Page 46
DESCRIPTION AND OPERATION
MACK PowerLeash™ Engine Brake
Components
The MACK PowerLeash™ engine brake consists
of the following primary components:
앫 Camshaft — The engine brake camshaft
has a 0.125-inch engine brake lift profile
(dimension from sub-base to base circle) on
the exhaust lobes.
The 0.125-inch brake-bump camshaft is
mandatory for the PowerLeash™ engine
brake.
43
Figure 43 — MACK Engine Brake Exhaust Lobe Profile
앫 Exhaust Rocker Arm/Hydraulic
Actuator — The exhaust rocker arm
incorporates a hydraulic actuator that fills
with oil and hydraulically locks to remove the
clearance between the actuator plunger and
the inboard exhaust valve. With clearance
between the actuator and the actuating pin
removed, the slight movement of the push
rod created when the camshaft rotates to the
area of transition from sub-base to base
circle, pushes the rocker arm and opens the
inboard exhaust valve before the piston
reaches top dead center of the compression
stroke.
44
Figure 44 — MACK Engine Brake Exhaust Rocker Arm
with Hydraulic Actuator
1. Valve Lash Adjusting
Screw
2. Engine Brake Hydraulic
Actuator
3. Constant (Lubrication) Oil
Passage
4. Engine Brake Lash
Adjusting Screw — This
is NOT the valve lash
adjusting screw.
5. Constant (Lubrication)
Oil Passage
6. Control Oil Passage
7. Constant (Lubrication)
Oil Passage
5-111.bk Page 46 Monday, July 10, 2006 2:26 PM
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