Kubota RTV1140CPX, Workshop Manual

Page: 213 / 379

TRANSMISSION
RTV1140CPX, WSM
2-S50
Readjustment of Relief Valve (When the HST does not work
due to its loose hexagon socket head screw)
IMPORTANT
• The KUBOTA does not recommend the readjustment of
relief valve. And KUBOTA will recommend the exhaustion
with genuine parts.
• As the HST may be damaged if the pressure is set to higher
by mistake, be careful when adjusting it.
NOTE
• The relief pressure is set in between (Forward: 25.5 to
26.5 MPa (260 to 270 kgf/cm
2
, 3700 to 3840 psi), Reverse:
20.5 to 21.5 MPa (209 to 219 kgf/cm
2
, 2980 to 3110 psi))
when shipped from the factory. But, for the purpose of
after-sales services, as it is impossible to reset the
pressure precisely as set in the factory, its setting range is
defined as a slightly wider range between (Forward: 22.6 to
26.5 MPa (231 to 270 kgf/cm
2
, 3280 to 3840 psi, Reverse:
18.9 to 21.5 MPa (193 to 219 kgf/cm
2
, 2750 to 3110 psi)).
1. Measure the pre-adjustment distance "A" .
2. Compress the spring of the relief valve with a relief valve
assembling tool (3).
3. Then, find the distance "A" by turning the poppet (4) with a
screwdriver.
Reference: The distance
"A" changes by about 0.5 mm
(0.0197 in.) per one turn of the poppet (4).
4. Repeat the same operation a few times to find the distance "A"
as it is difficult to acquire at the first time.
5. After finding the distance "A" , hold the setscrew (6) to a vice
and fasten the hexagon socket head screw (2) with specified
torque.
On this occasion, use a copper plate, etc. for the vice jaws not
to damage the setscrew (6).
6. Install the relief valve in the HST.
7. Check the relief pressure as indicated in checking section.
The distance "A" is for refresh only. Make sure to check the
relief pressure after readjustment.
8. If the relief pressure does not fall within the readjustment
pressure range, repeat the processes of the above item 1
onward.
Reference: The pressure changes by 1.47 MPa (15 kgf/cm
2
,
213.3 psi) per 0.1 mm (0.0039 in.) in distance "A" .
9Y1210293TRS0061US0
Tightening torque Hex. socket head screw
2.5 to 3.0 N·m
0.26 to 0.30 kgf·m
1.9 to 2.2 lbf·ft
Relief valve readjusting
pressure
Forward
22.6 to 26.5 MPa
231 to 270 kgf/cm
2
3280 to 3840 psi
Reverse (Brake)
18.9 to 21.5 MPa
193 to 219 kgf/cm
2
2750 to 3110 psi
Distance
"A"
Reference
valve
Forward
38.60 to 38.70 mm
1.520 to 1.523 in.
Reverse (Brake)
38.80 to 38.90 mm
1.528 to 1.531 in.
(1) Relief Valve Assembly
(2) Hexagon Socket Head Screw
(3) Relief Valve Assembling Tool (4) Poppet
(5) Valve Seat
(6) Setscrew
KiSC issued 05, 2014 A