Purdue University Agricultural Extension Service
Mimeo AE-39 January, 1956
PROPELLING MODEL TRACTORS With Rubber Bands
The many scale-model farm tractors available may be vastly more useful for safety demonstrations if capable of propelling themselves. Methods which have been used are electric motors, spring wound motors and rubber bands.
The adaptation of the rubber band propulsion is made with commonly available tools and materials. The intent of this sheet is to outline the fundamental necessary steps of doing the job.
Many details of the operation are left to the ingenuity of the individual for two reasons; (1) Using the following pictures as a guide, you may be able to make improvements for the adaptation you have in mind, (2) Tractors other than those shown are available and will require different methods for their conversion.
Figure 1. The tractor at left has had small strips of cork cemented to its square axle. Often a knife will cut the opening in a plastic tractor.
An electric drill will cut the outline in plastic or metal models. A small metal cutting saw is useful on some tractors. Stretched tightly around the axle, the plastic electrical tape increases the diameter of the axle (which will increase torque) and provides a good friction surface. Different sizes of rubber bands.are shown. The size will influence the speed, travel distance and pulling ability of the unit.