cx trans

CX TRANSMISSIONS

Learning Outcomes

• Identify Components of the CX38 Transmission
• Identify Power Flow Through the CX38 Transmission
• Perform Diagnostic Tests and Calibrations on the CC38 Transmission
• Discuss and practice troubleshooting on the CX38 Transmission
• Identify Hydraulic and Electronic Control of the CX38 Transmission

ELECTRONIC CLUTCH PRESSURE CONTROL (ECPC) VALVES

Knowledge Check

TORQUE CONVERTER

• Fluid coupling that transfers power from the engine to the transmission

• Increases torque as the torque load on the machine increases

• Contains:
• Impeller
• Turbine
• Stator with one way clutch
• Housing
• Lock up clutch

Torque Converter Cutaway

ONE WAY CLUTCH

Rollers

Stator

Springs

Hub

Cam

Lockup

Freewheel

r(<

Clutch Pack Pressure Tap Location

125+/- 20PSI (HIGH IDLE) 36+/- 20PSI (LOW IDLE)

160+/- 20PSI 435+/- 20PSI (REVERSE)

Clutch Pack Pressures

31+/- 5PSI (HIGH IDLE) 20+/- 5PSI (LOW IDLE)

435+/- 20PSI

310+/- 20PSI 410+/- 20PSI (WARM UP MODE)

435+/- 20PSI

73+/- 10PSI (HIGH IDLE) 28+/- 10PSI (LOW IDLE)

380+/- 20PSI

260+/- 20PSI

435+/- 20PSI

460+/- 20PSI

TRANSMISSION MODULATING VALVE

NO SIGNAL COMMANDED

RETURN OIL TO TANK

PRESSURE FROM TRANSMISSION PUMP

TRAPPED OIL IN CLUTCH PACK

TRANSMISSION MODULATING VALVE

COMMANDED SIGNAL AT MAXIMUM Test Port

PRESSURE FROM TRANSMISSION PUMP

RETURN TO TANK

PRESSURE TO CLUTCH PACK

TRANSMISSION MODULATION CYCLE

Fill Calibration Parameters

Engagement Calibration Parameters

Fill Pulse

Clutch Engagement Level Maximum Clutch Pressure

Pressure and Current

Ramp Level

Modulation

Current

Hold Level

Pressure

Pulse Time

Ramp Time

Hold Time

Desired Slip Time

Full On Time

Pulse Dela

TRANSMISSION SHIFT CONTROL FUNCTIONS

• Fully Automatic (1C-2C, 2L-6L, or 2L-9L)
• Shift Points Match Engine Operating Range
• Elevated Downshift Point with Compression Brake or Hydraulic Retarder
• Operator may Override Desired Gear W/Shift Pad
• Transmission will Upshift when Engine Overspeeds
• D-N-R Shifts are Torque and Speed Limited

• Transmission Disengages LUC for ABS Events

End Retraction Case Plate Spring

CLUTCH CALIBRATION

Piston

Case

Current / Pressure

Clutch with Clearance

Clutch Pressure

Full On Level

Case Piston End Retraction Case Plate Spring

Full Off Level

No Pressure

Pressure Modulation

Touch Up

Fill

Full Engagement

Application Table Time

Clutch Solenoid Current

Clutch Fill Touch Up Pressure Volume No Clearance

Clutch Pressure

WHEN TO PERFORM CALIBRATION

Initial transmission installation

Transmission ECM replacement

Transmission modulating valve replacement

Transmission main relief valve replacement

Transmission or torque converter replacement

Transmission charge pump replacement

Oil cooler replacement

Poor shift quality

WHAT TO DO AFTER CALIBRATION

• Neutral to drive and DRIVE to REVERSE shifts
• Upshifts
• Coasting downshifts
• Five to four step through shifts
• Second at mid speed steady state

TROUBLESHOOTING

Customer Questions - Define Concern Slipping / Rough Shifts Noises No start / Will Not Shift out of Neutral Warning Light(s) On

Clutch Pack T'shoot

• As a result of a failure of the electronic main relief valve ("eMRV"), the transmission does not operate or engages slowly.
• As a result of a failure of "Clutch 1", the transmission will not operate in the 1R, 2R, 2F, 5F, 7F, and 8F positions.
• As a result of a failure of "Clutch 2", the transmission will not operate in the 3F, 6F, 7F, 8F, and 9F positions.
• As a result of a failure of "Clutch 3", the transmission will not operate in the 1F, 2F, 3F, 4F, 5F, 6F, 8F, and 9F positions.
• As a result of a failure of "Clutch 4", the transmission will not operate in the 1R, 1F, 2F, and 3F positions.
• As a result of a failure of "Clutch 5", the transmission will not operate in the 2R, 4F, 5F, 6F, and 7F positions.
• As a result of a failure of "Clutch 6", the transmission will not operate in the 1R, 2R, 1F, 4F, and 9F positions.
• The transmission will not upshift to the maximum selected gear.

Noises

Slips/Rough shifts

Check oil level

Check oil level

Check for Fault Codes and Event codes

check for fault codes and event codes

Change oil/ Filter

Change oil/filter

Check Transmission mainline pressure

Check Transmission main line pressure

Check clutch pack pressures

Check Clutch Pressures

Check pto vibration/ noise

Recalibrate Transmission

Recalibrate Transmission