DRESSTA TD-25M EXTRA, Service Manual

Page: 78 / 595

SECTION 7
DRIVE TRAIN
Page 26
TD-25M EXTRA DRESSTA
SERVICE DIAGNOSIS
Steering Drive Diagnostic Chart
PROBLEM PROBABLE CAUSE
1. No clutch and brake pressures.
a. Low main pressure. Refer to “Transmission
and Torque Converter Diagnostic Chart”
above.
2. Low or zero right or left clutch pressure with
drive train control lever in low range.
a. RH or LH hose in rear main frame leaking.
b. RH or LH low range piston seal ring leaking.
c. Steering valve gasket leaking.
3. Low or zero right or left clutch and brake
pressure with drive train control lever in low
and high range.
a. RH or LH metering spool in upper steering
valve seized.
b. Steering valve gasket leaking.
4. Low or zero right or left clutch pressure with
drive train control lever in high range.
a. RH or LH hose in rear frame leaking.
b. RH or LH solenoid valve or sequence valve
faulty.
c. Steering valve gasket leaking.
d. High range piston seal rings leaking.
5. Low or zero right or left brake pressure. a. RH or LH hose in rear main frame leaking.
b. Brake piston seal ring leaking.
14. STEERING SYSTEM FUNCTIONAL CHECK
Before performing the steering system function check, the steering valve pressures must be
checked. Refer to Paragraph 13, STEERING SYSTEM OIL PRESSURE CHECK.
With machine on level and hard ground and with the Test Pressure Gauges Kit (refer to SERVICE
/SPECIAL TOOLS in this Section) still connected to right and left brake quick disconnect fittings on
the diagnostic center and to the RC and LC test ports on the steering valve (Refer to Step 2, in
Paragraph 13 of this Section) start the engine. Set the engine speed at low idle, engage the
transmission in third forward and proceed as follows:
Brake Release and Engagement Pressure Check
1. Hold the drive train control lever fully shifted to the left in the LH brake position.
2. Increase the engine speed until the RH track begins to creep.
3. Apply the foot brake slowly and record the RB brake clutch pressure (gauge connected to
RB on the diagnostic center) when the track stops creeping.
4. Slowly release the foot brake and record the RB brake clutch pressure (gauge connected to
RB on the diagnostic center) when the track begins to creep.
5. Repeat steps 1 through 4 for the LB brake clutch by actuating the foot brake with the drive train
control lever fully shifted to the right in the RH brake position and record the LB brake clutch
pressure (gauge connected to LB on the diagnostic center).
6. The pressures obtained should be between 550 – 690 [kPa].