SC-57 Felling Head Felling Head Caterpillar

Note: Some machines may be equipped with a disc saw blade with heavier bolt-on segments that changes the inertia of the disc saw blade. The performance of the saw may vary depending on the equipment and operating conditions.

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Personal injury can result from rotating and moving parts. Stay clear of all rotating and moving parts. Never attempt adjustments while the machine is moving or the engine is running unless otherwise specified. The machine must be parked on a level surface and the engine stopped.

1. Prepare the machine for adjustment.

   ReferenceTesting and Adjusting, "Preparation for Troubleshooting".

2. Warm the hydraulic oil to normal operating temperature. Normal operating temperature is 45 °C (115 °F) to 70 °C (160 °F). Use the following procedure in order to warm the hydraulic oil.

   1. Operate the engine at 1800 RPM to 2000 RPM.

   2. Move lift until you reach the normal operating temperature.

3. Lower the felling head to the ground. Shut off the engine.

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Illustration 1	g02511108

4. Install the transport guard on the felling head.

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Illustration 2	g02586796
(1) Bolt. (2) Access plate.

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Illustration 3	g02586797
(1) Bolt. (2) Access plate.

5. Remove bolts (1) from access plate (2) on each side of the felling head.

   Note: Hold access plate (2) in place when you remove the last bolt in order to keep access plate (2) from falling.

6. Remove access plates (2) .

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Illustration 4	g02568306
Felling Head without plate (3) Pressure tap on saw motor. (M) Pressure tap on the shuttle valve.

7. Attach the 198-4240 Digital Pressure Indicator to pressure port (3) (discharge pressure port of the saw pump) that is on the machine.

   Note: Pressure port (3) will read system pressure of the saw. This pressure will be the output from the saw pump that is on the machine.

8. Locate the access hole on the front of the felling head. The access hole is in the transport guard. Refer to Illustration 1

9. Thoroughly clean the top surface of the disc saw in order to ensure the accuracy of the following test.

   Note: The disc saw has a shiny surface. The photo pickup may not be able to recognize the reflective tape. You may need to paint the top of the disc saw with a suitable black paint. Use 4C-5842 Black Paint or an equivalent, in order to obtain an accurate measurement from the reflective tape.

10. Place one 3 inch strip of reflective tape on the surface of the disc saw. Position the tape so that the tape is perpendicular to the hub of the disc saw.

11. Install the magnetic base onto the transport guard. Position magnetic base at the edge of the access hole.

    Note: Ensure that you position the wire for the photo pickup so that the wire does not contact any moving parts or hot surfaces.

    Note: Position the photo pickup no less than 2 inches away from the reflective tape. Tighten the pinch bolt in order to prevent the photo pickup from falling into the access hole.

12. Observe the reading on the display of the 348-5430 Multi-Tool Gp . Record the speed of the disc saw. The speed should be 1250 RPM.

13. Start the engine. Increase the engine speed to 2250 ± 10 RPM.

14. The performance of the saw should be to the following steps.

    1. (Stage 1) The saw pump is upstroking and the saw motor is at maximum displacement. This stage lasts for 12 to 15 seconds. Read the inlet pressure of the motor at port (3) . The pressure should be 27580 ± 345 kPa (4000 ± 50 psi).

    2. (Stage 2) The saw pump is at maximum displacement and the saw motor is destroking. This stage will last for 15 to 18 seconds. Read the inlet pressure of the saw motor at pressure tap (M) should be 24130 kPa to 24821 kPa (3500 psi to 3600 psi). Refer to the "Adjust the Compensator of the Saw Motor".

    3. (Stage 3) The saw pump is at maximum displacement and the saw motor is at minimum displacement. The inlet pressure of the saw motor falls significantly. The saw will reach full speed.

(Stage 1) If the inlet pressure at the saw motor is not within the limit, then adjust the pressure of the saw pump. Refer to the "Adjust the Compensator of the Piston Pump (Disc Saw)".

(Stage 2) If the inlet pressure at the saw motor is not within the limit, then adjust the pressure of the saw motor. Refer to the "Adjust the Compensator of the Saw Motor".

(Stage 3) If the disc saw does not reach full speed, then adjust the speed of the disc saw. Refer to the "Adjust the Speed of the Disc Saw".

Note: If the saw motor is equipped with a sleeve for higher maximum displacement, additional horsepower will be used in the circuit of the disc saw.

The inertia of the disc saw blade will be greater than the inertia of the one-piece disc saw blade.

Adjust the Compensator of the Piston Pump (Disc Saw)

The saw pump supplies oil to the saw motor. This procedure demonstrates how to adjust the saw pump pressure.

Note: Machine Operator Required

Note: Parking brake must be set and cab doors must be closed before machine can be started or operated.

Note: Shut down engine, remove key, and remove engine left side screen. Thoroughly clean the area to be serviced.

Illustration 5	g02563761
Hydraulic Diagnostic Center on older models (N) Saw Pump Pressure Port

Illustration 6	g02719675
Hydraulic Diagnostic Center on newer models (N) Saw Pump Pressure Port

1. Attach the 8T-0856 Pressure Gauge to Saw Pump Pressure Port (N) at the Hydraulic Diagnostic Center shown in Illustration 5.

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Illustration 7	g02580859

2. Block the disc saw from turning using the supplied transport bolt. Shown in Illustration 7.

3. Remove all personnel from the area. Have the operator start the engine, and bring engine to required 1200 RPM. Bring oil temperature to 60° C (140° F) by holding bunching finger over relief while pressing Interlock Bypass switch.

4. Have the operator increase engine speed to HIGH IDLE and press the ATTACHMENT RUN switch on the right dash. Observe the 8T-0856 Pressure Gauge . The pressure should read 27580 ± 345 kPa (4000 ± 50 psi).

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Illustration 8	g02565216
Left side view of saw pump showing compensator adjusting screw on older models

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Illustration 9	g02719741
View of saw pump showing compensator adjusting screw on newer models

5. Pressure must be adjusted if not correct. To adjust pressure, follow these steps:

   1. Shut down the engine.

   2. Gain access to saw pump on left side of machine. Locate compensator adjusting screw (4) .

   3. Loosen seal lock nut with 13 mm (0.5 inch) Box End Wrench .

   4. While holding the seal lock nut, place the 11 mm (0.45 inch) Box End Wrench on the adjustment screw. Turn the screw IN clockwise to increase pressure and OUT counter clockwise to decrease pressure.

      Note: DO NOT TURN MORE THAN 1/4 TURN AT A TIME.

   5. Hold the adjusting screw stationary while tightening the seal lock nut to secure the setting.

6. Repeat steps 3 - 5 until pressure is correct.

7. Shut down engine. Remove 8T-0856 Pressure Gauge . Remove transport bolt. Install the engine left side screen.

Adjust the Compensator of the Saw Motor

The following procedure adjusts the start of destroke pressure for the saw motor.

The saw pump supplies oil to the saw motor. The saw motor starts at maximum displacement. After the pump pressure to the saw motor drops from the maximum to the pressure of the compensator, the displacement of the saw motor decreases. The compensator pressure controls the shift point of the saw motor from maximum displacement to minimum displacement. The compensator pressure will be adjusted in this procedure.

Note: The following procedure requires two people. The procedure should be performed outside.

1. Block the disc saw from turning using the transport bolt as shown in Illustration 7.

2. Connect the pressure gauge to pressure tap (M) .

3. Start the engine.

4. Increase the engine speed to 2250 ± 10 RPM.

   Note: The switch for the disc saw must be activated in order to perform this test. Activate the switch for the disc saw.

5. Temporarily set the compensator valve of the saw pump to 24130 ± 345 kPa (3500 ± 50 psi) on the machine. Ensure that the pressure gauge at pressure port (3) reads the pressure that is given above. This pressure reading will be the output of the saw pump that is on the machine.

   Note: Refer to the "Adjust the Compensator of the Piston Pump (Disc Saw)".

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Illustration 10	g02568578
Felling Head without plate (2) (5) Displacement valve. (6) Cap. (7) Adjustment screw.

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Illustration 11	g02568617
Displacement Control Valve (8) Locknut

6. Remove cap (6) . Loosen locknut (8) . Turn adjustment screw (7) on displacement control valve (5) until the pressure reading from pressure tap (M) reads 2750 ± 690 kPa (400 ± 100 psi).

   Note: The adjustment screw is sensitive. The pressure may rise from this pressure to a much higher pressure with little change on the adjustment screw. This increase indicates that the shift point for the motor has been reached. If the shift point of the motor changes, the performance of the saw will change.

7. When the correct pressure has been reached, tighten locknut (8) to a torque of 69 N·m (50 lb ft). Install cap (6) .

8. Reset the discharge pressure on the saw pump that is located on the machine. Reset the discharge pressure to 27580 ± 345 kPa (4000 ± 50 psi).

   Note: Refer to the "Adjust the Compensator of the Piston Pump (Disc Saw)".

9. If the pressure at the inlet of the saw motor is not within the specification for Stage 2 of the saw performance test. Then repeat Steps 5 through 9. Adjust the pressure in Step 5. Use increments of 345 kPa (50 psi) above the pressure setting or below the pressure setting for the machine that is being serviced. Adjust the pressure of the saw pump until the specification is reached. If the pressure of the saw motor is within the specification, then proceed to Step 10.

10. Turn the switch for the disc saw to the OFF position.

11. Reduce the engine speed to low idle.

12. Shut off the engine.

13. Remove the hoses and pressure gauges.

14. Install access plates (2) with bolts (1) .

15. Repeat the test for the saw performance.

Adjust the Speed of the Disc Saw

The saw pump supplies oil to the saw motor. The flow of oil from the saw pump controls the speed of the disc saw. The displacement of the saw motor cannot be adjusted. Use the following procedure to check that the maximum displacement is set to the correct specification. Two people are required for the following procedure.

Note: There is no need to start the engine during this procedure.

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Illustration 12	g02511108

1. Install the transport guard.

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Illustration 13	g02568778
(9) Displacement adjusting stud on older models

2. Gain access to the saw pump by removing the front left engine side screen. Thoroughly clean the area around the displacement adjusting stud (9) .

3. Hold the stud stationary with a 6 mm (0.24 inch) Allen Wrench and loosen the seal nut with a 19 mm (0.75 inch) Open End Wrench .

   Note: Record the number of turns required to complete 4.

4. Turn the stud counterclockwise OUT until you feel the stud lose contact with the stroking piston inside the pump. Record the number of turns required.

5. Carefully turn the stud clockwise IN until you feel the stud touch the stroking piston, then turn the stud clockwise IN 1/8 turn more. The pump is now at the maximum displacement of 125 L/min (33 US gpm). Hold the stud while tightening the seal nut to secure the setting.

6. Retighten the seal nut and torque the nut to 87 N·m (64 lb ft).

7. Start engine and check the serviced area for leaks. If no leaks are detected, shut down the engine, remove the key and secure all access openings.