Any mods for faster hydraulics of portable woodmizer

Bibbyman · February 28, 2008, 01:25:06 PM

Would there be any added danger in this mod?

As the WM loading arms are powered, there is a "fuse" that would prevent the loading arms from falling should pressure be lost - as in a broken line.

logwalker · February 28, 2008, 02:25:57 PM

Quote from: Dan_Shade on February 28, 2008, 12:52:40 PM
what about the other direction?

That is the rub, with this configuration there is no other way. Have to throw the selector valve back to normal.

logwalker · February 28, 2008, 02:29:20 PM

Quote from: Bibbyman on February 28, 2008, 01:25:06 PM
Would there be any added danger in this mod?

As the WM loading arms are powered, there is a "fuse" that would prevent the loading arms from falling should pressure be lost - as in a broken line.

I think it would depend on where the fuse is located in the circuit. If I remember right they are at the cylinder where the extend line goes in. They would probably still function correctly. Maybe...

Dan_Shade · February 28, 2008, 02:42:45 PM

so you'd have to have a selector valve at the cylinder, or other hoses running back to the control box?

MikeH · February 28, 2008, 06:30:41 PM

Six times faster loading arms? better get offbearer a nut cup.

Dave Shepard · March 01, 2008, 09:07:31 PM

My Kubota L48 uses a regen circuit on the dump side, it's really fast. I thought something was wrong with the loader when I got it because you could not lift the tractor when the bucket was flat on the ground. The loader on my tractor takes care of all functions in a number of hydraulic blocks, it also has automatic leveling. Lot's of hoses.

Dave

Dave Shepard · March 02, 2008, 04:23:43 AM

Doing a little late night insomnia inspired engineering here. If you were to use electric solenoid valves, you could easily set up your regen circuit. Bibbyman, what is this "fuse" you are talking about? Does the system pressure have to excede a certain amount before the cylinder will move, like on a man lift? I wouldn't think that would come into play for what we want to do, unless it won't flow the added volume. The available pressure to overcome it would be the same. I would think some care would be in order, don't want the log to hop over the backstops. :D

Dave

MartyParsons · March 02, 2008, 08:39:26 AM

OK,
The velocity fuse is located on the bottom of the loading arm clyinder. It is rated at 5 gpm on the LT40 and the 6 gpm on the LT70. Its function is to keep the loader from falling if there was a failure of the hose. It is a small fitting that has holes rated at a rated gpm if there is more oil passing through these holes it pushes a check ball on a seat and keeps oil from passing. So if you and a friend are doing a sawing job and you are loading a log and your friend is helping with a BIG Log Rite Cant hook trying to help the log on the mill and the hose failes your friend and you will be away and then you will repair the hose and go on with life. If you remove the safety fuse you or you good friend will be under the log or loader and you will be saying o ----- how do I get my buddy out from under the log! :'(
Be safe out there!

Marty

freddycougar · March 02, 2008, 07:57:31 PM

:P... forget the regen circuit.. u lose power.. add an accumulator

Brucer · March 04, 2008, 12:37:33 AM

You don't need to do any "plumbing" at the cylinders. You've got 2 hoses connected to the 2 cylinder ports, so you can do everything in the hydraulic control box.

I believe (could be wrong) that the velocity fuses work one way -- they kick in if fluid is leaving the "extend" side of the lift cylinder too fast. Regeneration will cause extra high velocity only when the fluid is entering the cylinder. This is certainly something to check out before getting too far into this mod. I would most definitely not remove or bypass the velocity fuses. It's the biggest and heaviest logs that fall the fastest (and are more likely to cause a hose to fail).

The point of the mod is to allow a faster lift with lighter logs. Yes, regen sacrifices lifting force for speed. The downside of accumulators is that you have to run the hydraulic pump for a while to charge them up. That's fine on a conventional hydraulic circuit where the pump is running constantly. It's not so great on a mill that only runs the pump when a control lever is activated.

I'll dry to come up with a circuit diagram sometime this week (but don't hold your breath).

Dave Shepard · March 04, 2008, 01:04:00 AM

If you had a diverter valve setup, you could select between standard and regen. If the velocity valves are truely one way, then it is a simple matter of gettin' some parts and git'n'r'done.

Dave

Brucer · March 10, 2008, 12:40:14 AM

Been thinking about his some more. Theory is all very well, but looking at it from the practical side raises some safety issues.

What the regen circuit does, in effect, is allow you to switch from the normal size cylinder (3" on the WM lifting arms) to a cylinder the size of your cylinder rod (1-1/4" on the WM). That's about a 6-1 ratio. Just throw a selector valve and you've effectively got a different sized cylinder. Six times the speed and one-sixth the force.

Here's the problem. Suppose you were to lift a heavy log (say 3000 lb). You'd have to use the "normal" mode to do it, and you'd be running about 1000 PSI in your hydraulic circuit (relief valve setting is just over 2000 PSI). Now suppose for some reason, you stopped lifting when the log was still on the loader arms, and then switched over your regen selector valve. That would be exactly the same as replacing the 3" cylinders with 1-1/4" cylinders, and the weight of the log would push the system pressure up by a factor of 6 -- in other words, about 6000 PSI. With the control valve not in use the system's relief valve would be separated from the extra load, making it useless.

In this situation, you'd for sure blow a hose. That would immediately disable the regen effect, but meanwhile you'd have a falling log to deal with. If you were smart enough not to remove the velocity fuses, they would hopefully stop the fall. But now you've got a suspended log and a ruptured hose to deal with. No way to shift the log with the hydraulics until you fix them, so you've got a real mess on your hands.

To make this a safe(r) circuit, you must add a relief valve between the regular control valve and the cylinder. It goes in the hose that connects to the bottom of the cylinder (the "extend" side). This relief valve will have to be set higher than the system's regular relief valve but lower than the safe operating pressure of the hoses and components in the system. And no, you can't rely on the sawmills existing relief valve. Remember, it's on wrong side of the control valve.

This little addition complicates the plumbing a lot, because now you have to vent the new relief valve back to the reservoir.

Realistically, a 6-1 regen ratio is not ideal. You'd be better off with a 3" cylinder with a 1-3/4" rod. That would give you a 3-1 regen ratio, which is a little more useful and also keeps the potential system overload down to a more manageable level.

Hydraulics packs a lot of energy into a very small package, and you've got to be careful when you mess around with it.

Dave Shepard · March 10, 2008, 09:52:35 AM

I may be wrong, but I think we are only changing the volume of oil, not pressure. The pressure on the rod is not going to change, only the speed that it is lifting. Another question: what happens when the valve is in regen, and we aren't putting pressure into the system, isn't the oil going to try and go to the other side of the circuit and lower the arms?

Dave

Brucer · March 14, 2008, 01:50:17 AM

You aren't changing the pressure on the cylinder when you're sending oil to it. The arms lift faster and with proportionately less force. However, when a dead load is applied to the arms, it generates pressure. With regen active, the pressure is much higher.

When you have the system in regen and the main control valve is closed, the oil might "try" to flow through the system to the other side of the piston, but there's no room for it! Don't forget, the cylinder rod is there, taking up some of the space the recirculation oil would occupy.