56 1 ENGINE SYSTEMS
Operation of Diamond Logic® Engine Brake in
Braking Mode
Figure 48 Brake shut-off valve and brake actuator– ON
1. High-pressure oil rail
2. High-pressure oil flow to brake
oil gallery
3. Brak e oil gallery
4. Brake shut-off valve assembly
5. Brake actuator piston assembly
6. Exhaust valve b ridge
7. Valve lash (actuator deploye d)
8. Normal oil s eepage
9. Oil inlet
The E CM mo nitors the following criteria to make sure
certain conditions are m et.
• ABS (inactive)
• RPM (greater than 1200 )
• APS (less than 5%)
• Idle validation
• EOT (greater than or equal to 60 °C [140 °C])
• Operato r input switches (On/Off) (power selection
– Low, Med, High)
If On is selecte d, and the preced ing criteria is met, the
engine brake will activate.
When the engine brake is activated, the ECM provides
the po wer to activate the brake shut-off v alve to allow
oil from the injector oil gallery to flow to the brake oil
gallery. High oil pressure activates the brake actuator
pistons to open the ex haust valves.
During an ABS event, the engine brake is deactivated.
The e ngine brake is activated once the ABS event is
over.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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