WÄRTSILÄ PAAE051728, Инструкция по эксплуатации

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14.1.2 Function
The movement of the valve tappets (9) is governed by the cam
profile on the camshaft. The valve tappets transfer the movement
through push rods (6) to the rocker arms (2). The rocker arms
operate the inlet and exhaust valves through a yoke (4).
The bracket (5) for the rocker arms is fastened to the cylinder
head by three long screws (1). The shaft is positioned by one fixing
screw (1) in the bracket. The positioning of the shaft is essential
for the oil supply.
The adjusting screws in the rocker arms act on the valve yokes,
which are guided by an yoke pin. To compensate for heat expan-
sion a clearance, valve clearance, must exist in the valve mecha-
nism. All adjustments are made on a cold engine, and this
adjusting procedure is explained in chapter 12. Each valve yoke
operates two valves simultaneously, one for inlet and one for
exhaust.
The valve mechanism is lubricated from the main flow through
oil drilling’s. Oil to the valve yokes (4) and to push rod upper bull
joint passes through the rocker arm bracket (5) in an intermittent
flow controlled by the drilling’s in the rocker arm and shaft. The
rocker arm is in position to supply oil only when it is in the “open
valve” position. When the rocker arm is in "valve closed" position
is the surface between rocker arm and shaft lubricated. Oil which
is passed to the yoke is lubricating the yoke guidance and through
the drilling’s also lubricates the valve rotators. Oil is returned to
the crankcase in a free flow through the protecting pipes (7) for
the push rod.
Note! The intermittent oil flow will cause an optimized oil flow to the
valve mechanism. To completely check the oil flow to a
cylinder head, the engine must be cranked during prelubrica-
tion.
14.1.3 Maintenance of valve mechanism
Normally, the valve mechanism need no maintenance, but inspec-
tion of the components and check for wear should be made at
intervals stated in chapter 04. See chapter 06. for adjustments
and wear limits. If the valve mechanism is dismantled, the
components should be marked and later assembled in the same
position and cylinder as before to avoid unnecessary wear.
14.1.3.1 Dismantling of valve mechanism
1 Open the upper cover for the cylinder head and remove
the camshaft cover from the cylinder concerned.
2 Turn the crankshaft to a position where the valve tappet
rollers of the valves are on the base circle of the cam.
14 Valve Mechanism and Camshaft 32-200106
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