2.1 DESCRIPTION AND OPERATION OF CAMSHAFT AND ROCKER SHAFT/ENGINE BRAKE ASSEMBLY AND RELATED PARTS 2.1.1 Engine Braking The engine uses an integral engine brake. Engine braking is controlled electronically by the engine control system with an electric solenoid. When activated, the solenoid allows oil pressure to activate a piston on the exhaust rocker arm. Engine braking is accomplished with a single exhaust valve in each cylinder. The exhaust camshaft uses a separate engine brake-only lobe that allows for double valve activation for high efficiency braking.
The exhaust valve is first operated toward the completion of the intake stroke, closed during the compression stroke and opened a second time when the compression stroke is completed. The engine brake system is enabled using the following components: For EPA07 engines: Engine brake solenoid valve in front of engine applies low engine braking. Engine brake solenoid valve in rear of engine applies medium engine braking. For high, both front and rear solenoids are activated. Six exhaust rocker arms with actuator pistons. Six brake rocker arms which are actuated by the brake cam lobes. Exhaust camshaft has one brake cam lobe per cylinder. All information subject to change without notice.
2-4 DDC-SVC-MAN-0081 2010 Copyright © 2010 DETROIT DIESEL CORPORATION