GB2158402A - Lifting trolley - Google Patents

Abstract

A lifting trolley has a chassis comprising side members (10) joined by a rear cross member (12), the forward ends of the side members (10) having wheels (14), and the rear of the chassis having a pair of close coupled wheels (22) steerable about an axis (26) by means of a handle (30) which can also be used for manually moving the carriage. A mast (16) mounted to the rear of the chassis supports a vertically movable carriage (50) from which a pair of forks (60) project forwardly between the side chassis members (10) for engaging and lifting a load. The carriage is lifted by a ram (66) operated by reciprocating movement of the handle (30) causing brake shoes (44) to bear upon the wheels (22) to immobilise the trolley. The trolley provides a much cheaper alternative to a powered forklift truck, and which is more appropriate to operation in confined spaces and on building sites. <IMAGE>

Description

SPECIFICATION Lifting trolley This invention relates to devices for lifting and transporting loads.

One of the most common devices of this kind is the fork lift truck, which comprises a self-propelled vehicle, usually operated by a driver, and having at its front end a mast up and down which travels a carriage carrying a pair of forwardly directed forks which engage under a load and lift it clear of the ground for transport by the truck. A fork lift truck is an expensive piece of machinery, and is also heavy and not very suitable for operating in confined spaces.

The present invention provides a lifting trolley, which comprises a frame having a pair of forwardly directed side members joined by a cross member at their rearward end portion and having wheels at their forward end portions, steerable wheel means being provided at the rear end portion of the frame, the rear end portion of the frame also having a mast defining an upright track along which travels a carriage which carries forwardly directed forks located between the side members of the frame, lifting means being provided for raising the carriage, manually operable steering means being provided associated with the steerable wheel means for steering the trolley, whereby with the carriage in a lowered position the trolley may be brought up to a load to be lifted and transported, so that the side arms of the frame pass on either side of the load and the forks engage under the load, the carriage then being raised to lift the load clear of the ground between the side arms of the frame ready for transport, and the manually operable steering means comprising a towing arm connected to the steerable wheel means and extending in the direction away from the forks, with a handle at its free end so that the trolley can be simultaneously steered and moved by an ambulating operator, the towing arm being mechanically linked to a brake mechanism which operates if the towing handle is lowered.

Preferably the steerable wheel means comprises a single wheel or a pair of close coupled wheels located on the centre line of the trolley. A hydraulic ram is preferably provided for lifting the carriage. The ram can conveniently be raised by means of a hydraulic pump operated by reciprocating upward movements of the towing arm.

In order that the invention may be more clearly understood, one embodiment will now be described with reference to the accompanying drawings, wherein: Figure 1 shows a cross-sectional side view of the trolley, Figure 2 shows a plan view of the trolley, and Figure 3 shows a detail of a fork tilting mechanism.

Referring to the drawings, the trolley comprises a rigid fabricated steel frame having a pair of side members joined at their rear ends by a cross member 12, with wheels 14 at their forward ends. A mast 1 6 is fixed to the cross member 12, and comprises two upright mutually inwardly directed channel members 1 8 joined at the top by a cross piece 20. A pair of close coupled wheels 22 on a common axle 24 are mounted by a vertical pivot pin 26 on a central column 32 to a rearwardly directed bracket 28 fixed to the centre of the cross member 1 2 of the frame. The wheels 22 can thus pivot about the pivot pin 26 for steering the trolley. A towing arm 30 is connected to the wheel mounting column 32 and extends in the direction away from the trolley frame and has a cross handle 34 at its free end.By this means, an operator can push, pull and steer the trolley. A pair of arms 36, 38 are pivotally interconnected by a transverse bar 40, and are pivoted at their outer ends to the towing arm 30 and the axle 24 respectively. A spring 42 acting between the arms 30 and 36 acts as a counterbalance against the weight of the arm 30. Arcuate brake shoes 44 made fast at their upper end 46 have cam surfaces 48 which engage the bar 40 so that when the arm 30 is forcibly lowered it presses the brake shoes 44 against the wheels 22, thereby producing a braking action.

A carriage 50 comprises a pair of side members 52 joined at their upper end by a cross member 54, and lower down by a pair of forwardly located upper and lower fork mounting plates 56, 58 respectively. Over these plates can be slidably fitted and locked in conventional manner a pair of L-shaped forks 60. The side members 52 of the carriage have laterally projecting upper and lower rollers 62, 64 respectively which engage in the tracks defined by the channels of the mast side members 1 8. The carriage is raised by means of a hydraulic ram 66 which is operated by a hydraulic reservoir 68 and hydraulic pump 70. Conveniently the pump has a projecting reciprocating piston member 72 which is operated by reciprocating upward movements of the towing arm 30 to extend the ram 66 and raise the carriage.A hydraulic pressure release lever 74 can be provided on the handle 34 to allow the ram to retract and lower the carriage. Another lever 76 can be provided on the handle to release the brakes in the event that a brake locking device, such as a pawl and ratchet, is provided for locking the brake in the engaged position.

The roller tracks in the channel members 1 8 can be further defined, as shown in Fig. 3, by plate elements 78, which have ramp surfaces 80, the plates being arranged so that as the carriage lifts from its lowermost position the rollers 62, 64 ride up the ramp surfaces thereby tilting the carriage, and hence the forks, backwards to a certain extent.

In operation, with the carriage in the lowered condition, the operator manoeuvres the trolley up towards the load so that the wheeled frame arms 10 pass on either side of the load and the forks engage under the load.

The arm 30 is then reciprocated upwardly to raise the carriage and lift the load clear of the ground. The operator then uses the handle 34 to tow the trolley away to the location where it is desired to deposit the load. He then releases the hydraulic ram, allowing the carriage to descend and deposit the load on the ground, whereafter the trolley can be removed. During the lifting or lowering of the load the trolley can be held stationary by using the braking system.

The device as described and illustrated could be modified in various ways. A single steerable wheel could be provided if desired.

The hydraulic ram could be operated in a different manner, for example by a separate manually operable lever or by an electric motor. The hydraulic ram could be replaced by a mechanical lifting mechanism such as a worm and screw, or by an electrically operated lifting mechanism. A fail-safe device may be provided in the hydraulic system, for example in the form of a valve fitted to the ram so that if there is a sudden leak in the hydraulic system the valve closes to prevent the carriage from descending suddenly. Instead of the cam operated tilting system shown in Fig. 3, tilting of the carriage may be provided by one or more additional hydraulic rams or other mechanical means.

The forks can be positioned as desired on their mounting plates, according to the spacing required by the load. The forks can be removed to be interchanged with other forks of different size if desired.

The invention is particularly suitable for use in lifting packs of bricks or building blocks, which are conventionally wrapped and banded with openings left in the stack to receive lifting forks. The trolley of the present invention is much more suited to use around the building site or on the floors of partially completed buildings, than is a conventional fork lift truck.

Claims (6)

1. A lifting trolley, which comprises a frame having a pair of forwardly directed side members joined by a cross member at their rearward end portion and having wheels at their forward end portions, steerable wheel means being provided at the rear end portion of the frame, the rear end portion of the frame also having a mast defining an upright track along which travels a carriage which carries forwardly directed forks located between the side members of the frame, lifting means being provided for raising the carriage, manually operable steering means being provided associated with the steerable wheel means for steering the trolley, whereby with the carriage in a lowered position the trolley may be brought up to a load to be lifted and transported, so that the side arms of the frame pass on either side of the load and the forks engage under the load, the carriage then being raised to lift the load clear of the ground between the side arms of the frame ready for transport, and the manually operable steering means comprising a towing arm connected to the steerable wheel means and extending in the direction away from the forks, with a handle at its free end so that the trolley can be simultaneously steered and moved by an ambulating operator, the towing arm being mechanically linked to a brake mechanism which operates if the towing handle is lowered.

2. A lifting trolley according to claim 1 wherein the brake mechanism comprises a shoe which is applied to the steerable wheel means as the towing handle is lowered.

3. A lifting trolley according to any one of the preceding claims wherein the steerable wheel means comprises a single wheel or a pair of close coupled wheels located on the centre line of the trolley.

4. A lifting trolley according to any one of claims 1, 2 and 3 wherein a hydraulic ram is provided for lifting the carriage.

5. A lifting trolley according to claim 4 wherein the ram is raised by means of a hydraulic pump operated by reciprocating upward movements of a towing arm.

6. A lifting trolley according to claim 1, having steering and brake means substantially as described herein with reference to the drawings.