M313C, M315C, M316C, M318C and M322C Excavators and M318C and M322C Material Handlers Hydraulic System Caterpillar

Margin Pressure - Test and Adjust

Usage:

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Table 1
Required Tools
Part Number	Part Description	Qty
	IBM-COMPATIBLE personal computer with an installed current version of Caterpillar Electronic Technician software ⁽¹⁾	1
8T-0855	Pressure Gauge (0 to 4,000 kPa (0 to 580 psi))	1
8T-0861	Pressure Gauge (0 to 60,000 kPa (0 to 8,700 psi))	2
171-4400	Communication Adapter Gp	1
6V-3989	Fitting (TEST)	2
6V-4143	Quick Connect Coupler	4
6V-3014	Hose As	2
	Wrench (17 mm)	1
	Allen Wrench (5 mm)	1

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^( 1 )

Refer to Special Publication, JEBD3003, "ET Software CD and Getting Started Guide". Instructions for the use of Electronic Technician software are included in the software.

Note: Two technicians are required for this test.

Machine Preparation

Start the engine.

Lower the left console.

Position the machine on level ground.

Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).

Lower the stabilizers, the blade tip, and/or the implement in order to raise the front axle and the rear axle. This will allow the wheels to turn freely. All tires must be fully off the ground.

Release the service brake pedal.

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Illustration 1	g01215682
Soft Switch Panel (1) Automatic Engine Speed Control (AEC) (2) Creeper Speed Control (3) Hydraulic Modulation Control (4) Hydraulic Lockout Control (5) Transmission Control

Push down on button (1) in order to disable the AEC. The indicator light will not be illuminated.

Push down on button (4) in order to deactivate the hydraulic lockout control. The indicator light will not be illuminated.

Push down on button (5) in order to select FIRST GEAR. The first indicator light will illuminate when the transmission is in FIRST GEAR.

Push down on button (2) in order to activate the creeper speed control. When the creeper speed control is activated, the indicator light will illuminate.

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Illustration 2	g01215702
Right Joystick (6) Switch (hydraulic modulation)

Disable hydraulic modulation control (3). Press front switch (6) on the right joystick in order to deactivate the soft panel switch for hydraulic modulation. None of the indicator lights will be illuminated.

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Illustration 3	g01215907
The remote pressure taps are located behind the left rear access door. (7) Pressure tap (Main pump pressure) (8) Pressure tap (Load sensing signal pressure)

Connect 60000 kPa (8600 psi) pressure gauges to pressure taps (7) and (8) .

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Illustration 4	g01215705
Right Side of Cab Seat (9) Service tool connector

Connect the Electronic technician (ET) to service tool connector (9) of the machine.

Start Electronic Technician.

Select the "Machine ECM" from the list of available controls.

Go to the "Diagnostics/Override Parameters" menu.

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Illustration 5	g01216444
ET Configuration Screen

Select "Travel Pilot Solenoid Current Override".

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Table 2
Travel Pilot Solenoid Current Override
Machine Model	Current Value (Ampere)
M313C	0.460
M315C	0.460
M316C	0.460
M318C and M318C MH	0.545
M322C and M322C MH	0.545

Adjust the current value for "Travel Pilot Solenoid Current Override" to the current value that is shown in Table 2 for your machine.

Test

Adjust the engine speed to HIGH IDLE by turning the engine speed dial to position 10.

Note: Use two technicians to perform the following steps. Use one technician to depress the travel pedal and use one technician to read the gauges.

Depress the travel speed pedal fully in the FORWARD position.

Check the margin pressure on the pressure gauges while the travel pedal is fully depressed. Margin pressure is the difference between the pressure at pressure tap (7) and pressure tap (8). Refer to Testing and Adjusting, "Specifications" in this manual for the correct margin pressure.

If margin pressure is not within the specification, the spring for the load sensing spool needs to be adjusted.

Adjust

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Illustration 6	g01215658
Main Pump (10) Load sensing valve (11) Hydraulic Modulation Solenoid

Note: If hydraulic modulation solenoid (11) is installed, the hydraulic modulation solenoid must be deactivated in order to test the margin pressure. Do not deactivate the hydraulic modulation solenoid by disconnecting.

Place the engine start switch in the OFF position.

Remove the cap and loosen the locknut on the adjustment screw for load sensing valve (10) .

Turn the adjustment screw clockwise in order to increase the margin pressure. Turn the adjustment screw counterclockwise in order to decrease the margin pressure.
Note: Turn the load sensing screw by a 1/8 turn in order to change the margin pressure by approximately 200 kPa (29 psi).
Note: Always make the final pressure adjustments on the pressure rise.

Verify that the margin pressure is within specifications.

Repeat the "Adjust" procedure, as needed.

Standby Pressure (Minimum Displacement Adjustment)

Note: The minimum displacement of the main pump should only be adjusted if the main pump has been replaced or rebuilt.

Note: Do not activate any implement while you are performing this test.

Connect a 4000 kPa (580 psi) pressure gauge to pressure tap (1) .

Start the engine.

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Illustration 7	g01215913
Soft Switch Panel (1) Automatic Engine Speed Control (AEC)

Push down on button (1) in order to disable the AEC. The indicator light will not be illuminated.

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Illustration 8	g01215702
Right Joystick (6) Switch (hydraulic modulation)

Disable hydraulic modulation control (3). Press front switch (6) on the right joystick in order to deactivate the soft panel switch for hydraulic modulation. None of the indicator lights will be illuminated.

Adjust the engine speed to HIGH IDLE by turning the engine speed dial to position 10.

Check the standby pressure on the pressure gauge. The pressure reading should be 2800 kPa (406 psi) to 3400 kPa (493 psi).

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Illustration 9	g01215818
Main Pump (12) Minimum displacement

Remove the cap and loosen the locknut on the adjustment screw for minimum displacement (12) .

Turn the adjustment screw until the main pump pressure is set to the correct specification. Refer to Testing and Adjusting, "Specifications" in this manual for the correct main pump pressure.
Note: Turn the adjustment screw clockwise in order to increase the standby pressure. Turn the adjustment screw counterclockwise in order to decrease the main pump pressure.
Note: Always make the final pressure adjustments on the pressure rise.