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.

Preventing Overheating

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 overheating.

Ensure oil is at the proper level.

Remove dirt and mud from lines, reservoir, and coolers.

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 too long.

If the system still overheats, refer to the manufacturer's manuals for charts that list the causes and remedies for overheating.

REVIEW 1 QUESTIONS

Q1. 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 inches?

Q3. What type of hydraulic fluid contains additives to reduce the foaming action?

Q4. A properly constructed hydraulic reservoir should be capable of what three functions?

Q5. That device is installed in a hydraulic system to prevent foreign particles from remaining in the system?

Q6. What component of a hydraulic system supplies a flow of fluid to the system?