WÄRTSILÄ Vasa R22, Instruction Manual

Page: 166 / 297

14.1.2 Function
The movement of the valve tappets is governed by the cam profile.
The valve tappets transfer the movement through push rods to
the rocker arms. The rocker arms operate the inlet and exhaust
valves through a yoke.
The bracket for the rocker arms is made of nodular cast iron and
is fastened to the cylinder head by four screws. The steel journal
is press fitted in the bracket.
The rocker arms act on the valve yokes, which are guided by an
eccentrically placed yoke pin. To compensate for heat expansion
a clearance must exist between the rocker arm and yoke. All
adjustments are made on a cold engine, and this work procedure
is explained in chapter 12. Each valve yoke operates two valves
simultaneously.
The valve mechanism is lubricated from the main flow with pipe
connections. All flows in the cylinder head are through drillings.
Oil to the valve yokes passes through the rocker arm bracket. Oil
which is passed to the yoke tappet is lubricating the tappet and
by splashing through the bores also lubricates the valve rotators.
Oil is returned to the crankcase in a free flow through the
protecting sleeves for the push rod.
14.1.3 Maintenance of valve mechanism
Normally, the valve mechanism needs no maintenance, but in-
spection and adjustment of the components and check for wear
should be done at intervals according to section 04. Data are
stated in chapter 06. The valve clearance adjustments are de-
scribed in section 12.4.
Components, which have been working together for a long time
and thus have worn somewhat in relation to each other should be
installed in the same place to avoid unnecessary wear.
14.1.3.1 Dismantling and assembling the rocker arm
bearing bracket
1 Remove the covers of the valve mechanism and cam-
shaft from the cylinder concerned.
2 Turn the crankshaft to a position where the valve tappet
rollers of the valves and the injection pump are on the base
circle of the cam.
3 Remove the rocker arm bearing bracket (13) from the
cylinder head by loosening the nuts (1), see Fig 14-1.
4 The rocker arms can be dismantled by removing the lock-
ing ring (2) with the pliers 843001.
5 When cleaning the rocker arm bearing bracket and the
bearing pin, pay special attention to the oil holes.
14 Valve Mechanism and Camshaft 22-9601
14 - 2 VASA 22