MRO Magazine

Fighting hydraulic hammer and vibration in hydraulic lines

MRO Magazine   

Machinery and Equipment Maintenance

The anticipated hose failures were avoided by:

The anticipated hose failures were avoided by:



Using 45º fittings at each end, rather than 90º fittings, in order to allow smoother flow of the hydraulic oil in the system.


Letting the Unistrut metal framing to float on top of the table, allowing it to move, rather than trying to fight the hammer and vibration.

The system has been in regular use for six years without a hose failure.

Mr. O’s thanks for this tip go out to Harold Paulson, design manager at Hemlo Equipment. For more information, he can be reached at


A large industrial plant located about 300 km east of Thunder Bay, ON, had a new 5,000-psi hydraulic system installed. There were some last minute changes to the pump location and a number of hoses had to be shortened and re-located. There had been a lot of hydraulic hammer noticed before the changeover and the management felt that this anticipated problem should be addressed at the same time.


Hemlo Equipment Ltd. of Marathon, ON, was asked to design and install a system that would solve both problems. The design consisted of a table made with 1-in. pipe and Kee clamps, with a 1/2-in. x 4-ft x 16-ft plywood top. Unistruts were laid on top of the table so that they were free to move. Gates G6K, SAE 100R15, 6,000-psi hydraulic hose and couplings were used. The fittings at both ends were 45º elbows, in order to allow the smoothest possible flow.


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