GB2296003A

GB2296003A - Uderfloor Passenger Lift

Info

Publication number: GB2296003A
Application number: GB9525738A
Authority: GB
Inventors: David Phillips
Original assignee: Passenger Lift Services Ltd
Current assignee: Passenger Lift Services Ltd
Priority date: 1994-12-17
Filing date: 1995-12-15
Publication date: 1996-06-19
Also published as: GB9425500D0; GB9525738D0

Abstract

An underfloor passenger lift for use on a vehicle comprises a storage box mounted beneath the vehicle, a carriage which runs in and out of the storage box, and a lifting platform mounted upon the carriage. Hydraulic power is used to raise and lower the lifting platform, and to drive a hydraulic motor which moves the carriage in and out of the storage box through a rack 12 and pinion to engagement. The hydraulic drive to the motor is provided with a pressure relief valve that enables the carriage to be moved in and out of the storage box manually in the event of hydraulic failure. Preferably, the carridge is guided by rollers 16. <IMAGE>

Description

UNDERFLOOR PASSENGER LIFTS This invention is concerned with improvements in and relating to lifts for persons in wheelchairs, or other loads, particularly for vehicles.

An underfloor vehicle lift commonly comprises a storage box which is mounted beneath the vehicle floor. A carriage is arranged to move in and out of the box, being stowed protectively when within the box and being presented for use when out of the box. A load-carrying platform is mounted on the carriage, commonly by means of lifting arms which can raise and lower the platform relative to the carriage, the box and the vehicle floor. Operation of the lifting mechanism, through the arms, is usually hydraulic. The carriage becomes stowed in the box together with the arms and the platform itself. Such a lift is referred to hereinafter as a lift of the aforementioned kind.

In some such lifts, there is no provision for the carriage to be driven into and out from the box and such operation is wholly manual. However, various powered arrangements have been known for some time. In one a hydraulically-operated scissors mechanism, lying in a horizontal plane, is used to move the carriage to and from the box. In others an electric drive is used, an electric motor being used to drive a pinion (or a pair of pinions) to drive the carriage through engagement with a rack. These known arrangements present various problems. The use of a scissors mechanism has tended to give irregular loadings during movement of the carriage, which can result in less than smooth operation. The more popular use of an electric motor has a profound disadvantage that should the motor fail it may not be possible, or at best may be difficult, to return the carriage to the box manually.

Ordinarily, the electric motor is arranged to drive the carriage through a slipping clutch, but in practice this can often leave manual operation very difficult, or even impossible.

It is an object of the present invention to provide an improved underfloor lift, which is both of a simple construction and which readily permits manual movement of the carriage.

The invention provides, in one of its aspects, an under floor lift of the aforementioned kind in which the carriage is arranged to be driven into and out of the box by means of a hydraulic motor through a rack and pinion engagement, hydraulic pressure relieving means being provided to enable the carriage to be moved alternatively manually.

In a preferred arrangement, the hydraulic motor is secured to the carriage and a rack is secured in the box. Preferably, a single rack is utilised, extending centrally longitudinally of the carriage. However, more than one rack could be used, for example for engagement by pinions on a common axle from a single hydraulic motor. The rack may form a guide rail between horizontally opposed guide wheels of the carriage, the rack teeth being presented on upper or, preferably, lower faces of the rack member.

Alternatively, the rack teeth could be presented on a side face of the rack member and lateral stability be achieved through opposing the pinion (engaging the rack) with one or more guide rollers on the opposite side. The pressure-relieving means may simply be a pressure relief valve associated with a supply pump which supplies hydraulic fluid under pressure to the motor.

The accompanying drawing is a sectional side view of one embodiment which illustrates the invention by way of example, the drawing showing in an underfloor passenger lift a region of engagement between a drive pinion and rack.

An underfloor passenger lift for use on a vehicle, for example for loading and unloading passengers in wheelchairs, comprises a storage box mounted beneath the vehicle floor. A carriage is arranged to run on guides horizontally into and out from the box, and in a well-known and conventional manner bears a hydraulically-actuated lifting platform. The carriage and the platform can become stowed together in the box for protection when not in use.

The carriage is arranged to be driven into and out of the box by means of a hydraulic motor which is secured to the carriage. The motor is secured horizontally, transversely of the carriage, and bears a pinion 10 for transmitting drive. The pinion 10 is in engagement with a toothed undersurface 12 of a rack member 14 which extends horizontally longitudinally of the box. For lateral stability, guide rollers 16 (two only shown) engage opposite side faces of the rack member 14, the guide rollers being mounted on the carriage to rotate about vertical axes. The rack member 14 being fixed to the box, and the carriage being movable within the box, the carriage can be driven into and out of the box by means of the hydraulic motor.

The hydraulic supply to the motor is through a pump (not shown). The pump is provided with a readily operable relief valve which ensures that resistance from the hydraulic circuit drive can be relieved, so that the carriage can be moved manually in the event of a hydraulic failure, or for any other reason.

Claims

1. An underfloor lift of the aforementioned kind in which the carriage is arranged to be driven into and out of the box by means of a hydraulic motor through a rack and pinion engagement, hydraulic pressure relieving means being provided to enable the carriage to be moved alternatively manually.

2. An underfloor lift according to claim 1 in which the hydraulic motor is secured to the carriage and one or more racks are secured to the box for engagement by one or more pinions driven by the motor.

3. An underfloor lift according to either of claims 1 and 2 in which a single rack is provided extending centrally longitudinally of the carriage.

4. An underfloor lift according to either of claims 1 and 2 in which more than one rack is provided, the racks being engaged by pinions on a common axle from a single hydraulic motor.

5. An underfloor lift according to any preceding claim in which a rack-providing member forms a guide rail between horizontally opposed guide wheels of the carriage, the rack teeth being presented on upper or lower faces of the rack member.

6. An underfloor lift according to any one of claims 1 to 4 in which rack teeth are presented on a side face of a rack member, lateral stability of the carriage being achieved by opposing the pinion which engages the rack teeth with one or more guide rollers on the opposite side of the member.

7. An underfloor lift according to any preceding claim in which the pressure relieving means comprises a pressure relief valve associated with a supply pump which supplies hydraulic fluid under pressure to the motor.

8. An underfloor lift substantially as described herein with reference to Figure 1 of the accompanying drawings.