GB2143185A

GB2143185A - Road wheel differential for light conveyances

Info

Publication number: GB2143185A
Application number: GB8318999A
Authority: GB
Inventors: Philip Lewis Cracknell; Alfred Joseph Pinfold
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-07-13
Filing date: 1983-07-13
Publication date: 1985-02-06
Also published as: GB8318999D0

Abstract

A four wheel or a three wheel conveyance is provided with a frame 1 whereby one or two road wheels mounted to it at one end are capable of a steering action, and two chain driven wheels 16 are mounted to it at the other end to separate axles 13, at the inner ends of which are attached conventional bicycle free wheel and gear units 11. A bicycle pedal assembly 4 mounted to the frame drives an intermediate gear wheel 6 by chain drive, the intermediate gear wheel 6 being mounted onto a shaft 7 which has two further gear wheels 9 attached to it each separately driving a conventional bicycle free wheel and gear unit 11 mounted onto the aforesaid separate axes 13. <IMAGE>

Description

SPECIFICATION Road wheel differential for light conveyances This invention relates to a 4 wheel or 3 wheel conveyance whereby the two rear wheels are chain driven.

To ensure a reasonable and acceptable steering response it is necessary to provide a differential action between the driving wheels, ie one wheel to rotate at a different speed to the other dependent on the path of the vehicle. On light conveyances the normal practice is to drive one road only and to allow the other wheel to revolve free which limits the traction to one wheel. The invention described shows a means to drive both rear wheels and provide a cheap differential action between them, thus providing traction to both rear wheels.

According to the present invention there is provided a simple frame carrying one or two wheels at one end which are capable of a steering action and at the other end two wheels that are chain driven. These wheels are fixed rigidly to separate axles which are free to revolve in housings. Fixed to each axle and at the opposite end to the road wheel is a screwed bush carrying an end stop. The screw thread is arranged to enable a conventional bicycle free. wheel and gear unit to be assembled to it, so that each axle can be driven separately by a chain and each axle has its own free wheel.

It should be understood that a conventional bicycle free wheel and gear unit is a chain gear or sprocket mounted to freely revolve on a fixed circular base in one direction only and by means of a pawl arrangement be made integral with the base to revolve with it in the opposite direction.

When the aforesaid conveyance is driven round a corner the wheel mounted to the inside of the curve will be driven and the other wheel mounted to the outside of the curve will need to rotate faster to ensure correct steering and the freewheel mounted to its shaft will enable this to be achieved.

It is to be noted that in a straight line direction both wheels are equally driven to provide maximum traction.

In the accompanying drawings: Figure 1 is a foreshortened plan view of a mid to rear part of a frame assembly.

Figure 2 is a foreshortened side view through section l-l of a mid to rear part of a frame assembly.

Following is a description by way of example only and with reference to the accompanying drawings of a method of carrying the system into effect.

Frame (1) consists of two side members (2) and a centre member (3). Mounted to member (3) is a conventional bicycle pedal assembly (4) which by means of chain (5) drives gear wheel (6) mounted rigidly to shaft (7) which is free to revolve in housing (8), the housing is mounted to centre member (3).

The shaft (7) has also two more gear wheels (9) mounted rigidly to it at opposite ends.

Two separate chain drives (10) connect these gear wheels to conventional bicycle free wheel gear assemblies (11) mounted rigidly on the inner ends of axles (12) by screw thread means (not shown). The axles are free to revolve in housings (13) which in turn are connected to side members (2) by means of brackets (14) and cross member (15). At the outer ends of axles (12) are mounted road wheels (16).

1. A differential action between two chain driven rear wheels of a four wheel or three wheel steerable conveyance. Wherein there is provided two separate axle shafts, one on each side of the centre of the conveyance. At the outer end of each shaft is a road wheel, rigidly attached, and at the inner end of each shaft is a conventional bicycle free wheel and gear unit, rigidly attached.

2. A differential action as claimed in claim 1 wherein the bicycle free wheel and gear units are mounted onto screw threaded bushes fixed rigidly to the inner end of each axle shaft.

3. A differential action as claimed in claim 2 wherein the screw threaded bushes are provided with a raised stop at the end of the thread.

CLAIMS 1. A differential action between two chain driven rear wheels of a four wheel or three wheel steerable conveyance. Wherein there is provided two separate axle shafts, one on each side of the centre of the conveyance. At the outer end of each shaft is rigidly attached a road wheel, and at the inner end of each shaft is rigidly attached a conventional bicycle free wheel and gear unit, whereby each gear unit provides drive in a forward direction and each gear unit provides a free wheel action when drive ceases.

2. A differential action as claimed in claim 1 wherein the bicycle free wheel and gear units are mounted onto screw threaded bushes fixedly rigidly to the inner end of each axle shaft.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Road wheel differential for light conveyances This invention relates to a 4 wheel or 3 wheel conveyance whereby the two rear wheels are chain driven. To ensure a reasonable and acceptable steering response it is necessary to provide a differential action between the driving wheels, ie one wheel to rotate at a different speed to the other dependent on the path of the vehicle. On light conveyances the normal practice is to drive one road only and to allow the other wheel to revolve free which limits the traction to one wheel. The invention described shows a means to drive both rear wheels and provide a cheap differential action between them, thus providing traction to both rear wheels. According to the present invention there is provided a simple frame carrying one or two wheels at one end which are capable of a steering action and at the other end two wheels that are chain driven. These wheels are fixed rigidly to separate axles which are free to revolve in housings. Fixed to each axle and at the opposite end to the road wheel is a screwed bush carrying an end stop. The screw thread is arranged to enable a conventional bicycle free. wheel and gear unit to be assembled to it, so that each axle can be driven separately by a chain and each axle has its own free wheel. It should be understood that a conventional bicycle free wheel and gear unit is a chain gear or sprocket mounted to freely revolve on a fixed circular base in one direction only and by means of a pawl arrangement be made integral with the base to revolve with it in the opposite direction. When the aforesaid conveyance is driven round a corner the wheel mounted to the inside of the curve will be driven and the other wheel mounted to the outside of the curve will need to rotate faster to ensure correct steering and the freewheel mounted to its shaft will enable this to be achieved. It is to be noted that in a straight line direction both wheels are equally driven to provide maximum traction. In the accompanying drawings: Figure 1 is a foreshortened plan view of a mid to rear part of a frame assembly. Figure 2 is a foreshortened side view through section l-l of a mid to rear part of a frame assembly. Following is a description by way of example only and with reference to the accompanying drawings of a method of carrying the system into effect. Frame (1) consists of two side members (2) and a centre member (3). Mounted to member (3) is a conventional bicycle pedal assembly (4) which by means of chain (5) drives gear wheel (6) mounted rigidly to shaft (7) which is free to revolve in housing (8), the housing is mounted to centre member (3). The shaft (7) has also two more gear wheels (9) mounted rigidly to it at opposite ends. Two separate chain drives (10) connect these gear wheels to conventional bicycle free wheel gear assemblies (11) mounted rigidly on the inner ends of axles (12) by screw thread means (not shown). The axles are free to revolve in housings (13) which in turn are connected to side members (2) by means of brackets (14) and cross member (15). At the outer ends of axles (12) are mounted road wheels (16). CLAIMS

1. A differential action between two chain driven rear wheels of a four wheel or three wheel steerable conveyance. Wherein there is provided two separate axle shafts, one on each side of the centre of the conveyance. At the outer end of each shaft is rigidly attached a road wheel, and at the inner end of each shaft is rigidly attached a conventional bicycle free wheel and gear unit, whereby each gear unit provides drive in a forward direction and each gear unit provides a free wheel action when drive ceases.