Cooling System - Perkins 1104D NH1 Systems Operation Testing And Adjusting

14
Systems Operation Section
Valve System Components
Illustration 15
Valve system components
(1) Bridge
(2) Rocker arm
(3) Pushrod
(4) Lifter
(5) Spring
(6) Valve
The valve system components control the flow of
inlet air into the cylinders during engine operation.
The valve system components also control the flow
of exhaust gases out of the cylinders during engine
operation.
The crankshaft gear drives the camshaft gear through
an idler gear. The camshaft must be timed to the
crankshaft in order to get the correct relation between
the piston movement and the valve movement.
The camshaft has two camshaft lobes for each
cylinder. The lobes operate either a pair of inlet
valves or a pair of exhaust valves. As the camshaft
turns, lobes on the camshaft cause the lifter (4)
to move the pushrod (3) up and down. Upward
movement of the pushrod against rocker arm (2)
results in a downward movement that acts on the
valve bridge (1). This action opens a pair of valves
(6) which compresses the valve springs (5). When
the camshaft has rotated to the peak of the lobe, the
valves are fully open. When the camshaft rotates
further, the two valve springs (5) under compression
start to expand. The valve stems are under tension of
the springs. The stems are pushed upward in order
to maintain contact with the valve bridge (1). The
continued rotation of the camshaft causes the rocker
arm (2), the pushrods (3)and the lifters (4) to move
downward until the lifter reaches the bottom of the
lobe. The valves (6) are now closed. The cycle is
repeated for all the valves on each cylinder.
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Cooling System

Introduction (Cooling System)
The cooling system has the following components:
•
Radiator
•
Water pump
•
Cylinder block
•
Oil cooler
• Cylinder head
•
Water temperature regulator (thermostat)
RENR7967
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