With the hook and rubber-band properly adjusted, this is what happens when the car ascends to the top of the shaft.
The toy motor-boat shown in Figs. 48 and 49 is propelled by a tin propeller run by a rubber-band motor.
The rubber-band ends must project an equal distance beyond the spool-ends.
Wrap the spool pulleys with bicycle-tape, to keep the rubber-band belts from slippin ...