TM 10-3930-659-34 1-12. SERVICE BRAKE SYSTEM (Con’t). e. Wheel Brakes. The wheel brakes are a wet disc-type brake arrangement. When hydraulic pressure is routed to the  brake  pistons  via  the  brake  valves,  the  pistons  move  outward  and  compress  the  brake  disc  against  the  stationary backing plate, slowing or stopping the forklift truck. f. Parking Brake. The parking brake mechanism is mounted on the transmission. The actuating pedal and release handle are located in the operator’s cab. A red light flashes and an audible alarm sounds if the parking brake is applied while the engine is running and the transmission is in gear; a yellow light flashes if the parking brake is applied and the transmission is in N (Neutral). 1-13. STEERING SYSTEM. a.  General.  The  steering  system  is  a  full-time  power  assist-type.  A  secondary  electrically  operated  pump  is included  to  provide  emergency  steering.  The  other  components  of  the  system  are  the  steering  valve,  cylinders,  and crossover relief valve. b.  Main  Hydraulic  Pump.  The  main  hydraulic  pump  supplies  the  steering  system  only.  It  is  mounted  on  the transmission and is driven by the engine. It is a fixed displacement, external gear-type pump. c.  Secondary  Steering  Pump.  The  secondary  steering  pump  is  electrically  powered.  It  operates  when  the  key switch is in the ON position and low steering system pressure is sensed by a pressure switch. 1-14. FORKLIFT HYDRAULIC SYSTEM. a. General. The forklift hydraulic system includes the service brake system, steering system, hydraulic reservoir, and  attachment  components.  The  service  brake  and  steering  systems  are  described  in  paragraphs  1-12  and  1-13.  The attachment components consist of the forklift control valve, oil cooler, and two oil filters. b. Hydraulic Reservoir. The hydraulic reservoir is a 20 gl (76 1) tank, located just ahead of the engine. c. Forklift Control Valve. The forklift control valve controls the operation of the forks for boom raise and lower, tilt, and spacing. d. Oil Cooler. The oil cooler is mounted alongside the engine radiator and cools both the hydraulic system oil and the transmission oil in separate sections. e. Oil Filters. There are two filters that are contained in the hydraulic system. The hydraulic reservoir suction filter, located  at  the  hydraulic  reservoir,  filters  larger  contaminates  and  uses  a  washable  screen.  The  hydraulic  oil  return  filter contains a bypass valve and a replaceable cartridge-type filter. It filters contaminants entering the hydraulic reservoir from the components of the system. Should the hydraulic oil return filter become clogged, a hydraulic oil filter restriction switch will light and the bypass valve will open. 1-15. ELECTRICAL SYSTEM. a.  Charging  System.  The  24-volt  charging  system  consists  of  the  batteries  and  an  alternator  with  an  internal regulator. b. Lighting System. The lighting system is protected by a circuit breaker and contains two front driving lights, an adjustable  floodlight,  two  rear  cab  mounted  worklights,  front  and  rear  turn  signals,  taillights,  a  domelight,  front  and  rear blackout lights, and instrument panel lights. 1-9