Page 50
DESCRIPTION AND OPERATION
49
Figure 49 — Exhaust Yoke, Actuating Pin and Valve
Stem Cap
앫 Spring-Loaded Push Rods — To prevent
excessive valve “clatter” created by the
increased exhaust valve lash, and also keep
the lifter roller in contact with the cam lobe,
spring-loaded push rods are used. These
push rod assemblies contain a spring on the
rocker arm end. The spring allows the push
rod to “expand” during the “valve closed” (or
cam sub-base circle) cycle, thus eliminating
excessive lash in the valve train and keeping
the lifter roller in contact with the cam lobe.
During the “valve opening” cycle, the spring
compresses as the lifter roller travels up the
ramp of the cam lobe. The push rod
becomes a “solid assembly” when the
internal stops of the upper and lower push
rod seats make contact. When the push rod
is “solid,” the upward force of the valve lifter
is transmitted to the rocker arm.
50
Figure 50 — Spring-Loaded Push Rod Assembly
앫 Cylinder Head Cover — The MACK
PowerLeash™ engine brake is completely
integrated with the valve train; therefore,
cylinder head cover spacers are not
necessary. The cylinder head cover contains
an electrical pass-through connection that
connects the engine brake solenoid wire to
the engine wiring harness.
51
Figure 51 — Cylinder Head Cover with Electrical
Pass-Through Connection
1. Valve Yoke, Exhaust
2. Actuating Pin
3. Cap, Inboard Exhaust
Valve Stem Tip
1. Push Rod Spring
1. Electrical Pass-Through Connector
5-111.bk Page 50 Monday, July 10, 2006 2:26 PM
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