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344
FIAT - 850 PASSENGER CARS
Fig. 560 • Sectional vIew of ldroconvert transmission.
1. Impeller.
4
2. Turbine. - 3. Stator.• 4. Torque converter guaranlee seal. - 5. Engine flywheel and starter ling gear. ·6. Uni·directionel
clutch lor torque converter by-pass .• 7. Clutch driven plate. - 8. Stator uni·directional clutch. - 9. Oil pump. - 10. Torque conlJerter output
shaft. - 11. Solenoid .• 12. Pressure regulating valve.
A disc type return spring is used to exert a con-
stant pressure
in
the direction of engagement, so
as to obtain the torque transfer necessary for engine
starting
by
towing or pushing.
The torque converter unit is enclosed in a pressed
sheet-metal casing consisting of two halves welded
on assembly to ensure perfect sealing. The casing
outer surface is finned to facilitate oil cooling.
Clutch engagement and release are obtained by
reversing the direction of oil pressure within the
hydraulic circuit inside the converter. Flow reversal
is achieved by means of a plunger type valve en-
closed in a valve body and operated by a solenoid
which is, in turn, controlled by the knob switch in
selector lever (signalling the driver's intention to
change gear) as well as by the neutral switch situated
in the gearbox cover and operated via a gear
selector rod.
A constant supply of oil under pressure is main-
tained by the gear type oil pump situated in the
transmission outer casing.
Two dog teeth on the impeller are used to drive
the pump.
It
should be noted that this pump is used to main-
tain oil circulation under pressure and not to supply
oil to the torque converter. Indeed, the converter
must at all times be full of fluid both during oper-
ation and when stationary.
A pressure regulating valve with return to supply
reservoir maintains the oil pressure within the
specified limits: 71-85 psi (5-6 kg/em') maximum.
The main oil reservoir is situated in the torque
converter outer casing, in proximity of the plunger
valve, and is closed at the top by a cover (3, fig. 662).
Its outer surface is finned for faster cooling and a
strainer inside the reservoir provides adequate
fil-
tration of the oil coming from the secondary reser-
voir.
The secondary reservoir
is
situated above the
transmission and carries a dip-stick
(1,
fig. 573) in
the filler neck.
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