Testing and Adjusting

Usage:

Troubleshooting

Machine Preparation for Troubleshooting

SMCS Code:4250-035

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine.

To prevent possible injury, perform the procedure that follows before testing and adjusting the steering system.

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Personal injury or death can result from escaping fluid under pressure.
Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

Always use a board or cardboard when checking for a leak.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide," for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

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

NOTE: Permit only one operator on the machine. Keep all other personnel away from the machine or in the operator's sight.

2. Put the transmission control in the NEUTRAL position and any speed position. Engage the primary steering/transmission lock lever (STIC steer machines) or the transmission neutral lock (wheel steer machines).

3. Engage the parking brake. Place wheel blocks in front of the wheels and behind the wheels.

4. Lower the bucket or the attachments to the ground.

5. Install the steering frame lock pin.

6. Stop the engine.

7. Move the hydraulic control lever several times through the full range of travel. This will release any pressure that may be present in the implement hydraulic system.

8. Move the STIC steering control several times in both directions to release the pressure in the steering system.

9. Release the braking system oil pressure.

Reference: For the correct procedure to release the braking system oil pressure, refer to Systems Operation, Testing and Adjusting, "Braking System Pressure - Release" for the machine that is being serviced.

10. Depress the breaker relief valve on the hydraulic tank in order to release the hydraulic oil pressure.

11. The pressure in the hydraulic system has been released. Lines and components can be removed.

When you are analyzing a hydraulic system for poor performance, remember that correct oil flow and correct oil pressure are necessary for correct operation. Oil flow is a function of the pump output. The pump output is a function of engine speed. A restriction to the flow of oil causes oil pressure.

Visual Inspection

SMCS Code:4250-035

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Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

Always use a board or cardboard when checking for a leak.

1. Check the oil level in the hydraulic tank. Locate the breaker relief valve on the hydraulic oil tank. Press and hold down the plunger on the breaker relief valve. Permit the pressure in the hydraulic tank to be removed before the cap is removed.

2. Inspect all oil lines and connections for leaks, wear or damage.

3. Check the tightening torque of all bolts.

4. Remove the filter elements. Check for foreign material. Use a magnet to check for metal material. If metal material is found, the component with damage needs to be located and repaired. The hydraulic system must then be flushed.

Braking System Troubleshooting

SMCS Code:4250-035

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Always use a board or cardboard when checking for a leak.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar tools and Shop Products Guide," for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulation and mandates.

This section provides probable causes to known problems. Since there may be several probable causes, specific inspections or instrument tests may be recommended. These inspections and tests will help identify the causes that are most probable.

NOTE: Before making any test of the braking system, ensure the oil in the system is at operating temperature. Check for correct accumulator charging pressure and correct nitrogen charge in the accumulators.

NOTE: Make sure that you use an oil with the correct viscosity for the operating conditions.

Reference: For additional information about the various lubricant viscosities for your machine, refer to Operation and Maintenance Manual, "Lubricant Viscosities" for the machine that is being serviced.

Troubleshooting Problem List

Service Brake Problem List

1. Service brakes slow to apply.

2. The accumulator pressure will not reach cut-out pressure at low idle. This typically causes a Warning Category 3 to occur. This problem may also engage the parking brake.

3. The front service brakes do not operate and the warning system is not activated.

4. The rear service brakes do not operate and the warning system is not activated.

5. The service brakes slip and the warning system is not activated.

6. The service brakes are not applied evenly.

7. Service brakes will not release completely.

8. Pedal kickback when brakes are applied.

Parking Brake Problem List

9. The parking brake will not disengage.

10. The parking brake does not engage when the parking brake control knob is pulled out.

Service Brake Problems

Problem 1: Service brakes slow to apply.

Probable causes:

1. No gas charge in accumulators.

2. The brake discs and associated components in the axle housing are excessively worn.

3. Hydraulic lines or fittings leaking.

4. Damaged hydraulic brake lines.

5. Air in braking system.

Problem 2: The accumulator pressure will not reach cut-out pressure at low idle. This typically causes a Warning Category 3 to occur. This problem may also engage the parking brake.

Probable causes:

1. When the hydraulic oil is hot and the engine is running at low idle, the output of the brake and pilot pump is not sufficient to overcome the pump's own internal losses.

Problem 3: The front service brakes do not operate and the warning system is not activated.

Probable causes:

1. The brake group within the axle housing is damaged.

2. The lines to the front service brakes are obstructed.

3. The front circuit of the service brake control valve is faulty

Problem 4: The rear service brakes do not operate and the warning system is not activated.

Probable causes:

1. The brake group within the axle housing is damaged.

2. The lines to the rear service brakes are obstructed.

3. The rear circuit of the service brake control valve is faulty.

Problem 5: The service brakes slip and the warning system is not activated.

Probable causes:

1. One or both axles contain an incorrect oil additive.

2. The brake discs in the axle housings are worn.

Problem 6: The service brakes are not applied evenly.

Probable causes:

1. The brake discs and associated components in the axle housing are excessively worn.

2. The service brake control valve is sticking because of contaminated oil.

3. The service brake control valve is not delivering the correct amount of pressure.

Problem 7: Service brakes will not release completely.

Probable causes:

1. The brake group within the axle housing is damaged.

2. Pedal angle out of adjustment.

3. Defective service brake control valve.

4. Back pressure on return line too high.

Problem 8: Pedal kickback when brakes are applied.

Probable causes:

1. Air in braking system.

Parking Brake Problems

Problem 9: The parking brake will not disengage.

Probable causes:

1. The brake group within the axle housing is damaged.

2. Parking brake solenoid control valves sticking or faulty.

3. Parking brake solenoid control valves not activating because of an electrical fault.

Problem 10: the parking brake does not engage when the parking brake control knob is pulled out.

Probable causes:

1. Parking brake control switch faulty.

2. Parking brake relay faulty.

3. Parking brake solenoid control valves sticking or faulty.

Brake Control Valve (Service) Troubleshooting

SMCS Code:4265-035

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Always use a board or cardboard when checking for a leak.

NOTE: Before making any tests of the service braking system, ensure the oil in the system is at operating temperature. Check for correct accumulator charging pressure and correct nitrogen charge in the accumulators.

Troubleshooting Problem List

Brake Control Valve Problem List

1. Service brakes will not release completely.

2. Service brakes will not release.

3. Service brakes will not apply.

4. Excessive accumulator leakage when service brakes are applied.

5. Excessive accumulator leakage when service brakes are not being used.

6. Insufficient service brakes.

Brake Control Valve Problems

Problem 1: Service brakes wild not release completely.

Probable causes:

1. Piston (1) binding.

2. Pedal angle out of adjustment.

3. Spring (5) broken.

Service Brake Control Valve

(1) Piston.

(2) Spring (not shown).

(3) Upper valve spool.

(4) Lower valve spool.

(5) Spring.

Problem 2: Service brakes will not release.

Probable causes:

1. Binding spools (3) & (4).

2. Piston (1) binding.

Problem 3: Service brakes will not apply.

Probable causes:

1. Piston (1) binding.

2. Broken spring (2).

Problem 4: Excessive accumulator leakage when service brakes are applied.

Probable causes:

1. Damaged spools (3) & (4).

Problem 5: Excessive accumulator leakage when service brakes are not being used.

Probable causes:

1. Damaged spools (3) & (4).

Problem 6: Insufficient service brakes.

Probable causes:

1. Broken spring (2).

2. Pedal travel is inhibited.

Braking System Pressure - Release

SMCS Code:4250-553-PX

This procedure should be followed when the technician is removing a hydraulic line or a hydraulic component.

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Always use a board or cardboard when checking for a leak.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide", for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

1. Engage the parking brake. Stop the engine.

Location of the Service Brake Pedal

(1) Service brake pedal.

2. Depress service brake pedal (1) at least 80 times to remove oil pressure from the brake accumulators.

Location of the Brake Pressure Test Point

(2) Brake pressure test point.

3. Check the readings on the brake pressure gauges (if equipped) on the dash panel are 0 kPa (0 psi) when the brake pedal is depressed. If gauges are not fitted then connect a 0-15 850 kPa (0-2300 psi) pressure gauge with a quick connect coupling to test point (2). Check the pressure on the gauge.

4. If the pressure on any of the gauges does not read 0 kPa (0 psi), repeat Steps 2 through 4.

Pump Flow - Test

SMCS Code:5073-032-ON; 5073-032-TB

Reference: For additional information on the Specifications for the hydraulic pump, refer to Service Manual Module for Specifications for the machine that is being serviced.

This test is designed to determine whether a pump is operating within design parameters. Presently, only a bench test is available for this purpose. This test should be performed only if all cylinder cycle times are too slow.

For any pump test, the pump flow at 690 kPa (100 psi) will be larger than the pump flow at 6900 kPa (1000 psi) if the pump is operating at the same rpm. The pump flow is measured in L/min (US gpm).

The difference between the pump flow of two operating pressures is the flow loss.

NOTE: The values in the examples are not set values for any specific pump or for any specific pump condition. See the Specification for the pump flow of a new pump at 690 kPa (100 psi) and 6900 kPa (1000 psi).

Table 1

Table 2

Flow loss that is expressed as a percentage of pump flow is used as a measure of pump performance.

Table 3

Table 4

Machine Test

Install a flow meter. Run the engine at high idle. Measure the pump flow at 690 kPa (100 psi) and at 6900 kPa (1000 psi). Use three values in the formula in Table 5.

Table 5

Bench Test

If the test bench can be run at 6900 kPa (1000 psi) and at full pump rpm, use the formula in Table 5 to determine the percent of flow loss.

If the test bench cannot be run at 6900 kPa (1000 psi) or at full pump rpm, run the pump shaft at 1000 rpm. Measure the pump flow at 690 kPa (100 psi) and at 6900 kPa (1000 psi). Use these values in the top portion of the formula in Table 6. For the bottom part of the formula, run the pump shaft at 2000 rpm. Measure the pump flow at 690 kPa (100 psi).

Table 6

Brake Accumulator - Test and Charge

SMCS Code:4263-045; 4263-081

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Dry nitrogen is the only gas approved for use in the accumulators. The charging of oxygen gas in an accumulator will cause an explosion. An explosion can be eliminated by using nitrogen gas cylinders with standard CGA (Compressed Gas Association, Inc.) No. 580 connectors. When nitrogen gas is ordered, make sure to order the cylinders with CGA No. 580 connectors.

Do not rely on color codes or other methods of identification to tell the difference between nitrogen and oxygen cylinders. In any application, never use an adapter to connect your nitrogen charging group to a valve outlet used on both nitrogen, oxygen or other gas cylinders. BE SURE YOU USE DRY NITROGEN (99.8% purity).

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication NENG2500, "Caterpillar Tools and Shop Products Guide," for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

Stop the engine. Release the braking system oil pressure.

Reference: For the correct procedure to release the braking system oil pressure, refer to Systems Operation, Testing and Adjusting "Braking System Pressure - Release" for the machine that is being serviced.

The accumulator piston must be on the bottom of the cylinder to be sure that the pressure of the nitrogen charge is correct.

Gas pressure is variable with temperature. The accumulator must be at the same temperature as the air around it before it can be checked or charged.

Nitrogen Charging Group

(1) Pressure gauge.

(2) Connection to nitrogen cylinder valve.

(3) Regulator assembly.

(4) Valve.

(5) Pressure gauge.

(6) Pressure regulating screw.

(7) Valve handle.

(8) Chuck.

Use the following chart for the correct nitrogen charging pressure for the service brake accumulator.

Test Procedure

1. Remove cover (10) and cap (9) from the valve assembly on the accumulator.

2. Use a 0 to 13 800 kPa (0 to 2000 psi) gauge (5) to check the nitrogen charge in the accumulator.

Parts from Nitrogen Charging Group

(4) Valve.

(5) Pressure gauge.

(7) Valve handle.

(8) Chuck.

3. Install chuck (8) on the valve on the accumulator.

4. Turn valve (7) on chuck (8) completely in (clockwise). Check the temperature of the air around the accumulator. The reading on the pressure gauge must be within the tolerances shown in the chart.

Service Brake Accumulator

(9) Cap.

(10) Cover.

5. If the reading on the pressure gauge is too high, slowly open valve (4) to lower the pressure.

6. If the reading on the pressure gauge is too low, use the following procedure to charge the brake accumulator.

Charge Procedure

1. Connect the hose from the nitrogen cylinder to valve (4).

2. Close valve (4) and open the valve on the nitrogen cylinder. Make an adjustment to screw (6) on the regulator assembly until gauge (1) is at the pressure needed to correctly put a charge into the accumulator. Use the chart as a reference for the correct charging pressure.

3. Open valve (4) and put a charge into the accumulator. Close valve (4). If the pressure on gauge (5) is the same as gauge (1) and does not change, the accumulator has the correct charge. If there is a decrease in pressure on gauge (5), open valve (4) and let more nitrogen go to the accumulator. Do this procedure as many times as necessary until the pressure on gauge (5) is the same as gauge (1) and does not change when valve (4) is closed.

4. Close valve (4). Close the valve on the nitrogen cylinder.

5. Turn valve (7) on chuck (8) completely out (counterclockwise).

6. Remove the test equipment.

7. Fit cap (9) and cover (10).

8. Perform this procedure for the other brake accumulator.

Charge Procedure for a New or Rebuilt Accumulator

It is necessary to remove all air from the nitrogen chamber of the brake accumulator. When the accumulator is new or rebuilt, put approximately 1.9 L (0.5 US gal) of SAE 10W hydraulic oil in the nitrogen end of the accumulator. This oil will be used to help remove the air out of the nitrogen chamber of the brake accumulator and also to put lubricant at the top seal of the accumulator piston. After the brake accumulator is installed on the machine, charge it as follows:

1. Use the same equipment as used to check the nitrogen charge in the brake accumulator.

2. Install chuck (8) on the accumulator valve.

3. Turn valve (7) on chuck (8) completely in (clockwise). Open valve (4).

4. Start and run the engine until it reaches normal operating temperature. As hydraulic oil goes into the bottom of the brake accumulator, the air and then the oil will be pushed out of the top through the test equipment. When the oil flow stops, the top of the accumulator will be free of air.

5. Close valve (4) completely.

6. Stop the engine. Release the braking system oil pressure. When there is no pressure in the system, the piston in the brake accumulator will be at the top of the accumulator.

7. Put a charge of nitrogen in the brake accumulator. Follow the procedure in Steps 1 through 8 in "Charging Procedure." The charging cycle will take longer because the piston will have to be moved to the bottom and the oil will have to be moved out of the brake accumulator.

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NOTICE

Low nitrogen charge can cause early pump failure because of short cycle times between the cut-in and cut-out operations of the brake accumulator charging valve.

Accumulator Charging Valve (Brake) - Test and Adjust

SMCS Code:4264-025; 4264-081

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Always use a board or cardboard when checking for a leak.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication NENG2500, "Caterpillar Tools and Shop Products Guide," for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

NOTE: There are two separate procedures that may be used to check the operation of the accumulator charging valve and several associated components.

Procedure 1 is a quick method to check for correct cut-out pressure and indicates whether or not the low brake oil pressure switch and alert indicator are working correctly. It will also provide an estimate of the accumulator pre-charge pressure and indicate approximately how many brake applications an operator may have before the low brake oil pressure alert indicator turns on (providing the service brake system is operating correctly).

Procedure 2 determines if the cut-in and cut-out pressures for the accumulator charging valve are correct. It also provides the steps required to adjust the accumulator charging valve.

Procedure 1

1. Stop the engine. Engage the parking brake. Depress the service brake pedal at least 80 times to remove oil pressure from the brake accumulators.

Location of the Accumulator Charging Valve Pressure Test Point

(1) Accumulator charging valve.

(2) Test Point.

2. Connect a 0 to 20 700 kPa (0 to 3000 psi) pressure gauge and hose to test point (2) on accumulator charging valve (1).

3. Look at the pressure gauge. Before the engine is started the oil pressure must be 0 kPa (0 psi).

4. Start the engine. Allow the oil pressure to increase to the cut-out pressure. The correct cut-out pressure should be 14 485 ± 345 kPa (2100 ± 50 psi).

5. After the service brake accumulators have been completely charged and the cut-out pressure has been obtained, stop the engine.

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

7. Apply the service brakes repeatedly, pausing for a second or two between each brake application. Count the number of brake application while watching the pressure gauge.

8. When the pressure on the gauge decreases to 8300 ± 345 kPa (1200 ± 50 psi), low brake oil pressure alert indicator (3) on the dash panel should illuminate. This will indicate the operational status of the low brake oil pressure switch and alert the indicator.

Dash Panel

(3) Low brake oil pressure alert indicator.

9. Continue applying the service brakes and pausing for a second or two between each brake application. Also continue counting the number of applications and observing the pressure gauge. There will be a point where the pressure drops off rapidly. The point where the pressure drops of rapidly is the approximate nitrogen charge (pre-charge) pressure in the accumulators.

10. Determine the number of brake applications that were required before the pressure dropped off rapidly in Step 9. The number of service brake applications should be approximately 75 times.

11. If the accumulator charging valve cut-out pressure is not within specification, complete Steps 7 through 12 in procedure 2. If the precharge pressure is not within specification test the brake accumulator for the correct charge pressure.

Reference: For the correct nitrogen pre-charge pressure and for information on testing the brake accumulator, refer to Systems Operation, Testing and Adjusting, "Brake Accumulator - Test and Charge" for the machine that is being serviced.

Procedure 2

1. Stop the engine. Engage the parking brake. Depress the service brake pedal at least 80 times to remove oil pressure from the brake accumulators.

Location of the Accumulator Charging Valve Pressure Test Point

(1) Accumulator charging valve.

(2) Test point.

2. Connect a 0 to 20 700 kPa (0 to 3000 psi) pressure gauge and hose to test point (2) on accumulator charging valve (1).

3. Look at the pressure gauge. Before the engine is started the oil pressure must be 0 kPa (0 psi).

4. Start the engine. Raise the engine speed to high idle. Look for a stop (pause) in the increase in oil pressure. Make a record of the oil pressure at this point. This is the approximate nitrogen charge (pre-charge) pressure in the accumulators. If the pre-charge pressure is not within specification test the brake accumulator for the correct charge pressure.

5. The oil pressure must increase to a maximum pressure. Make a record of this pressure also. This is the cut-out pressure of the accumulator charging valve. The correct cut-out pressure should be 14 485 ± 345 kPa (2100 ± 50 psi).

6. Apply the service brakes several times while the engine is running. Confirm that the pressure drops consistently and at he point of specified cut-in, the pressure begins to increase quickly. The cut-in pressure should be 11 75 ± 345 kPa (1700 ± 50 psi).

7. If the cut-in and cut-out pressure are not within specification, stop the engine and completely remove all oil pressure from the brake circuit by repeating Steps 1 through 3. Be sure there is no residual pressure in the hydraulic tank by depressing the breaker relief valve.

Accumulator Charging Valve

(3) Cover plug for the adjustment screw.

8. Remover cover plug (3) for the adjustment screw.

NOTE: The charge limits will move together. The range between the cut-in and cut-out pressures is not adjustable.

9. Turn the hex plug that is located under cover plug (3), one quarter of a turn. Turning the hex plug clockwise will increase the cut-in and cut-out pressure. Turning the hex plug counterclockwise will decrease the cut-in a cut-out pressure.

10. Install cover plug (3) on the accumulator charging valve.

11. Start the machine and verify that the cut-in and cut-out pressures are within specification. If they are not within the specification, repeat Steps 7 through 11.

12. If the cut-in and/or cut-out pressures can not be adjusted within the specification, the accumulator charging valve may need to be replaced or repaired.

Service Braking System Pressure - Test

SMCS Code:4250-032-PX

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Personal injury or death can result if two persons are not used in the following procedure.

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Always use a board or cardboard when checking for a leak.

1. Stop the engine. Place the transmission direction control in the NEUTRAL position.

2. Engage the parking brake.

3. Release the braking system oil pressure.

Location of the Front Axle Service Brake Pressure Test Point

(1) Front service brake test point.

4. Remove the protective cap from test point (1) on the front axle. Attach the correct hose and pressure gauge to the pressure test point.

5. Look at the pressure gauge. The oil pressure must be 0 kPa (0 psi).

6. Start the engine and allow the hydraulic oil to reach normal operating temperature.

7. With the accumulator charging oil at full operating pressure, depress and hold down the service brake pedal and look at the pressure gauge. The brake pressure should be 4310 ± 345 kPa (625 ± 50 psi).

8. If the brake oil pressure is not in the correct range and the brake accumulator charging valve is functioning correctly, replace the service brake control valve.

Location of the Rear Axle Service Brake Pressure Test Point

(2) Rear service brake test point.

9. Repeat this procedure for the rear service brakes at test point (2) on the rear axle.

NOTE: The pressure at the rear brakes should be approximately 345 kPa (50 psi) higher than the pressure at the front brakes.

Foot Brake Control - Check and Adjust

SMCS Code:4269-535-FU; 4269-025-FU

If the service brake pedals become out of position, perform the following procedure.

This procedure will set the service brake pedal to the proper position.

NOTE: Adjust the service brake pedals to the proper position. Check the adjustment of the stop light switch and the transmission neutralizer switch.

Reference: For the correct procedure to adjust the stop light switch, refer to Braking System Specifications, "Limit Switch (Stop Light)" for the machine that is being serviced.

Reference: For the correct procedure to adjust the transmission neutralizer switch, refer to Systems Operation, Testing and Adjusting, "Limit Switch (Transmission Neutralizer) - Adjust" for the machine being serviced.

Location of the Service Brake Pedals

(1) Service brake and transmission neutralizer pedal.

(2) Service brake pedal.

Left Service Brake Pedal Assembly

(A) Angle of the service brake pedal.

(3) Adjustment screw.

(4) Jam nut.

NOTE: When the left or right service brake pedal is in the RELEASED position, angle (A) should equal 30 ± 1°.

1. Loosen jam nut (4). Rotate screw (3) to adjust the left service brake pedal to equal angle (A).

2. Rotate screw (3) clockwise to increase the angle of dimension (A). Rotate screw (3) counterclockwise to decrease the angle of dimension (A).

3. Adjust the service brake pedal to the correct angle (A). Tighten jam nut (4) against the brake pedal assembly.

Limit Switch (Transmission Neutralizer) - Adjust

SMCS Code:4269-025-ZS

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Personal injury or death can result if two persons are not used in the following procedure.

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Always use a board or cardboard when checking for a leak.

1. Stop the engine. Place the transmission in NEUTRAL position.

2. Engage the parking brake.

3. Release the braking system oil pressure.

Location of the Front Axle Service Brake Pressure Test Point

(1) Front service brake test point.

4. Remove the protective cap from test point (1) on the front axle. Attach the correct hose and pressure gauge to the pressure test point.

Left Service Brake Pedal Assembly

(2) Pedal.

(3) Screw.

(4) Plug.

(5) Receptacle assembly.

5. Disconnect receptacle assembly (5) from the machine wiring harness.

6. Connect an ohmmeter (or continuity tester) to Pin 1 and Pin 4 of receptacle assembly (5). With pedal (2) in the retracted position (fully released), the ohmmeter should indicate a closed circuit condition.

7. Start the engine and allow the hydraulic oil to reach normal operating temperature.

8. With the accumulator charging oil at full operating pressure, depress the left brake pedal until the pressure on the gauge reads 795 ± 100 kPa (115 ± 15 psi). At this pressure the ohmmeter should now indicate an open circuit condition. An audible "click" should be heard which indicates that the switch has been actuated.

9. If the previous steps do not indicate an open circuit, remove plug (4) and insert a 3.18 m (.125 inch) hex wrench in screw (3).

10. Rotate the wrench in one-quarter turn increments and repeat Step 8 until the desired result is obtained.

11. Install plug (4).

NOTE: The final adjustment of the transmission neutralizer switch can be altered to suit the operator.

12. Stop the engine. Remove the gauge and test equipment.

Parking Brake System Pressure - Test

SMCS Code:4250-032-PJ

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Escaping fluid under pressure, even a very small pin-hold size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.

Always use a board or cardboard when checking for a leak.

Location of the Parking Brake Oil Pressure Test Point

(1) Pressure test point for parking brake system.

1. Attach the correct hose and pressure gauge to pressure test point (1).

2. Put blocks in front of and behind the wheels.

3. Start and run the engine at low idle rpm. Disengage the parking brake. The pressure reading with the oil at normal operating temperature should be 3315 ± 70 kPa (510 ± 10 psi).

4. If the pressure is not correct, engage the parking brake and stop the engine.

5. Depress the service brake pedal at least 80 times to release any pressure in the brake accumulators.

6. Move the hydraulic control lever several times through the full range of travel to release any pressure in the implement pilot circuits.

7. Move the STIC steering control several times in both directions to release any pressure in the steering system.

8. Press and hold the breaker relief valve to release any pressure in the hydraulic tank.

Location of the Pilot Oil Pressure Reducing Valve

(2) Pilot oil pressure reducing valve.

Pilot Oil Pressure Reducing Valve

(2) Pressure reducing valve.

(3) Adjusting screw (internal).

9. Using an 8 mm (.3149 inch) allen wrench, turn adjusting screw (3) inside valve (2) clockwise to increase pressure and counterclockwise to decrease pressure.

10. Repeat Step 3.

11. If the pressure reading is correct, engage the parking brake and stop the engine. Remove the test equipment from test point (1). Place the protective cover over the test fitting.

12. If the pressure reading is not correct, stop the engine and engage the parking brake. Repeat Steps 5 through 10.

Brake Discs - Check

SMCS Code:4255-535

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Personal injury or death can result if two persons are not used in the following procedure.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any compartment containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide," for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

Brake service life can vary greatly because of the different applications. The following conditions can lead to premature brake failure:

* Check for oil leaks at the yoke and drive axles. A leak can also allow contamination from water and debris to occur. Water and debris can enter the axle through the lip seal at the drive yoke. The water and debris can mix with the oil and lead to premature brake failure.

* When the axle housing breather is plugged or damaged. Check the axle housing breather for proper operation.

* Excessive heat can be generated if the service brakes are used as a retarder. Excessive heat can be generated if the service brakes are used as a device to maintain a slower ground speed. This type of operation should be avoided by using a lower transmission speed.

Grooves are cut in the faces of the friction discs. It is very important to change the friction discs as soon as possible once the groove depth has reached the maximum wear limit. As the depth of the grooves is reduced, the flow of cooling oil is reduced. This causes heat to build up. The heat causes the rapid wear of the disc material. Eventually, the friction material will wear off the disc. This will cause metal to metal contact between the discs and plates. This problem is known as spalling.

The buildup of the friction material in the oil could cause damage to the very smooth surface finish of the plates. Spalling will also destroy the surface finish of the plates. This will make replacement of these brake components necessary.

If the failure has progressed to metal to metal contact, the complete axle must be thoroughly cleaned. This process of cleaning the axle must be done correctly, or the debris will continue to contaminate the oil. This will cause the material on the brake discs to wear rapidly. This condition will also cause premature failure of the wheel brakes.

Procedure with Brake Group Assembled

Wheel brake disc wear can be checked without having to remove the wheel brake assemblies from the machine. Inspection ports are located on each side of the axle housing and can be used for checking the amount of travel of the spring guides in each wheel brake assembly.

Use the following procedure to determine the amount of wear on the wheel brake discs and to estimate the remaining service life of the discs.

NOTE: If one wheel brake assembly is found to have disc wear, both of the wheel brake assemblies on the axle must be repaired.

1. To allow access to the front wheel brake assemblies, raise the left arms and install the bucket control group safety pins.

Reference: For information on installing the bucket control safety pins, refer to Operation and Maintenance Manual, "Bucket Control Safety Pins" for the machine that is being serviced.

2. Engage the parking brake and stop the engine. Put blocks in front of and behind the wheels.

Wheel Brake Assembly

(1) Plug.

3. Remove plug (1) from the brake inspection port.

Illustration A - New Wheel Brake Assembly

(2) Guide.

(3) Spring.

(4) Parking brake piston.

(5) Service brake piston.

(6) Brake discs.

(7) Plates.

4. Check the position of guide (2) in the brake inspection port. If the head of guide (2) is positioned towards the differential side of the inspection port, wheel brake disc wear is within tolerance. Illustration A shows the position of guide (2) for a new wheel brake assembly.

Illustration B - Worn Wheel Brake Assembly

(2) Guide.

(3) Spring.

(4) Parking brake piston.

(5) Service brake piston.

(6) Brake discs.

(7) Plates.

5. If the head or guide (2) is positioned in the center or towards the wheel side of the inspection port, the brake discs are worn and need replacing. Illustration B shows the position of guide (2) for a worn wheel brake assembly.

6. Install plug (1) in the brake inspection port.

7. Repeat Steps 3 through 6 for the remaining wheel brake assemblies on the machine.

Procedure with Brake Group Disassembled

If the wheel brake groups have been disassembled, use the following information to calculate the wear on the brake discs and to determine whether the discs require replacement.

Wheel Brake Assembly

(C) Thickness of a disc.

(4) Parking brake piston.

(5) Service brake piston.

(6) Brake discs.

(7) Plates.

1. Check each brake disc (6) in each wheel brake assembly. The thickness (C) of a new disc is 7.10 ± 0.13 mm (.280 ± .005 inch). The minimum thickness of a worn disc should not exceed 5.70 mm (.224 inch). Service the brake before discs (6) reach the minimum thickness.

Measuring the Depth of the Grooves on the Wheel Brake Disc

NOTE: Groove depth is most critical dimension. If the depth of the grooves on the brake discs are too shallow, oil flow to the wheel brakes will be inadequate.

2. Check the groove depth on both sides of the brake disc. Use a depth gauge for this procedure. Check all brake discs in each wheel brake assembly.

3. The depth of the oil grooves must be greater than 0.46 mm (.018 inch).

Reference: For disassembly and assembly information on wheel brake groups, refer to Power Train, Disassembly & Assembly, "Final Drive Spindle and Wheel Brakes" for the machine that is being serviced.

Brake System Air - Purge

SMCS Code: 4250-542-Al

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Personal injury or death can result if two persons are not used in the following procedures.

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Always use a board or cardboard when checking for a leak.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any compartment containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide," for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

Purge the Air from the Service Brakes

1. Check the level of the oil in the hydraulic tank. Keep the tank full during the air removal procedure. Use the correct oil in the hydraulic system.

2. Engage the parking brake and bock the wheels. Start the engine and allow the braking system oil pressure to increase to full operating pressure. Disengage the parking brake. Keep the engine running at low idle. Maintain accumulator pressure within working limits throughout the air removal procedure.

3. Have an assistant slowly depress the brake pedal, holding it down for at least 20 seconds. Repeat this procedure three times, permitting 30 seconds between each pushing of the pedal.

Location of the Front Service Brake Air Purge Screw

(1) Air purge screw.

Location of the Rear Service Brake Air Purge Screw

(2) Air purge screw.

4. Connect one end of a transparent tube that is 6.4 mm (.250 inch) in diameter to the service brake air purge screw on the wheel brake assembly closest to the service brake control valve. Put the other end of the tube into a suitable container for collecting of the hydraulic oil.

5. Open the air purge screw. Turn the screw one-half turn to permit oil flow through the tube. Have an assistant slowly depress the brake pedal. Hold the pedal in this position throughout Step 6.

6. As the hydraulic oil flows through the tube, look for air bubbles in the oil. Allow the oil to flow into the container until no air bubbles are visible. Close the air purge screw. Release the brake pedal.

7. Perform this procedure for each wheel brake, but do only one wheel are closed.

8. Engage the parking brake and stop the engine. Fill the hydraulic tank, if necessary.

9. If the brakes feel soft during application in the first few hours of operation, repeat Steps 1 to 8 again until no air is present in the service brake system.

Purge the Air from the Parking Brake

1. To allow access to the front wheel brake assemblies, raise the lift arms and install the bucket control group safety pins.

Reference: For information on installing the bucket control group safety pins, refer to Operation and Maintenance Manual, "Bucket Control Group Safety Pins" for the machine that is being serviced.

2. Engage the parking brake and block the wheels.

Front Wheel Brake Assembly

(1) Cover.

3. Remove cover (1) from each front wheel brake assembly.

4. Check the level of the oil in the hydraulic tank. Keep the tank full during the air removal procedure. Use the correct oil in the hydraulic system.

Location of the Front Parking Brake Air Purge Screw

(2) Air purge screw.

Location of the Rear Parking Brake Air Purge Screw

(3) Air purge screw (shown with wheel removed).

5. Start the engine and allow the braking system oil pressure to increase to full operating pressure. Keep the engine running at low idle throughout the air removal procedure.

NOTE: For machines equipped with the optional towing brake release system, it is recommended to operate the machine at high idle while purging the air from the parking brake release system.

6. Have an assistant move the parking brake control switch to the DISENGAGED position.

7. Connect one end of a transparent tube that is 6.4 mm (.250 inch) in diameter to the parking brake air purge screw on the wheel brake assembly closest to the parking brake control valve. Put the other end of the tube into a suitable container for collecting hydraulic oil.

8. Open the air purge screw. Turn the screw one-half turn to permit oil flow through the tube. As the hydraulic oil flows through the tube, look for air bubbles in the oil. Allow the oil to flow into the container until no air bubbles are visible. Close the air purge screw.

9. Perform this procedure for each wheel brake, but do only one wheel brake at a time. After the air has been removed, be sure all air purge screws are closed.

10. Engage the parking brake and stop the engine. Install cover (1) on each front wheel brake assembly. Fill the hydraulic tank, if necessary.

11. If the parking brakes are not correctly disengaging in the first few hours of operation, perform Steps 1 to 10 again until no air is present in the parking brake system.

Towing Brake Release System Air - Purge

SMCS Code:4284-542-Al

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Personal injury or death can result if two persons are not used in the following procedures.

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Always use a board or cardboard when checking for a leak.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any compartment containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide," for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

1. Check the level of the oil in the hydraulic tank. Keep the tank full all through the air removal procedure. Use the correct oil in the hydraulic system.

2. Put blocks in front of and behind the wheels. Start the engine and allow the braking system oil pressure to increase to full operating pressure.

3. Disengage the parking brake. Run the engine at high idle.

Location of the Towing Brake Release Air Purge Screw

(1) Air purge screw.

4. Connect one end of a transparent tube that is 6.4 mm (.250 inch) in diameter to air purge screw (1) on the towing brake release cylinder. Put the other end of the tube into a suitable container for collecting the hydraulic oil. Open air purge screw (1) one-half turn.

5. Engage and disengage the parking brake until hydraulic oil, without air bubbles, flows through the tube into the container.

6. Close the air purge screw and remove the tube.

Towing Brake Release System - Test

SMCS Code:4284-032-PX

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Always use a board or cardboard when checking for a leak.

Location of the Pressure Test Point for the Towing Brake Release System

(1) Pressure test point.

1. Engage the parking brake. Put blocks in front of and behind the wheels.

2. Remove the protective cover from the test fitting.

3. Attach the correct hose and pressure gauge to pressure test point (1).

4. Fully compress the piston in the towing brake release cylinder. The oil pressure reading on the gauge should be within the range as shown in the following chart.

5. If the pressure reading on the gauge is too low, there may be air present in the towing brake release system.

Reference: For the correct procedure to purge the air from the towing brake release system, refer to Systems Operation, Testing and Adjusting, "Towing Brake Release System Air - Purge" for the machine being serviced.

6. If the reading on the gauge is still too low, then perform the following checks:

a. Check the braking system for oil leaks.

b. Inspect the brake discs for wear.

Reference: For the correct procedure to check brake disc wear, refer to Systems Operation, Testing and Adjusting, "Brake Discs - Check" for the machine that is being serviced.

c. Check for air in the system.

7. After completing the checks, release the force compressing the piston in the towing brake release cylinder.

Towing Brake Release Cylinder

(A) Length of protruding piston rod.

8. Measure the length (A) of the piston rod protruding from the cylinder. The piston rod length protruding should be 34 ± 0.5 mm (1.08 ± .020 inch).

9. If the piston length is incorrect, investigate the cause and rectify the problem.

10. Remove the gauge and hose from the test fitting. Place the protective cover over the test fitting.

Towing Brake Release Sequence Valve Pressure - Test

SMCS Code:4284-032-PX

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Always use a board or cardboard when checking for a leak.

The towing brake release sequence valve ensures that when the parking brake is disengaged during normal machine operation, the towing brake release system is disabled.

Left Hand Side of Torque Converter Compartment

(1) Bolts.

(2) Towing brake release sequence valve.

(3) Manifold.

1. Remove all hoses from towing brake release sequence valve manifold (2). Put identification marks on the hoses for installation purposes.

2. Remove bolts (1) and manifold assembly (3). Connect manifold assembly (3) to a hydraulic test bench. Check the pressure setting of the towing brake release sequence valve.

3. The correct pressure setting for towing brake release sequence valve (2) is 345 ± 35 kPa (50 ± 5 psi).

4. If the pressure setting for sequence valve (2) is not correct, loosen the locknut. Turn the adjusting screw counterclockwise to decrease pressure or clockwise to increase pressure.

5. Install towing brake release system manifold assembly (3) on the machine. Purge the air from the towing brake release system.

Parking Brake - Manual Release

SMCS Code:4267-553-MA

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Personal injury or death can result from a brake malfunction. Do not operate the machine if the brake was applied due to a malfunction of the oil system or the brake.

Correct any problem before attempting to operate the machine.

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NOTICE

Certain Elphinstone machines may be equipped with an optional Automatic Brake Application (ABA) system. The ABA system warns the operator of an impending brake application (low transmission oil pressure) and engages the parking brake if the pressure further decreases, e.g. engine stalled. If your machine is equipped with the optional ABA system, a loop wire needs to be connected to the wiring harness of a transmission oil pressure switch to enable the brake release function to operate.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any compartment containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide," for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.

Location of the Automatic Brake Application Switch

(1) 3E-7811 Switch.

(2) Loop wire.

NOTE: Perform Steps 1 and 17 of the following procedure only to machines fitted with the optional Automatic Brake Application (ABA) system.

1. Disconnect the transmission wiring harness from 3E-7811 Switch (1) at the harness connector. Connect loop wire (2) between the EL331 blue wire and the EL330 grey wire of the transmission harness, as shown.

Auxiliary Brake Release Group

(3) 1DE3048 Portable Hydraulic Pump.

(4) Receptacle.

2. Connect receptacle (4) of the 1DE3048Portable Hydraulic Pump (3) to the machine's 24V DC power supply.

NOTE: The machine batteries must be fully charged for the operation of the portable hydraulic pump. If battery charge is low, connect to an external 24 volt DC power supply.

3. Depress the service brake pedal at least eighty times to remove the oil pressure from the brake accumulators.

4. Move the joystick control lever several times through the full range of travel to release any pressure in the implement pilot circuits.

5. Move the STIC steering control several times in both directions to remove any pressure in the steering system.

6. Press and hold the breaker relief valve to remove any pressure in the hydraulic tank.

Location of the Quick Connect Coupler

(5) Quick connect coupler.

Location of the Quick Connect Coupler

(6) Quick connect coupler.

7. Remove the caps from hydraulic fittings (5) and (6). Connect the hydraulic hoses from the portable hydraulic pump to fittings (5) and (6).

8. Turn the battery disconnect switch ON.

9. Turn the engine start switch key to the ON position.

10. Position the brake release switch (from the portable hydraulic pump) inside the operator's compartment.

Operator's Compartment

(7) Brake release switch.

11. Press and hold brake release switch (7) in the ON position to activate the portable hydraulic pump. Low brake oil pressure alert indicator (9) will go out when the braking system has full oil pressure.

NOTE: Operation of the brake release switch should only take place from inside the operator's compartment. Observe brake indicators and gauges (if equipped) while operating the portable hydraulic pump.

Dash Panel

(8) Parking brake indicator.

(9) Low brake oil pressure alert indicator.

(10) Parking brake control knob.

12. When the braking system has full oil pressure, move parking brake control knob (10) to the DISENGAGED position to release the brakes. Parking brake indicator (8) on the Caterpillar Monitoring System panel should go out when the brakes are released.

NOTE: The service brakes can be used to stop the machine when the machine has brake oil pressure. Use the service brakes to control the machine when the machine is being towed.

13. Hold the brake release switch in the activated (ON) position when required in order to ensure the low brake oil pressure indicator remains out until towing is completed.

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NOTICE

Operating the brake release pump for extended periods of time may cause overheating and possible damage of the electric motor. If overheating is observed, stop operating the brake release pump and allow it time to cool before towing is continued.

NOTE: For the removal of the portable hydraulic pump from the machine refer to Steps 14 through 16.

14. Repeat Steps 3 through 6.

15. Disconnect and remove the portable hydraulic pump from the machine.

16. Replace the caps on the quick connect couplers.

Location of the Harness Connector