How fast should your buggy be?
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Belt pulleys that really work
The elastic band pulley system has the advantage that it is forgiving in terms of the accuracy required. In a gear system an error of 1 or 2 millimetres in positioning the shafts will cause the drive mechanism to fail because this will prevent the gears from meshing properly. Elastic bands stretch, so small errors like this do nor prevent the pulley drive from working.
But there are some features of the elastic band pulley system that are critical. It is important that the elastic band is neither too tight nor too loose. Over thick bands and over stretched bands give too much tightness and this makes it difficult for the motor shaft to turn. If the band is too loose the movement of the motor shaft is not transmitted to the pulley wheel. If the elastic band pulley system is to be efficient it is important that the motor shaft and the axle holding the pulley wheel are parallel. The pulley wheel must be positioned so that the elastic band drive is perpendicular to both the axle and the motor shaft. If the elastic band is at a different angle it does not transmit the movement so effectively and may fly off.