GROVE
Published 1-20-2017, Control# 483-02
7-3
CD5515-2/YB5515-2 SERVICE MANUAL
TRANSMISSION AND TORQUE CONVERTER
7
DESCRIPTION OF OPERATION
Torque Converter
The torque converter Figure 7-1 is the hydraulic link between
the engine and the drive train. There are three main
components in the torque converter:
•
A turbine
•
An impeller (pump)
•
A stator and One-Way Clutch
The
impeller
is the pump for the torque converter. This
component starts the movement of the oil to the other
components. The impeller is connected to the engine
flywheel through the torque converter and a drive plate. The
impeller rotates at engine speed. Similar to a centrifugal
pump, the impeller takes oil at the inner diameter and
releases the oil at the outer diameter.
The
turbine
is opposite the impeller and is connected by
splines to the input shaft of the Powershift Transmission. The
turbine receives oil at the outer diameter and releases the oil
to the stator at the inner diameter. The movement of oil from
the impeller to the turbine makes a multiplication of torque
possible. The torque converter gives maximum torque when
the turbine is at zero (0) rpm.
The
stator
is between and at the center of the impeller and
turbine. The stator changes the direction of the oil which
leaves the turbine so the oil will enter correctly again into the
impeller.
The torque converter and transmission have a common
hydraulic system. Figure 7-3 shows the arrangement of the
system.
Transmission
The Powershift Transmission is an electo-hydraulic
transmission unit. Gear shifting and direction selection are
controlled using multi-disc clutch packs.
Electrically operated solenoid valves divert pressurized oil
(provided by pump
Q
Figure 7-2) to the selected clutch
packs.
A combined lever/swivel switch (travel select lever) on the
steering column actuates both gear ratio and direction
solenoids.
The Powershift transmission consists of a torque converter
A
Figure 7-2, input clutch assembly
B
, forward clutch
C
,
layshaft assembly
E
, and a mainshaft assembly
D
.
The torque converter is a fluid coupling bolted to a drive plate
which is bolted to the engine flywheel. As the engine
crankshaft begins to rotate, the torque converter gives a
smooth power takeoff gradually increasing the torque
transmitted. This torque is transferred from the torque
converter assembly to the clutch/gear assemblies via the
input shaft
H
.
The input clutch assembly
B
contains two hydraulically
operated clutches; one clutch provides reverse low ratio
drive and other a reverse high ratio drive. The three-position
solenoid
G
, when energized, directs pressurized oil to either
the reverse low or reverse high clutch.
The forward clutch assembly
C
is similar to the input clutch
assembly. It contains two hydraulically operated clutches;
one clutch provides forward low ratio drive and the other
forward high ratio drive. The three-position solenoid valve
L
,
when energized, directs pressurized oil either to the forward
low or forward high clutch.
Forward drive is transmitted via constant meshing of spur
gears
Z
.
FIGURE 7-1
a0230
OUTPUT
Impeller
Turbine
INPUT
Stator
Torque Converter Cross-Section
CAUTION
Normal operating temperature is 82° - 88°C (180° -
190°F). High temperatures will cause damage and
leakage in the seals and gaskets of the torque converter.
Do not continue operation if the temperature increases
above 82° - 88°C (180° - 190°F). A warning light on the
cab instrument panel will illuminate when the temperature
rises above a safe temperature. Put the transmission in
“neutral” position and let the engine run at low RPM until
the temperature returns to normal and the warning light
goes out. If temperature does not return to normal, check
for restriction in the lubrication and cooling lines of the
torque converter.
Reference Only
