Clutches refer to a part of the power train that is used to connect/disconnect power to the rear wheels.

In automotive industry, clutches is described as:

1) a device for connecting and disconnecting the power flow between the engine and standard transmissions, used during starting, shifting, and stopping;

2) a device used to connect two collinear shafts to a driving mechanism such as a motor, engine, or line shaft, and to disconnect them at will; and 3) an electromagnetic clutch used to engage and disengage the compressor, to turn the air conditioner on and off.

-see also:
"Clutches" is in the HS Code "8483.60"