Hydraulic motor flow valve

ericm979 · Apr 11, 2017

I have a new Woodmaxx wood chipper, with hydraulic feed. It's got a control valve on it, looks similar to this: hydraulic flow control from Northern Tool + Equipment

As I move the lever the motor does not turn until about '3' on the scale. It turns at 17 rpm right at '3'. Above that it's 45 rpm, which is the rated max feed speed for this chipper. So it's two speeds, 17 and 45 rpm.

is that normal for this type of control valve?

Leejohn · Apr 11, 2017

Kind of sounds like the GPM flow doesn't match.

jabelding · Apr 11, 2017

Do you have the hoses hooked up in the correct direction? They are very picky on the correct flow path. If I remember correctly my fathers did the same thing when it was backwards. When you push forward on the crash bar the motors should spit out the tree towards you if it is opposite the flow is reversed.

ericm979 · Apr 11, 2017

The hoses are as shipped from the factory. I verified that the CF port on the flow control goes to the directional control valve and then to the motor.
GPM not matching does sound like a possibility but would't it still be able to vary the speed more than just two speeds even if it tops out early? This is the first of these types of valves I have used. I don't know if they're supposed to be infinitely variable or what.

I think this is the valve, the model numbers match: Lkf-6 Hydraulic Flow Control Valve,Adjust -6l/min Flow,High Flow Control Valve With Hydraulic For Motor Or Tractor - Buy Control Valve,Flow Control Valve,Lkf Hydraulic Flow Control Valve For Tractor And Motor Product on Alibaba.com

jabelding · Apr 11, 2017

I meant the flow direction from the ports on your tractor they are reversible depending on witch direction you select. The valve is infinity variable and just directs some flow to the motor and rest to tank.

ericm979 · Apr 11, 2017

I could see how that might be a problem if you were using the remoted but the Woodmaxx is self-contained and does not use the tractor hydraulics. It's got a PTO driven pump, tank, etc. My problem is the Woodmaxx flow control valve is not infintely variable even though it looks like it should be.
Generally how variable are these valves? Maybe it's just a poor quality valve.

jabelding · Apr 11, 2017

Ok sorry I missed that it was self contained, It should be infinitely variable I would call the dealer and tell them its not safe they will probably fix it quickly!

ericm979 · Apr 11, 2017

I called the vendor and they said it's normal. Is it?

Steave · Apr 12, 2017

ericm979 said:
I called the vendor and they said it's normal. Is it?

You might could post a question in "attachments" somebody that has one of these machines might chim in. Just a thought. Sounds like the vendor is blowing you off.

ericm979 · May 3, 2017

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.

oldnslo · May 3, 2017

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 · May 3, 2017

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 · May 3, 2017

ericm979 said:
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 · May 4, 2017

ericm979 said:
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 · May 4, 2017

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 · May 4, 2017

ericm979 said:
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 · May 4, 2017

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 · May 4, 2017

bigdeano said:
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 · May 4, 2017

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.