Figure 10-28.-Cylinder type of accumulator.
Emergency Power Supply
The energy stored in an accumulator may be used
to actuate a unit in the event of normal hydraulic system
failure; for example, the hydroboost power braking
system used in the 1 1/4-ton tactical cargo truck or cucv
has sufficient energy stored in the accumulator for
limited emergency braking operation.
When small bits of metal, rubber, paper, dust, and
dirt enter into a system, they contaminate the fluid. The
fluid may be contaminated in many different ways. The
contaminants may enter the system during the
manufacturing of the components or during servicing
and maintenance of the system; they can be created in
the system by internal wear of the components, or
because of deterioration of seals, hoses, and gaskets.
These impurities can become suspended in the fluid and
circulate throughout the system. Because of the close
tolerance of the system components, the contamination
in a system must be kept at an acceptable level; other-
wise, the components are damaged, destroyed, or
become clogged and inoperative. It is for these reasons
that filters are essential in hydraulic and pneumatic
A filter in a hydraulic system is a screening or
straining device used to remove impurities from the
hydraulic fluid. Filters may be located within the
reservoir, in the pressure line, in the return line, or in
other locations where they are needed to safeguard the
hydraulic system against impurities. There are several
different types and arrangements of filters. Their posi-
tion in equipment and design requirements determine
their shape and size.
The filter element is the part or parts (single or dual
element) of the filter that removes the impurities from
the hydraulic fluid as the fluid passes through the filter.
Filter elements are usually classified by either their
material and/or their design and construction. The most
common filter elements used in CESE equipment are
wire mesh, micronic, and porous metal.
WIRE MESH FILTER. A wire mesh filter
element is made of a fine wire mesh (screen) and is
usually used where the fluid enters and/or leaves a