Mechanical Accumulators vs Diaphragm Accumulators

Technological advances have seen some hammer manufactures start to move away from diaphragm accumulators to mechanical designs.

So what are the pros and cons of both?

Diaphragm Accumulators:  Hydraulic hammers require a nitrogen gas charge inside an accumulator, allowing the hammer to make its impact once a required pressure is reached.  Most hammers use a diaphragm accumulator, which is very similar to a football bladder.  The diaphragm is filled with gas (nitrogen) and is housed inside a chamber.  When this chamber is filled with hydraulic fluid, the gas inside the diaphragm starts to compress.  Once at a required pressure, the fluid is released and the gas re-expands, forcing the hammer piston down sharply.  This all happens hundreds to thousands of times a minute depending on the size of the hammer. 

Unfortunately this expansion and compression of the diaphragm can cause it to leak and fail after relatively short amounts of use.  On the positive side, diaphragms are easy to repair and simple to manufacture.

Mechanical Accumulators:  Mechanical designs do not feature a diaphragm.  Most commonly they feature seals and a piston with a gas filled chamber. 

One of the benefits of this design is a much longer maintenance life, in some cases over 300% longer than a flexible diaphragm.  The other benefit is that they have a higher impact force, in most cases over 30% more impact force per blow.  The only downside is that they cannot operate at the higher frequency of a diaphragm accumulator, however as explained in our article on high and low frequencies in hydraulic hammers, we actually believe this to be a positive attribute.