Can I Use a Double Acting Valve with a Singe Acting Cylinder?

[Tx Jim]

Makes sense...but now I知 confused.
What happens when you plug in a single acting cylinder into 1 port of a tractor痴 (2 port) SCV?
This is done all the time, but are you sending pump into relief when you retract the cylinder?

I've operated a single acting(1 way) cylinders on my tractors since I started custom farming in 1987. I also plug male tip to 1 side & leave other side of breakaway with NOTHING inserted. I've never had that 1 way operation cause a problem. If operating a dump trailer while lowering the bed heats the hyd oil due to over-riding relief valve then just stop engine from operating,lower bed & restart engine. Hyd oil heating problem solved!

 

[Dave M7040]

Reading this page on rear remotes from a M7040 Operators manual might add something to the thread.

Dave M7040

 

[CobyRupert]

I can see that moving lever to float, to retract a single acting cylinder, is probably better as it doesn’t dead-head pump and send it into relief.
But practically, most people don’t do this and have no problems.

 

[ptsg]

In your application, since the loader is something that's almost always up and down, I would either run a hose from the non used port to the tank or replace the cylinders with double acting cylinders as the downforce is very useful.

Most people have run a single acting cylinder on a double acting valve but that's usually for a short time and kind of sporadic (ie: Unfolding a batwing mower, dumping a trailer, etc) and not constantly moving it up and down like a loader.

 

[Iplayfarmer]

What model mower is that out of? I have a couple of Jacobson reel mowers for parts, if any of those valves are for the reel motors then they most likely won't work for the cylinders since they are open in neutral to allow the motors to spin down on their own.

I don't remember the model, but these are the valves for the cylinders that raise and lower the reels. Should work fine for loader cylinders. I just have to look at all of the extra sensors, etc. on the valve block to see what can come off.

 

[Iplayfarmer]

Cute little CRITTER. What's it's name?

For now we've decided to name this little crawler "The Mustard Seed" because if you have faith as a grain of mustard seed you can move a mountain.

It will probably make more sense if I ever get around to painting the thing the yellow color that I want to.

 

[TMGT]

I don't remember the model, but these are the valves for the cylinders that raise and lower the reels. Should work fine for loader cylinders. I just have to look at all of the extra sensors, etc. on the valve block to see what can come off.

Got it, the ones I have use a combo valve that had spools for the lift and motors together. I'd just make sure that the valve is rated for your pumps flow, a lot of the mowers use a separate low flow pump for the lift circuit.

 

[Iplayfarmer]

Got it, the ones I have use a combo valve that had spools for the lift and motors together. I'd just make sure that the valve is rated for your pumps flow, a lot of the mowers use a separate low flow pump for the lift circuit.

I guess the first step here is to find some kind of identifying information on the pump so that I can look up specs. Judging from the size of the hoses that are attached, I think I'll be okay. This pump is rated at 6.5 gpm.

 

[Iplayfarmer]

I made some time last night to putter with the Terratrac hydraulics some more. I took a bunch of measurements and did a bunch of figuring. I also pulled the alternator out so that I can figure out a way to fit both the hydraulic pump and the alternator in the space where the alternator used to be.

First of all some detail about the valve. The first two attached pictures are of the numbers I found on the bottom of the valve. I didn't see any brand name like Prince or Vickers. If these numbers mean anything to anyone please chime in. The main thing I need to determine is if this valve will handle the 10 gpm max flow of my new pump. If it helps the discussion, the hoses coming off the valve have a measured I.D. of 0.269". The OD of the rigid section is 0.382", and the O.D. of the rubber part is 0.685".

Next are the cylinders. I let the loader bucket all the way down (loosened a fitting and drained some fluid). The pin to pin distance of the lowered cylinder is 44", and the existing cylinder still has 4.5" of travel left before it is completely retracted. I'm debating between a 32" cylinder stroke and a 34" cylinder stroke. The retracted lengths are 40" and 42" respectively. The shorter stroke gives me an extra 7" of downward travel past level at the bucket and a 7 foot dump height. The longer stroke gives me 3.5" of extra downward travel and an 8 foot + dump height. In my little brain the dump height is much more valuable than the extra few inches of downward travel, but that's why I post here... for different opinions. Are there reasons why one might want that extra few inches of downward travel?

I also measured my cylinder O.D. at 3.016". I still need to look up specs to see if that correlates to a 2" cylinder or 2.5" cylinder.

The last question isn't exactly hydraulic related, but there's a stray wire on my Delco-Remy alternator. In the last attached picture there is a white wire that the positive terminal (to battery) was connected to. Then there's the black wire that wasn't connected to anything. What is it? Should I connect it to something?

 

[Iplayfarmer]

I think I may have answered my own question about the hose size. I found a calculator on Surplus Center
It gives the formula Q = 2.45 X D squared X V where Q is GPM, D is the hose diameter, and V is the velocity. The recommended velocities are also listed on the same page. At max flow I actually need a 3/4" hose to stay at the minimum recommended velocity. I think I may be able to get away with 1/2" for the hoses to the cylinders, but I'd better be a little bigger for the pressure line coming into the valve.

The bottom line is that my valve is likely too small. The good news is that I have a bigger valve on my massey 1215 tractor. It only puts out about 2.2 gpm. I may be able to swap the valves. It may be good to have a third function on my tractor loader anyway. Stay tuned.