled to dispel any water that may collect in the well of the working platform 6. The foregoing describes the structure and assembly of the invention the following will describe the electrical and mechanical parts and how it works : Mounted on the main frame 1 on a base plate underneath a hinged box cover the electro-hydraulic power pack 2 is sited.This is comprised of as a power source a 12v heavy duty, 90 ampere, long life industrial battery which is fed from a 240v single phase x 4 amp charger unit adjacent to it. Sited next to the battery and charger is the hydraulic unit which is made up of a 5 litre oil reservoir on which is mounted a hyraulic pump and valve block driven by a 12v D.C. motor with integral starter. The hydraulic pump delivers 2cc/rev at a working pressure of 180 bar and the 12v motor is 1.5kw rotating at 2000rpm and is 6 minute continuous rated. In the hydraulic valve block is a 12v solenoid operated load discharge valve, External to the hydraulic unit is a flexible hydraulic pipe which runs directly to the first of two flow control valves which anpositioned back to back immediately prior to the single acting hydraulic cylinder 3 to give full speed control in both directions.Apart from one remote two-button switch box mounted in working platform 6 (not shown) and two remote limit switches (also not shown) but both mounted on the main frame 1 and all wired in series 1/2 (Wiring diagram) & 2/2 (Hydraulic diagram) refer to the foregoing paragraph. The remote limit switches (not shown) but position on the main frame 1 are located one at the rear of the main frame 1 to be set so that the fork truck keeps it depressed thereby proving its presense and the other on the main frame 1 upright using one of the parallel arms 5 as a striker when the hydraulic cylinder 3 reaches the top of its stoke, so that the hydraulic pump cuts out and cannot contiue to pump.

Having now identified and described the equipment and how it is assembled and arranged the following describes its operated. Having secured the complete assembly to the forks of the truck as previously described the fork lift truck driver can raise the forks so that everything is clear of the ground and move into the position required. The operator can now get onto the safety working platform 6 and using recognised hand signals get the fork lift driver to raise or lower him vertically to any point within the reach of the mast. He can also independantly of the truck raise himself up and down within the range of the arc of the twin-boom arm 4, parallel arms 5 and the length of the stroke of hydraulic cylinder 3. This is acheived by pressing the up button on the remote two button station located in the working platform 6.By pressing the button continuously the starter will start the motor which drives the hydraulic pump delivering oil under pressure to the base of the cylinder which will lift the piston right up to the end of its stroke. This will raise the twin-arm boom 4 up which in turn will raise the working platform 6 the two parallel arms 5 will follow and are designed to keep the working platform 6 upright in every position from completely down to fully up. At any time or position of the upward movement the operator stops pressing the up button the motor will stop and thenthat position will be sustained until such time as the button is pressed again. To lower it is simply necessary to push the down button which will open the load discharge valve allowing the oil to flow back to the tank at a controlled speed through one of the flow control valves. As with the up movement if the operator stops pressing the down button it will stop and sustain itself in that position until either the up or down button is pressed again. Using this method of operation the operator can place himself in any of the mode positions shown in Drawing 4/4 plus any position on that arc in between the three extremes.

Claims

1 :- An electro-hydraulic working platform that can be attached to most counterbalanced and reach type industrial fork lift trucks which can be operated independant of the truck.

2 :- When it is in up mode 3/Drg 4/4, the base of the working platform 6 will reach a height of 3.430 metres above the top of the forks it is attached to.

3 :- When it is in mid mode 2/Drg 4/4, the base of the working platform 6 will cantilever forward 2.700 metres from the upright posts of main frame 1 4 :- Any height can be achieved from zero in the down mode 1/Drg 4/4, for the base of the working platform 6 up to the maximum of 3.430 metres in mode 3/Drg 4/4 as claimed in claim 2.

New claims have been filed as follows: 1. A working platform for use with a fork lift truck, comprising a main frame adapted to engage with the tines of a fork lift truck, a working platform greferably connected to the main frame by a twin arm boon, a pair of links equal and parallel to the twin arm boom and also pivotally connected to the main frame so as to form a parallel link mechanism such that throughout the motion of the working platform, it is maintained in a horizontal position, an hydraulic ram adapted to operate the parallel link mechanism to raise and lower the working platform in a single plane, a self-contained electrohydraulic system for operating the hydraulic ram and a control system for the electro-hydraulic system.

2. A working platform according to Claim 1 wherein the hydraulic ram is single-acting and there is provided an electrically powered pressure pump, a unidirectional flow control device arranged to admit hydraulic fluid to the hydraulic ram to raise the working platform, a solenoidoperated pressure release valve arranged to allow hydraulic fluid to flow from the hydraulic ram to a reservoir to lower the working platform and a control panel arranged to control the operation of the pump and the pressure release valve.

3. A working platform according to Claim 2 wherein there is included a safety switch adapted to inhibit the operation of the pump unless the working platform is correctly positioned in relation to the fork lift truck.

4. A working platform according to Claim 2 or Claim 3 wherein there is included a safety switch adapted to inhibit the operation of the pump when the hydraulic ram reaches the end of its stroke.

5. A working platform according to any preceding claims wherein there is included a pair of unidirectional flowcontrol devices arranged in series so asctq control the rate of flow of hydraulic fluid into and out of the hydraulic ram.

6. A working platform for use with a fork lift truck substantially as hereinbefore described and with reference to the accompanying drawings.