The instruments are very helpful when removing and installing V-belts
on pulleys. The application of one device to the pulley during the rotation
of the wheel causes the tensioned belt to slide down, the second device
causes the belt to slide on the wheel when the wheel is rotated
The belt disassembly and assembly operation is almost impossible
without the help of tools, the amateurs try to help themselves with a
screwdriver or other piece of sheet metal, which may cause damage to
the pulley or belt.