Variable feed rate for chipper

[mangoland]

I have been working with my new Bailey's/GME 6" PTO chipper,and thought a slight modifiction would be helpful. The feed rate for the hydraulic brush dragger is OK for the softer or small stuff, but it needs to feed a bit slower on the bigger hardwoods that we have. I wonder what is the best way to slow down the feed motor? I had thought to tee into both sides of the motor and put in a bypass valve across inlet and outlet. Or is there a better way?

Some of the bigger chippers, like the Vermeer down the road, have a feedback control to automatically do this. What kind of electronic valve would be needed to do this job? I could handle the electronics OK. I assume that the internal pressures in this pump/motor circuit aren't all that high.

Thanks for your help.

Here are some pictures, for those interested.
http://www.shaka.com/~kalepa/chipper.htm

 

[J_J]

Why not put a hydraulic speed control valve in the circuit. Any hyd shop has them, and northern tools, and surplus hydraulics. First determined if you have an open center or closed center system.

 

[mangoland]

I see now that it is pretty simple. (I'm just getting up to speed on hydraulics.) The system is open center. I found a valve at Surplus center that looks right, ~ $50. I figured that it should be easy.

Thanks.

 

[cadblaster]

A friend of mine has a Vermeer 625 tow behind chipper with speed sensing feed. It is awesome! I had a bunch of these long spindly trees that I cleard from the fence line, about 25 ft long by 4-7" in diameter (not good firewood). The chipper would take a big bite, slow down a bit, then speed back up and take another bite and so on until the tree was gone. It could eat up a long tree while I was off cutting more to feed in to it.
Anyway, the control for the autofeed is definately a speed sensor of some type, I never took that close of a look at it. The black box controls a couple of solenoid valves to shut off and bypass the feed rollers until flywheel speed resumes.

 

[cadblaster]

hey mangoland,
You really need to fill out your profile. Are you in Hawaii? I looked at your pictures, nice view! Are those sun tracking solar panels you have?

 

[mangoland]

Yes, you guessed that right. We're in an off grid area, so all our electricity is home made. I added a little to the profile page too. So the Vermeer is using solenoids rather than fine tuning the feed. Even easier ! That should be quite doable.

 

[SimS]

MangoLand;

I have a Vermeer 620 chipper with the "auto feed" system. The way it works, is a "black box" senses the engine rpm (they count the pulses from the alternator) and when the rpm drops below the threshold it pops the hydraulic solenoids going to the feed motor. It works pretty slick and the engine stays in it's power band so the chipping is always at it's maximum effort possible.

Sim

 

[mangoland]

I think that, in the case of a PTO driven system, I would want to sense the actual flywheel speed rather than engine rpm, since I have heard the belts chirp a little (the big Brush Bandits would do that too), and I know that it is also possible for the PTO clutch to slip as well. A JD 1050 down the road had its clutch go from too many big logs.

Shouldn't be too hard, attach a magnet to the shaft, and use a pickup (coil or Hall effect) to sense. I'll put it on the list of "Things To Do". (!)