Gearboxes, couplings and bearings.
A jaw coupling that tolerates misalignment, shock loads and every scenario QA forgot to test.
A cast-iron pillow block with a 25 mm sealed ball bearing and grease fitting. Spins freely in any reality.
A compact 40 mm planetary gearbox with ratios from 3:1 to 100:1 and low backlash, for motion that means something.
