740 Ejector Articulated Truck Caterpillar

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Hydraulic oil pressure can remain in the hydraulic system on this machine after the engine and pump have been stopped. Serious injury can result if this pressure is not released before any service is done on the hydraulic systems. In order to prevent possible injury, release the hydraulic system pressure before working on any fitting, hose, or hydraulic component. Lower all attachments to the ground before service is started. If the hydraulic system must be serviced, tested, or adjusted with the attachment in the raised position, the attachments and lift cylinders must be supported properly. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made.

Specifications

Introduction

This story includes the following tests:

• Ejector Pilot Pressure

This story includes the following adjustment procedures:

• Ejector Pilot Pressure

Required Tools

Illustration 1	g02094501
Tooling (B) is the 198-4240 Digital Pressure Indicator Gp.

Test Preparation

1. Move the machine to a smooth, horizontal location that is away from operating machines and away from personnel.

2. Permit only one operator on the machine. Keep all other personnel away from the machine or in the operator sight.

3. Rotate the steering wheel to a NEUTRAL position.

4. Move the transmission control to park to engage the parking brake.

5. Lower or retract the implements.

6. Stop the engine.

7. Turn the key to the ON position, but do not start the engine.

8. Verify that the implement controls are UNLOCKED.

9. Move the control levers through the full range of travel several times. Moving the control levers should relieve any pressure that may be present in the implement hydraulic system.
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   Illustration 2	g06206700
   (C) Ejector Pilot Pressure Test Point (TPHP)

10. Remove the dust cap from ejector pilot pressure test point (C) and install a 6900 kPa (1000 psi) pressure gauge.

Test Procedure

1. Start the engine and run the engine at low idle.

2. Ensure that the braking system is fully charged. Refer to Testing and Adjusting, "Brake System Charging Pressure - Check".

   Ensure that the system is at standby. Refer to Testing and Adjusting, "Piston Pump (Brake, Ejector, Fan) - Test and Adjust".

3. Record the pressure that is displayed on tooling (A). The pressure should match the value provided in Table 1.

   If the pressure is correct, proceed to step 4.

   If the pressure is incorrect, the pressure must be adjusted. Refer to the "Adjustment Procedure" section for instructions.

4. Shut off the engine and remove the pressure gauge from the machine.

5. Remove the steering frame lock. Refer to Operation and Maintenance Manual, "Steering Frame Lock".

Adjustment Procedure

Illustration 3	g06206701
(D) Pressure Reducing Valve

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Illustration 4	g06174852
(D) Pressure reducing valve (E) End cap (F) Adjustment screw (G) Jam nut

1. Remove end cap (E) from pressure reducing valve (D) to access adjustment screw (F).

   Note: Cap (E) will be broken when the cap is removed.

2. Loosen jam nut (G).

3. Turn adjustment screw (F), which is inside pressure reducing valve (D) to adjust the pressure.

   Turn the adjustment screw clockwise to increase the pressure.

   Turn the adjustment screw counterclockwise to decrease the pressure.

   Note: Turning adjustment screw (F) by 90 degrees clockwise will increase the pressure setting by approximately 345 kPa (50 psi). Turning adjustment screw (F) by 90 degrees counterclockwise will decrease the pressure setting by approximately 345 kPa (50 psi).

4. Tighten jam nut (G).

5. Repeat the "Test Procedure" section.