B R A K E S Y S T E M
3-7
Engine Brake
Exhaust Brakes cannot be used on ISB engines with common rail fuel systems. The variable geometry
turbocharger (VGT) takes the place of the exhaust brake and requires no maintenance. The VGT works in
conjunction with the engine and transmission to provide an integrated braking system used to help slow the
vehicle. This braking power is achieved by modulating the turbo sliding nozzle ring to restrict the flow of
exhaust gases from the engine, which in turn creates a high back pressure on the engine. The high back
pressure creates a high level of resistance to the motion of the pistons within the engine and this resistance is
used to reduce engine speed and thus vehicle speed. The engine brake feature will only function when the
driver turns the exhaust brake switch to the on position. Once the switch is in the on position and the vehicle is
moving faster than 8 k/h (5 MPH); the exhaust brake will operate when the driver removes pressure from the
throttle pedal allowing the engine to see 0% throttle and 0% fuel delivery and taps the service brake. Engine
braking is most effective when the engine RPM is higher. The automatic transmission has been programmed to
downshift more aggressively when the exhaust brake is enabled to increase brake performance.
As mentioned above:
The engine brake is activated when the following conditions are satisfied:
1.
The engine brake switch is in the “ON” position
2.
The accelerator pedal is released
3.
The vehicle is moving faster than 8 k/h (5 mph)
4.
The service brake is depressed momentarily
Summary of Contents for ALLEGRO BREEZE
Page 6: ...T I R E C A R E 1 1 TIRE CARE Chapter 1 ...
Page 10: ......
Page 14: ...A L L I S O N T R A N S M I S S I O N O P E R A T I O N 2 4 ...
Page 15: ......
Page 16: ...B R A K E S Y S T E M 3 1 Brake System Chapter 3 ...
Page 19: ...B R A K E S Y S T E M 3 4 Compressed Air System ...
Page 20: ...B R A K E S Y S T E M 3 5 ...
Page 23: ......
Page 38: ......
Page 39: ...S C H E D U L E D M A I N T E N A N C E 5 1 Scheduled Maintenance Chapter 5 ...
Page 53: ...S C H E D U L E D M A I N T E N A N C E 5 15 ...
Page 54: ......
Page 55: ...P R E T R I P I N S P E C T I O N 6 1 Pre Trip Inspection Chapter 6 ...
Page 58: ......
Page 59: ...I N S T R U M E N T S C O N T R O L S 5 1 Instruments Controls Chapter 5 ...
Page 68: ......
Page 69: ...A I R S U P P L Y 8 1 Air Supply Chapter 8 ...
Page 71: ...A I R S U P P L Y 8 3 ...
Page 72: ......
Page 73: ...W A R R A N T Y 9 1 Warranty Chapter 9 ...
Page 75: ...W A R R A N T Y 9 3 ...