T
ransmission
9803/3280
Issue 1
Synchro Shuttle Gearbox
Component Identification
A
Forward/reverse clutch unit
B
Transmission oil pump
C
Torque converter pressure regulating valve
D
Oil pressure maintenance valve
E
Solenoid control valve
F
Mainshaft
G
Synchromesh unit - 3rd/4th gears
H
Layshaft
J
Synchromesh unit - 1st/2nd gears
K
Transfer gear, output shaft and yoke
L
4WD output yoke (if fitted)
M
2/4WD clutch unit (if fitted)
N
4WD solenoid control valve (if fitted)
P
Oil strainer
Q
Oil filter
R
Gear selection turret assembly
S
Torque Converter
T
Driveshaft (drives machine main hydraulic
pump)
U
Hydraulic pump mounting face
V
Torque converter relief valve
W
Oil pressure switch
X
Hose connection - to cooler
Y
Hose connection - from cooler
Z
Gearbox oil cooler
Principle of Operation
This Illustration shows a typical JCB Syncro Shuttle
which consists of a torque converter, hydraulic
reverser unit, and integral manual 4-speed gearbox.
The reverser unit
A
has a pair of hydraulically
operated clutches giving forward - neutral - reverse
drive. Oil pressure is provided by a crescent type
pump
B
driven at engine speed by the drive lugs of
the torque converter. The oil pressure is controlled
by maintenance valve
D
, and clutch selection is
achieved by means of an electric solenoid valve
E
.
Drive is transferred from the reverser unit by helical
gears to the mainshaft
F
, which carries the 3rd/4th
synchromesh unit
G
, and to the layshaft
H
, which
carries the 1st/2nd synchromesh unit
J
.
Synchromesh unit
G
is of the 'Blocking Pin' type, a
full description of which is given in this section.
Synchromesh unit
J
features rings and cones with a
sliding sleeve.
Drive is transmitted finally via the output shaft
K
to
the rear axle. If 4 wheel drive is selected, the front
wheels are also driven via 4 wheel drive output
yoke
L
.
Driveshaft
T
is permanantly driven by the engine
and runs through the hollow forward/reverse unit
shaft to the back of the gearbox. The shaft (
T
)
drives the gearbox mounted machine main
hydraulic pump.
Gearbox oil is cooled by an air blast cooler
Z
. The
cooler is part of the front mounted machine ‘cooling
pack’.
16 - 2
16 - 2
Basic Operation
Section F
Section F
A401330
Z