Powershift Torque Converter; Description And Operation - Case 580SR Service Manual

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POWERSHIFT TORQUE CONVERTER

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DESCRIPTION AND OPERATION

Engine power is transmitted from the engine flywheel to the impeller through the impeller cover.
This element is the pump portion of the torque converter and is the primary component which starts the oil flowing
to the other components which results in torque multiplication. This element can be compared to a centrifugal pump
in that it picks up fluid at its centre discharges at its outer diameter. The torque converter turbine is mounted opposite
the impeller and is connected to the turbine shaft or clutch shaft. This element receives fluid at its outer diameter and
discharges at its centre. The stator of the torque converter is located between and at the centre of the inner diame-
ters of the impeller and turbine elements. Its function is to take the fluid which is exhausting from the inner portion of
the turbine and change its direction to allow correct entry for recirculation into the impeller element. This recirculation
causes the converter to multiply torque. The torque multiplication depends on the regularity of certain elements (fan,
turbine and stator) and on the output speed of the converter (turbine speed). The converter will multiply engine
torque to its designed maximum multiplication ratio when the turbine shaft is at zero RPM (stall). Therefore we can
say that as the turbine shaft is decreasing in speed, the torque multiplication is increasing. In the impeller cover a
splined shaft is fitted which runs inside and through the turbine shaft to drive a hydraulic pump which is fitted at the
back of the transmission. Since the shaft is connected to the centre of the impeller cover, the pump speed will be
the same as engine speed. The rear side of the impeller cover has a tanged drive which drives the transmission
charging pump located in the converter housing. The transmission charging pump speed is also the same as the
engine speed.
TORQUE CONVERTER AND LUBRICATION PRESSURE TEST PORTS
1. System pressure port
2. Torque converter in port
3. Torque converter out port
SECTION 17 - TORQUE CONVERTERS
4. Oil temperature converter out port
5. Oil temperature cooler out port
6. Lubrication pressure port
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