Besides "GV" Drummotors, Van der Graaf also manufactures Friction Clutches and Gearboxes.

Lever operated "FK" Friction Clutches can be used between a prime-mover and driven machine to simply 'clutch' the power on and off.

"TV" Gear boxes find uses in many driving systems. Speed reduction and increase is possible and a wide range of ratios bores and powers are available.

Friction clutch	Gear