Introduction

Reference: For Specifications with illustrations, refer to the Specifications for the CB-534 Steering System, Form No. KENR2418. If the Specifications in Form No. KENR2418 are not the same as listed in the Systems Operation and the Testing And Adjusting, look at the print date on the back cover of each book. Use the Specifications listed in the book with the latest date.

Troubleshooting

The 6V4161 Pressure Gauge Kit can be used to make pressure tests on the steering system. Before any tests are made, visually inspect the complete hydraulic system for leakage of oil and for parts that are damaged. For some of the tests a magnet and a mm (in) measuring rule are usable tools

NOTE: The 6V4161 Pressure Gauge Kit has JIC connectors and NPT threads on the fittings. JIC-to-metric and NPT-to-metric adapters must be used as necessary when checking pressures on this machine.

When any test is made of the steering hydraulic system, the hydraulic oil must be at the normal temperature for operation.

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Sudden movement of the machine or pressure oil release can cause injury to persons on or near the machine. To prevent possible injury, do the procedure that follows before testing and adjusting the steering hydraulic system.

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel. Stop the engine.

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

3. Activate the parking brake.

NOTE: During certain performance tests it will be necessary to release the parking brake to help drum movement when turns are required.

4. Carefully loosen the filler cap on the hydraulic tank to release any pressure in the tank.

5. Make sure all hydraulic pressure is released before any fitting, hose or component is loosened, tightened, removed or adjusted.

Visual Checks

A visual inspection of the steering system and its components is the first step when a diagnosis of a problem is made. Stop the engine, make the following inspections.

1. Measure the oil level.

2. Look for air in the oil that is in the tank. Do this immediately after the machine is stopped. Use a clear bottle or container to get a sample of the oil. Look for air bubbles in the oil that is in the bottle.

3. Remove the filter elements and look for particles removed from the oil by the filter elements.

4. Check all oil lines and connections for damage.

Performance Tests

Performance tests of the steering system can be used for a diagnosis of poor performance and to find the source of oil leakage inside the hydraulic system.

Problem: Steering pump makes noise and the steering cylinder rods do not move smoothly.

Probable Cause:

1. Air in the steering hydraulic circuit.

2. The pump is worn too much.

3. Loose oil line connection on the inlet side of the pump.

4. The relief valve opens at low oil pressure.

5. Low oil level in the tank.

6. Viscosity of the oil is wrong.

Problem: Too much force is needed to turn steering wheel.

Probable Cause:

1. Relief valve is open.

2. Low oil level in the tank.

3. Pump oil pressure is too low, caused by a worn pump.

4. Steering control unit covers are too tight.

5. Steering control unit has defects.

6. Oil is cold.

7. Alignment of steering column is not correct.

Problem: Machine does not turn when steering wheel is turned.

Probable Cause:

1. Low oil level in the tank.

2. Air in the system.

3. Dirt in the system.

4. Pump operation is not correct.

5. Steering metering valve operation is not correct.

6. Frame articulation is locked because the lock pin is in position.

Problem: Machine turns too slow in both directions.

Probable Cause:

1. Not enough oil flow from steering pump.

2. Pump suction line restricted.

3. Operation of steering control unit is not correct.

4. Pump operation is not correct.

5. Seal leakage in the steering cylinders.

Problem: Machine turns too slow in one direction.

Probable Cause:

1. Restriction in steering metering valve.

2. Steering cylinder rod loose in piston.

Problem: The steering control unit does not return to center position correctly.

Probable Cause:

1. Steering control unit covers are too tight.

2. Alignment of the steering column is not correct.

3. Valve spool in the steering metering valve has a restriction.

Problem: Temperature of oil is too hot.

Probable Cause:

1. Viscosity of the oil is wrong.

2. Air is mixed with the oil.

3. Steering relief valve has a defect.

4. There is a restriction in the circuit line.

Problem: Steering wheel turns without the operator turning it.

Probable Cause:

1. Foreign material causes the sleeve valves in steering control unit to stick.

2. Centering springs are broken or damaged in the steering control unit.

3. Timing of the steering control unit drive is not correct. The drive must be timed as follows.

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If the steering control unit (SCU) drive is not timed correctly, the machine can turn in the opposite direction as the steering wheel. To prevent personal injury, loss of life and/or property damage, make sure the drive is timed as follows.

Timing Of SCU Drive
(1) Cross pin. (2) Rotor tooth used for alignment. (3) Rotor. (4) Stator.

Pin (1) must align with the root of rotor tooth (2).

Steering System

Pump Efficiency Check

For any pump test at a given rpm, the pump flow at 690 kPa (100 psi) will be larger than the pump flow at 6900 kPa (1000 psi). The difference between the pump flow of the two operating pressures is the flow loss.

Method of finding flow loss:

Flow loss when expressed as a percent of pump flow is used as a measure of pump performance.

Example of finding percent of flow loss:

If the percent of flow loss is more than 10%, pump performance is not good enough.

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^*Numbers in examples are for illustration and are not values for any specific pump or pump condition. See Specifications for pump flow of a new pump at 690 kPa (100 psi) and 6900 kPa (1000 psi).

Machine Test

Install a Flow Meter. For Formula I, measure pump flow at 690 kPa (100 psi) and at 6900 kPa (1000 psi) with the engine at high idle rpm.

Bench Test

If the test bench can be run at 6900 kPa (1000 psi) and at full pump rpm, find the percent of flow loss using Formula I.

If the test bench cannot be run at 6900 kPa (1000 psi) and 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 part of Formula II. For the bottom part of the formula, run the pump shaft at 2000 rpm. Measure the pump flow at 690 kPa (100 psi).

Steering Force Check

Check the force needed to turn the steering wheel. The torque must be as follows:

a. With the steering wheel turned very slowly and the engine stopped, the torque must be 4.0 to 4.5 N·m (35 to 40 lb in).

b. With the steering wheel turned very slowly and the engine at low idle, the torque must be 2.3 to 2.8 N·m (20 to 25 lb in).

Steering Time Check

Both the direction and the speed of a turn are controlled by the steering control unit.

The oil volume supplied to the cylinders is proportional to the angular rotation of the steering wheel. As the steering wheel is turned faster, there is an increase in the flow rate of oil to the steering cylinders. The cylinders will therefore move farther and faster.

To check the steering time of the compactor, place the machine on a dry, hard, smooth surface. This will reduce the resistance of the drum ground contact area.

With the engine at high idle, the time for a full turn from stop to stop must not be more than 5.5 to 6.0 seconds, with ten full turns of the steering wheel.

NOTE: When testing compactors with a parking brake mounted on both the front and rear drums, it will be necessary to release both brakes.

Steering System Pressure Check

Main Relief Valve

Frame Lock Pin Installed
(1) Lock pin (2) Yoke.

1. Apply the parking brake.

2. Install frame lock pin (1) in the hole provided in articulation yoke (2).

Pressure Tap For Main Line Steering Pressure
(3) Pressure gauge. (4) Pressure tap.

3. Connect 0 to 28 000 kPa (0 to 4000 psi) pressure gauge (3) to pressure tap (4) on the output line from steering pump.

Special Pressure Tap Connector
(5) Pressure tap with inside diameter of 16.0 mm (.63 in). (6) M24 X 150 thread. (7) M8 X 100 thread.

NOTE: For machines not equipped with a pressure tap, a special connector, part number 814227, can be installed between the pump and the output line. Install another connector, part number 814543, to pressure tap (5). Then install the pressure gauge to the connector.

4. Turn the steering wheel in both directions until the relief valve opens. Note the reading on the gauge. The correct relief valve pressure is 14 000 kPa (2050 psi).

Relief Valve
(8) Adjustment screw. (9) Plug.

5. If the relief valve pressure is not correct, do the procedure that follows:

a. Remove plug (9) from relief valve.

b. Turn adjustment screw (8) clockwise to increase the pressure or counterclockwise to decrease the pressure. One full turn of screw (8) will change the pressure approximately 1800 kPa (260 psi).