My hammer was fine a week ago, now it’s weak/slow/quit/erratic!

We hear this every spring and fall, and regularly in between. The most likely culprit is that the nitrogen head charge on your breaker has been affected by a large swing in temperature.

Many operators have no idea there is nitrgogen inside their hydraulic hammer. Almost all breakers are gas-fired, though there are several brands of European breakers that are oil-fired. 

A gas-fired breaker will have a chamber at the top (opposite of the striking end) of the piston. This chamber is filled with compressed nitrogen to cause the piston to strike with the force it does. There are special seals on the upper end of the piston to seal the gas in the chamber. Once the piston has struck the tool, it is hydraulically driven upward which compresses the nitrogen yet more. When reaching what the engineers have determined to be the optimum peak of its stroke, oil will then quit pushing up and instead begin to drive the piston down. Once the piston direction shifts, the compressed nitrogen sharply drives the piston downward, striking the tool and helping compromise the integrity of the rock/concrete. 

The amount of nitrogen in the chamber is critical to the proper function of the breaker. To visualize why, imagine your kid’s soccer ball. If it’s overinflated, you can jump on it and your knees take a beating but nothing else happens. Underinflation will result in no rebound or at best weak rebound. Once properly inflated, you jump on the ball and it launches you upward. 

Now that we understand what nitrogen’s function is, the explanation of why your hammer is doing what it does is simple. If the temperature made a significant change, the head charge becomes too high or low because nitrogen is a gas that expands or contracts with the temperature. Summertime temperatures will increase the nitrogen’s pressure in the head as the gas has expanded, and winter will make the breaker want more nitrogen due to contraction. A tool specific to your hammer is required to measure the charge and fill or reduce nitrogen. 

Dramatic temperature change will most likely be the cause of improper head charge, but not the only cause. A faulty charge valve, or if the special gas seals on the piston are beginning to fail, can cause nitrogen to be lost. The charge valve can be removed (after making sure ALL nitrogen is bled out of the head) and replaced with a new valve when determined it is faulty (simply spritz it with glass cleaner and watch for bubbles). It is also easy to determine if the piston gas seal is bad. Charge the head. If gas begins to gurgle into the breaker, the seals have failed and the breaker has to come apart and be resealed. A failed charge valve is the most common of the two. 

Finally, don’t be that guy the feels he has outsmarted the system by charging the head with air from his air compressor. Air has moisture in it that will cause the seals to deteriorate and the inside of the head to rust and THE OXYGEN IN THE AIR CAN EXPLODE.