GB2423500A

GB2423500A - A trolley chassis with a sideways movement inhibiting guide member

Info

Publication number: GB2423500A
Application number: GB0504009A
Authority: GB
Inventors: Emils Gailis
Original assignee: Leec Ltd
Current assignee: Leec Ltd
Priority date: 2005-02-26
Filing date: 2005-02-26
Publication date: 2006-08-30
Also published as: GB0504009D0

Abstract

In the trolley chassis field there is a need for a trolley chassis which an operative easily steer at can easily steer around a tight corner as well as easily move in a given direction when desired. A trolley chassis (10) has at least three caster wheels (12) for moving the chassis (10) on a support surface (18). The trolley chassis (10) further comprises a guide member (16) moveable so as to maintain contact with the support surface (18), whereby the guide member (16) inhibits sideways movement of the chassis (10). The trolley chassis (10) also includes a locking mechanism (40) that is engagable with the guide member (16) so as to prevent rotation thereof, thereby creating a brake for the trolley chassis (10). The guide member may be attached to a suspension arm (20 figure 4) so that it is resiliently biased into contact with the ground. The trolley chassis is particularly intended for use with a hospital trolley, but may also be attached to a supermarket shopping trolley basket or luggage rack.

Description

A TROLLEY CHASSIS

This invention relates to a trolley chassis for use with in particular, but not exclusively, a medical trolley.

Medical trolleys intended for use in hospitals and other medical establishments generally include a support platform for receiving a support tray or mattress on which a body may lie. The trolleys have four caster wheels, one at each corner thereof The caster wheels allow operatives to move the trolley in many different directions thereby facilitating the positioning of the trolley over short distances into a desired position.

However, the trolleys are difficult to move about over longer distances, especially when loaded with a body. Typically two operatives are required, one at each end of the trolley, in order to control the trolley and prevent the trolley drifting off course.

In addition it is also difficult to steer the trolley around corners, especially the tight corners found in many medical establishments.

One attempt at improving the manoeuvrability of medical trolley uses a trolley chassis having a fifth caster wheel. Generally the fifth wheel is located at the centre of the trolley, equally spaced from front and rear pairs of caster wheels. The inclusion of a fifth wheel provides a pivot point about which it is possible to rotate the trolley thereby assisting an operative in steering the trolley around a corner. A caster wheel is used so as to also pennit sideways movement of the trolley when desired.

Often the support surfaces on which a trolley moves are uneven. As a result the fifth wheel often becomes spaced from the support surface as the rigid chassis moves over the undulations, thereby limiting the occasions when the fifth wheel is able to provide useful assistance with steering the trolley.

As a result, it is known to position the fifth caster wheel slightly lower than the other four caster wheels, thereby creating a fulcrum about which the front and rear pairs of castors are able to pivot. This ensures that the fifth wheel remains in contact with the support surface at all times.

1-lowever, pivoting about the fifth wheel in this way is undesirable since it creates instability. This is especially undesirable in a medical trolley since any movement of the Support platform away from a horizontal orientation may result in dislodging of the body carried thereon.

Furthermore, the inclusion of a fifth caster wheel in either of the foregoing arrangements does very little to improve the straight-line stability of the trolley when pushed or pulled along, e.g. a corridor. Consequently a trolley including a fifth caster wheel still tends to drift to one side or another, depending on the undulations or camber of the support surface.

Therefore it is a general aim of the invention to provide a trolley chassis which an operative can easily steer around a tight corner as well as easily move in a given direction when desired.

According to the invention there is provided a trolley chassis having at least three caster wheels for moving the chassis on a support surface, the trolley further comprising a guide member moveable so as to maintain contact with the support surface, whereby the guide member inhibits sideways movement of the chassis.

inhibiting sideways movement of the trolley chassis improves the straightline stability thereof, thereby making it easier for even a single operative to move the chassis in a desired direction. This functionality is achieved while still allowing an operative to rotate the chassis, thereby assisting in steering the chassis around, e.g. tight corners.

A moveable guide member allows the trolley chassis to accommodate undulations in the support surface while maintaining contact of the guide member therewith, whereby the guide member continuously inhibits sideways movement of the trolley chassis.

Preferably the guide member is moveable between a first position in contact with the support surface and a second position spaced from the support surface.

The ability to move the guide member into a second position spaced from the support surface allows an operative to selectively move the chassis sideways, as desired.

Optionally the trolley chassis further includes a locking mechanism engagable with the guide member so as to prevent rotation thereof while the guide member is in contact with the support surface, thereby creating a brake for the trolley chassis.

This permits an operative to lock the trolley chassis in a desired position.

In a preferred embodiment of the invention the guide member is rotatably attached to a suspension arm which defines a first axis passing from one side of the chassis to another, the suspension arm being pivotable about a second axis spaced from the first axis so as to move the guide member between the first and second positions.

Preferably the trolley chassis further includes a biasing member for resiliently biasing the suspension arm so as to resiliently bias the guide member into contact with the support surface when in the first position.

The foregoing features provide a convenient way of resiliently biasing the guide member into contact with the support surface.

Optionally the biasing member defines an over centre bias on the suspension arm so as to urge the guide member towards each of the first and second positions.

Such an arrangement retains the guide member in the second position spaced from the support surface when desired. It also resiliently biases the guide member against the support surface when in the first position.

Conveniently the biasing member is or includes a pneumatic actuator. Pneumatic actuators are compact and readily available Optionally the trolley further includes a pedal for moving the guide member between the first and second positions. A pedal allows an operative to engage and disengage the guide member, as desired, using one of his feet, thereby allowing him to retain hold of the trolley chassis with both hands.

In another preferred embodiment of the invention a connecting rod interconnects the suspension arm and the pedal. This provides a convenient arrangement for spacing the pedal from the suspension arm, thereby allowing the pedal to be located at an extremity of the trolley chassis where it is readily accessible by an operative.

Conveniently the connecting rod further defines a part of the locking mechanism, the connecting rod being rotatable about a longitudinal axis thereof so as to selectively move a locking pin into engagement with one of a plurality of recesses spaced around a hub of the guide member, thereby preventing rotation of the guide member. This arrangement reduces the number of moving parts required to provide a desired functionality in the trolley chassis.

There now follows a brief description of a preferred embodiment of the invention, by way of non-limiting example, with reference being made to the accompanying drawings in which: Figure 1 shows a trolley chassis according to a first embodiment of the invention; Figure 2 shows a guide member according to the first embodiment of the ivention in a first position resiliently biased into engagement with a support surface; Figure 3 shows the guide member according to the first embodiment in a second position spaced from the support surface; Figure 4 shows a suspension arm according to the first embodiment of the invention; Figure 5 shows a biasing member according to the first embodiment of the invention; Figure 6 shows a pedal according to the first embodiment of the invention; and Figure 7 shows a locking mechanism according to the first embodiment of the invention.

A trolley chassis according to a preferred embodiment of the invention is designated generally by the reference numeral 10. The trolley chassis 10 has four caster wheels 12, one at each corner thereof.

The trolley chassis has a support platform 14 attached thereto. The support platform 14 is for receiving a support tray or mattress (not shown) on which a body may lie. In the embodiment shown the support platform 14 is moveable vertically by way of a hydraulically operated scissor-like arrangement between the platform 14 and the trolley chassis 10.

In other embodiments of the invention the trolley chassis may have a differing arrangement attached thereto. For example, the trolley chassis of the invention may have a supermarket trolley basket attached thereto or a luggage rack for moving, e.g. suitcases, around an airport.

The trolley chassis 10 includes a guide member in the form of a guide wheel 16 which is moveable so a to maintain contact with a support surface 18 on which the trolley chassis 10 moves. In the embodiment shown the guide wheel 16 is constrained to rotate in a single plane. In other embodiments of the invention different guide members are also possible.

In addition, maintaining the guide wheel 16 in contact with the support surface 18 results in a desirable coefficient of friction between the guide wheel 1 6 and the support surface 18.

The two preceding features combine to inhibit sideways movement of the chassis, thereby making it easier for an operative to control the direction in which the trolley chassis 10 moves.

In the embodiment shown, the guide wheel 16 is moveable between a first position in which it is in contact with the support surface 1 8, as shown in Figure 2, and a second position in which it is spaced from the support surface 18, as shown in Figure 3.

While the guide wheel 16 is in the second position an operative is able to move the trolley chassis 10 sideways so as to position the trolley 10, e.g. adjacent to a hospital bed.

The guide wheel 16 is rotatably attached to a suspension arm 20 which extends between a first side 22 and a second side 24 of the trolley chassis 1 0. The suspension arm 20 defines a first axis 26 about which the guide wheel 16 is rotatable. The first axis 26 passes from the first side 22 of the trolley chassis 10 to the second side 24.

The suspension arm 20 is pivotable about a second axis 28 so as to move the guide wheel 16 between the first and second positions. The pivoting of the suspension arm also allows the guide wheel 16 to accommodate undulations in the support surface 18.

The trolley chassis 10 also includes a biasing member 30 for biasing the guide wheel 16 into contact with the support surface 18. in the embodiment shown the biasing member 30 is a pneumatic actuator 32 which seeks to return to its original length when compressed. In other embodiments of the invention different types of biasing member 30 are also possible.

Resiliently biasing the guide wheel 16 into contact with the support surface 1 8 maintains a high coefficient of friction between the guide wheel 16 and the support surface 18, thereby helping to ensure inhibition of sideways movement of the trolley chassis 10.

The pneumatic actuator 32 defines an over centre bias on the suspension arm 20.

In other words, at a given angular position of the pneumatic actuator 32 a first end 34 thereof is urged downwardly by the actuator 32 seeking to return to its original length, thereby resiliently biasing the guided wheel 16 into contact with the support surface 18 (as shown in Figure 5), and at another angular position the first end 34 is urged upwardly, thereby retaining the guide wheel 16 in the second position.

The trolley chassis 10 includes a pedal 36 (Figure 6) for moving the guide wheel 16 between the first and second positions. A connecting rod 38 interconnects the pedal 36 and the suspension arm 20.

The connecting rod 38 is rotatable about a longitudinal axis thereof so as to selectively engage a locking pin 40 with one of a plurality of recesses 42 in a hub 44 of the guide wheel 16. Such engagement prevents rotation of the guide wheel 16 about the first axis 26, thereby braking the trolley chassis 10 so as to lock it in position when the guide wheel 16 is in the first position. In other embodiments of the invention different locking arrangements are also possible.

The connecting rod 38 includes a second biasing member 46 in the form of an extension spring 48, as shown in Figure 7. In other embodiments of the invention different biasing members are also possible.

The extension spring 48 defines an over centre bias on the connecting rod 38 so as to selectively, rotationally urge the connecting rod 48 towards each of an engaged position in which the locking pin 40 is engaged with a respective recess 42, and a disengaged position.

The connecting rod 38 also includes a T-bar 50 which facilitates rotation of the connecting rod 38 by an operative's foot.

In use an operative selectively moves the guide wheel 16 into one of the first or second position, using the pedal 36, according to the task at hand.

When the guide wheel 16 is in the first position an operative is able to easily control the direction in which the trolley chassis 10 moves. The operative is also able to rotate the trolley chassis 1 0 about a vertically extending axis centred on the guide wheel 16, SO as to manoeuvre the trolley chassis 10 around a corner.

When the trolley chassis 10 is in a desired position the operative may lock the trolley chassis 10 in position by engaging the locking pin 40 in one of the recesses 42. The operative does so by rotating the connecting rod 38 via the T-bar 50.

Releasing the brake in order to move the trolley chassis 10 is done by reversing the above steps.

The operative moves the guide wheel 16 into the second position, spaced from the support surface, when he wishes to move the trolley chassis 10 sideways so as to position it adjacent to, e.g. a hospital bed.

When moving the trolley again the operative may move the guide wheel 16 back to the first position in order to retain a greater degree of control over the direction in which the trolley chassis 10 moves.

Claims

CLAIMS: 1. A trolley chassis having at least three caster wheels for

moving the chassis on a support surface, the trolley further comprising a guide member moveable so as to maintain contact with the support surface, whereby the guide member inhibits sideways movement of the chassis.
2. A trolley chassis according to Claim I wherein the guide member is moveable between a first position in contact with the support surface and a second position spaced from the support surface.
3. A trolley chassis according to Claim 1 or Claim 2 further including a locking mechanism engagable with the guide member so as to prevent rotation thereof while the guide member is in contact with the support surface, thereby creating a brake for the trolley chassis.
4. A trolley chassis according to any of Claims 2 or 3 wherein the guide member is rotatably attached to a suspension arm which defines a first axis passing from one side of the chassis to another, the suspension arm being pivotable about a second axis spaced from the first axis so as to move the guide member between the first and second positions.
5. A trolley chassis according to Claim 4 further including a biasing member for resiliently biasing the suspension ann so as to resiliently bias the guide member into contact with the support surface when in the first position.
6. A trolley chassis according to Claim 5 wherein the biasing member defines an over centre bias on the suspension arm so as to urge the guide member towards each of the first and second positions.
7. A trolley chassis according to Claim 5 or claim 6 wherein the biasing member is or includes a pneumatic actuator.
8. A trolley chassis according to any of Claims 2 to 7 further including a pedal for moving the guide member between the first and second positions.
9. A trolley chassis according to Claim 8 when dependent from any of Claims 4 to 7 wherein a connecting rod interconnects the suspension arm and the pedal.
10. A trolley chassis generally as herein described with reference to and/or illustrated in the accompanying drawings.

10. A trolley chassis according to Claim 9 wherein the connecting rod further defines a part of the locking mechanism, the connecting rod being rotatable about a longitudinal axis thereof so as to selectively move a locking pin into engagement with one of a plurality of recesses spaced around a hub of the guide member, thereby preventing rotation of the guide wheel.

11. A trolley chassis generally as herein described with reference to and/or illustrated in the accompanying drawings.

Amendments to the claims have been filed as follows 1. A trolley chassis having at least three caster wheels for moving the chassis on a support surface, the trolley further comprising: a guide member moveahle so as to maintain contact with the support surface. whereby the guide member inhibits sideways movement of the chassis: and a locking mechanism engagable with the guide member SC) as to prevent rotation thereof thereby creating a brake for the trolle) chassis 2. A trolley chassis according to Claim 1 wherein the guide member is moveable between a first position in contact with the support surface and a second position spaced from the support surface.

3. A trolley chassis according to Claim 2 wherein the guide member is is rotatab]y attached to a suspension arm which defines a first axis passing from one side of the chassis to another, the suspension arm being pivotable about a second axis spaced from the first axis so as to move the guide member between the first and second positions.

4. A trolley chassis according to Claim 3 further including a biasing member for resiliently biasing the suspension arm so as to resiliently bias the guide member into contact vith the support surface when in the first position.

5. A trolley chassis according to Claim 4 wherein the biasing member defines an over centre bias on the suspension arm so as to urge the guide member towards each of the first and second positions.

6. A trolley chassis according to Claim 4 or Claim 5 wherein the biasing member is or includes a pneumatic actuator.

7. A trolley chassis according to any of Claims 2 to 6 further including a pedal for moving the guide member between the first and second positions.

8. A trol1e chassis accordmg to Claim 7 when dependent from an\ of Claims 3 to 6 wherein a connecting rod interconnects the suspension arm and the pedal.

9. A trolley chassis according to Claim 8 wherein the connecting rod further defines a part of the locking mechanism, the connecting rod being rotatable about a longitudinal axis thereof so as to selectively move a locking pin into engagement with one oF a plurality of recesses spaced around a huh of the guide member.

thereby preventing rotation of the guide wheel.