Detailed Explanation of Grease Filling Locations for Oil-Immersed Screw Air Compressor Motors

I. Standard Screw Air Compressor Motor (7.5kW and above, with grease filling structure)

The motor bearings have independent lubrication points at both ends: the drive end (connected to the compressor main unit) and the fan end (rear cooling fan).

1. Grease Filling Port (Grease Filling Port, Grease Nozzle/Grease Cup)

- Location: On the side of the motor end cover, an upward-sloping metal nozzle (with a dustproof rubber cap), one on the drive end and one on the fan end.

- Appearance: A short, protruding metal nozzle used to connect a manual grease gun for grease filling.

2.Waste Oil Plug (Waste Oil Outlet, must be opened simultaneously)

- Location: Located directly below the grease inlet, at the bottom of the motor end cover (5-6 o‘clock position), a small hexagonal screw/spring-loaded drain plug. Function: When adding new grease, old, blackened waste grease will drain through this port, preventing grease buildup and bearing overheating damage.

II. Two Special Motor Types Without External Grease Fillers

1. Low-Power Motors (≤5.5kW, Small Screw Air Compressors)

These motors use fully sealed, maintenance-free bearings (ZZ double-sealed bearings). They are pre-lubricated at the factory and require no additional lubrication throughout their lifespan. There is no grease filler port.

2. High-Speed Permanent Magnet Direct Drive Motors (Integrated Permanent Magnet Screw Compressors)

Some models have a hidden grease filler hole in the center of the spindle; the rubber dust cover at the motor tail needs to be removed. For the plugs and hexagonal bolts, grease is added through the center hole of the spindle, ensuring the grease filler is completely hidden.

III. Standard Operating Procedure for Adding Grease

1. Stop the machine, disconnect the power, lock the locking device, and open the drain plugs at both ends;

2. Clean the dust cap on the grease fitting and connect the grease gun to the nozzle;

3. Slowly inject new grease until clean, new grease flows out of the drain port;

4. Tighten the drain plug, wipe away excess grease, and replace the dust cap on the grease fitting;

5. Run the machine unloaded for 10-20 minutes to drain excess grease and prevent overheating and oil leakage.

IV. Grease Requirements

Generally, our compressors use UNIREX N2 grease.

You can also use other brands of grease, but the temperature range should be -20℃ to 280℃.