Educate me about Breakers please

[AndrewMawson]

Breakers / peckers / concrete breakers - How do they reciprocate?

Are they basically a hydraulic cylinder with valves? I know some (such as my manual JCB Beaver) have a compressed nitrogen buffer / shocker. Are any actually a rotating hydraulic motor / eccentric weight sort of arrangement?

I've never used a machine mounted one, only free standing manual small ones, but am considering getting one to convert to a fence knocker.

[Muz]

Can only speak of the ones I have which use a porting system which propels an internal piston downwards to connect with the top of the tool above the chuck giving the blow. There are 2 accumulators one at each end, a high and a low pressure, which are charged with nitrogen to a specific pressure, the gas is retained in a sealed chamber with a diaphram that is designed to cushion the shock of the returning oil from the piston traveling in each direction. Nitrogen is used as its pressure does not vary quite as much as air would do when it heats up IIRC plus its also cheap, abundant, and reasonably unreactive. If the diaphram fails, the hammer will loose blow strength, and the hydraulic hoses will vibrate more violently due to the lack of cushioning inside the hammer.