Gravity Racer - Construction

Construction

A typical Gravity racer cart is usually made of steel, and has 4 wheels, arranged as a fixed rear axle, and a steerable front beam axle - usually with a very simple single central pivot. A seat is arranged at the back, and perhaps the seat area is enclosed, as in the original soap-box design. More sophisticated designs might employ a fully enclosed body. The types of wheels employed vary according to what can be obtained easily - wheels from baby carriages, pushchairs, prams, and discarded bicycles being common. Ready-made wheels are also available from hardware suppliers. Steering is typically actuated using a rope connected to the ends of the steerable beam (which can then double as a useful manual pulling device).

More sophisticated steering methods are sometimes seen. Brakes are also not commonly used, though some soap-box cart racing contests require these. Often a simple friction brake operated by a lever which bears on one of the tires, which will be of dubious effectiveness, is all that is required under the rules.

Gravity racer carts are unpowered, and are either pushed by willing helpers, or are run down a suitable slope. Races will usually take place downhill and the most efficient and skillfully driven cart will win - gravity applying equally to all.

Gravity racer carts also make great construction projects for children, requiring only an intuitive sense of engineering, and a few basic construction skills. There are also predesigned kits available, though for many this defeats the purpose of the exercise.

Recently, more advanced Gravity racers are beginning to emerge. These, intended for competition in the major soapbox races, are sometimes made of carbon fibre and feature a monocoque design, although most use a more traditional chassis or spaceframe design with bodywork made from materials such as plywood, corrugated plastic or similar. Examples of such soapboxes include the Lotus 119c and the Formula Gravity VXR Nimbus.

In Australia billy carts tend to conform, even in the 21st century, to a more traditional or rudimentary specification often being constructed informally by juveniles from found or inexpensive materials with minimal adult input and used without safety equipment. However even when construction of vehicles is more formally organised, such as for the annual Blacktown and District Cub Scout Billy Cart Derby at Rooty Hill, NSW the vehicle is still constructed to a deliberately relatively unsophisticated design, although safety is a consideration.

In Indonesia, billy carts are also known as 'gokar'. They are raced in different regions as a community social activity. The form of the cart is similar to the Australian one however the wheels are often motor cycle wheel bearings.

Electric soapboxes are a new development and are in fact not soapboxes at all. This, as they are electrically powered.