56 ENGINE SYSTEMS
Operation o f Diamond Logic® Engine Brake in
Braking Mode
Figure 49 Brake shutoff valve and brake actuator– ON
1. High-pressure oil rail
2. High-pressure oil flow to brake
oil gallery
3. Brake oil gallery
4. Brake shutoff valve assembly
5. Brake actuator piston assembly
6. Exhaust valve bridge
7. Valve lash (actuator deployed)
8. Normal oil seepage
9. Oil inlet
The ECM monitors the following criteria to make sure
certain conditions are met.
• ABS (inactive)
• RPM (greater than 1200)
• APS (less than 5%)
• Idle validation
• EOT (greater than or equal to 60 °C [140 °C])
• Operator input switches (On/Off) (power selection
– Low, Med, High)
If On is selected, and the above criteria is met, the
engine brake will activate.
When the engine brake is activated, the ECM provides
the power to activate the brake shutoff valve to allow
oil from the injector oil gallery to fl ow to the brake oil
gallery. High oil pressure activates the brake actuator
pistons to open the exhaust valves.
During an ABS event, the engine brake is deactivated.
The engine brake is activated once the ABS event is
over.
EGES-265-2
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© 2009 Navistar, Inc.
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