A
condition that can be experienced with a set of Series Cylinders (Master and
Slave(s)) is hydraulic cylinder creep, drift or movement when the hydraulic cylinder
is not in use. There can also be a
condition that Series Cylinders will become out of sync, or not extend and
retract at the same rate. Below is a
brief over view of some of the possible conditions that contribute to cylinder
creep, drift or the series cylinder getting out of sync. Keep in mind that the cylinders are only part
of the hydraulic circuit and there can be other contributing causes.
Cylinder rod measurement:
Cylinder
by-pass is a common field issue in Series Cylinder Systems, and a system review is required to determine
the problem.
-Extend
cylinders to the re-phasing position and lower hydraulics approximately
2".
-Then
immediately disconnect the hydraulics from the tractor.
-Measure
the length of the extended cylinder rod on each cylinder.
-Leave
implement to stand for some time, i.e. 3 hours.
-Re-measure
length of rods again and compare before and after measurements.
Please note: Variation can be expected if
implement is left over a period of time where the temperature change affects
the hydraulics by contraction or expansion. Warm to cooler temperatures
will cause the series cylinders to move. Make sure measurements are taken
at similar temperatures.
-When
the 'suspect' cylinder has been identified, it is important that dis-assembly is
carried out in a clean environment. The scoring of barrels and piston seals
will usually indicate contamination of some type has entered the system.
Air
in the system:
If
one or all of the cylinders drift down or the system is 'spongy' air is likely
present. Check for air bubbles going back to tank or by removing the return
line and catching oil in a clean container. With the rod clevises disconnected
and the cylinders vertical, hold in the re-phasing position until no aerated
oil flows. Hydraulic oil flow should be kept to a minimum minimize heat while
purging the air from the system.
Please note: Check the reservoir levels when
carrying out this exercise. Once the air has been pushed out of the system the
reservoir can become low. This can introduce air in to the system again.
Miss-staged
series cylinders:
Over
a period of time the series cylinders may become miss-staged due to seal
by-pass or differences between the rod side of the master cylinder and the
extend side of the slave cylinder(s). To restage the cylinders it is necessary
to extend them to the re-phasing position of for 30 seconds to 1 minute.
Retract and then extend the cylinders to ensure that they are working evenly
and staged with each other. It may be necessary to repeat this process.
Below are a few scenarios where the main or master cylinder drifts in retract and how this retract drift could cause the slave cylinder(s) to extend or retract.
Below are a few scenarios where the main or master cylinder drifts in retract and how this retract drift could cause the slave cylinder(s) to extend or retract.
Keep in mind that Prince Manufacturing Corporation provides custom designs to fit specific applications. Click here for details.
You may visit www.princehyd.com to view Prince Manufacturing Corporations standard Series Cylinders for further details. Our Series Cylinder parts manuals can be accessed by clicking here.
