This is the work of a Genius, or a Madman.
(another post about brakes!?)
There is alot going on with the left rear of this pedalcar. First, the arm that goes on the outside of the wheel comes off with two bolts to access the tire. The brake caliper is mounted to that bar, and the handle shares the shaft that has the transfer axle sprocket, that handle also has the twist-shift for the derailer. Crazy, works really well. This car is one wheel drive, and one wheel brake.