PIN 1631494 - Caterpillar

Test 5. Primary Clutch Pressures
This test will show if the clutch pressures are adjusted correctly.
Make reference to the given in Test 4.
Procedure:
Use the PROCEDURE TO MANUALLY SHIFT THE TRANSMISSION WITH THE ENGINE RUNNING (Drive Axles Removed) given in Test 4.
Make sure the drive axles on the machine are removed for this test or the clutches of the transmission will be damaged.
1. If 6V6064 Transmission Test Cover (97) is used, remove large cover (91) from the top of the transmission case. If FT1874 Transmission Test Cover (98) is used, remove it from the transmission case.2. Remove seven load piston plugs (99) from their bodies.3. Put the test cover back in position and install four bolts to hold it in place.
GAUGES INSTALLED FOR PRIMARY PRESSURE TEST (769C Shown) 36. Downshift solenoid.98. FT1874 Transmission Test Cover.A. Pressure tap for No. 2 clutch.B. Pressure tap for No. 1 clutch.C. Pressure tap for No. 7 clutch.E. Pressure tap for No. 5 clutch.F. Pressure tap for No. 4 clutch.G. Pressure tap for No. 6 clutch.H. Pressure tap for No. 3 clutch.M. Pressure tap for pilot oil.4. At pressure taps (A), (B), (C), (E), (F), (G) and (H), connect pressure gauges [700 kPa (100 psi)] to the nipples as shown.5. Start and run the engine at LOW IDLE rpm in NEUTRAL.6. Make a record of the pressures on the gauges.7. Use the .25 (1/4) in. sq. drive ratchet and extension. Move the transmission rotary selector spool to REVERSE position (toward the front of the machine).8. Make a record of the pressures on the gauges.9. Manually shift the transmission into all forward speeds and make a record of the pressures on the gauges.10. Stop the engine with the transmission rotary selector spool in NEUTRAL.11. Make a comparison of the actual primary clutch pressure with the specification given in the chart for each clutch.12. After the problem is corrected, remove the pressure gauges and test cover. Install load piston plugs (99).13. Install large cover (91), small cover (92) and the solenoid guard. Connect the wiring harness to the solenoids.Problem 1:
Pressure at ONE clutch is 0 kPa (0 psi). PROBABLE CAUSE: a. Selector piston plug is not installed.Problem 2:
Primary pressures at ALL clutches are 0 kPa (0 psi). PROBABLE CAUSE: a. Pilot pressure. Do Test 3.Problem 3:
Primary pressures at ALL clutches are too low. PROBABLE CAUSE: a. Pilot pressure. Do Test 3. Problem 4:
Primary pressure at ONE clutch is too low. PROBABLE CAUSE: a. Add shims (100) for the modulation reduction valve of the clutch that has low pressure. See SHIM CHART FOR PRESSURE CONTROL GROUP.Problem 5:
Primary pressure at ONE clutch is too high. PROBABLE CAUSE: a. Remove shims (100) for the modulation reduction valve that has high pressure. See SHIM CHART FOR PRESSURE CONTROL GROUP.Problem 6:
An additional clutch gets pressure oil in some speeds (too many clutches are engaged). PROBABLE CAUSE: a. A selector piston is stuck (will not go back to its original position.b. Weak or broken INNER spring for the modulation reduction valve.Problem 7:
Maximum