JLG TF6-42 Service Manual - Manuale (Pagina 671)

T12000 ID 04/99 6-2
Operation of the transmission
6.1.1 The converter, pump drive section and pressure regulating valve
Engine power is transmitted from the engine flywheel to the impeller through the impeller cover.
This element is the pump portion of the hydraulic 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, that picks up fluid at its centre and discharges it at the outer diameter.
The torque converter turbine is mounted opposite the impeller and is connected to the turbine shaft of the
torque converter. This element receives fluid at its outer diameter and discharges it at its centre.
The reaction member of the torque converter is located between and at the centre of the inner diameters 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 will make the converter to multiply torque.
The torque multiplication is function of the blading (impeller, turbine and reaction member) and the converter
output speed (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.
The hydraulic pump is connected with the pump drive gear. This pump drive gear is driven by the impeller hub
gear. Since the impeller hub gear is connected with the impeller cover, the pump speed is in direct relation
with the engine speed.
Note
T HE PRESSURE REGULATOR VALVE IS MOUNTED BEHIND THE FILTER , IN THE FILTER ADAPTER HOUSING .
1 ST 2 ND
4 TH -H I 3 RD
3 RD
REV FWD
THE CONVERTER, PUMP DRIVE SECTION AND PRESSURE REGULATING VALVE