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Revision B December 2013
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Hydraulic Cylinders
1. Diagnosing and Troubleshooting Hydraulic Cylinders
A. Single acting (Ram type)
1.
Most ram type failures are caused by one of the following reasons:
a. Excessive side load
b. Stroking the rod to full extension
2.
Excessive side load can be diagnosed by observing the following:
a. Cracked gland nut
b. Gouged rod
c. A cracked or bent rod that will not retract back into the tube
3.
Overstroking can be diagnosed by the following:
a.
Premature leakage past the V-rings
b. System filters that become prematurely clogged with pieces of rubber due to V-
ring crushing (See section on Filters.)
[1] Provide a mechanical stop or electrical switch to prevent overstroking.
B. Double acting
1.
In addition to the same types of failures as found in single acting ram type cylinders
(above), it is also possible to have a piston seat failure. This feature will show up as
a cylinder drift in the hold position. Troubleshoot in the following manner:
a.
Put the cylinder in the hold position.
b.
Place a jack under the load.
c.
Remove the high-pressure hose from the cylinder port on the side opposite the
holding end.
d.
Let the jack down slowly: If the position seal is bad, oil will escape from the port.
Caution:
Do not get near the load! USE CAUTION!!
2. Repairing Hydraulic Cylinders
A. Single Acting cylinder
1. Remove cylinder from the assembly, disconnect hose line(s) and drain oil.
2. Remove gland nut, rod, spreader, and packing assembly from the tube assembly.
3. Clean internal tube and inspect chrome rod for gouges, scratches, or wear. Replace
if necessary.
4. Replace chrome rod back into tube assembly.
5. Insert steel spreader.
6. Grease the V-ring set on the inside and outside diameters.
7. Re-assemble one V-ring at a time making sure each V-ring lies flat on the ring prior
to it.
8. Replace the gland nut complete with a new wiper ring if worn. Thread it down until it
makes contact with the V-rings, then tighten an additional 1 to 1 1/2 turns. The
distance between the top of the threaded collar and the bottom of the large section
on gland nut should be 1/4'' – 5/16” [6.35 mm - 7.94 mm]. Do not over tighten.
