Nuffield Spring Unit
This unit is used to demonstrate the reversible series of changes from electrical energy (battery or power pack), to mechanical energy (motor), to potential energy (stored in the spring), back to mechanical energy (the spring driving the motor/generator), finally returning to electrical energy to light a lamp. The large clock spring is provided with a ratchet and pawl and geared to the motor/generator. The spring may be wound by hand if necessary. Guard strips are provided over the spring and the gears.