Short answer
Grease goes in with the tool pressed upward. With the tool hanging free it drops under its own weight and opens a gap between tool and bushing; grease pumped into that gap escapes straight out instead of spreading through the bushing. Press the tool against the ground or the material so it is pushed up, and the gap closes, sending the grease exactly to the surface that needs it. The breaker must be stopped and the hydraulic line depressurised.
Why tool position matters this much
The tool can move axially inside the bushing by a certain amount. With the breaker in the air, the tool drops under its own weight and a gap opens at the top. Grease from the gun takes the easiest path and leaves through that gap; it never reaches the load-bearing part of the bushing.
Press the tool against the ground so it is pushed up, and that gap closes. The only place the grease can go is the narrow clearance between bushing and tool, which is exactly the surface that needs lubricating.
That is why bushings can still finish early on a site where everyone insists greasing was done. Grease went in, but at the wrong moment, and it never reached its target.
A simple check
After greasing, look around the tool. Done properly, grease shows as a thin ring at the bushing mouth, mixed with dust. If grease only sits around the nipple, or does not appear at all, it did not reach the bushing.
The correct sequence
- Stop the breaker and bring the machine to idle.
- Rest the tool on the ground or the material; lower the boom slightly so the tool is pushed up inside the bushing.
- Release the pressure in the hydraulic line; never work at a nipple under pressure.
- Wipe the nipple and the gun tip with a clean cloth. Grease pumped through a dirty nipple carries dust straight into the bushing.
- Pump the amount your manual specifies; stop when clean grease starts to appear at the bushing mouth.
- Wipe away the excess around the tool; grease left on site collects dust.
Is too much grease harmful?
On the bushing side, excess grease is usually expelled and does little harm; the waste is mostly money. But greasing excessively every time builds a dust-holding mound around the tool, and that mound is abrasive.
The real problem is excess grease in the wrong place. On some models, forcing grease behind the seal can lift it from its seat. So "more must be better" is not right; the amount described in the manual is what governs.
On machines with automatic lubrication, adding manual grease is usually unnecessary; the system is already metering the dose.
When to grease
The common practice is greasing at the start of the shift, but that is not the only right answer. What decides it is how long the breaker will work that day: on a long, dusty shift, one more round of grease at midday protects the bushing noticeably.
Grease at every tool change, without exception. When a tool comes out, the bushing surface is exposed for a while; greasing after the new tool goes in both coats the surface and pushes out any dust that got in.
Grease also at the first start after a long stand. In a breaker left standing, grease may have drained under gravity and the film thinned.
The three most common mistakes on site
- Greasing with the breaker in the air: the grease misses the bushing and escapes.
- Pumping through a dirty nipple: the grease carries dust straight in and abrades instead of lubricating.
- Greasing at the end of the shift and parking the machine: the grease drains overnight and the morning starts dry. Grease close to the time work begins.