120M, 12M, 140M and 160M Motor Graders Caterpillar

Transmission Pressures - Test and Adjust

Usage:

12M B92

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When testing and adjusting the transmission and power train, move the machine to an area clear of obstructions, with safe exhaust ventilation for the exhausts. Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before testing and adjusting the transmission and power train.

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Personal injury can result from spring force released when removing cap screws.
Internal spring force will be released when cylinder assembly cap screws are removed causing injury.
Always restrain cover as cap screws are loosened.

Follow the established procedure in the Service Manual to service these parts.

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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 machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Dispose of all fluids according to local regulations and mandates.

Specifications

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Table 1
Transmission Clutch Pressure
Test Port	NEUTRAL	FIRST GEAR FORWARD	SECOND GEAR FORWARD	FIRST GEAR REVERSE
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)

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Table 2
Transmission Clutch Pressure
Test Port	NEUTRAL	FIRST GEAR FORWARD	SECOND GEAR FORWARD	FIRST GEAR REVERSE
(1)	0.0 kPa (0.00 psi)	2760 ± 50 kPa (400 ± 10 psi)	0.0 kPa (0.00 psi)	0.0 kPa (0.00 psi)
(2)	0.0 kPa (0.00 psi)	0.0 kPa (0.00 psi)	2760 ± 50 kPa (400 ± 10 psi)	0.0 kPa (0.00 psi)
(3)	0.0 kPa (0.00 psi)	0.0 kPa (0.00 psi)	0.0 kPa (0.00 psi)	2760 ± 50 kPa (400 ± 10 psi)
(4)	0.0 kPa (0.00 psi)	0.0 kPa (0.00 psi)	2760 ± 50 kPa (400 ± 10 psi)	0.0 kPa (0.00 psi)
(5)	2760 ± 50 kPa (400 ± 10 psi)	0.0 kPa (0.00 psi)	0.0 kPa (0.00 psi)	0.0 kPa (0.00 psi)
(6)	0.0 kPa (0.00 psi)	2760 ± 50 kPa (400 ± 10 psi)	0.0 kPa (0.00 psi)	2760 ± 50 kPa (400 ± 10 psi)
(7)	0.0 kPa (0.00 psi)	2760 ± 50 kPa (400 ± 10 psi)	2760 ± 50 kPa (400 ± 10 psi)	2760 ± 50 kPa (400 ± 10 psi)
(8)	2760 ± 50 kPa (400 ± 10 psi)	0.0 kPa (0.00 psi)	0.0 kPa (0.00 psi)	0.0 kPa (0.00 psi)

Introduction

The following procedure is used to test the pressure at each of the control valves for the clutches of the transmission.

Required Tools

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Illustration 1	g01089423

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Illustration 2	g01623868

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Illustration 3	g02140681
View of tooling (D)

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Table 3
Tool	Item	Part Number	Description	Qty
A	A1	8T-0855	Pressure Gauge (0 to 4,000 kPa (0 to 580 psi))	1
	A2	6V-3989	Fitting	1
	A3	6V-4143	Quick Connect Coupler	2
	A4	177-7860	Hose As (3.0 m (10 ft))	1
B		198-4240	Digital Pressure Indicator Gp
	B1	198-4234	Digital Indicator	1
	B2	198-4237	Pressure Sensor Gp (0 to 3,445 kPa (0 to 500 psi))	1
	B3	198-4236	Adapter Cable As	1
D	D1	326-8026	Transmission Test Cover	1

Machine Preparation

Reference: Before you perform this procedure, refer to Testing and Adjusting, "Machine Preparation".

Operate the machine until the transmission oil is at operating temperature of 80° ± 10°C (176° ± 18°F).

Stop the machine on a hard level surface. Place the transmission in NEUTRAL. Turn off the engine. Place blocks in front of the wheels and place blocks behind the wheels.

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Illustration 4	g01285415
(1) Test port for clutch 1 (forward high) (2) Test port for clutch 2 (forward low) (3) Test port for clutch 3 (reverse) (4) Test port for clutch 4 (second speed) (5) Test port for clutch 5 (third speed) (6) Test port for clutch 6 (first speed) (7) Test port for clutch 7 (low range) (8) Test port for clutch 8 (high range)

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Illustration 5	g01285414
Rear view of the transmission (9) Cover for the transmission control valve

Remove cover (9) from the transmission.
Remove the drive shaft guard.
Remove the differential drive shaft.
Assemble Tooling (D) with the 50.8 mm (2.00 inch) bumper.
Use the bolt holes for the drive shaft guard in order to attach Tooling (D) to the parking brake housing.

Test Procedure

Attach Tooling (A) to test ports (8) and (5). Operate the engine at high idle with the transmission in NEUTRAL. Tooling (A) should read 2760 ± 50 kPa (400 ± 10 psi). Record the pressure readings in Table 1. Remove Tooling (A).
Attach Tooling (A) to test port (1), (6), and (7). Operate the engine at high idle with the transmission in FIRST GEAR FORWARD. Tooling (A) should read 2760 ± 50 kPa (400 ± 10 psi). Record the pressure readings in Table 1. Remove Tooling (A).
Attach Tooling (A) to test ports (2), (4), and (7). Operate the engine at high idle with the transmission in SECOND GEAR FORWARD. Tooling (A) should read 2760 ± 50 kPa (400 ± 10 psi). Record the pressure readings in Table 1. Remove Tooling (A).
Attach Tooling (A) to test ports (3), (6), and (7). Operate the engine at high idle with the transmission in FIRST GEAR REVERSE. Tooling (A) should read 2760 ± 50 kPa (400 ± 10 psi). Record the pressure readings in Table 1. Remove the sensors.
Turn off the engine.
Remove Tooling (B).
Install the cover (9) and the differential drive shaft.

Adjustment Procedure

If every one of the pressure readings are not within the specified pressure range that is listed in Table 2, the main relief valve may need adjusted. Refer to Testing and Adjusting, "Transmission Charging Pump Pressure - Test and Adjust" for information about adjusting the main relief valve. The Testing and Adjusting, "Transmission Calibration - Fill Calibration" procedure will not affect the top pressure of the clutch.

Note: If some of the pressure readings are not within the specified pressure range that is listed in Table 2, those modulating valves may need replaced.