by Doug Hanson » Tue May 11, 2010 7:13 pm
Check to see whether there is a load holding valve built into the cylinder. Lock valves, or PO checks do not like to operate smoothly. Sometimes instead of a lock valve, there will be a counterbalance valve, these arn't usually as violent but can chatter do to hysterisis. I assume you have ruled out mechanical binding?
Look for a cartridge valve in the base cap of your cylinder, or on a block attatched to your cylinder. If it is a counter balance valve, there will most likely be an adjustment screw on it, if it is a lock valve it will just be a hex head. Do not remove or adjust either without making sure that the load is blocked and cannot fall. Also there may be pressure trapped behined the valve, so be careful when removing.
Doug Hanson
Predsident
Hanson Hydraulics Ltd.