GB2215012A

GB2215012A - Vehicle with optional hydraulic transmission

Info

Publication number: GB2215012A
Application number: GB8803193A
Authority: GB
Inventors: Robert Jankel
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-02-11
Filing date: 1988-02-11
Publication date: 1989-09-13
Also published as: GB8803193D0

Abstract

The power driven multi-wheeled vehicle, of the kind in which power normally applied to one wheel or a pair of wheels can selectively also be applied to more than one wheel or a pair of wheels to increase the tractive effort when required, comprises an engine (1) and gearbox (2) through which one or a pair of wheels (R) is driven, and an hydraulic pump (6) driven from an engine gearbox output shaft (3) and forming part of an hydraulic circuit which includes at least one hydraulic motor (M) associated with at least one other wheel or pair of wheels (F) for driving the same when the hydraulic pump (P) is operative. The mechanical drive may be to the front wheels instead of the rear (Fig 2). Pressure relief valves enable wheels on the same axle to be driven at different speeds and the motors may freewheel in excess of a road speed of thirty miles per hour. The hydraulic transmission is controlled by electronically actuated valves. <IMAGE>

Description

"DRIVE TRANSMISSION TO MULTI-WHEELED VEHICLES" This invention relates to power driven multi-wheeled vehicles of the kind in which power normally applied to one wheel or a pair of wheels can selectively also be applied to more than one wheel or pair of wheels to increase the tractive effort when required.

Conventionally. such vehicles have a transfer gearbox associated with the main gearbox and which is selectively actuated for mechanically driving more than one, or more than one pair. of the vehicle wheels.

In accordance with the present invention there is proposed a power driven multi-wheel vehicle of the kind referred to, comprising an engine and gearbox through which one or a pair of wheels is driven, and an hydraulic pump driven from an engine or gearbox output shaft and forming part of an hydraulic circuit which includes at least one hydraulic motor associated with at least one other wheel or pair of wheels for driving the same when the hydraulic pump is operative.

Two embodiments of the invention are schematically illustrated in plan view in the accompanying two figures of drawings.

Fig. 1 illustrates a 4-wheeled vehicle comprising an engine 1 which transmits rotary motion through a gearbox 2, a transmission shaft 3. a differential unit 4 and half-shafts 5 to a pair of rear wheels R. Adjacent the differential unit there is mounted an hydraulic pump P which is driven, when required. from the transmission shaft 3 by means of a belt 6.

Associated with each of the vehicle front wheels F is an hydraulic motor M which is connected in parallel circuit with delivery (D) and return (R) hydraulic flow pipes connected to the pump (P). Suitable pressure relief valves (not shown) are also provided.

Thus when the front wheels (F) are to be driven simultaneously with the mechanically driven rear wheels it is only necessary by means of a remote switch or remotely controlled mechanical coupling to actuate the hydraulic pump P.

Fig. 2, in which the same references have been used to indicate components equivalent to those shown in Fig.

1, illustrates a 4-wheeled vehicle with the engine 1, gearbox 2, and differential unit 4 driving the front wheels F, with the hydraulic pump P connected in circuit with the motors M associated with the rear wheels R, the mode of operation being essentially as above described in Fig. 1.

In each instance the hydraulic system may be controlled by means of valves which may be electronically actuated.

A principal advantage of the vehicle according to the present invention is that it is cheaper and more economic to manufacture than existing vehicles with mechanical transmission of power to all the driving wheels. Thus it is not necessary to provide differential gearing between the extra drive wheels since by use of pressure relief valves in the hydraulic circuit the hydraulic motors and wheels can be driven or revolved at different speeds when the vehicle is negotiating bends. Additionally the hydraulic motors can have a freewheel action so as to cease to be effective automatically when, say, vehicle road speed exceeds 30 miles per hour. Another advantage is that there is no need for a torque splitter unit to divide the application of power between two or more wheels or wheel pairs. Also when changing to multi-wheel drive operation there is no need to stop the vehicle.

Claims

1. A power driven multi-wheel vehicle of the kind referred to, comprising an engine and gearbox through which one or a pair of wheels is driven, and an hydraulic pump driven from an engine or gearbox output shaft and forming part of an hydraulic circuit which includes at least one hydraulic motor associated with at least one other wheel or pair of wheels for driving the same when the hydraulic pump is operative.

2. A vehicle as claimed in claim 1 in which the hydraulic pump is driven by means of a belt from a gearbox output shaft.

3. A four wheeled vehicle having a mechanical and hydraulic drive transmission substantially as hereinbefore described with reference to, and as shown in, Fig. 1 or Fig. 2 of the accompanying drawings.