gearhead

gear +‎ head

gearhead (plural gearheads)

1. A mechanical device used to increase the torque of gears.
   • 2007 December 17, “Animatics buys UK’s Harmonic Linear Drive”, in Drives & Controls, UK:

     HLD has developed a linear belt actuator that circulates the belt in an unusual way, resulting in a gearing reduction of up to 40:1 without a gearhead.

gear +‎ -head

gearhead (plural gearheads)

1. (informal) An enthusiast for new technology, or for motoring.
   • 2000, "Ford Harley-Davidson Truck Rumbles Onto Web to Benefit Charities," PickupTruck.com (US), retrieved 23 Dec/07,

     A self-proclaimed gearhead, Leno loves fast Fords and hot Harley-Davidson motorcycles.

• (car enthusiast): (British English), petrolhead

• motorhead

• Heegaard, headgear