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| Illustration 1 | g01068348 |
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Electrical schematic of the automatic lubrication system (1) TWIN Display. (2) Pressure switch. (3) Pump and control unit. | |
| Tools Needed | Qty | |
| 6V-7070 Digital Multimeter | 1 | |
- Disconnect the 2 pole connector from the pressure switch.
- Use a multimeter in order to measure the resistance between the two contacts. When there is no pressure in the system the contact of the switch should be open. If necessary, remove the switch in order to make sure that no pressure is present below the pressure switch. You will only need to remove the upper part. The diverter valve can be left in place. When the adjusted pressure is reached, the contact should close.
- Press the test button on the pump in order to start a test cycle.
- When possible, mount a pressure gauge between the diverter valve and the pressure switch in order to check the switching point.
Note: Use a pressure gauge that is suitable for a grease pressure of
25000 kPa (3626 psi) . - Since the connector of the switch is disconnected, the control unit cannot switch off the pump when the adjusted pressure is reached. Therefore, turn off the engine start switch when the pressure (switching) for the pressure switch has been reached. The test cycle is now complete.
- Disconnect the connector for the pump.
- Connect both contacts of the connector of the pressure switch with a separate wire.
- Measure the resistance between pin 7 and pin 8 of the connector. The measured resistance should be approximately 0 ohms.
- Remove the wire between the contacts of the connector of the pressure switch. The multimeter should read "open load".
Check for the Pump and the 5/2 Magnetic Valve
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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. |
- Disconnect both grease lines from the pump unit.
Note: Pressure may still be present in the channels.
- Connect a pressure gauge to each channel of the pump unit. Use a pressure gauge that is suitable for a grease pressure of
25000 kPa (3626 psi) . - Press the test button for four seconds in order to start a cycle. The pump will pump grease from one of the channels. The pressure reading of the gauge that is connected to this channel should increase to the maximum attainable pressure of
24000 ± 1000 kPa (3500 ± 145 psi) .Note: The pump is not switched off by the pressure switch because the system is disconnected.
If the pump does not reach the indicated pressure, several situations must be considered:
- There are air bubbles in the grease. Disconnect the pressure gauge. Permit the grease to flow until all of the air bubbles have escaped from the line. If necessary, refill the reservoir with oil in order to remove air from the pump element.
- Grease is viscous. Therefore, the grease cannot be drawn in by the pump piston. Replace the grease in the reservoir and the grease in the main lines.
- The pump is faulty. Replace the pump.
- Turn off the engine start switch or disconnect the connector for the pump momentarily in order to end the test cycle.
- Use the test button on the pump in order to start another test cycle. The pump should start in the second channel. The pressure gauge will quickly increase to the maximum adjusted grease pressure of
24000 ± 1000 kPa (3500 ± 145 psi) . The first channel should have no pressure.
If the pressure in the first channel does not drop and no pressure is built up in the new channel, the 5/2 magnetic valve is faulty. Replace the valve or replace the pump.
- Turn off the engine start switch or disconnect the connector for the pump momentarily in order to end the test cycle.
Check for an Internal System Leak
- Disconnect primary grease line (B) of the pump unit.
Note: Pressure may still be present in the channel.
- Press test button (4) for four seconds in order to start a test cycle. The pump is started. The pump pumps grease through one of the channels. If the active channel is not channel (A), stop the test cycle. Turn off the engine start switch or disconnect the connector for the pump momentarily in order to end the test cycle.
- Start another test cycle with test button (4). The pump will start automatically in primary grease line (A).
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| Illustration 2 | g01077304 |
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(A) Primary grease line
(B) Primary grease line (4) Test button | |
- Disconnect the main line from primary grease line (B) directly after the first distribution block after the pump.
- Restart the pump in primary grease line (A).
When the grease leaks from channel (B) of the first distribution block, the leak must be found in the first distribution block. When the grease leaks from the disconnected line, the leak must be found further down the system. Therefore, repeat the procedure and proceed to each of the remaining distribution blocks until the leak is found.
Note: Follow the main lines from the pump to the distribution blocks in order to determine the connections between the main lines and the channels.
When there is only a little leak, it may be impossible to establish the leak with the pump. Therefore, turn off the pump when the maximum pressure is reached. Turn off the engine start switch or disconnect the connector for the pump momentarily. The pressure should be steady and the pressure should not be below
When there is no pressure drop and there is no grease that is returning, a metering unit is leaking. This will cause one of the lubrication points to be lubricated excessively. Check all connected lubrication points.