The four main parts of a tricycle are the frame, wheels, handlebars and seat. Each of these main parts can be broken up into several smaller sub parts.
The frame of a tricycle consists of the fork, plate fork, fender, rear deck and frame, which are then held together by hex bolts, hex nuts and lock washers. The fork holds the front pedal wheel in place and connects it to the rest of the tricycle.
The wheels include the pedal wheel that is placed in the front of the tricycle as well as the two rear wheels. The front wheel also features two pedals with a bearing and nut push. The rear axel connects the two rear wheels with flat washers, more hex bolts, locking rings and tee nuts. A spacer on the back axel helps keep the wheels in place properly.
The handlebars typically come with one grip or cover per handle as well as a locking collar that secures the handlebar to the frame with screws. The tricycle seat attaches to the frame with screws. Sometimes the tricycle seat comes as a single piece, though other times it comes as two parts with a seat that attaches to a rod, allowing for height adjustment.