Subaru 2002 Impreza Service Manual page 160

AUTOMATIC BELT TENSION ADJUSTER
Mechanical
3. Automatic Belt Tension Adjuster
The automatic belt tension adjuster consists of a tensioner unit and a bracket. It maintains the tim-
ing belt tension automatically at a specified level to enable the belt to transmit power correctly,
reduce operating noise and increase the life of the belt.
The cylinder of the tensioner unit incorporates an adjuster rod, wear ring, plunger spring, return
spring, check ball and silicone oil.
The automatic belt tension adjuster gives tension to the belt by a levering action which is produced
by the push force of the tensioner unit's adjuster rod. It operates in the process detailed below.
(1)
Oil seal
(2) Wear ring
(3) Oil reservoir chamber
(4) Return spring
(5) Adjuster rod
(6) Plunger
(7) Oil pressure chamber
(8) Plunger spring
(9)
Check ball
(10)
Timing belt
(11) Belt tension pulley
(1 2) Tensioner bracket
(1 3) Cylinder
NF0368
M E-4