Hydraulic motor flow valve

[oldnslo]

3 GPM pump in that size valve could definitely cause a very small adjustment range. If only 3 GPM pump I would be looking for a priority flow control that is closer in size.

 

[aczlan]

I agree. I wouldn't go over a five or six gallon per minute valve and a four gallon per minute valve would be even better.

Aaron Z

 

[Steave]

I escalated to the CEO. He sent a nice email explaining that that's how it works. He also offered to take the unit back which was very nice of him. I like it other than this one issue, and it's not keeping me from using it, so I'm keeping it.

He did say that the pump's 3 gpm. The valve's 16 gpm. Based on some dial setting vs gpm response curves I found (for a different make of valve) I can see how a mismatch of valve max flow vs pump flow would cause the control to have a very narrow range. I'm thinking that a better quality valve that's closer to the GPM of the pump could result in more adjustment. The Chinese valve may leak more past the seals than an american one and that may have something to do with it as well.

If I get a round to it I may buy a replacement valve. Some engineering info I found said that the valve should be sized a bit larger than the max flow. Would a 4 gpm valve be big enough or should I go with 5 or 8? The only bolt on replacement I find with relief valve is Brand, are they decent?

The other suggestion he made was to use a heavier weight oil. (which is one reason I think the valve may leak a little internally) I've got ISO 46 in it now and could go with 68, whcih is about 50% higher viscosity.

I'm a bit confused. You said in post # 6 that the unit is all self contained. If they knew the pump only put out 3 GPM why would they install a 16 GPM flow control valve. I feel they should install the correct flow control if it needs to be variable. If I missed something please straighten me out.

 

[oldnslo]

If I get a round to it I may buy a replacement valve. Some engineering info I found said that the valve should be sized a bit larger than the max flow. Would a 4 gpm valve be big enough or should I go with 5 or 8? The only bolt on replacement I find with relief valve is Brand, are they decent?

Eric,
Brand hydraulics make a decent product but I do not believe they make a direct interchange in the 5 GPM range.

 

[ericm979]

No, you got it right. He said they tried an 8gpm valve and it made no difference. But I could not get him to say if theirs have only two speeds or if they just have a narrow range of adjustment. The options were to return the unit or deal with it myself. The CEO stopped returning my emails so I don't think that I'll be getting anything else out of them on this.

I've seen a few people with these units post that they find the speed adjustment range to be narrow. I can't get any other owners to say if they also only have two speeds. I suspect that many people don't notice the feed speed. Many people don't chip larger material like I sometimes do and they can run it all at full speed. Few people are nerdy enough to put a tach on it to check.

 

[aczlan]

No, you got it right. He said they tried an 8gpm valve and it made no difference. But I could not get him to say if theirs have only two speeds or if they just have a narrow range of adjustment. The options were to return the unit or deal with it myself. The CEO stopped returning my emails so I don't think that I'll be getting anything else out of them on this.

I've seen a few people with these units post that they find the speed adjustment range to be narrow. I can't get any other owners to say if they also only have two speeds. I suspect that many people don't notice the feed speed. Many people don't chip larger material like I sometimes do and they can run it all at full speed. Few people are nerdy enough to put a tach on it to check.

If it's a 3gpm pump and a 16gpm valve, you will have usable adjustment for about 18% of the adjustment range. After that it will be wide open.
A 8gpm valve such as: 3/8 NPT HYD FLOW CONTROL VALVE W/RELIEF RDRS137-8 | Flow Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com will help, but it will still be wide open after about 37.5% of the adjustment range.
Edit, it looks like this valve would be close to doing what you need: Brand Hydraulics FCR51-1/2(-4) Flow Control 1/2 NPT/-4 GPM Spool/Adjustable Spring Relief: Amazon.com: Industrial & Scientific
This one would be a perfect fit and it also looks like it would do full speed reverse (if the reverse valve is before the flow control valve): Brand Hydraulics FC55-1/2(-3) Variable Flow Control 1/2 NPT/-3 GPM Spool/Rev Flow: Amazon.com: Industrial & Scientific

Aaron Z

 

[bigdeano]

Unless you have another use for the valve the way it is, you should be able to modify it to a lower flow. If you pull the spool out that's fastened to the handle there's a hole in it that the oil goes thru which creates back pressure to move the main flow control spool. If you make that hole smaller you will reduce the flow control range. You could tap it part way thru and jam a set screw in there with a hole drilled in it.

I once bought a surplus flow control valve with 3/4 npt ports but it would only allow a small flow. I drilled out the hole in the spool to increase the flow to what I needed. It still goes to zero.

 

[aczlan]

Unless you have another use for the valve the way it is, you should be able to modify it to a lower flow. If you pull the spool out that's fastened to the handle there's a hole in it that the oil goes thru which creates back pressure to move the main flow control spool. If you make that hole smaller you will reduce the flow control range. You could tap it part way thru and jam a set screw in there with a hole drilled in it.

I once bought a surplus flow control valve with 3/4 npt ports but it would only allow a small flow. I drilled out the hole in the spool to increase the flow to what I needed. It still goes to zero.

That would let you reduce the max flow, but it wont do anything to make the control more granular.

Aaron Z

 

[ericm979]

Aaron, the FCR51-1/2(0-4) was the one I was looking at. There's already a forward/neutral/reverse valve in the system so this just needs to set the flow. I thought there was a 0-5 gpm but that's an unusual value so it may have been an error in Amazon's listing- I didn't check on Brand's site.

 

[bigdeano]

That would let you reduce the max flow, but it wont do anything to make the control more granular.

Aaron Z

How do you know that? After I drilled mine, it has a smooth control from zero to max, just like it did when the hole was smaller.