Subaru SVX 1992 Manual page 143

2-3 [M3001
ENGINE
3 . Belt Tension Adjuster
The belt tension adjuster provides a constant value of
tension for the timing belt . Proper belt tension is main-
tained using a rod to push the tension pulley. The
location of the tensioner pulley shaft center is offset in
relation to the center of the pulley's outside diameter .
The tensioner adjuster rod provides a rotary movement
for the tensioner pulley by both tension of the spring
housed in the adjuster .
(1) Action when the belt is loose
When the belt is loose, the force between the arm and
rod is unbalanced so that the rod is pushed out to the
left by the force of the main spring . Then, the oil
pressure in the reservoir compressed by the pressure of
the main spring is increased more than in the oil pres-
sure chamber, and the oil in the reservoir pushes past
the check ball to flow into the oil pressure chamber . In
this way the rod is pushed to the left until the force
between the arm and rod is balanced . Since the thrust F
works to the arm, the pulley is rotated counterclock-
Fig. 3
wise, giving tension PB to the belt .
(2) Action for balancing the belt tension
When tension PB is given to the belt and the belt tension
reaches the normal level, the belt generates the reaction
TB, which works as the reaction P at the pressure cone
apex of the rod . Since the reaction force pushes the rod
to the right, the check ball in the oil pressure chamber is
closed . When the rod is pushed to the left by the oil
inflow, the balance between the rod and arm is main-
tained to stop the arm, and the belt tension is main-
tained at the fixed level .
(3) Action when the belt is too tight
When the timing belt reaction force increases to such an
extent that the belt will be too tight, the arm force P is
larger than the rod thrust F. Consequently, the oil in the
oil pressure chamber passes through the clearance
between the adjuster body and rod and is returned to
the reservoir in small amounts. This oil return is stopped
when the rod thrust F and arm force P are balanced to
maintain tension at the fixed level .
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