Optimizing Machine Performance Over the Lifetime of the M318 Excavator{1900, 5051, 5137, 5479, 5480} Caterpillar

Excavators:

M318 (PIN: 8AL; 6ES; 8SS)

Introduction

This Special Instruction provides the procedures to maintain machine performance of the M318 Excavator. If the procedures are performed, the following improvements will be made on the machine:

• Implement response

• Travel speed up grades

• Lifting capability

• Overall engine performance

• Overall functionality of the machine

To maintain optimum machine performance, several components must be set to the correct specifications. The interaction between these components is critical to good performance. The interaction between the engine, the controller and the hydraulics will be covered. The following checks and adjustments should be made in order to determine the root cause of the performance complaints. These checks and adjustments have the following purposes:

• Identify deficiencies.

• Restore the machine to the proper specification.

• Identify components that cannot be adjusted.

The following procedures should be performed in the listed sequence. The 123-6472 Portable Diagnostic Tool (PDT) or the 133-4742 M300 Technician will be needed to perform the procedures.

Follow the recommended procedures in the following service manuals:

• Service Manual, SENR6265

• Testing and Adjusting, RENR1182

Adjustments

Engine Speed - Adjust

1. Record the low idle in Table 1.

2. Record the high idle in Table 1.

3. Record the rpm difference in the "Initial Measurement (Prior to any Adjustment)" column in Table 2 prior to any adjustment.

   Note: To use the "RPM Difference" function on the PTS, select the "Status" option and create a "New Group" that includes "Engine RPM", "RPM Difference" and "Mode".

   Note: The "RPM Difference" is a function under the "PROC" option on the PDT.

4. If the values are not to the proper specification, check the governor actuator linkage.

   Note: While the engine is stopped, the actuator rod should extend 33.0 to 33.5 mm (1.3 to 1.4 inch) from the large nut on the actuator housing. Refer to dimension (A) in Illustration 1.

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Illustration 1	g00541044
(A) Length of actuator rod (1) Low idle stop (2) High idle stop

5. Recalibrate the engine speed dial. Refer to Testing and Adjusting, "Engine Speed - Adjust" for the proper procedure.

   Note: This will ensure that the full range of the engine speed dial is used to control the engine speed.

6. Calibrate the governor actuator (speed calibration).

   1. Enter a low idle speed of 900 to 950 rpm on the PDT.

   2. Save the values in the PDT.

7. Recheck the governor actuator.

8. Record the low idle in Table 1.

9. Record the high idle in Table 1.

Difference in Engine RPM

1. After performing the previous engine calibrations, record the rpm difference in the "After Calibration" column in Table 2 for Mode I, Mode II and Mode III.

   Note: To use the "RPM Difference" function on the PTS, select the "Status" option and create a "New Group" that includes "Engine RPM", "RPM Difference" and "Mode".

   Note: The "RPM Difference" is a function under the "PROC" option on the PDT.

2. Record the rpm difference in high idle in Table 2 for Mode I, Mode II and Mode III.

   Note: To use the "RPM Difference" function on the PTS, select the "Status" option and create a "New Group" that includes "Engine RPM", "RPM Difference" and "Mode".

   Note: The "RPM Difference" is a function under the "PROC" option on the PDT.

Illustration 2	g00541046
RPM Difference (B) RPM difference (3) "Loaded" engine speed (4) "No Load" engine speed

Note: The difference in engine rpm is the difference between the "No Load" engine speed and the "Loaded" engine speed. Refer to Table 2.

The correct difference must be maintained between the "No Load" and the "Loaded" engine speeds. If the difference is too low, the pumps will prematurely destroke. This will result in slower implement response times.

If the difference is too high, the pumps may destroke too late. This will cause excessive engine lug in Mode III when you travel on steep grades.

Note: The difference in engine rpm can only be read. Adjustments must be made on the "No Load" engine speed and on the "Loaded" engine speed in order to obtain the correct differences.

Note: The "Initial Measurement (Prior to any Adjustment)" and "After Calibration" columns should be filled with the appropriate values from the procedures.

Relief Valve (Pilot) - Test and Adjust

1. Record the pilot pressure in Table 3.

2. If necessary, adjust the pilot pressure.

   Note: Low pilot pressure can cause sluggish response from the implement. The parking brakes might be applied unexpectedly because of low pilot pressure.

Margin Pressure - Test and Adjust

1. Record the margin pressure in Table 4.

2. If necessary, adjust the margin pressure.

   Note: Low margin pressure can cause sluggish response from the implement.

Relief Valve (Signal Limiter) - Test and Adjust

1. Stall the bucket circuit.

2. Record the load sensing signal limiter pressure in Table 5.

3. If necessary, adjust the load sensing signal limiter pressure.

   Note: Low load sensing signal pressure can decrease the lifting capability. This can also reduce the breakout force of the bucket.

Solenoid Valve (Pump Pressure Proportional Reducing) - Test and Adjust

1. Record the main pump PRV pressure for Mode I in Table 6.

2. Record the main pump PRV pressure for Mode II in Table 6.

3. Record the main pump PRV pressure for Mode III in Table 6.

   Note: Correct PRV pressures are needed in order to regulate the main pump.

Main Pump (Destroke Pressure) - Test and Adjust

1. Record the main pump destroke pressure in Table 7.

2. If necessary, adjust the main pump destroke pressure.

   Note: If the main pump destrokes too early, hydraulic horsepower will be lost. If the main pump destrokes too late, additional load will be required from the engine.

Engine Speed - Adjust (Load)

1. Record the PRV pressure for Mode I in Table 8.

2. Record the PRV pressure for Mode II in Table 8.

3. Record the engine rpm for Mode III in Table 8.

4. If necessary, adjust the parameters.

   Note: Refer to Testing and Adjusting, "Engine Speed - Adjust (Load)".

   The values must be correct to maintain the balance between the available engine horsepower and the demand for hydraulic power. The engine load speed is stored in the controller.

   When the actual engine operating speed approaches the "Loaded" engine speed, the controller begins to destroke the main pump in order to maintain the ideal engine speed. Refer to Table 8.

   Deviations from the "Loaded" engine speed are called the load shift rpm. This adjustment is typically needed after the main pump or the engine has been replaced.

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   Table 8

   Main Pump PRV at High Idle (Load)
   	Specification		Initial Measurement (Prior to any Adjustment)	After Calibration
   Main Pump PRV at High Idle (Load)	Mode I	1420 to 1520 kPa (205 to 220 psi)
   Main Pump PRV at High Idle (Load)	Mode II	1750 to 1850 kPa (245 to 268 psi)
   Main Pump PRV at High Idle (Load)	Mode III	1950 to 2000 rpm

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Illustration 3	g00541045
Load rpm shift (Mode III) (C) Load rpm shift (3) "Loaded" engine speed (4) "No Load" engine speed

5. Record the rpm difference in the "After Setting the Engine Speed" column in Table 2.

   Note: The "RPM Difference" is a function under the "PROC" option on the PDT.

Swing Pump PRV

1. Record the swing pump PRV pressure for Mode I in Table 9.

2. Record the PRV pressure for Mode II in Table 9.

   Note: The swing pump PRV pressures for the swing circuit are used to determine the swing speed. The pressure acts on the swing servo piston or the spring. The servo is attached to the swashplate on the swing pump. The servo determines the pump flow as the swashplate moves.

   Since Mode II has a higher PRV pressure, the servo shifts farther and the swing speed increases. If the PRV pressures are incorrect, the swing speed will vary accordingly since the swing pump is not signalled by the controller.