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IDROCONVERT TRANSMISSION
343
IDROCONVERT TRANSMISSION
CONSTRUCTION AND OPERATION
GENERAL
The Idroconvert transmission, available as an op-
tional extra on the 850 model, consists mainly of:
1) A
torque converter, inclusive of:
- a hydrokinetic coupling comprising an impel-
ler
I
a turbine and stator used to transmit power
and give torque multiplication from 2-1 to 1-1;
- a release mechanism fixed to the turbine
I
controlled
by
the oil pressure;
- a urn-directional clutch which, when coasting
cuts off the torque converter positively intercon-
necting the flywheel, the release mechanism and
the torque converter output shaft.
2) A
transmission casing. in
replacement of the
conventional clutch bell housing, enclosing the
following equipment:
- a gear type oil pump. fitted with a special
regulating valve to ensure constant feed and lubrica-
tion of torque converter, uni-directional clutch and
release mechanism;
- a main oil reservoir with strainer;
- a solenoid-operated flow control valve. The
valve is connected hydraulically to the release mech-
anism and monitors its operation.
3)
An
auxiliary, compensating oil reservoir con-
nected to the
main
reservoir by means of a flexible
hose.
4) A floor-mounted selector lever fitted with a
knob switch which closes the electrical circuit at
any movement of the lever.
5) A neutral switch, situated on transmission
cover, which closes the electrical circuit when
selector lever is in neutral position.
6) A relay for the solenoid-operated flow con-
trol valve and a starter motor inhibitor switch.
The IDROCONVERT transmission eliminates the
need for a conventional clutch and allied control.
The IDROCONVERT transmission is fitted bet-
ween engine and gearbox in place of the clutch.
The conventional gearbox has been retained and
a small friction-ring brake has been added to facil-
itate engagement of reverse gear (not synchronised).
DESCRIPTION
The use of a hydrokinetic torque converter cou-
pled to the input shaft of a conventional gearbox
gives exceptionally smooth and progressive vehicle
operation. In fact, because of the torque multipli-
cation given by the torque converter and then by
the gearbox, extreme flexibility and optimum pick-
up are readily available at
all
speeds.
The torque converter consists of:
- an impeller, fixed to the crankshaft;
- a turbine, connected to the release mechanism
which, in turn, is connected to the torque converter
output shaft;
- a stator, fitted with a uni-directional clutch.
Both impeller and turbine are made of pressed
sheet metal with inserted vanes (peened on assem-
bly). The stator is a light alloy casting.
The torque converter sleeve bearing, which is
fixed to the outer casing, carries a race for the
urn-directional clutch.
A second urn-directional clutch, fitted between
release mechanism and torque converter casing,
causes these to lock together when coasting so as
to give an uninterrupted drive from road wheels to
engine, thus by-passing the torque converter. Such
a design ensures positive engine braking and facil-
itates engine starting by towing at low speed, as
well as parking on a gradient with the car in gear
(lst gear downhill and reverse gear uphill).
The release mechanism consists of a single, wet
plate clutch (oil bath) which is used to disconnect
the engine from the transmission during gear shifts,
and whenever the hand lever is moved to the neutral
position (with engine running).
This clutch consists of a bell housing, a pressure
plate and a driven plate.
Both bell housing and
pressure plate rotate together
with
the turbine and,
during coasting, are made to engage the conver-
ter casing (and therefore, the impeller) via the
urn-directional clutch.
The driven plate, placed between bell housing
and pressure plate, is free to move axially on its
hub which, in turn, is fixed to the converter output
shaft.
Oil pressure is brought to bear on either side of
the pressure plate to engage and release the clutch.
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