776D, 777D and 777D HAA Off-Highway Truck/Tractors Air System and Brakes Caterpillar

(1) Air tank for the air start (attachment)

(2) Relief valve

(3) Relay valve for the air start (attachment)

(4) Air starting motor (attachment)

(5) Check valve

(6) Service brake and retarder air tanks

(7) Drain valve

(8) Air compressor governor

(9) Air compressor

(10) Air dryer

(11) Pressure gauge for the air start (attachment)

(12) One-way check valve for the air start (attachment)

(13) Solenoid valve for the air start (attachment)

(14) Inversion valve for the exhaust diverter (attachment)

(15) Cylinder for the exhaust diverter (attachment)

(16) Solenoid valve for the exhaust diverter (attachment)

(17) Regulator for the exhaust diverter (attachment)

(18) Brake air relay valve

(19) Brake air relay valve

(20) Brake air relay valve for the Automatic Retarder Control (ARC) (attachment)

(21) Pressure protection valve for the brake air system

(22) Double check valve

(23) Brake valve

(24) Parking and secondary brake valve

(25) Inverter valve (front brake)

(26) Double check valve

(27) Double check valves

(28) Air/hydraulic cylinder (front)

(29) Air/hydraulic cylinder (rear)

(30) Diverter valve

(31) Front brake air control valve

(32) Air ratio valve (front brake)

(33) This is the stop lamp air pressure switch. This pressure switch is normally open. This pressure switch is closed by air pressure when the service brakes, the retarder, or the Automatic Retarder Control (ARC) are applied. When this pressure switch is closed, this pressure switch activates the stop lamp.

(34) This is the pressure switch for the secondary and parking brakes. This pressure switch is normally open. The pressure switch is closed by air pressure when the parking brakes or the secondary brakes are released. When this pressure switch is open, this pressure switch signals the Power Train Electronic Control Module (Power Train ECM) to allow rapid shifts.

(35) This is the brake air pressure sensor. The brake air pressure sensor monitors brake air pressure. The operator will be alerted to a condition of low air pressure.

(36) Air system pressure protection valve

(37) Retarder air control valve

(38) Service brake air control valve

(39) Remove these lines when the Automatic Retarder Control (ARC) is installed. Also remove pressure switch (13).

(40) Secondary brake air control valve

(41) This is the pressure switch for the service brake and the retarder. This pressure switch is normally closed. This pressure switch is opened by air pressure when the service brakes, the retarder, or the Automatic Retarder Control (ARC) are applied. When this pressure switch is open, the pressure switch signals the Power Train ECM in order to allow the transmission to perform rapid shifts. The Power Train ECM also indicates that higher engine rpm is needed for upshifts or for downshifts of the transmission when this pressure switch is open.

(42) This is the Automatic Retarder Control pressure switch. This pressure switch is normally closed. This pressure switch is opened by air pressure in order to indicate that the Automatic Retarder Control (ARC) is operating. The pressure switch verifies that air pressure is being provided through the Automatic Retarder Control valve.

(43) This is the manual retarder pressure switch. This pressure switch is normally open. This pressure switch is closed when the retarder air control valve is applied. This switch operates the indicator in the cab.

(44) Parking brake air control valve

(45) Check valve

(46) Automatic Retarder Control (ARC) valve (attachment)

(47) Retarder air control valve for the pulled unit

(48) Air horn

(49) Horn valve

(50) Window wiper valve

(51) Window wiper motor

(52) Air suspension seat

(53) Window washer reservoir

(54) Secondary and parking brake air tank

(A) Standard air lines

(B) Air lines for attachments

(C) Signal line for the pulled unit

(37) Retarder air control valve

(33) Stop lamp air pressure switch

(41) Service brake and retarder pressure switch

(45) Check valve

(32) Air ratio valve (front brake)

(34) Pressure switch for the secondary and parking brakes

(35) Brake air pressure sensor

(42) Automatic Retarder Control (ARC) pressure switch (attachment)

(43) Manual retarder pressure switch

(8) Air compressor governor

(18) Brake air relay valve

(19) Brake air relay valve

(20) Brake air relay valve for the Automatic Retarder Control (ARC)

(21) Pressure protection valve for the brake air system

(22) Double check valve

(23) Brake valve

(24) Parking and secondary brake valve

(25) Inverter valve (front brake)

(26) Double check valve

(27) Double check valve

(2) Relief valve

(6) Service brake and retarder air tanks

(28) Air/hydraulic cylinder (front)