Hydraulic motor flow valve

[ericm979]

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]

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

 

[jabelding]

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]

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]

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]

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]

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]

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

 

[Steave]

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]

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.