JLG G12-55A Service Manual - Manual (Page 102)

Transmission
6-10 G10-55A, G12-55A
3. Low clutch
pressure.
1. Incorrect oil level. 1. Fill transmission to correct level with
hydraulic oil. Refer to Section Note:,
“Friction Modifier required for axle
differentials, see Section 2.5.3,
“Capacities.”.”
2. Main pressure valve stuck open. 2. Clean the valve spool and housing.
3. Broken or worn coupling shaft or
piston o-rings.
3. Replace coupling and/or o-rings.
4. Pressure reducing valve stuck open. 4. Clean the valve spool and housing.
4. Lack of power. 1. Park or service brake dragging. 1. Refer to Section 8.4, “Hydraulic Circuits.”
2. Low engine rpm causes
converter stall.
2. Adjust the engine rpm to specifications.
Refer to Engine Service Manual.
3. Pump output pressure is low. 3. Refer to Problem 2. “Low or no pump
flow or pressure.”
4. Clutch discs worn or damaged. 4. Replace clutch discs.
5. Transmission overheating. 5. Refer to Problem 5. “Transmission
overheating (oil above 248° F (120° C)).”
5. Transmission
overheating
(oil above 248° F
(120° C)).
1. Low oil level. 1. Fill transmission to correct level with
hydraulic oil. Refer to Section Note:,
“Friction Modifier required for axle
differentials, see Section 2.5.3,
“Capacities.”.”
2. Clogged radiator. 2. Remove debris from the radiator.
3. Transmission filled with incorrect oil,
or oil contaminated.
3. Drain transmission and fill to correct
level with hydraulic oil. Refer to Section
Note:, “Friction Modifier required for axle
differentials, see Section 2.5.3,
“Capacities.”.”
4. Excessive “roading.” 4. Stop and idle the engine.
5. Restriction in oil cooler hoses. 5. Replace cooler hoses.
6. Pump worn or damaged. 6. Repair or replace pump assembly.
7. Thermal by-pass valve damaged or
flow restricted.
7. Replace thermal by-pass valve cartridge.
Refer to Section 6.5, “Transmission
Cooler Thermal By-Pass Valve.”
Problem Cause Remedy