The winch gear-units used for this kind of winches is helical bevel gears which is very common in heavy duty industry. Crane or hoist duty is the most.
The electric motor power is from small o big and selected according to the actual need.
Usually with a VFD brake AC-motor. Explosion
Sometimes we can add a clutch in the roller of the winch. It is good for the frequency start and stop operating. and the most
important, it is more safe.
The gear-units is a two or three stages gearing type. With oil pump lubrication system and cooling system on. The housing is cast iron which is very strong to bearing big torque.