26
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September - October 2017
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www.machinerylubrication.com
HYDRAULICS
will result in leakage at the fitting or elbow.
A 45- or 90-degree sweep ell will reduce
the turbulent flow as the oil flows through
the line.
Proper clamping is essential to reduce shock
in the system. In the photo on the right, U-bolts
have been used to clamp the pipes. In this instal-
lation, you can see that the pipe has moved due
to hydraulic shock. This eventually will lead
to wearing of the pipe and leakage. U-bolts,
conduit clamps and beam clamps are not built
to withstand the shock in a hydraulic system.
A proper hydraulic clamp should be used
(as shown in the photo below). Clamps should
be spaced every 5-8 feet, depending on the
size of the line, and must be tightened on a
regular basis to eliminate movement of the
pipe and subsequent leakage. A clamp should
also be installed within 6 inches of the termi-
nation point.
When properly placed, hoses can absorb
shock in the system. A hose should be
installed at the outlet of the pump prior to
entering the manifold or main header. This
will reduce shock at the pump when the oil
flow is rapidly deadheaded.
Hoses should also be installed prior to
connecting to a valve, manifold or cylinder.
The only exception is if the cylinder is
mounted vertically. In these applications,
pilot-operated check valves or counterbalance
valves are used to maintain oil in the cylinder
when in the raised position. The hose should
therefore be installed before the check or
counterbalance valve.
Be sure to make the hose long enough,
as its length can change when the pressure
spike occurs. On the other hand, hoses
should not be made too long either, as they
will rub on another hose, catwalk, beam or
other structure.
U-bolts should not be employed to
clamp pipes.
Hoses should be installed at the pump
outlet prior to entering the manifold
or main header.
Hoses that are too long may rub on
another hose or other structure.
An example of a proper
hydraulic clamp