Figure 3-48.Replacement procedures for medium- and
high-pressure hose reusable fittings.
Cylinders may leak around piston rods or rams.
You can repair some leaks by tightening the packing
located in the cylinder end cap. Tighten the end cap
evenly until only a light film of oil is noticeable on the
rod when it is extended. DO NOT overtighten; this
results in rapid failure of the packing and causes scoring
of the rod. If you find an internal seal instead of packing,
the cylinder must be removed and disassembled to stop
the leak. Components can leak, but care in assembly and
use of new seals, packings, and gaskets during overhaul
will reduce this problem.
Heat causes hydraulic fluid to break down faster and
lose its effectiveness. In many systems, heat is dissipated
through the lines, the components, and the reservoir to
keep the fluid fairly cool. On high-pressure, high-speed
systems, oil coolers are used to dissipate the extra heat.
The following maintenance tips will help prevent
Ensure oil is at the proper level.
Remove dirt and mud from lines, reservoir, and
Repair dented and kinked lines.
Keep relief valves adjusted properly.
Do not overspeed or overload the system.
Never hold control valves in the power position
If the system still overheats, refer to the
manufacturer's manuals for charts that list the causes and
remedies for overheating.
REVIEW 1 QUESTIONS
If a force of 20 pounds is placed on an input
piston with an area of 4 square inches, what is
the pressure within the fluid?
Q2. If an input piston that is 3 square inches is
pushed down 2 inches, how far will the displaced
fluid raise an output piston that is 4 square
What type of hydraulic fluid contains additives to
reduce the foaming action?
A properly constructed hydraulic reservoir
should be capable of what three functions?
That device is installed in a hydraulic system to
prevent foreign particles from remaining in the
What component of a hydraulic system supplies
a flow of fluid to the system?