PG145 Transmission Caterpillar

Transmission Pressures - Test and Adjust

Usage:

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Hot hydraulic oil under high pressure can remain in the components of the hydraulic system or the power train system after the engine has been stopped. The uncontrolled release of the hydraulic oil can cause sudden machine movement and can also result in the following conditions:

Burns
The penetration of body tissue
Other personal injury
Death

If hydraulic oil penetrates body tissue, the injury must be treated immediately by a doctor who is familiar with this type of injury. Use a board or a piece of cardboard to check for a hydraulic oil leak. Make sure that all of the attachments have been lowered to the ground and that all trapped pressure has been released from the hydraulic system and the power train system. Also, make sure that the hydraulic oil is cool before the removal of any components or lines. Remove the hydraulic oil filler cap only when the engine is stopped and the filler cap is cool enough to touch with your bare hand.

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Personal injury or death can result from not engaging the parking brake.

Transmission engagement alone will not prevent machine from rolling when the engine is stopped.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat^® products. Dispose of all fluids according to local regulations and mandates.

Introduction

This story includes the following tests:

Transmission Oil Pump (Charge) Pressure
Torque Converter Inlet Pressure
Transmission Lubrication Pressure
Transmission Clutch Pressure

Required Tools

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Illustration 1	g01106077
Tooling (A)

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Illustration 2	g06089485
Tooling (B)

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Table 1
Tool	Item	Part Number	Description	Qty
A	A1	8T-0854	Pressure Gauge ( 0 to 1000 kPa (0 to 145 psi))	1
	A2	8T-0855	Pressure Gauge ( 0 to 4000 kPa (0 to 580 psi))	1
	A3	6V-3989	Fitting	1
	A4	6V-4143	Quick Connect Coupler	2
	A5	177-7860	Hose As ( 3 m (10 ft))	1
B		198-4240	Digital Pressure Indicator Gp
	B1	198-4234	Digital Indicator	1
	B2	198-4237	Pressure Sensor Gp ( 3445 kPa (500 psi))	1
	B3	198-4239	Pressure Sensor Gp ( 68900 kPa (10000 psi))	2
	B4	198-4236	Adapter Cable As	3
C		187-3547	Quick Disconnect Coupler As	10

Reference: Refer to Tool Operating Manual , NEHS0818 , "Using the 198-4240 Digital Pressure Indicator Group" for more information on using Tooling (B).

Machine Setup

Park the machine on a smooth, level surface.
Place the transmission in the NEUTRAL position.
Lower the work tool to the ground.
Engage the parking brake.
Place chocks in front of the wheels and behind the wheels.
Perform machine walk-around and check for any leaks or damage. Check transmission oil level and fill to proper level if necessary.
Allow only authorized personnel on the machine. Keep unauthorized personnel off the machine and in clear sight of the operator.
Transmission oil should at normal operating temperature.

Specifications

Transmission Oil Operating Temperature

Transmission oil must be between 80 to 85° C (176 to 185° F) for testing pressures.

Transmission Pressures

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Table 2
Transmission Charge (Main) Pressure
Engine Speed	Operating Pressure
High Idle (2000 to 2500 RPM)	1550 to 1750 kPa (224 to 253 psi)
Low Idle	1400 to 1600 kPa (203 to 232 psi)

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Table 3
Transmission Oil Filter Pressure Differential
Engine Speed	Filter Condition	Operating Pressure Differential
High Idle (2000 to 2500 RPM)	New	30 kPa (4.3 psi) Maximum
High Idle (2000 to 2500 RPM)	Replacement Required	400 kPa (58 psi)

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Table 4
Torque Converter Inlet Pressure
Engine Speed	Operating Pressure
High Idle (2000 to 2500 RPM)	700 to 1000 kPa (101 to 145 psi)

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Table 5
Transmission Lubrication Pressure
Engine Speed	Operating Pressure
High Idle (2000 to 2500 RPM)	200 to 350 kPa (29 to 51 psi)
Low Idle	50 to 150 kPa (7 to 22 psi)

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Table 6
Clutch Pressure (Engaged)
Engine Speed	Operating Pressure
All Engine Speeds	1200 to 1550 kPa (174 to 225 psi)

Clutch Engagement by Gear Selection

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Table 7
4 Speed Transmission Clutch Engagement by Gear⁽¹⁾
Gear	Active Clutches
Forward 1	Forward Low	Clutch 1
Forward 2	Forward Low	Clutch 2
Forward 3	Forward Low	Clutch 3
Forward 4	Forward High	Clutch 3
Reverse 1	Reverse	Clutch 1
Reverse 2	Reverse	Clutch 2
Reverse 3	Reverse	Clutch 3

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⁽¹⁾	Four speed models include: 458-3823, 458-3825, and 482-2979 Power Shift Transmission Ar.

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Table 8
6 Speed Transmission Clutch Engagement by Gear⁽¹⁾
Gear	Active Clutches
Forward 1	Forward Low	Clutch 1
Forward 2	Forward High	Clutch 1
Forward 3	Forward Low	Clutch 2
Forward 4	Forward High	Clutch 2
Forward 5	Forward Low	Clutch 3
Forward 6	Forward High	Clutch 3
Reverse 1	Reverse	Clutch 1
Reverse 2	Reverse	Clutch 2
Reverse 3	Reverse	Clutch 3

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⁽¹⁾	Six speed models include 460-9944 and 464-3295 Power Shift Transmission Ar.

Location of Pressure Test Ports

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Illustration 3	g06087595
Front view of transmission (1) Forward-high clutch pressure test port (2) Clutch 3 pressure test port

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Illustration 4	g06087600
Left view of transmission (3) Filtered charge oil pressure test port (4) Unfiltered charge oil pressure test port (5) Reverse clutch pressure test port (6) Transmission oil cooler return connection port (7) Transmission oil cooler supply connection port

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Illustration 5	g06087604
Rear view of transmission (8) Lubrication pressure test port (9) Forward-low clutch pressure test port

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Illustration 6	g06087609
Top view of transmission (10) Clutch 2 pressure test port (11) Clutch 1 pressure test port (12) Torque converter inlet pressure test port

Test Procedures

Transmission Oil Pump (Charge Pressure) Test

This test also serves to test the transmission pump (charge pressure) relief valve.

Perform the steps in "Machine Setup" and continue to the following steps.
Remove the plug from port (4) and install Tooling (C).
Select an appropriate gauge range. Attach Tooling (A) or (B) to Tooling (C).
Engage the parking brake. Apply service brake. Shift the transmission to the neutral position. Start the engine.
Observe and record operating pressures at low idle and high idle engine speeds.
Note: Compare observed pressures to the reference table in "Transmission Pressures" within the "Specifications" section above.

Transmission Oil Filter Pressure Differential Test

Perform the steps in "Machine Setup" and continue to the following steps.
Remove the plugs from ports (3) and (4) and install Tooling (C) into both ports.
Select an appropriate gauge range. Attach Tooling (A) or (B) to Tooling (C).
Note: Tooling quantities will be doubled for this procedure as two measurements will be taken at the same time.
Engage the parking brake. Apply service brake. Shift the transmission to the neutral position. Start the engine.
Observe and record operating pressures at high idle engine speed.
Subtract the lower pressure from the higher pressure reading to figure the oil filter pressure differential.
Note: Compare pressure differential to the reference table in "Transmission Pressures" within the "Specifications" section above.

Torque Converter Inlet Pressure Test

This test also serves to test the torque converter inlet pressure relief valve.

Perform the steps in "Machine Setup" and continue to the following steps.
Remove the plug from port (12) and install Tooling (C).
Select an appropriate gauge range. Attach Tooling (A) or (B) to Tooling (C).
Engage the parking brake. Apply service brake. Shift the transmission to the neutral position. Start the engine.
Observe and record operating pressure at high idle engine speed.
Note: Compare observed pressure to the reference table in "Transmission Pressures" within the "Specifications" section above.

Transmission Lubrication Pressure Test

Perform the steps in "Machine Setup" and continue to the following steps.
Remove the plug from port (8) and install Tooling (C).
Select an appropriate gauge range. Attach Tooling (A) or (B) to Tooling (C).
Engage the parking brake. Apply service brake. Shift the transmission to the neutral position. Start the engine.
Observe and record operating pressures at low idle and high idle engine speeds.
Note: Compare observed pressures to the reference table in "Transmission Pressures" within the "Specifications" section above.

Clutch Pressure Test

The following procedure is to be used for testing all clutch pressures.

Select a clutch to test. Use the clutch engagement charts in "Clutch Engagement by Gear Selection" to select a gear that will activate the clutch being tested. Locate the corresponding test port using the images in "Location of Pressure Test Ports" above.

Test any or all clutches as needed.

Perform the steps in "Machine Setup" and continue to the following steps.
Remove the plug from the corresponding clutch pressure test port. Install Tooling (C).
Select an appropriate gauge range. Attach Tooling (A) or (B) to Tooling (C).
Engage the parking brake. Apply service brake. Shift the transmission to the neutral position. Start the engine.
Observe and record operating pressure at low idle engine speed.
Note: Compare observed pressure to the reference table in "Transmission Pressures" within the "Specifications" section above.