GB2186255A - Restricted-lift load-handling vehicle - Google Patents

Abstract

A self-propelled steerable ground-travelling vehicle comprising: a) a main frame 11 carrying an operator station and a power unit which propels the vehicle; b) a sub frame connected to the main frame so the frames extend in opposite directions away from the frame connection, and the frames can pivot to a limited extent about that connection; c) first and second sets of ground-engaging wheels connected respectively to the frames at positions remote from the pivot axis to support the frame assembly in ground-travelling mode; d) a manually operated jack 26 pivots the frames about the axis so as selectively to increase or decrease the ground clearance of the frame connection; the jack being used to lock the frames in alternative low- ground-clearance and high-ground-clearance positions of the frame connection, in each of which positions the vehicle can travel; and e) lift forks 29 fixed to the main frame and moving therewith towards or away from the ground, and supported solely by the main frame throughout its lifting and lowering movement. <IMAGE>

Description

SPECIFICATION Restricted-lift load-handling vehicle Field of the Invention The invention relates to restricted-lift loadhandling vehicles.

Review of Art Known to the Applicant Restricted-lift load-handling vehicles are known in the form of so-called low lift pallet trucks. Examples of such trucks are shown in the following published UK patent specifications: 2 087 345 2 023 097 1 453 387 1 440 062 1 429 785 684 732 and in the following published US patent specifications: 2 944 689 2 833 435 The known arrangements described and illustrated in each of these previously published patent specifications comprise, in broad terms, a wheeled frame supporting generally horizontally extending fork tines, with power driven means to selectively raise and lower the tines relative to the wheels and to propel the truck; and with the lift being restricted by the presence of auxiliary wheels or rollers which are mounted beneath the fork tines and which, as the tines rise, are automatically lowered to engage the ground and to support the tines at all times during their load lifting and lowering movement.

The prior specifications listed above are given by way of example only. They do not constitute a complete list, nor even necessarily a representative list, of the prior art. They do constitute the most relevant art currently known to the applicant.

Summary of the Invention In its broadest aspect, the invention provides a self-propelled steerable ground-travelling vehicle comprising a) a main frame carrying an operator station and also carrying a power unit which, when operated, generates the primary power to pro pel the vehicle; b) a sub frame so connected tothe main frame that a major portion of the sub frame and a major portion of the main frame extend in respectively opposite directions away from the frame connection, and the frames can swing to a limited extent about that connection; c) first and second sets of ground-engaging units connected respectively to the main frame and to the sub frame at positions remote from the frame connection, to support the frame assembly in ground-travelling mode;; d) means to swing the frames, when so supported, about the frame connection so as selectively to increase or decrease the ground clearance of the frame connection; e) means to lock the frames in alternative low-ground-clearance and high-ground-clearance positions of the frame connection, in each of which positions the vehicle can travel; and f) a loading lifting and lowering platform, fixed to the main frame and moving therewith towards or away from the ground, and supported solely by the main frame throughout its lifting and lowering movement.

Some of the low lift pallet trucks in the specifications listed above do away with the fork-supporting rollers in order not to restrict the lift of the fork tines, and also in order to remove the danger (real or illusory) of damage to the fork-roller-lowering linkage caused by the need to lift the whole of the main frame of the truck whenever the tines are lifted.

These however involved the added complication of providing the tines with a carriage and power-driving the carriage up and down on the main frame. Others of these prior arrangements retain the fork-roller-lowering linkage and accept its potential drawbacks in order to be able simply to fix the tines to the main frame of the truck.- None of the previous arrangements, as far as the applicant can determine from these published specifications, shows or suggests a vehicle in which the load lifting and lowering means is simply fixed to the main frame and is supported solely by the main frame during the lifting and lowering movement.

The pallet trucks described and illustrated in these previous specifications are all auxiliary trucks designed for use with a parent lift truck. The lifting and lowering movements, and the propulsive movements, derive their power primarily from a power-generating unit carried on the parent truck and supplying (specifically) electrical and hydraulic power through lines connecting the auxiliary truck to the parent truck. Thus the prior arrangements are not properly self-propelled vehicles. The need to have the parent truck present and operating in order to be able to operate the auxiliary truck clearly adds excessively to the costs of the operation, as well as restricting the travel of the auxiliary truck.

A vehicle embodying the invention, by contrast, avoids these drawbacks. The invention thus lends itself ideally to embodiment in a vehicle which can be used to travel from one loading and offloading point to another over a wide area of ground, picking up and putting down relatively small single-unit loads such as crates of apples distributed about an apple orchard after apple-picking.

Preferably the frame connection is a pivotal connection. The construction of such connections is well known in general, and is thus easily engineered, and pivotal connections are generally more reliable than other forms of swinging connection involving slides and/or links.

In practical embodiments of the invention, the common axis (or the respective individual axes) of the wheels or other ground engaging units on the sub frame will span the load lifting and lowering platform. Preferably, in an arrangement embodying the invention, the platform swings through that axis (or those axes) as it moves into and out of its load lifting position and hence can be lowered virtually to the ground on which the vehicle stands.

The vehicle is also preferably steered by the set of wheels or other ground engaging units which are mounted on the main frame, rather than by those on the sub frame, and travels with its steerable wheels (or other units) leading whenever it intentionally travels for any appreciable distance. It is clearly easier to make the wheels or equivalent units on the main frame steer than to try to make those on the sub frame steer if, as outlined above, the load platform is preferably to swing virtually right down to the ground (the implication being that there must then be no common axle physically joining the sub frame wheels or wheel-equivalents tib one another). Most operators also find it easier to steer a vehicle which travels with its steerable wheels leading than one which travels with its steerable wheels trailing.

Where the steerable wheels or wheel-equivalents are on the main frame, i.e. with the main power-generating unit, then these wheels or wheel-equivalents may with advantage be power driven to propel the vehicle.

In the case just outlined, it is especially advantageous for the vehicle to have its main power-generating unit, its stearable and power driven wheels or wheel-equivalents, and the transmission from the one to the other, mounted on the main frame in a unitary "power pack". Such power packs are now commonplace in road going motor vehicles.

Their installation and servicing is familiar, they are readily available, and they lend themselves ideally in a vehicle embodying the invention to being readily demounted from the main frame and replaced with an equivalent (or even a different) power pack.

Brief Description of the Drawings The accompanying drawings show, by way of example only, one vehicle embodying the invention. In these drawings: Figures 1, 2 and 3 show the vehicle unloaded and viewed in perspective from the rear (Fig. 1) and from one side (Figs. 2 and 3) respectively; Figures 4, 5 and 6 show the vehicle in process of backing up to and under a load (Figs.

4 and 5) and having lifted the load (Fig. 6) again viewing the vehicle in all cases in perspective; Figs. 1, 2, 4 and 5 show the vehicle in its load lifting mode whilst Figs. 3 and 6 show the vehicle in its load carrying mode.

Description of the Preferred Embodiment The drawings show a vehicle specially built for handling individual palleted crates of apples in an apple orchard. The vehicle is self-propelled and steerable and travels, in use, about the orchard. A specific description of the vehicle now follows.

A main frame is substantially rectangular and incorporates side beams referenced 11 which, like the rest of the frame, comprise box-section steel. The main frame carries an operator station in the form of a seat 12 and a foot well 13. A unitary "power pack" housed generally beneath a bonnet 1 3a includes an internal combustion engine and gearbox (not visible in the drawings) driving a set of two spaced-apart steerable braked wheels 14 and with a gear lever 15 and steering column and steering wheel assembly 16 each projecting from the foot well 13 towards the seat 12.

In this particular vehicle, the power pack is taken from a road going motor car of the kind currently sold in the United Kingdom under the Registered Trade Mark MINI by Austin Rover Plc. The gear level 15, the steering wheel and steering column assembly 16, and the accelerator-clutch-brake pedal assembly (not visible in the drawings, but located in the foot well 13) also come from the road going MINI car. The engine is appropriately silenced, a petrol tank 17 supplies fuel to it in conventional manner, and the wheels 14 are shrouded by vestigial mudguards 1 8 carried one on each opposite longitudinal side of the bonnet 13a.

As this vehicle is only intended to be used on private land, it does not comply with regulations for road going use. Thus for example it has no lights, no weatherproofing, and only the wheels 14 are braked. Like the conventional road going MINI car, however, whenever it intentionally travels any relatively long distance it does so with its steerable wheels 14 leading.

A sub frame comprising elongate steel box beams 19 each fixed to one opposite end of a circular-cylindrical steel tube 21 is pivotally connected to the main frame 11 to swing, relative to that frame 11, about an axis (defined by the axis of the tube 21) spanning the vehicle just behind the seat 12. A major portion of the main frame 11, and a major portion of the sub frame 19, 21, thus extend in respectively opposite directions away from the pivot axis.

The main frame and the sub frame can swing to a limited extent about the pivot axis.

The tube 21 pivots inside bearings 22 fixed one to each corresponding and respective end of the main frame side beams 11; and inside further bearings 23 Bach fixed to a cross beam 24 spanning the beams 11. The cross beam 24 is fixed rigidly to each of the beams 11 and forms part of the main frame of the vehicle. It runs parallel with the tube 21 across the vehicle.

Trunnions 25 are fixed adjacent one another to the tube 21 and move with the tube whenever it pivots in the bearings 22 and 23. A hand-operated jack 26 acts between the upstanding portion of the trunnions 25 and the floor of the main frame of the vehicle. When a hand lever 27 is reciprocated, the jack 26 extends to swing the tube 21 anti clockwise (when the vehicle is viewed as in the drawings) and hence to swing the whole sub frame 19, 21 in that same sense relative to the main frame. Appropriately alternative operation of the lever 27 allows the jack 26 to retract.

and swing the sub frame 19, 21 in the opposite sense.

A second set of two wheels each referenced 28 is fixed one to each corresponding end of the box beams 19 at positions which (like those of the wheels 14) are remote from the pivot axis of the tube 21. The wheels 28 are trail wheels, i.e. they are freely rotatable and are each mounted on a respective stub axle fixed to the associated beam 19.

Two parallel. spaced-apart fork tines 29 are each welded to the underside of the cross beam 24 to emergetfrom beneath the tube 21 and run, generally parallel with the side beams 19 of the sub frame, away from the pivot axis of the tube 21. The tines 29 define a load lifting and lowering platform.

As can readily be appreciated from a study of Figs. 1 to 3, operating the jack 26 when the vehicle is supported in ground-travelling mode, as illustrated, selectively and alternatively increases or decreases the ground clearance of the pivot axis of the tube 21. In a low ground clearance position, illustrated in Figs. 1 and 2 (and Figs. 4 and 5) the side beams 19 of the sub frame and 11 of the main frame each run at an appreciable angle to the ground on which the vehicle stands; but the tines 29, although not literally on the ground, are substantially parallel to the ground. Whilst in a high ground clearance position, as illustrated in Fig. 3 (and in Fig. 6), the two sets of side beams 11 and 19 are substantially in line whilst the fork tines 29 slope noticeably towards the main frame 11, 13, 24.

The pressure in the jack 26 provides a means to lock the frames in their selected alternative positions as well as providing the means to -swing the frames about the pivot axis of the tube 21. Although the steerable driven wheels 14 may be supported on cushioned suspension units inherent in the original MINI power pack, the trail wheels 28 incorporate no suspension cushioning other than the inherent resilience of their pneumatic tyres (and whatever "give" there may be in the fluid pressurised within the jack 26).

To use the vehicle to pick up a pallet 31 supporting a crate 32 of apples, the jack 26 is operated to bring the fork tines 29 down to their near-ground position as illustrated in Figs.

1 and 2. The vehicle is then reversed towards the pallet (Fig. 4) and is backed up until the tube 21 abuts the front of the pallet in which position (Fig. 5) the tines 29 are fully underneath the pallet. The jack is then operated in the opposite sense to lift the tines into their Fig. 3 position. In this position (Fig. 6) the lifted palletised load is held with its centre of gravity well within the wheel-base of the vehicle; and is also held in a forward-sloping attitude to make it unlikely that the load will slip off the vehicle as the vehicle travels to the point at which the tines are to be lowered and the load put down.

Because there is no physical axle joining the common axis of the trail wheels 28, the tines 29 can swing through that common axis as they move into and out of their near-ground position. Loading and unloading the tines is thus facilitated.

Although the vehicle described and illustrated is specifically intended for use in an apple orchard vehicles embodying the invention and similarly intended for use in agricultural environments generally could be fitted with (for example) tank and pump units, spray booms, and spraying equipment generally.

Modifications could be made to the vehicle illustrated, within the scope of the invention.

For example, although the illustrated trail wheels 28 incorporate no suspension cushioning, suspension could be incorporated on these wheels. The trail wheels and/or the driven wheels 14 could be fitted with lowpressure flotation tyres in certain conditions and this would increase the effective amount of springing of the vehicle chassis. The mounting of the jack 26 could incorporate linkages and spring-damping means so that the "give" of the jack when locked in position is deliberately increased.

For extra ruggedness, the jack 26 is preferably fixed to the cross beam 24 and to the floor of the main frame of the vehicle, rather than being fixed to the main frame alone.

Claims (7)

1. A self-propelled steerable ground-travelling vehicle comprising a) a main frame carrying an operator station and also carrying a power unit which, when operated, generates the primary power to propel the vehicle; b) a sub frame so connected to the main frame that a major portion of the sub frame and a major portion of the main frame extend in respectively opposite directions away from the frame connection, and the frames can swing to a limited extent about that connection; c) first and second sets of ground-engaging units connected respectively to the main frame and to the sub frame at positions remote from the frame connection, to support the frame assembly in ground-travelling mode; d) means to swing the frames, when so supported, about the frame connection so as selectively to increase or decrease the ground clearance of the frame connection;; e) means to lock the frames in alternative low-ground-clearance and high-ground-clearance positions of the frame connection, in each of which positions the vehicle can travel; and f) a load lifting and lowering platform, fixed to the main frame and moving therewith towards or away from the ground, and supported solely by the main frame throughout its lifting and lowering movement.

2. A vehicle according to Claim 1 and in which the frame connection is a pivotal connection.

3. A vehicle according to Claim 1 or Claim 2, in which the common axis (or the respective individual axes) of the wheels or other ground-engaging units on the sub frame spans the load lifting and lowering platform, and in which the platform swings through that axis (or those axes) as it moves into and out of its loading lifting position such that it can be lowered virtually to the ground on which the vehicle stands.

4. A vehicle according to any of the preceding claims and steered by the set of wheels or other ground-engaging units which are mounted on the main frame and travels with its steerable wheels (or other units) leading whenever it intentionally travels for any appreciable distance.

5. A vehicle according to any of the preceding claims, in which the steerable wheels of wheel equivalents are on the main frame, and in which these wheels or wheel-equivalents are power driven to propel the vehicle.

6. A vehicle according to Claim 5 and in which the vehicle has its main power-generating unit, its steerable and power-driven wheels or wheel-equivalents, and the transmission from the one to the other, mounted on the main frame in a unitary "power pack".

7. A vehicle substantially as described herein with reference to, and as illustrated in, the accompanying drawings.