| Port | Electronic Monitoring System (EMS) | Vital Information Management System (VIMS) |
| 1 | Supply air from the primary air tank. | Supply air from the primary air tank. |
| 2 | Supply air to the secondary air tank and the starter solenoid valve. | Supply air to the secondary air tank and the starter solenoid valve. |
| 3 | Supply air to the parking and secondary brake valve. | Supply air to the parking and secondary brake valve. |
| 4 | Supply air to the torque converter and front brake cooling diverter valve. Supply air to the brake air relay valve. | Supply air to the brake air relay valve. |
| 5 | Supply air to the brake air relay valve for the pulled unit. | Supply air to the torque converter and front brake cooling diverter valve. |
| 6 | Supply air to the brake air relay valve for the Automatic Retarder Control (ARC). | |
| 7 | Supply air to the AUTO lube system. | Supply air to the AUTO lube system. |
| 8 | Supply air to the brake air relay valve for the pulled unit. |
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| Illustration 1 | g00329084 |
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(1) Air tank check valve
(2) Primary air tank (3) Starter relay valve (4) Starter solenoid valve (5) Air starting motor (6) Air compressor with air compressor governor (7) Air dryer with relief valve (8) External air supply (9) Air system pressure protection valve (10) Machine autolube solenoid (11) Window wiper air control valve (12) Secondary air tank (13) Horn valve (A) Brake air pressure sensor | |
Note: The darkened lines show air pressure and the arrows show the direction of flow.
If the pressure in primary air tank (2) is more than
When the starter pinion is engaged, internal passages allow air to flow from starter solenoid valve (4) to the control passage of starter relay valve (3). This air flow causes starter relay valve (3) to open. Air now flows from primary air tank (2) to air starting motor (5). Air starting motor (5) will crank the engine.
When the engine is started and the key switch is released from the start position, starter solenoid valve (4) closes. The flow of air to the starter pinion is stopped. The gear is disengaged by a spring. This also stops air flow to the control passage of starter relay valve (3). Starter relay valve (3) closes. Air starting motor (5) disengages.
The engine drives the air compressor (6). When the engine is started, the air pressure from the air compressor will build up until the air pressure reaches the cut-in pressure of the air compressor governor. Then, air flow from the air compressor will flow to air dryer (7). The air flows from air dryer (7) to air tank check valve (1) and into primary air tank (2). When the pressure in the system is more than
The Parking Brake Air Control Valve Is In The ON Position.
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| Illustration 2 | g00329086 |
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The engine is operating. The parking brake air control valve is in The ON position. The secondary brake air control valve is in the OFF position. (12) Secondary air tank (14) Parking and secondary brake valve (15) Parking brake air control valve (16) Secondary brake air control valve (B) Secondary brake and parking brake pressure switch | |
Note: The darkened lines show air pressure and the arrows show the direction of flow.
Note: The secondary brake and parking brake pressure switch (B) is activated when the parking brake air control valve is in the ON position.
Air pressure from secondary air tank (12) flows to the secondary brake air control valve (16). With secondary brake air control valve (16) in the OFF position, the air pressure flows to parking brake air control valve (15).
When parking brake air control valve (15) is in the ON position, parking brake air control valve (15) stops the flow of air to parking and secondary brake valve (14). The parking brakes are applied by springs and the parking brakes are released by pressure. When the air flow to parking and secondary brake valve (14) is blocked, the oil pressure to the brake housing will be blocked and the springs will apply the parking brakes.
The Secondary Brake Air Control Valve Is In The ON Position.
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| Illustration 3 | g00329087 |
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The engine is operating. The parking brake air control valve is in the OFF position. The secondary brake air control valve is in the ON position. (12) Secondary air tank (14) Parking and secondary brake valve (16) Secondary brake air control valve (B) Secondary brake and parking brake pressure switch | |
Note: The darkened lines show air pressure and the arrows show the direction of flow.
Note: The secondary brake and parking brake pressure switch (B) is activated when the secondary brake air control valve is in the ON position.
Air pressure from the secondary air tank (12) flows to the secondary brake air control valve (16). When the handle for secondary brake air control valve (16) is partially moved to the ON, the result is modulated air control for a slow rate of secondary braking action.
When the handle on secondary brake air control valve (16) is held in the full ON position, air pressure from secondary air tank (12) is blocked at secondary brake air control valve (16). This stops the flow of air to parking and secondary brake valve (14). The parking brakes are applied by springs and the parking brakes are released by pressure. When the air flow to parking and secondary brake valve (14) is blocked, the oil pressure to the brake housing will be blocked and the springs will apply the parking brakes.
When you release the secondary brake control lever, the secondary brake control lever is returned by a spring to the OFF position. When the secondary brake air control valve is in the OFF position, air pressure from secondary air tank (12) flows through secondary brake air control valve (16) to parking and secondary brake valve (14). This air flow will cause parking and secondary brake valve (14) to send oil to the brake housing. The oil pressure will release the parking brakes.
The Service Brake Air Control Valve Is In The ON Position.
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| Illustration 4 | g00329088 |
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The engine is operating. The parking brake air control valve is in the OFF position. The secondary brake air control valve is in the OFF position. The service brake air control valve is in the ON position. (2) Primary air tank (17) Brake air relay valve (pulled unit) (18) Brake air relay valve (19) Brake air relay valve for the Automatic Retarder Control (ARC) (20) Brake master cylinders (pulled unit) (21) Double check valve (22) Torque converter and front brake cooling diverter valve (23) Brake master cylinder (front) (24) Brake master cylinders (rear) (25) Service brake air control valve (B) Secondary brake and parking brake pressure switch (D) Pressure switch for the Traction Control System (TCS) (E) Service brake and retarder pressure switch (F) Stop lights pressure switch | |
Note: The darkened lines show air pressure and the arrows show the direction of air flow.
Note: Pressure switches (D), (E), and (F) are activated when the service brakes are applied or when the retarder is used.
Note: Secondary brake and parking brake pressure switch (B) is deactivated when the parking brake air control valve and the secondary brake air control valve are in the OFF position. The parking brakes are released.
When the pedal on service brake air control valve (25) is pushed down, air pressure from primary air tank (2) flows through service brake air control valve (25) and through double check valve (21). Some of this air pressure flows through double check valve (21) to torque converter and front brake cooling diverter valve (22). Air pressure at torque converter and front brake cooling diverter valve (22) causes oil to flow through the torque converter and front brake cooling oil cooler. The rest of the air pressure will flow to the control passage of brake air relay valve (18) and (17). Air pressure at the control passage of brake air relay valve (18) allows supply air from primary air tank (2) to flow through brake air relay valve (18) to front brake master cylinder (23) and to rear brake master cylinders (24). The double check valve above the brake master cylinders closes the passages to brake air relay valve (19) for the Automatic Retarder Control (ARC). Air pressure at the control passage of brake air relay valve (17) allows supply air from primary air tank (2) to flow through brake air relay valve (17) to master cylinders (20) for the pulled unit. Oil pressure from the brake master cylinders flows to the wheel brakes. The oil pressure activates the brakes.
When the pressure on the pedal of service brake air control valve (25) is released, the flow of air through service brake air control valve (25) is blocked. Air pressure between the control passages of brake air relay valve (18), brake air relay valve (17) and service brake air control valve (25) will flow outward through an exhaust passage in service brake air control valve (25). The air pressure between brake air relay valve (18) and the brake master cylinders flows outward through an exhaust passage in the brake air relay valve (18). The air pressure between brake air relay valve (17) and the brake master cylinders flows outward through an exhaust passage in the brake air relay valve (17). The oil pressure that had applied the brakes returns to the brake master cylinders as the pistons are drawn up by the spring in the brake master cylinders.
When the air pressure to the control passage of diverter valve (22) is blocked, the oil bypasses the torque converter and front brake cooling oil cooler.
The Retarder Air Control Valve Is In The ON Position.
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| Illustration 5 | g00329089 |
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The engine is operating. The parking brake air control valve is in the OFF position. The secondary brake air control valve is in the OFF position. The retarder air control valve is in the ON position. (2) Primary air tank (17) Brake air relay valve (pulled unit) (18) Brake air relay valve (19) Brake air relay valve for the Automatic Retarder Control (ARC) (20) Brake master cylinders (pulled unit) (21) Double check valve (22) Torque converter and front brake cooling diverter valve (23) Brake master cylinder (front) (24) Brake master cylinders (rear) (26) Retarder air control valve (B) Secondary brake and parking brake pressure switch (D) Pressure switch for the Traction Control System (TCS) (E) Service brake and retarder pressure switch (F) Stop lights pressure switch | |
Note: The darkened lines show air pressure and the arrows show the direction of flow.
Note: Pressure switches (D), (E), and (F) are activated when the retarder is applied.
Note: The secondary brake and parking brake pressure switch (B) is deactivated when the parking brake air control valve and the secondary brake air control valve are in the OFF position. The parking brakes are released.
When the lever for retarder air control valve (26) is in the ON position, air pressure from primary air tank (2) flows through retarder air control valve (26) and through double check valve (21). Some of this air flows through double check valve (21) to torque converter and front brake cooling diverter valve (22). Air pressure at torque converter and front brake cooling diverter valve (22) causes oil to flow through the torque converter and front brake cooling oil cooler. The rest of the air pressure flows to the control passage of brake air relay valve (18) and (17). Air pressure at the control passage of brake air relay valve (18) allows supply air from primary air tank (2) to flow through brake air relay valve (18) to front brake master cylinder (23) and to rear brake master cylinders (24). The double check valve above the brake master cylinders closes the passages to brake air relay valve (19) for the Automatic Retarder Control (ARC). Air pressure at the control passage of brake air relay valve (17) allows supply air from primary air tank (2) to flow through brake air relay valve (17) to master cylinders (20) for the pulled unit. Oil pressure from the brake master cylinders flows to the wheel brakes. The oil pressure activates the brakes. The engine speed must be kept between 1500 rpm and 1900 rpm in order to keep the oil to the brakes cool.
| NOTICE |
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Do not increase speed while the retarder is ON. |
The pressure of the air to the brake master cylinders is determined by the position of the lever for the retarder air control valve. When the lever is completely pulled down, the maximum amount of retarding is achieved.
When retarder air control valve (26) is in the OFF position, the flow of air through retarder air control valve (26) is blocked. Air pressure between the control passages of brake air relay valve (18), brake air relay valve (17) and retarder air control valve (26) will flow outward through an exhaust passage in retarder air control valve (26). The air pressure between brake air relay valve (18) and the brake master cylinders flows outward through an exhaust passage in the brake air relay valve (18). The air pressure between brake air relay valve (17) and the brake master cylinders flows outward through an exhaust passage in the brake air relay valve (17). The oil pressure that had applied the brakes returns to the brake master cylinders as the pistons are drawn up by the spring in the brake master cylinders.
When the air pressure to the control passage of torque converter and front brake cooling diverter valve (22) is blocked, the oil bypasses the torque converter and front brake cooling oil cooler.
Automatic Retarder Control (ARC) Is In The ON Position
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| Illustration 6 | g00329092 |
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The engine is operating. The parking brake air control valve is in the OFF position. The secondary brake air control valve is in the OFF position. The Automatic Retarder Control Is ON. (2) Primary air tank (17) Brake air relay valve (pulled unit) (18) Brake air relay valve (19) Brake air relay valve for the Automatic Retarder Control (ARC) (20) Brake master cylinders (pulled unit) (21) Double check valve (22) Torque Converter and front brake cooling diverter valve (23) Brake master cylinder (front) (24) Brake master cylinders (rear) (27) Automatic Retarder Control valve (B) Secondary brake and parking brake switch (D) Pressure switch for the Traction Control System (E) Service brake and retarder pressure switch (F) Stop lights pressure switch (G) Automatic Retarder Control pressure switch | |
Note: The darkened lines show air pressure and the arrows show the direction of flow.
Note: Pressure switches (D), (E), and (F) are activated when the service brake is applied or when the retarder is applied.
Note: Pressure switch (G) is activated when air is supplied by the Automatic Retarder Control (ARC) to the brakes.
Note: Secondary brake and parking brake pressure switch (B) is deactivated when the parking brake air control valve and the secondary brake air control valve are in the OFF position. The parking brakes are released.
When Automatic Retarder Control (ARC) is ON, the retarder will be used to keep the engine speed constant. Air pressure from primary air tank (2) flows through Automatic Retarder Control valve (27). Some of this air flows through double check valve (21). This air pressure flows to torque converter and front brake cooling diverter valve (22). Air pressure at torque converter and front brake cooling diverter valve (22) causes oil to flow through the torque converter and front brake cooling oil cooler. The rest of the air pressure flows to the control passage of brake air relay valve (19) and (17). Air relay valve (19) allows supply air from primary air tank (2) to flow through brake air relay valve (19) to front brake master cylinder (23) and to rear brake master cylinders (24). The double check valve above the brake master cylinders closes the passages to brake air relay valve (18) for the service brakes and for the manual retarder. Air relay valve (17) allows supply air from primary air tank (2) to flow through brake air relay valve (17) to master cylinders (20) for the pulled unit. Oil pressure from the brake master cylinders flows to the wheel brakes. The oil pressure activates the brakes.
| NOTICE |
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Do not increase speed while the retarder is ON. |
The pressure of the air to the brake master cylinders is determined by a proportional solenoid on Automatic Retarder Control valve (27).
When retarding is not needed, the flow of air through Automatic Retarder Control valve (27) is blocked. Air pressure between the control passages of brake air relay valve (19), brake air relay valve (17), and Automatic Retarder Control valve (27) will flow outward through an exhaust passage in Automatic Retarder Control valve (27). The air pressure between brake air relay valve (19) and the brake master cylinders flows outward through an exhaust passage in the brake air relay valve (19). The air pressure between brake air relay valve (17) and the brake master cylinders flows outward through an exhaust passage in the brake air relay valve (17). The oil pressure that had applied the brakes returns to the brake master cylinders as the pistons are drawn up by the spring in the brake master cylinders.
When the air pressure to the control passage of torque converter and front brake cooling diverter valve (22) is blocked, the oil bypasses the torque converter and front brake cooling oil cooler.
The Pulled Unit Air Control Valve Is In The ON Position.
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| Illustration 7 | g00329094 |
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The engine is operating. The parking brake air control valve is in the OFF position. The secondary brake air control valve is in the OFF position. The pulled unit air control valve is in the ON position. (2) Primary air tank (17) Brake air relay valve (20) Brake master cylinders (pulled unit) (21) Double check valve (28) Pulled unit air control valve | |
When the lever for pulled unit air control valve (28) is in the ON position, air pressure from primary air tank (2) flows through pulled unit air control valve (28) and through double check valve (21). The air pressure flows to the control passage of the brake air relay valve (17). Air pressure at the control passage of brake air relay valve (17) allows supply air from primary air tank (2) to flow through brake air relay valve (17) to master cylinders (20). Oil pressure from the brake master cylinders flows to the wheel brakes on the pulled unit. The oil pressure activates the brakes.
The pressure of the air to the brake master cylinders is determined by the position of the lever for the pulled unit air control valve. When the lever is completely pulled down, the maximum amount of braking is achieved.
When pulled unit air control valve (28) is in the OFF position, the flow of air through pulled unit air control valve (28) is blocked. Air pressure between the control passages of brake air relay valve (17) and pulled unit air control valve (28) flows outward through an exhaust passage in pulled unit air control valve (28). The air pressure between brake air relay valve (17) and the brake master cylinders flows outward through an exhaust passage in the brake air relay valve (17). The oil pressure that had applied the brakes returns to the brake master cylinders as the pistons are drawn up by the spring in the brake master cylinders.