GB2446679A - Hand carriage steering unit - Google Patents

Abstract

A hand carriage, such as a shopping trolley or cart, comprises a steering system operating on the front castor axle with a useable Ackermann angles steering operation. The front pair of castor wheels of a hand propelled trolley are connected by means of a tracking rod 5 so that both wheels may be turned when a steering action is required. The steering action may be brought about by a user pulling on either end of a handle 12, this in turn acting upon push/pull rods 3 connected to either end of the tracking rod. In an alternative embodiment the handle 12 may be dispensed with and a user may pull directly on the end of the rods 3, or said rods may be replaced with Bowden cables (figures 4 and 5). Springs 1 may be provided for maintaining the front castor wheels in a straight-ahead position when no steering action is being applied.

Description

A HAND STEERED SHOPPING TROLLEY OR PUSH-CARRIAGE

Shopping-Trolleys and Push-carriages usually use swivel castors on each corner or sometimes one pair of wheels is connected by an axle. To steer and manoeuvre the carriage these function very well on smooth flat surfaces like shopping Malls or Supermarkets but become very unmanageable when used in car parks on slopping, mmps and inclines. Carrying weight is a very important factor adding to an unwieldy steering operation. Swivel castors can take a 360 degree direction so the direction is a lottery, There is a need to provide a strait forward direction with a right and left hand turning motion to the swivel castors. To overcome the problem a basic vehicle geometry steering system is used on a hand operated push carnage, it as five basic settings castor, camber, toe in/out,asi and Ackermann angles for strait line steering, it can be adapted and used via a push and pull action which gives positive steering. The conventional steering would normally be used with a motorized vehicle, geared rack and pinion or worm and peg, steering wheel operation. Accordingly, this invention provides a connected pair of castor wheels with a hand operated lever or levers to a push pulled motion rods to steer a conventional hand trolley/carriage. As the system is reflective a wire cable or Bowdencable can also be utilized, replacing the push rods.

Navigation of the system will incorporate the rear swivel castors which will deliver 360 degrees rotation. The turning circle would be dependent on the wheel base and a limited amount of reverse guidance.

A preferred embodiment of the invention will now be described with reference to the accompanying drawing in which: Figure 1 shows in perspective a front axle steering system, using a central peg and cam operation for turning the front axle castors a steering limit stop is also incorporated.

Figure 2 shows in perspective a front axle steering system, with forward facing castors a front fixed track rod and an added stub steering bar to the castors. A push-pull connecting rod with a clevis-barrel nut universal joint is illustrated.

Figure 3 illustrates a plan view of the steering geometry, with added expansion springs connected to the chassis frame for central alignment if needed.

Figure 4 shows a hand calliper to operate wire or Bowden-cable fixings.

Figure 5 shows Bowden-cable fixings (2) In figure 1, a stub bar (2) operated by its push-pull bars (3)and its u/j (4) on its support (9), can swivel the track rod (S to the right or left acting on the castors (10) which are connect to and supporting the trolley frame this will give a right or left turn to the trolley. A steering limit stop (7) is used to control the turning operation.

Figure 2, shows an alterative embodiment in which the stub bars (2) are fixed to the castors (10) and sighted above wheel height. Operated by there respective push-pull rods (3) and there u/js (4), will give a right or left hand turning operation to the trolley.

A neutral position will be acquired by the steering geometry and the centring springs (1) on the release of the steering action.

Figure 3, shows the steering geometry in plan view of the front axle of a four castor trolley, a side elevation of the push pull rod (3) with an angled action of approx 45 degrees, on a carriage base utilising four castors. A right hand will start with a backwards pull on the right hand side of the handle bar (12) will pull the rod (3) via its top u/j joint (4) in an upwards direction, which will impact on the lower u/j joint (4) which will pull the steering rod (2) and its right hand castor in a right hand turn direction, this will reflect on the tracking bar (5) to turn the left hand castor into a right hand turn. The reflective action will effect the left hand forward castor via its steering bar (2) for a push down action to occur on the left hand push pull rod (3) and the handle bar (12)via its top u/j joint (4)will follow the push down action.

Turning to the left will be the reverse procedure.

The push pull rod (3) and the u/j joints (4) may be left floating or supported by the trolley frame.

If required the handle bar (12) can be dispensed with, a backwards pull on the right hand push-pull rod with still result in the above action.

The damper expansion springs (I) will enforce a return to strait ahead steering geometry.

Figure 4 shows a hand calliper operation for a Bowden cable installation.

Figure 5 shows possible Bowden cable connections for alterative steering geometry. (3)

Claims (1)

1. A hand trolley, push-carriage unit having four or more castors, a controllable manual hand held steering operation for attachment to its swivel castors giving a stable operation in its forward travel. Dependent on the castor track rod steering geometry connection to the front axle, utilising two rear free castors, a 360 degree turning circle is obtain with the base of the caniage.

2 A hand held hand lever operation for steering a mechanical linkage or cable operating linkage according to claim I in which the steering operation acts on the forward castors.