Excavator pins and bushings usually wear out early because grease is squeezed out of a slow, heavily loaded, oscillating joint faster than it is replaced, or because dirt gets in with it. The fix is the grease the machine maker specifies, often an extreme-pressure grease with molybdenum disulfide (moly), applied at the interval in the manual and pumped until clean grease pushes the old grease and dirt out of the seal.
This excavator pin grease guide explains why pin joints fail, which grease to use on pins, bushings and breaker tools, and how to tell when greasing is falling behind. It is published by Zhongtian, which makes construction-machinery greases.
Why do excavator pins and bushings wear out early?
- Boundary lubrication. A pin turns slowly and only part of a revolution under very high load, so no oil film builds up between pin and bushing. Protection depends on the grease that stays in the joint and on solid or extreme-pressure additives, and the grease is gradually pushed out.
- Small, fast movements. When the joint vibrates through a very small angle, for example while a hydraulic breaker is working, fresh grease is not drawn into the contact, and fretting wear can develop. Breakers deliver several hundred blows per minute; Montabert lists 400 to 1,050 blows per minute for its V32 and 510 to 1,160 for its V46SHD.
- Contamination. Dust and water enter through worn seals. If greasing stops before clean grease appears at the seal, abrasive dirt stays in the joint.
- The wrong grease. A general-purpose grease without extreme-pressure performance, or a grease too soft for the joint, is squeezed out faster.
What grease should I use on excavator pins and bushings?
The grease named in the machine’s operation and maintenance manual. For pins and bushings that is often an extreme-pressure grease with molybdenum disulfide. Caterpillar, for example, calls for a 5% moly grease. The data sheet for Irving Oil’s AF-Moly Plus, a 5% moly lithium complex grease, states that it satisfies Caterpillar’s 5% moly requirement and other equipment makers’ requirements where at least 3% moly is called for.
- Check the moly content on the data sheet if your manual specifies a percentage. “Contains moly” is not enough.
- NLGI 2 for manual greasing, NLGI 0 or 1 for automatic systems is the usual split; follow the manual and the lubrication system maker.
- Do not use moly grease in rolling bearings unless the bearing maker allows it. The same data sheet states that its moly grease is not intended for rolling bearing applications.
What grease goes on a hydraulic breaker tool?
A chisel paste, not ordinary grease. The tool and its bushings run hot from friction and impact. Breaker suppliers sell pastes with solid lubricants: Brokk describes the Atlas Copco paste as containing small copper and graphite particles, and advises choosing a paste rated to about 450 °F (about 230 °C). If grease is running down the tool, it is most likely the wrong product. Keep greasing the excavator’s boom and stick pins as well during breaker work, at the interval the manual gives for that duty.
How often should excavator pins be greased?
As often as the manual says for your duty, and more often when conditions are worse. Shorten the interval in wet or dusty work, in water or mud, and during breaker work. At each point, pump until fresh grease appears at the seal; that purge carries out water and dirt. A fitting that takes no grease is a blocked point, not a full one, and should be cleared.
What are the signs that pin greasing is falling behind?
- Old grease purged from the joint is dry, dark or gritty.
- Pins squeak or knock, or the bucket and linkage develop play.
- Bushings show scoring, or pins show pitting when removed.
- Seals are torn or missing, so grease does not stay in.
Zhongtian excavator pin grease
| Zhongtian grease | Key published data | Where it fits |
|---|---|---|
| Molybdenum disulfide lithium grease | NLGI 0 to 3; four-ball PB 588 N; service −20 to 120 °C | Heavily loaded, slow pins and bushings |
If your machine maker specifies a moly percentage, ask us for the MoS2 content of the batch before ordering. Our grease selector filters greases by temperature and duty, and our dropping point guide explains why operating range matters more than dropping point. Send us the machine model and the grease named in its manual and we will match it.
Frequently asked questions
Is moly grease good for excavator pins?
Yes, where the manufacturer specifies it. Moly gives a solid lubricant film when the grease is squeezed out of a slow, heavily loaded joint. Check the required percentage.
Can I use the same grease on pins and the breaker tool?
No. The breaker tool needs a chisel paste made for its heat and impact; ordinary grease melts out of the tool bushing.
Can I use moly grease in wheel bearings?
Not unless the bearing or vehicle maker allows it. Moly greases are generally made for sliding joints, not rolling bearings.