312F and 313F Excavator Machine Systems Relief Valve (Main)

Table 1
"Relief Valve (Main) - Test and Adjust"
Date		Machine Serial Number
Machine Settings		Engine Speed
Machine Settings		Speed Dial "10" AEC switch OFF
Item		Specification	Actual
Main Relief⁽¹⁾	Implement	30500 ± 500 kPa (4424 ± 73 psi)
Main Relief⁽¹⁾	Travel	35000 ± 500 kPa (5076 ± 73 psi)

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⁽¹⁾	To adjust the main relief valve, always adjust the travel main relief valve before adjustments are made to the implement main relief valve. An adjustment to the travel operation of the main relief valve will change the pressure setting of the implement operation of the main relief valve.

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Illustration 1	g02723671
Main relief valve

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Table 2
Torque Specification
Item	Part	Torque
(1)	Relief Valve	73.5 ± 4.5 N·m (54.2 ± 3.3 lb ft)
(3)	Locknut (implement)	29.4 ± 2 N·m (21.7 ± 1.5 lb ft)
(5)	Locknut (travel)	29.4 ± 2 N·m (21.7 ± 1.5 lb ft)

The main relief valve is located in the top of the main control valve. The main relief valve limits the maximum operating pressure of the travel hydraulic circuit and the implement hydraulic circuits when the machine is at a load condition.

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Illustration 2	g02723562
Main control valve (1) Main relief valve

Required Tools

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Illustration 3	g02571852
Tooling (A) 198-4240 Digital Pressure Indicator Gp

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Illustration 4	g03261789
(D) Track Block

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Table 3
Tool	Item	Qty	Part Number	Description
A			198-4240	Digital Pressure Indicator Gp
	A1	1	198-4234	Indicator
	A2	1	198-4239	Pressure Sensor 41,368 kPa (6,000 psi)
	A3	1	198-4236	Extension Cable
D		1	418-3610	Track Block

Machine Preparation

Position the machine on level ground and stop the engine.
Release the pressure in the hydraulic system. Refer to Testing and Adjusting, "System Pressure - Release".
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Illustration 5 g02761297

Pressure tap for the drive pump
Attach a 41,368 kPa (6,000 psi) pressure sensor to the pressure tap for the drive pump.

Test Procedure

Note: To adjust the main relief valve, always adjust the travel main relief valve before adjustments are made to the implement main relief valve. An adjustment to the travel operation of the main relief valve will change the pressure setting of the implement operation of the main relief valve.

Travel Operation

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Illustration 6	g03340595
(D) Track Block (6) Sprocket

Place track block (D) in sprocket (6) to block forward right travel.
Start the engine.
Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).
Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF.
Slowly move the right travel control lever to full FORWARD position and check the pressure gauge reading. The pressure setting should be 35000 ± 500 kPa (5076 ± 73 psi).
Return the right travel control lever to the NEUTRAL position.
If the main relief valve pressure setting is not within the specification, adjust the main relief valve pressure setting.

Implement Operation

Start the engine.
Place the machine controls at the following settings: engine speed dial "10" and AEC switch OFF.
Increase the hydraulic oil temperature to 55° ± 5°C (131° ± 9°F).
Slowly move the joystick for the bucket to the BUCKET CLOSE position (full extension of the bucket cylinder). Check the pressure gauge reading. The pressure setting should be 30500 ± 500 kPa (4424 ± 73 psi).
Return the joystick for the bucket to the NEUTRAL position.
If the main relief valve pressure setting is not within the specification, adjust the main relief valve pressure setting.

Adjustment Procedure

Travel Operation

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Illustration 7	g02552019
Cutaway of the main relief valve (1) Main relief valve (2) Adjustment screw (implement) (3) Locknut (implement) (4) Adjustment screw (travel) (5) Locknut (travel)

To adjust the travel main relief valve, loosen the locknut (5) and turn the adjustment screw (4) until the pressure reading at the pressure tap for the drive pump is 35000 ± 500 kPa (5076 ± 73 psi).
Note: Turn the adjustment screw clockwise to increase the pressure. Turn the adjustment screw counterclockwise to decrease the pressure.
Note: Always make final pressure adjustments on pressure rise.
Tighten the locknut (5) to a torque of 29.4 ± 2 N·m (21.7 ± 1.5 lb ft).

Implement Operation

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Illustration 8	g02552019
Cutaway of the main relief valve (1) Main relief valve (2) Adjustment screw (implement) (3) Locknut (implement) (4) Adjustment screw (travel) (5) Locknut (travel)

To adjust the implement main relief valve, loosen the locknut (3) and turn the adjustment screw (2) until the pressure reading at the pressure tap for the drive pump is 30500 ± 500 kPa (4424 ± 73 psi).
Note: Turn the adjustment screw clockwise to increase the pressure. Turn the adjustment screw counterclockwise to decrease the pressure.
Note: Always make final pressure adjustments on pressure rise.
Tighten the locknut (3) to a torque of 29.4 ± 2 N·m (21.7 ± 1.5 lb ft).