Page 44
DESCRIPTION AND OPERATION
41
Figure 41 — MACK Engine Brake Cut-Away View
Use of the MACK PowerLeash™ engine brake is
controlled by a dash-mounted switch that has two
power positions: a LOW position to apply
approximately one-half (three cylinders) of the
engine brake retarding capability, and a HIGH
position to apply full retarding power (all six
cylinders). The choice of LOW or HIGH operation
depends on the driving situation, vehicle load and
downhill percent grade. When the switch is in the
OFF position, the engine brake is deactivated.
42
Figure 42 — Dash-Mounted Engine Brake Switch
Engine brake operation is controlled by the
V-MAC
®
system. A constant 12 volts at a low
current is supplied to the engine brake solenoids
at all times. When the dashboard switch is turned
ON and no fuel is requested (0% throttle), the
engine electronic control unit (EECU) increases
the current to the engine brake solenoids,
causing the solenoid coils to energize.
When the engine brake is “enabled” (switch in
either LOW or HIGH position), the V-MAC
electronic control system commands engine
brake power (engine brake “active”) only when
the following conditions are true:
앫
The foot-operated engine accelerator pedal
is not depressed.
앫
The clutch pedal is not depressed (manual
shift transmissions only).
앫
The engine speed is at least 900 rpm.
앫
Coolant temperature is above 125
°
F (52
°
C).
Engine stalling and potential engine damage can
occur if the engine brake is operated at cold
engine oil temperatures. The V-MAC engine
control system includes a feature that prevents
the engine brake from being activated until the
engine coolant temperature reaches at least
125
°
F (52
°
C). The engine brake will not function
until sufficient engine warm-up time has elapsed,
regardless of the dashboard engine brake switch
setting.
1. Spring-Loaded Push Rod
2. Engine Brake Hydraulic
Actuator
3. Valve Actuating Pin
4. Valve Stem Tip Cap
5. Camshaft with Engine
Brake Profile
5-111.bk Page 44 Monday, July 10, 2006 2:26 PM
Содержание ASET AC
Страница 6: ...TABLE OF CONTENTS Page iii TABLE OF CONTENTS 5 111 bk Page iii Monday July 10 2006 2 26 PM...
Страница 14: ...INTRODUCTION Page 1 INTRODUCTION 5 111 bk Page 1 Monday July 10 2006 2 26 PM...
Страница 23: ...Page 10 NOTES 5 111 bk Page 10 Monday July 10 2006 2 26 PM...
Страница 24: ...VISUAL IDENTIFICATION Page 11 VISUAL IDENTIFICATION 5 111 bk Page 11 Monday July 10 2006 2 26 PM...
Страница 28: ...DESCRIPTION AND OPERATION Page 15 DESCRIPTION AND OPERATION 5 111 bk Page 15 Monday July 10 2006 2 26 PM...
Страница 96: ...COMPONENT LOCATOR Page 83 COMPONENT LOCATOR 5 111 bk Page 83 Monday July 10 2006 2 26 PM...
Страница 99: ...Page 86 NOTES 5 111 bk Page 86 Monday July 10 2006 2 26 PM...
Страница 100: ...TROUBLESHOOTING Page 87 TROUBLESHOOTING 5 111 bk Page 87 Monday July 10 2006 2 26 PM...
Страница 140: ...MAINTENANCE Page 127 MAINTENANCE 5 111 bk Page 127 Monday July 10 2006 2 26 PM...
Страница 153: ...Page 140 NOTES 5 111 bk Page 140 Monday July 10 2006 2 26 PM...
Страница 154: ...REPAIR INSTRUCTIONS PART 1 Page 141 REPAIR INSTRUCTIONS PART 1 5 111 bk Page 141 Monday July 10 2006 2 26 PM...
Страница 383: ...Page 370 NOTES 5 111 bk Page 370 Monday July 10 2006 2 26 PM...
Страница 384: ...REPAIR INSTRUCTIONS PART 2 Page 371 REPAIR INSTRUCTIONS PART 2 5 111 bk Page 371 Monday July 10 2006 2 26 PM...
Страница 454: ...REPAIR INSTRUCTIONS PART 3 Page 441 REPAIR INSTRUCTIONS PART 3 5 111 bk Page 441 Monday July 10 2006 2 26 PM...
Страница 479: ...Page 466 NOTES 5 111 bk Page 466 Monday July 10 2006 2 26 PM...
Страница 480: ...SPECIFICATIONS Page 467 SPECIFICATIONS 5 111 bk Page 467 Monday July 10 2006 2 26 PM...
Страница 505: ...Page 492 NOTES 5 111 bk Page 492 Monday July 10 2006 2 26 PM...
Страница 506: ...SCHEMATIC ROUTING DIAGRAMS Page 493 SCHEMATIC ROUTING DIAGRAMS 5 111 bk Page 493 Monday July 10 2006 2 26 PM...
Страница 513: ...Page 500 NOTES 5 111 bk Page 500 Monday July 10 2006 2 26 PM...
Страница 514: ...SPECIAL TOOLS EQUIPMENT Page 501 SPECIAL TOOLS EQUIPMENT 5 111 bk Page 501 Monday July 10 2006 2 26 PM...
Страница 519: ...Page 506 NOTES 5 111 bk Page 506 Monday July 10 2006 2 26 PM...
Страница 520: ...APPENDIX Page 507 APPENDIX 5 111 bk Page 507 Monday July 10 2006 2 26 PM...
Страница 528: ...INDEX Page 515 INDEX Index fm Page 515 Monday July 10 2006 2 48 PM...
Страница 535: ...Page 522 NOTES Index fm Page 522 Monday July 10 2006 2 48 PM...