No matter if you are a substitute operator, a main operator, or especially an apprentice, you must have done greasing work before! If someone claims they’ve never done it, nobody will hire you—unless it’s your own family’s machine. In that case, your father would have already kicked you for being lazy!

Since the 1970s, when I started driving tractors, I was also one of those who often did greasing. I still remember: once, the drain plug of the auxiliary engine crankcase on a Dongfanghong-75 tractor (the auxiliary engine was a two-stroke gasoline engine requiring a gasoline-oil mixture for lubrication) got lost. Coincidentally, a grease nipple had the same thread, so one of my coworkers used a grease nipple as a replacement. Later, our new tractor team leader (a former Type 59 tank commander in the army) came to the field to bring us lunch. While operators were eating, he decided to grease the tractor. The operators told him: “Every grease nipple must be greased until oil comes out.” He started greasing, but while other nipples took just a few strokes, this one wouldn’t discharge grease even after four pumps! Luckily, one of the operators noticed it after lunch. In the end, we had to spend half a day disassembling and cleaning the auxiliary engine. Lesson: not all grease nipples are actually meant for greasing!

About Grease Grades

I don’t need to explain much, but generally:

• Low-viscosity grease suits winter use.

• High-viscosity grease suits summer use.
  This rule applies across the Northern Hemisphere, with the opposite being true for the Southern Hemisphere. Experts may complicate the viscosity classification, but that’s another story.

Based on my experience and lessons, here are the key points:

1. Don’t go cheap with grease.
   There’s no such thing as something that’s both excellent and cheap. If you think capitalists will sell you top-quality grease at a low price, you’re mistaken. As the saying goes: “The most expensive may not be the best, but the best will never be cheap!” Famous brands, at least, are far more reliable than unknown ones.

2. Prefer molybdenum disulfide grease (MoS₂ lithium grease).
   The outdated calcium-based grease has long been eliminated. MoS₂ grease is always black (though not all black grease is MoS₂—coal is black too). Using MoS₂ grease reduces greasing frequency, lowers wear, and extends the service life of bushings.

   • In the 1960s, in Northeast China, Swedish Scania trucks were imported without maintenance supplies like lubricants. During harsh winters, trucks failed due to poor lubrication. The “three-in-one” technical group solved the problem by mixing MoS₂ powder with diluted oil. MoS₂ itself is an excellent solid lubricant.

   • Nowadays, many engine pistons are coated with a thin black layer—its main ingredient is MoS₂.

3. Do not casually change the greasing cycle.
   Unless proven effective by tests, stick to the manufacturer’s recommended schedule. The factory settings represent the minimum requirement for your machine’s safe use.

4. Replace cylinder bushings and piston rod bushings in time.
   Don’t use cheap, low-quality parts.

   • In 2011, a large gold mining company in Shandong ran six CAT365C excavators. After 5,000+ hours, bucket cylinder piston rods began to fracture. Investigation revealed excessive bushing wear (clearance reached 3.6 mm). After replacing bushings and following proper greasing intervals (with a dedicated technician), the issue never recurred.

   • For Caterpillar B/C/D series machines:

     • B-series: steel bushings with hardened shafts.

     • C-series: soft bushings with hardened shafts (but had common wear issues on stop plates and collars).

     • D-series: improved bushing material to reduce wear.

5. Practical lessons from the field:

   • A Shandong customer’s CAT320B excavator made squeaking noises when lifting the boom. It turned out they had installed cheap bushings. Solution: apply grease at a different angle. Noise stopped immediately.

   • Many similar cases occurred—experienced operators knew the cause, but young operators didn’t.

Key Takeaways for Operators and Maintenance Teams:

1. Don’t buy cheap bushings.
   A quality bushing protects the pin shaft. A poor bushing destroys both bushing and pin. For example, a boom pin shaft may cost over 10,000 RMB, while a poor bushing only a few hundred RMB—but damages the shaft. Sometimes, repairing worn areas and rotating the pin can extend life by thousands of hours.

2. Grease technique matters.
   Don’t just pump grease blindly. Change the machine’s position and grease again—for example, when the bucket is pressing down, pump a few strokes, then lift it and pump again. This spreads grease evenly in the bushing clearance.

3. Replace bushings once clearance is excessive.
   Otherwise, piston rod breakage at the welded end will happen sooner or later. Larger machines are more prone to this, as they bear heavier loads.

4. Check structural cracks.
   If booms or arms repeatedly crack despite welding, excessive bushing clearance may be the root cause. This requires in-depth technical evaluation.

Conclusion

Greasing is a daily task for operators. But if done according to proper scientific principles, it not only reduces workload but also extends the service life of machine components significantly.