Subaru XT 1988 Service Manual page 531

AUTOMATIC TRANSMISSION AND DIFFERENTIAL
3-2
(6) Forward clutch & overrunning clutch
• Construction
Snap ring
Dish plate
lip seal
Retainer
Snap ring
Bushing
Sleeve
Return spring
Drive plate
Drive pi
Driven plate
Fig.
26
The forward clutch drum is manufactured by pressing sheet
metal. The clutch drum, outer race and sleeve are welded
together by the electron beam welding technique. This clutch
drum accommodates two multi-plate clutches (forward clutch
and overrunning clutch). The overrunning clutch piston is
mounted on the internal periphery of the forward clutch
piston for common use of the return spring and reduction in
size.
~
Forward clutch
Overrunning
clutch
No. of drive plates
5 3
No. of driven plates 5 3
0.0. mm (in) 147 (5.79) 133 (5.24)
Piston
1.0. mm (in)
73 (2.87) 75 (2.95)
17
• Function
Forward clutch piston
Lip seal
Drift ball
Forward clutch drum
Overrunning clutch piston
Snap ring
Plate
O.W.C. (1-2)
Needle bearing
Lathe cut ring
Snap ring
Outer race
(II)
L3-918
When hydraulic pressure is applied to the pressure chamber (I)
from the hydraulic pressure controller during forward opera-
tion in the "0", "3", "2" range or "1st hold", the forward
clutch piston forces the overrunning clutch piston. This causes
the drive and driven plates of the forward clutch to engage
while causing the drive and driven plates of the overrunning
clutch to slide forward.
A groove is provided on the outside of the retaining plate and
driven plate of the overrunning clutch in which the forward
clutch piston sl ides.
When hydraulic pressure is appl ied to the pressure chamber
(II)
from the hydraulic pressure controller during "3" range,
"2" range or "1 st hold" operation, the forward clutch piston
is forced onto the side of the forward clutch drum. The over-
running clutch piston, however, is moved to the left by the
hydraulic pressure. This causes the drive and driven plates of
the overrunning clutch to engage. When this occurs, the out-
side splines of the overrunning clutch retaining plate and
driven plate fit into the internal spline grooves of the forward
clutch. This allows power to be transmitted between the over-
running clutch hub and the forward clutch drum.