TM10-3930-660-20 1-19. STEERING AND BRAKE SYSTEMS STEERING CYLINDERS. Two cylinders are mounted at each axle and controlled by the steering  wheel. STEERING CONTROL VALVE. Connected directly to the steering wheel and located behind the instrument access panel. Controls the steering function. STEER  SELECT  VALVE. Externally mounted under the cab. Allows the selection of two wheel, four wheel, or crab steering. BRAKE CONTROL  VALVE. Located under the cab. Provides a priority flow to the brake system. Excess flow is directed by the priority valve to the frame tilt system. SERVICE  BRAKES. Dry disk type brakes are mounted on all four wheels. The service brakes are hydraulically actuated. An accumulator in the braking system provides a limited number of stops without engine power. PARKING  BRAKES. Mechanically actuated drum brakes are mounted on the front axle input  shaft. A lever in the operator’s station engages and disengages the parking brake. 1-12