GB2155431A

GB2155431A - Work platforms for fork lift vehicles

Info

Publication number: GB2155431A
Application number: GB08406350A
Authority: GB
Inventors: Melville James
Original assignee: AERIAL PLATFORMS U K Ltd
Current assignee: AERIAL PLATFORMS U K Ltd
Priority date: 1984-03-10
Filing date: 1984-03-10
Publication date: 1985-09-25
Also published as: GB8406350D0; FR2561036B1; FR2561036A1

Abstract

A fork lift vehicle 1, mounts a platform 8 by means of forks 2 engaging a pocket 3 underneath said platform. A latch releasably fastens the platform to the forks and a first switch is responsive to tilt of the platform so as to interrupt the ignition circuit of the vehicle, and a second switch is responsive to the latch being open, also to interrupt the ignition circuit. Further switches may be provided to interrupt the ignition circuit if the platform gate is not closed, and if the platform is more than a predetermined distance above the ground. <IMAGE>

Description

SPECIFICATION Work plafforms for fork lift vehicles It is known that at least one load can be lifted or lowered by means of a platform (which can be called a work platform) elevatable by means of forks received in pockets comprised by the underside of the platform. See for example the specifications GB 2060555A, GB 2060555B of our UK patent 2060555, and the specification GB 2075261A of our UK patent application 8013621.

According to a first aspect of the present invention, there is provided switch apparatus for a piatform for releasably fastening to at least one fork of a fork lift vehicle, said vehicle comprising an ignition circuit and a handbrake), said platform comprising: (a) load support surface; (b) a pocket underneath said platform, said pocket being for receiving a said fork; and (c) a latch for releasably fastening said platform to a said fork; wherein said switch apparatus comprises: (i) at least one first switch means, responsive to at least one tilt (optionally a minimum value of tilt of said platform), so as to interrupt said ignition circuit, said first switch means optionally disabling that interruption when said tilt is less than said minimum value of tilt, optionally by a predetermined amount; (ii) at least one second switch means, responsive to said latch being open, so as to interrupt said ignition circuit, said second switch means optionally disabling that interruption when said latch is closed, said at least one second switch means optionally being coupled (optionally in series by optional relay means) with circuitry of said at least one first switch means;; (iii) optionally, at least one third switch means, when said platform comprises a barrier at least partly surrounding said load support surface, at least one portion of said barrier being openable or closable, said third switch means being responsive to that portion when open, so as to interrupt said ignition circuit, said third switch means optionally disabling that interruption when that portion is closed, said at least one third switch means optionally being coupled with circuitry of said at least one first switch means and/or of said at least one second switch means;; (iv) at least one fourth switch means, responsive to the level of said load support surface above ground on which said vehicle is proposed to be driven, so as to interrupt said ignition circuit when that level reaches a maximum value (optionally substantially 150 mm or optionally substantially 6 in) above said ground, said fourth switch means optionally disabling that interruption when said level is less than said maximum value, optionally by a predetermined amount, said at least one fourth switch means optionally being coupled with circuitry of at least one switch means chosen from any of: said first switch means, said second switch means, and said third switch means, said at least one fourth switch means optionally being coupled (optionally in series) with at least one further switch means, said handbrake optionally being provided with at least one said further switch means such that said ignition circuit is interrupted when both said at least one third switch means and said at least one fourth switch means are open, that interruption optionally being disabled by closing both said at least one third switch means and said at least one fourth switch means; (v) optionally, at least one actuation means responsive to surface of said ground, so as to provide at least one said opening of said at least one fourth switch means, that opening optionally being disabled by a suitable mode of said actuation means.

A second aspect of the present invention provides a platform for releasably fastening to at least one fork of a fork lift vehicle, said platform being according to said first aspect of the present invention.

A third aspect of the present invention provides a fork lift vehicle, comprising a platform according to said second aspect of the present invention.

Said switch apparatus can enable a fork lift vehicle (optionally a fork lift truck) to be manoeuvred when said platform is at a low level above said ground (e.g. earth, a floor, or any other suitable surface over when said vehicle is proposed to be driven). Also said vehicle cannot be driven when said platform is at a predetermined high level above said ground. The absence of driving minimises danger from instability caused by dynamic forces induced by the vehicle accelerating or stopping. Said at least one first switch means can be utilised to ensure that the mast of a fork lift truck is sufficiently vertical (e.g. 90 ) when said platform is used.Said at least one first switch means can ensure that the vehicle (when provided with said platform) is only used on non-tilting ground surface, i.e. ground surface not able to actuate said at least one first switch means. Said at least one fourth switch means (preferably when said at least one third switch means is present) can prevent the fork lift truck from being driven when said load support surface is at a level above e.g. substantially 150 mm or above e.g. substantially 6 in above said ground, but enable that truck to be driven when said load support surface is at a level below either of those values.

The present invention can be embodied in any suitable manner. Preferably, said platform, said fork lift vehicle, said switch apparatus utilise the disclosures of our said specifications GB 2060555A, GB 2060555B, and GB 2075261 A. The whole contents of all of those specifications are hereby imported into the present specification. For example, said first switch means can be according to Fig. 3 of the specification GB 2075261 A. Preferably, said fourth switch means comprises or is constituted by a microswitch. Preferably, said actuation means for said at least one fourth switch means comprises ground contact means for responding to the profile of the surface of said ground.Preferably, said actuation means comprises at least one pivotable arm having first and second opposite ends, said first end being pivoted to said platform, said second end being adapted to provide said ground contact means, e.g. said second end comprises rollable means and/or skid means for contacting the surface of said ground. Preferably, said rollable means comprises at least one roller and/or wheel.

The present invention will now be described by way of example with reference to the accompanying drawings, wherein: Figure 1 illustrates a switch apparatus of the present invention.

Figures 2,3,4 are respectively Figures 1,2,3 of our said specifications GB 2060555A, GB 2060555B.

Figures 5,6 are respectively Figures 2,3 of our said specification GB 2075261A. The accompanying drawings and their description given below are to be read together with the whole contents of our said specifications GB 2060555A, GB 2060555B, GB 2075261 A.

In Figs. 1,5 of the accompanying drawings there is a work platform respectively designated 4 or 24, provided in any suitable manner with a pendulum actuated switch 30 of Fig. 6, e.g. provided as switch 26 in Fig. 5. In Fig. 1, switch 30 is connected in series by a relay 50 with the latch microswitch 31 of Fig. 4. When switch 30 is open (i.e. position A of switch 30 in Fig. 1), relay 50 is closed to disable a corresponding interruption in the ignition circuit of the fork lift truck 1 or 21 respectively in Figs. 1,5, that truck being provided with said work platform.

When switch 30 is closed (i.e. position B of switch 30 in Fig.1), relay 50 is open, thereby providing said corresponding interruption in said ignition circuit.

Mounted to platform 4 or 24, as shown in Fig. 1, is a microswitch 60, together with a pivoted actuation arm 61 having opposite ends 62,63, end 62 being pivoted to platform 4 or 24, end 63 having a ground contact roller or wheel 64. When arm 61 is in position A thereof, switch 60 is closed. When arm 61 is in position B thereof, switch 60 is open.

The closed position A of switch 60 disables a corresponding interruption in said ignition circuit. The open position B of switch 60 orovides the corresponding interruption just mentioned, such that said ignition circuit is interrupted unless door switch 33 in Fig. 3 is closed, and also a switch (not shown in our said prior specification or in the accompanying drawings hereto) fitted to the handbrake (not shown) of fork lift truck 1 or 21 is closed, i.e. when said handbrake is closed. Switch 60 is connected in series with said handbrake switch and latch microswitch 31.

It will be appreciated that the above described switches enable said ignition circuit to be interrupted in various manners so as to enable enhanced safety of operation of a fork lift truck or other fork lift vehicle. A said switch that interrupts said ignition circuit can be in circuitry connected to an ignition switch in said ignition circuit.

Further details of the accompanying drawings are in our said prior specifications, whose whole contents are to be regarded as being part of the present specification.

The present invention includes equivalents of the above disclosures of the present invention.

Claims

1. Switch apparatus for a platform for releasably fastening to at least ore fork of a fork lift vehicle, said vehicle comprising an ignition circuit and a handbrake, said platform comprising: (a) load support surface; (b) a pocket underneath said platform, said pocket being for receiving a said fork; and (c) a latch for releasably fastening said platform to a said fork; wherein said switch apparatus comprises: (i) at least one first switch means, responsive to at least one tilt so as to interrupt said ignition circuit; and (ii) at least one second switch means, responsive to said latch being open, so as to interrupt said ignition circuit.

2. Apparatus as claimed in claim 1, wherein said at least one first switch means is responsive to a minimum value of tilt of said platform, so as to interrupt said ignition circuit.

3. Apparatus as claimed in claim 2, wherein said at least one first switch means is such that said corresponding interruption of said ignition circuit is disabled when said tilt is less than said minimum value of tilt, optionally by a predetermined amount.

4. Apparatus as claimed in any one of claims 1 to 3, wherein said at least one second switch means is such that said corresponding interruption of said ignition circuit is disabled when said latch is closed.

5. Apparatus as claimed in any one of claims 1 to 4, wherein said at least one second switch means is coupled with circuitry of said at least one first switch means.

6. Apparatus as claimed in claim 5, wherein said at least one second switch means is coupled in series with circuitry of said at least one first switch means.

7. Apparatus as claimed in claim 6, wherein said at least one second switch means is coupled in series by relay means with circuitry of said at least one first switch means.

8. Apparatus as claimed in any one of claims 1 to 7, comprising: (iii) at least one third switch means, when said platform comprises a barrier at least partly surrounding said load support surface, at least one portion of said barrier being openable or closable, said at least one third switch means being responsive to that portion when open, so as to interrupt said ignition circuit.

9. Apparatus as claimed in claim 8, wherein said at least one third switch means is such that said corresponding interruption of said ignition circuit is disabled when said at least one portion of said barrier is closed.

10. Apparatus as claimed in claim 8 or 9, wherein said at least one third switch means is coupled with circuitry of said at least one first switch means and/or circuitry of said at least one second switch means.

11. Apparatus as claimed in any one of claims 1 to 10, ccmprising: (iv) at least one fourth switch means, responsive to the level of said load support surface above ground on which said vehicle is proposed to be driven, so as to interrupt said ignition circuit when that level reaches a maximum value above said ground.

12. Apparatus as claimed in claim 11, wherein said at least fourth switch means is such that said maximum value is substantially 150 mm above said ground.

13. Apparatus as claimed in claim 11 or 12, wherein said at least one fourth switch means is such that said corresponding interruption of said ignition circuit is disabled when said level is less than said maximum level, optionally by a predeter mined amount.

14. Apparatus as claimed in any one of claims 11 to 13, wherein said at least one fourth switch means is coupled with circuitry of at least one switch means chosen from any of: said first switch means, said second switch means, and said third switch means.

15. Apparatus as claimed in any one of claims 11 to 14, wherein said at least one fourth switch means is coupled with at least one further switch means, said handbrake being provided with at least one said further switch means such that said ignition circuit is interrupted when both said at least one third switch means and said at least one further switch means are open.

16. Apparatus as claimed in claim 15, wherein said at least one further switch means is such that said ignition circuit is interruted when both said at least one third switch means and said at least one further switch means are open, that interruption being disabled by closing both said at least one third switch means and said at least one further switch means.

17. Apparatus as claimed in claim 15 or 16, wherein said at least one fourth switch means is coupled in series with at least one said further switch means.

18. Apparatus as claimed in any one of claims 11 to 18, wherein said at least one fourth switch means comprises or is constituted by at least one microswitch.

19. Apparatus as claimed in any one of claims 11 to 18, comprising: (v) at least one actuation means responsive to surface of said ground, so as to provide at least one opening of said at least one fourth switch means.

20. Apparatus as claimed in claim 19, wherein said at least one actuation means is responsive to surface of said ground, so as to provide at least one opening of said at least one fourth switch means, that opening being disabled by a suitable mode of said at least one actuation means.

21. Apparatus as claimed in claim 19 or 20, wherein said at least one actuation means comprises ground contact means for responding to the profile of said aground.

22. Apparatus as claimed in any one of claims 19 to 21, wherein said at least one actuation means comprises at least one pivotable arm having first and second opposite ends, said first end being pivoted to said platform, said second end being adapted to provide said ground contact means.

23. Apparatus as claimed in claim 21 or 22, wherein said ground contact means comprises rollable means end/or skid means.

24. Apparatus as claimed in any one of claims 21 to 23, wherein said ground contact means comprises at least one roller and/or at least one wheel.

25. Apparatus as claimed in claim 1, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.