General parts can be roughly divided into the following categories
Transmission category
Gear drive,
chain drive,
belt drive
Shaft
Couplings,
Clutches,
Bolling bearings
Connection
Mainly fasteners, including nuts, bolts, screws, studs, pins (keys), washers, retaining rings, wood screws, self-tapping screws, rivets, welding nails, assemblies and connection pairs, as well as other non-standard fasteners firmware.