Land vehicles – Body elevation or tilt – Establishing riding or trim height
Patent
1998-04-21
2000-01-25
Mai, Lanna
Land vehicles
Body elevation or tilt
Establishing riding or trim height
312 71, 108136, B60S 900
Patent
active
060170409
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a platform or trolley, particularly, though by no means exclusively, to a trolley for use in commercial laundry operations.
BACKGROUND OF THE INVENTION
Presently, in commercial laundry operations, loads of linen etc. are transported around a factory in wheeled bins or trolleys. Individual items are retrieved from a bin for further processing. This may entail a person bending into a trolley a number of times, usually between 50 and 400 times depending on the load involved. This amount of bending and lifting puts workers in this industry at risk from back strain and injury. In addition it has been noted that production rates drop significantly when operators are retrieving items from the lower half of trolleys where a greater degree of bending and lifting is required.
The present invention overcomes at least to some extent, the problems aforesaid.
SUMMARY OF THE INVENTION
According to the present invention there is provided a trolley having generally upright walls surrounding a base, said base comprising a platform supported on a biasing mechanism, the biasing mechanism being arranged to urge the platform upwardly towards a first working position whilst permitting downward movement of the platform when a load is placed on the platform, the amount of downward movement being dependent upon the load.
This arrangement uses the combination of changes in the degree of biasing to provide for incremental movements of the platform, in response to increasing loads placed thereon.
Using a trolley in accordance with the invention, the platform descends towards a lowermost position as items are loaded into the trolley and said platform rises again as items are unloaded, thereby maintaining items towards the top of the trolley enabling trolleys to be unloaded without an operator having to bend to retrieve items from the trolley. Whilst the sensitivity of the biasing mechanism may be adjusted manually, the arrangement of the invention provides for automatic upwards and downwards movement of the platform during use.
The biasing mechanism may comprise a scissors jack arrangement that incorporates a tension spring to provide a biasing force.
The scissors jack arrangement may comprise two arms pivotably connected at the central point. The first arm may be fixed to the underside of the platform at its upper end and be moveable within the base at its lower end. The second arm may be moveable along the underside of the platform at its upper end and fixed to the tension spring at its lower end.
In operation, when there is no load on the platform, the spring is lightly pre-tensioned and the second arm is pulled towards an upright position, thereby moving at its upper end towards the centre of the platform, raising the platform into an upright position. The first arm of the scissors jack arrangement moves in cooperation with the second arm.
When a load is placed on the platform, the tension spring resists any movement and urges the platform towards its uppermost position. As the load increases, the second arm moves away from the centre of the platform and the spring lengthens, lowering the platform. A particularly advantageous feature of the invention is that the incremental movement of the platform is directly related to the weight applied to the platform. Smooth movement of the platform is achieved irrespective of whereabouts on the platform an article is placed or removed; the scissors jack arrangement providing uniform support across the whole area of the platform.
The load/tension ratio of the spring may be adjusted to allow the platform to react to different densities of load.
To achieve tensioning of the spring, one end of the spring is preferably attached to one end of a beam member. The beam member is supported for rotation about a fulcrum, the position of the fulcrum determining the load applied to the spring and hence the sensitivity of the spring.
The position of the fulcrum is preferably variable along the length of the beam, to enable variation of the sprin
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patent: 3941440 (1976-03-01), Menzin et al.
patent: 4300611 (1981-11-01), Silverman
patent: 4764075 (1988-08-01), Cox et al.
Ergo-Lift Limited
Mai Lanna
McClellan James S.
LandOfFree
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