GB2537387A - A Wheeled vehicle and a hub - Google Patents

Abstract

A wheeled vehicle 10 is a tricycle comprising two sprockets on a common axle or hub 102 which is driven by cranks 26, each sprocket driving a chain each chain driving a ground engaging wheel 14, 16 through a free wheel hub 60, 62. The driven ground engaging wheels 14, 16 are on opposite sides of the vehicle 10, so that the driven ground engaging wheels 14, 16 are driven at the same speed, but can free wheel by means of the free wheel hub 60, 62, if the ground speed of that wheel 14, 16 is higher than the driven speed.

Description

A Wheeled Vehicle and a Hub The invention relates to a wheeled vehicle and to a hub.

An example of a wheeled vehicle is a pedal tricycle. A known pedal tricycle has one steerable wheel at the front and two wheels at the back. There are pedals to be pushed round by a rider, which drive a chain, which drives the axle of one of the rear wheels. The other rear wheel simply rolls freely. If both wheels were driven, it would create problems when the bicycle was cornering, for example, as the rear wheels would try to move over the ground at different speeds and would skid. Because only one of the rear wheels is driven, the tricycle will lose drive if that wheel slips, for example because of mud or ice, or if the wheel loses contact with the ground, as it might over rough terrain, or when trying to take the tricycle up a kerb.

According one aspect of the invention there is provided a wheeled vehicle comprising two sprockets on a common axle or hub which is driven, each sprocket driving a chain, each chain driving a ground engaging wheel through a free wheel hub, the driven ground engaging wheels being on opposite sides of the vehicle, so that the driven ground engaging wheels are driven at the same speed, but can free wheel by means of the free wheel hub, if the ground speed of that wheel is higher than the driven speed.

In this way, two wheels on opposite sides of the wheeled vehicle are driven. Thus, if one driven wheel is on a slippery surface such as ice or mud, but the other still has grip, the vehicle can still be driven forward. Equally, if one wheel is off the ground, but the other driven wheel is still in contact with the ground, the wheeled vehicle can still be driven forwards.

The wheeled vehicle may be of any suitable type and may be motorised, but in a preferred embodiment the vehicle is a pedal vehicle, which preferably includes pedals driving a sprocket, which drives the common axle or hub. The vehicle preferably includes a common hub, rather than a common axle, and in a preferred embodiment the common hub is a hub gear. The two sprockets may thus be mounted on the driven part of the hub gear.

The vehicle may have any desired number of ground engaging wheels, such as three, four, or six. In a preferred embodiment the vehicle has three ground-engaging wheels.

In that case, where the vehicle is a pedal vehicle it will be a tricycle The third ground-engaging wheel may be at the back, but in a preferred embodiment the third ground engaging wheel is at the front.

The wheeled vehicle preferably includes a space frame which may extend over and around the free wheel hubs and chains to connect the axle supports of the driven ground engaging wheels The space frame may form a load carrying rack on the vehicle.

According to another aspect of the invention there is provided a hub gear carrying two sprockets on a driven part.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 s a perspective view of the wheeled vehicle of the embodiment; Fig. 2 is a side elevation of the vehicle of Fig. 1; Fig. 3 is a rear elevation of the vehicle of Fig. 1; Fig. 4 is an underneath plan view of the vehicle of Fig. 1, and Fig. 5 is a fragmentary detail view of part of the view of Fig. 4.

The wheeled vehicle 10 of the first embodiment is a tricycle with a single front wheel 12 and two rear wheels 14, 16 The tricycle 10 is of a step through design. The front wheel 12 is supported on forks 18 leading through a head tube 20 to handlebars 22. The head tube 20 is connected to a down tube 24 connected to a bottom bracket 25 mounting cranks 26 and a front chain ring 28 The cranks 26 are arranged to mount pedals (not shown). A seat tube 30 stands up on the bottom bracket 25 and carries a seat post 32 with saddle 34.

Extending rearward from the bottom bracket 25 is a single chain stay tube 36 which is connected to the front face of a transverse box section tube 38. Two seat stays 40 extend rearwardly from the top of the seat tube 30 and also connect to the box section tube 38, on either side of the end of the chain stay 36. Two frame struts 42 extend from substantially half way along the down tube 24 to the front face of the transverse box section tube 38 being attached one each side between the chain stay tube 36 and seat stay 40.

The box section tube 38 is connected to a prism shaped space frame 50. The axle 52, 54 of each rear wheel 14, 16 is joumalled in a support tube 56, 58. The inner end of each axle 52, 54 carries a free wheel hub 60, 62, the two free wheel hubs, 60, 62 facing each other with a space between them.

The space frame 50 comprises two top lateral tubes 70, 72 which extend from one side of the tricycle 10 to the other within the wheel base of the rear wheels 14, 16. At each end of each axle tube 56, 58, two struts 74, 76 extend upwards to connect, one to the front lateral tube 70 and the other to the rear lateral tube 72. A second box section tube 78 is connected to the underside of the rear lateral tube 72 in the same way as the first box section tube 38.

A central lateral top tube 80 is provided between the first and second lateral top tubes 70, 72 and is connected to the first and second lateral top tubes 70, 72 by four front to rear bars above the struts 74, 76.

On each side of the tricycle 10, an angled strut 82 extends from near to the outer end of the axle tube 56, 58 upwards at an angle to connect more centrally to the central lateral top tube 80.

An inverted U-shaped bracket 90 depends from the front box section tube 38. The arms 92, 94 of the bracket 90 include apertures 96, 98 to mount the ends of the axle 100 of a Sturmey Archer TM three speed hub gear 102 adapted so that the flanges 104 defining lace holes that would normally mount spokes of a wheel instead each carry a sprocket 106, 108. The chain 110 from the front ring 28 goes around the input sprocket 112 of the hub gear 102. There are two chains 114, 116 at the rear of the tricycle 10 and one chain 114 is over the left hand output sprocket 106 of the hub gear 102 and the sprocket 118 of the free wheel 60 of the left hand rear wheel 14 of the tricycle, and the other chain 116 goes over the right hand output sprocket 108 of the hub gear 102 and the sprocket 120 of the free wheel 62 of the right hand wheel 16 of the tricycle 10. The drive to each rear wheel 14,16 is the same. The sprockets 106, 108 on the hub gear 102 are the same, the rear chains 114, 116 are the same and the rear sprockets 118, 120 are the same In use, when the rider pedals to turn the cranks 26, this drives the front chain 110, which drives the input sprocket 112 of the hub gear 102, which in turn drives the output sprockets 106, 108 of the hub gear 102 and through the two rear chains 114, 116 drives the rear free wheel sprockets 118, 120 to drive the rear wheels 14, 16 of the tricycle 10. In normal use travelling in a straight line on a surface with good friction, both wheels 14, 16 will drive the tricycle 10 along. If one wheel 14, 16 should slip or come off the ground, the other wheel 14, 16 will still be driven. When the tricycle 10 goes around a corner, the rear wheel 14, 16 on the inside will drive the tricycle 10, but the ground speed of the wheel 14, 16 on the outside will be faster than the driven wheel 14, 16 and it will therefore free wheel, rolling at a faster rate than the inside wheel 14, 16. By means of the invention, drive can be more reliably obtained on surfaces where one wheel 14, 16 may slip, and the tricycle 10 can also provide reliable drive when off road or going up a kerb, when one rear wheel 14, 16 may leave the ground.

In a variant on the embodiment, an electric assist motor can be provided to drive the Sturmey Archer hub gear 102, or indeed the tricycle may solely be driven by electric power in which case the pedals, cranks 26, front ring 28 and front chain 110 can be omitted.

In another variant, the vehicle can have two steerable front wheels and hence be a quadricycle.