Mechanical Bijur Lube Pump - How it Works and Troubleshooting Guide

How it Works

The lubrication system is powered on whenever the spindle is turning or when there is an axis in motion. The pump motor turns a cam, which pushes the plunger up. The plunger drops to the bottom of its stroke every 30 minutes to pressurize the oil system and push oil to the axis trucks, the ballscrews, and the spindle.

The oil to the axis linear guides and ballscrews is supplied through copper lines with flow restrictors to ensure consistent metering of oil to the lubrication points.

The oil to the spindle is metered and flows to the spindle in an air/oil mist.

If the oil level in the reservoir runs low, or if there is no oil pressure during a pump cycle, the system generates Alarm 121, LOW OIL LEVEL OR PRESSURE.

  1. Power cable: Supplies power to the lube pump
  2. Oil pressure gauge: Shows the oil pressure
  3. Oil pump motor and gearbox: Pumps the oil from the reservoir
  4. Oil filter: Removes contamination from the oil. Some machines have an external filter next to the oil reservoir.
  5. Oil reservoir: Stores the oil
  6. Low-level switch: Shows if the oil level is low. This activates Alarm 121 LOW OIL LEVEL OR PRESSURE.
  7. Pressure switch: (behind pump) Shows if the pressure is low.

Some symptoms are resolved by regular maintenance. Refer to Bijur - Mechanical - Oil Pump - Service and Test for detailed information on how to perform proper maintenance on your oil pump.

Symptom Possible Cause Corrective Action Section
Alarm 121 LOW OIL LEVEL OR PRESSURE Oil level is low. Add oil. 1
The pressure switch is faulty. Replace the pressure switch. 2
There is no voltage going to the pump, or the pump is damaged. Check the voltage to the pump and I/O PCB. 3
The filter is clogged. Replace the filter. 4
The pump does not hold pressure. There is a leak from the fittings. Stop fittings from leaking. Replace if necessary. 5
Pressure remains high for more than 10 minutes. One of the oil lines or metering units are clogged. Clean out the clogged oil line or meter unit. 6

Section 1

Symptom: Alarm 121 LOW OIL LEVEL OR PRESSURE

Possible Cause: Oil level is low.

Corrective Action:

Add oil to the tank.

Go to diy.haascnc.com for details on adding oil.

Section 2

Symptom: Alarm 121 LOW OIL LEVEL OR PRESSURE

Possible Cause: The pressure switch is faulty.

Corrective Action:

Check the pressure switch for correct operation. The switch is located behind the lube pump assembly. Use a multi meter set to Ohms to measure the resistance between both leads on the switch. The plunger activates approximately every (30) minutes.

When the plunger is NOT activated, the reading on the multi meter should be very high or "O.L." Once you manually activate the plunger, you will see 1 Ohm. If the switch operates correctly, go to diy.haascnc.com to troubleshoot the I/O PCB.

Section 3

Symptom: Alarm 121 LOW OIL LEVEL OR PRESSURE.

Possible Cause: There is no voltage going to the pump, or it is damaged.

Corrective Action:

Command the spindle to operate at 5 rpm. Measure the voltage to the lube pump motor.

Use a multi meter set to VAC. If the voltage is 120 VAC, but there is no movement, replace the pump.

Examine the worm screw inside the tank. If the lube pump is receiving voltage, the screw rotates slowly at 1 rpm.

Section 4

Symptom: The pump does not hold pressure.

Possible Cause: The filter is clogged.

Corrective Action:

Replace the filter. Go to Haasparts.com. Order the BIJUR OIL PUMP SERVICE KIT (P/N 93-2166).

Section 5

Symptom: The pump does not hold pressure.

Possible Cause: There is a leak from the fittings.

Corrective Action:

Test the system for leaks by manually lifting the plunger. The gauge will show pressure and gradually drop to zero. This takes 3-10 minutes. If pressure drops immediately, check for leaks at the lube pump. Examine all axis linear guide trucks and ballscrews for signs of lubrication. Examine each of the flow meters, lube fittings, and connectors.

Look for drips of oil near the axis flow meters, tees, and connectors.

Check for leaks in the system. Start with the fittings located at the lube pump assembly. Repair the leaks.

Repair all leaks. Make sure the pressure is correct.

Section 6

Symptom: Pressure remains high for more than 10 minutes.

Possible Cause: One of the oil lines or metering units are clogged.

Corrective Action:

Clogged orifices are the only cause of high pressure for more than 10 minutes. Remove the cause of the clogged oil lines or meter units.

Go to diy.haascnc.com for information on machine maintenance.

Be aware: Many service and repair procedures should be done only by authorized personnel. The service technicians at your Haas Factory Outlet (HFO) have the training, experience, and are certified to do these tasks safely and correctly. You should not do machine repair or service procedures unless you are qualified and knowledgeable about the processes.

Danger: Some service procedures can be dangerous or life-threatening. DO NOT attempt a procedure that you do not completely understand. Contact your Haas Factory Outlet (HFO) and schedule a service technician visit if you have any doubts about doing a procedure.

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