PURPOSE: To simplify the structure and operation while to perform braking reliably in neutral state of speed changer, by constructing such that the side brake will function as parking brake.

CONSTITUTION: A link mechanism is provided between an arm 30 or an outer pipe supporting member for a wire coupling between side clutch levers 12, 13, side clutch and side brake and a travel clutch lever 11 to be interlocked with such motion as to further rotate said lever 11 from the declutch position thus to rotate the outer pipe supporting member over the fulcrum and to function side brake. Consequently, extended rotary motion of travel clutch lever will produce side brake to serve as parking brake or imergency brake. While since the side brake will also brake the shaft in the down stream from the speed changer, brake will function reliably even under neutral position.