Counterbalance Valves 

Thank you for your comment - I'll pass this along to Alan!

Thank you for your comment!

Thank you, Matt!

Thank you, Wristy!

Thanks for your comment, John! If your valve has no external pilot, it's probably not really a counterbalance valve. I would like to see the schematic to explain fully, but the likelihood is that either your valve is an anti-cavitation relief valve or a velocity fuse to keep the press from dropping. Sometimes the external pilot is there but is not easy to find (perhaps a small internal line drilled in a manifold), but in order for it to be a counterbalance valve, the external pilot must be there somewhere. Hope this helps!

That is correct, Angelo - most of them do adjust clockwise to decrease, but some adjust clockwise to increase. The way to tell, when you are making the adjustment, if the adjuster screw moves in and out with the adjustment, it adjusts clockwise to increase. If, like most counterbalance valves however, the adjustment simply turns without going in or out, it adjusts clockwise to decrease pressure. Hope this helps!

@@JackWeeks when I does adjust CVV my move was check the rotation of adjustment...by the way im always watch your video

Sounds to me like your counterbalance valve is improperly set. As the cylinder is going down, if it is safe to do so, adjust until you find the exact stall point. Then lower the pressure about 1/4 turn. Hope this helps!

If there is no load, pressure builds in the pilot line to whatever it takes to open the counterbalance valve and the cylinder extends.

What if no pilot

@@Eagle2pro Then the cylinder will never move unless the pressure is turned down very low. If there is no pilot line, it probably isn't a counterbalance valve, it's probably a relief valve to absorb shock.

Ever had a counter balance valve stuck in the closed position however can freely go through the check valve only.

@@Eagle2pro It can happen, yes. But it's much more likely to fail open than closed. It usually takes relatively large contaminants on the cylinder side of the valve to stick one closed.

In general, lower pilot ratios provide the best stability and motion control. This is why most of them are 3:1. Higher ratios are only used when greater efficiency by producing less heat is of greater concern than motion control. I don't think that your pilot ratio is the cause of the jerking. It is more likely that you either have bypassing somewhere or the valve is not properly adjusted. Hope this helps!

@@Gpmhydraulic there were no proplems until operator try to reduce the throttle valve to speed lowering load down.

@@samerasaad7010 Then apparently the counterbalance valve is handling the load. Your issue appears to be one of adjustment.

Thank you for your question! Yes, that is probably pretty close, but you will likely have to tweak it a bit one way or the other as said in the video.

@@Gpmhydraulic thank you for your answer. another question is: its hard to me find non vented counterbalance valve for spring set 390 bar. I use proportional valve with open throttled center, so backpressure is not forsee. is it necessary to use vented valve if spring set more than 350 bar? ps. piston ride side counterbalance spring set has 105 bar, so there I use 3 ports non vented valve.

@@ttshechkah only use a non-vented valve in applications that have no back-pressure in port 2 (inlet). Never use a non-vented valve in regeneration circuits, master-slave circuits and servo/proportional valve circuits.

@@Gpmhydraulic why does have to be a vented counterbalance valve with proportional valves? Can't a non vented counterbalance valve be used even if the proportional valve is the float center type? Thank you and greetings.

@@troubleshooter3052 It doesn't HAVE to be vented, but it usually is. This is to keep the counterbalance valve from throttling the actuator, limiting control by the valve. If your proportional valve doesn't control speed, then I suppose you don't need a vented counterbalace.

Silkanlal, sorry I missed your question - I see it was asked a whole month ago! I must have missed the notification email I usually get. The ratio is between the two surface areas of the internal and external pilots. If there is a 1:3 ratio, that means that it takes 3 times the pressure to open the valve from the internal pilot than it does the external (the external pilot is always the larger surface area and therefore requires less pressure to open the valve). Hope this helps!

@@JackWeeks thanks

Agreed, Adrian. Unfortunately that was beyond our control when this was recorded. It is our hope that the message was informative enough to overcome the lighting.

@@JackWeeks yes is was really informative you bring it really good

Do you all give online training from your school

@@adriansamuel1474 We used to. Unfortunately, as of September 30th, GPM Hydraulic Consulting had to shut down its operation as a result of the effects of Covid-19. Now, having said that, I am currently building my own online fluid power training solution incorporating not only an online course such as the one this video came from as well as shorter courses for those who may not want the full course. In addition to the self-paced learning, I will also be doing webinars and live streaming virtual classroom training. The courses can be purchased separately or get a monthly subscription with full access to all materials and classes. I'm hoping to launch by the first of the year.

@@JackWeeks when you start count me in don’t forget to message me

Thank you for your question, Gaurish. There must be an external pilot in order to avoid excessive resistance and to maintain the flow through the valve at the rate supplied by the pump without respect to gravity. With only one pilot, gravity will influence the speed of descent.