This is where I get confused. Are all the valves except for the primary solenoid controlled PTO open center valves? I know that you shouldn't switch on the primary PTO without a motor attached because you'll overpressure the system causing the relief valves to kick in, correct? If so, are most log splitter designed to hook into a tractors hydraulics going to have open center valves? And lastly, if I wanted to be able to reverse a motor would this valve work?: Prince Energy Motor Spool Open Center Control Valve — 20 GPM, Model# RD-2575-M4-EDA1 |Valves | Northern Tool + EquipmentBobRip said:
Log Splitter
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KentT
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ddonnell said:
The ones controlled by the joystick are just the first two banks of the same circuit as the Aux PTO. There are actually three valves stacked together down there. The joystick controls two for lift and curl, while the Aux PTO lever controls the third.
Yes, as far as I can tell (I'm a hydraulics newbie also) open-center valves have continuous flow through them and divert fluid one way or the other to control things like dual-action cylinders to push or pull.
KentT,
I'm not trying to put you on any kind of a spot and I am not holding you to your response, but as you understand it, are these "stacked" pumps selective in the way that they divert fluid to the the primary functions of the PT? Through other posts, I've gotten impression that steering is proprietary, lift/tilt is secondary to that, and PTO output is tertiary. The aux. circuit is, for all intents and purposes, a seperate entity except that at any given moment it could/would draw down on the overall hydraulic capabilities of the PT. Am I in the ballpark?
I'm not trying to put you on any kind of a spot and I am not holding you to your response, but as you understand it, are these "stacked" pumps selective in the way that they divert fluid to the the primary functions of the PT? Through other posts, I've gotten impression that steering is proprietary, lift/tilt is secondary to that, and PTO output is tertiary. The aux. circuit is, for all intents and purposes, a seperate entity except that at any given moment it could/would draw down on the overall hydraulic capabilities of the PT. Am I in the ballpark?
KentT
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ddonnell said:
That's partially correct. There are three pumps on my older 425, at least:
1. The variable displacement tram (drive) pump powers ONLY the 4 wheel motors.
2. There's a fixed displacement pump that drives ONLY the main PTO that we've been talking about. Again, I think it's an 8 GPM pump, as I recall.
3. There's a third fixed displacement pump that drives the steering, the lift/tilt circuit, AND the Aux PTO.
Here's a great picture that shows those last two pumps, from MR's site. Note that they are stacked on the rear of the Kohler CH25, with #2 mounted to the engine and #3 piggy-backed on it. The drive pump is on the opposite end of the engine's crankshaft. With the Robins engines, this layout is different, but there's still three pumps, unless I'm mistaken.
In summary, the Aux PTO is shared with the steering and lift/tilt circuits, but nothing else. I think the routing is such that it goes to the steering first, then the tilt, lift and aux PTO valves in that sequence. However the tilt, lift and aux PTO valves are all stacked, so none of them would clearly have priority, I don't think. However, the steering valve would, as I understand it. In most usage, you're likely using a couple of those functions at a time...
Sometimes you will notice the lift or tilt slow down, when you have the steering wheel turned to the point the tractor if fully articulated... but that's all I've noticed.
KentT,
That makes sense. Wheels are on there own. Steering, lift/curl, and aux. share, and PTO is on its own.
On my CUT when I am full turned left or right with steering pressure, the loader won't operate (until I let off the steering pressure). Is that how it works with the PT? Also, you mention a variable displacement pump for the wheel motors. Is this how PT effectively creates a "differential axle" for turning, i.e. do the outside wheel motors get more fluid to turn the wheels faster than the inside motors so you don't get the "skidding" effect of a straight axle?
I guess I'm hitting you up for "Hydraulics 101" here. Sorry.
That makes sense. Wheels are on there own. Steering, lift/curl, and aux. share, and PTO is on its own.
On my CUT when I am full turned left or right with steering pressure, the loader won't operate (until I let off the steering pressure). Is that how it works with the PT? Also, you mention a variable displacement pump for the wheel motors. Is this how PT effectively creates a "differential axle" for turning, i.e. do the outside wheel motors get more fluid to turn the wheels faster than the inside motors so you don't get the "skidding" effect of a straight axle?
I guess I'm hitting you up for "Hydraulics 101" here. Sorry.
KentT
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hogi said:
Hogi, I think all three in that bank are open-center, but the lift valve also has a detent for float, so it is different from the other two...
I can't answer you question about the Prince valve, but I'm sure JJ (our resident hydrualics guru) can...
It does look much larger than what you need, however, since it is rated for 20GPM and large connections/port openings...
J_J
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KentT said:
Hogi, Some tractors have open center, and some have closed center valves. You need to match up the log splitter valve with the same kind of valve. To control a hydraulic motor, you really need a motor spool valve.
Open center lets the fluid go back to tank in the neutral position. On my 1445, I have a motor spool valve on my PTO, and I can vary the speed of the PTO. Other units have a solenoid valve which is either on or off. My third valve on the three is called an aux valve to control another hydraulic cyliinder as on the blade to angle left or right. or what ever else you want to control. If you want to use a hydraulic log splitter on the PT, you need an open center valve and select the PTO on. The fluid will then go back to tank in the neutral position. You could use any open center valve for the log splitter, but they make a valve that will automatically return to the neutral posotion on the back stroke. I use a hydraulic log splitter on the back of my Kubota, and it does an excellent job. I have thought about switching it to my 1445. A gear pump normally uses an open center valve, because that pump is always pumping fluid, and the fluid has to go some where. A variable speed pump only pumps fluid when it is call for, as when you activate the closed center valve. Lever on, fluid flows, lever off, fluid stops.
Anyway, that's my story and I am sticking to it.
MossRoad
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KentT said:That's partially correct. There are three pumps on my older 425, at least:
1. The variable displacement tram (drive) pump powers ONLY the 4 wheel motors.
2. There's a fixed displacement pump that drives ONLY the main PTO that we've been talking about. Again, I think it's an 8 GPM pump, as I recall.
3. There's a third fixed displacement pump that drives the steering, the lift/tilt circuit, AND the Aux PTO.
Here's a great picture that shows those last two pumps, from MR's site. Note that they are stacked on the rear of the Kohler CH25, with #2 mounted to the engine and #3 piggy-backed on it. The drive pump is on the opposite end of the engine's crankshaft. With the Robins engines, this layout is different, but there's still three pumps, unless I'm mistaken.
In summary, the Aux PTO is shared with the steering and lift/tilt circuits, but nothing else. I think the routing is such that it goes to the steering first, then the tilt, lift and aux PTO valves in that sequence. However the tilt, lift and aux PTO valves are all stacked, so none of them would clearly have priority, I don't think. However, the steering valve would, as I understand it. In most usage, you're likely using a couple of those functions at a time...
Sometimes you will notice the lift or tilt slow down, when you have the steering wheel turned to the point the tractor if fully articulated... but that's all I've noticed.
Very good description (and nice picture, too, by the way
). Notice in that picture the larger hose coming out of the left pump section and the smaller hose coming out of the right section. The left section (on my 2001 PT425) is the main PTO pump, rated at 8 GPM. The right section is the pump for the steering/lift/ and aux PTO. It does not flow 8GPM, but does flow a good bit of fluid. I think the folks at Power Trac said around 6GPM.Now look at this picture.
The blue caps are the main PTO connections and the connections to the outside of both of them are for the AUX pto which operates the quick attach cylinder down behind the quick attach plate when... look at this picture...
You operate the lever that is just in front of your right knee, visible here, under the key tag marked 25.
If I were going to operate a log splitter, I would probably use the main PTO and an open center valve on the splitter. Then it would just be a matter of attaching the log splitter, hooking up the two main PTO hydraulic connections, starting the engine, and flipping the electric PTO switch (visible in the picture above, just above the key tag marked 25). You could adjust the flow with the throttle. That is how I plan on powering my backhoe. If it proves to be too much flow, I could always connect into the AUX PTO instead, but then I would have to find a way to hold the AUX PTO lever up or down to get flow out of that circuit.
J_J
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I am sure that some one will correct me if I am wrong, but I was sure when I researched the steering valve, that there is a priority circuit in the steering to divert most , if not all the hyd fluid to the steering cylinders. On my 1445, most all lifting and tilt is inhibited, until I stop steering. With the steering all the way left or right, there is no lift or tilt. I believe the same will happen to the aux circuit.
Charlie_Iliff
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J_J said:
Same on the 1845.
For the post driver, the connection is to the main PTO. The valve on the driver is open center. If I put a wedge on the driver, it would be an extremely powerful log splitter.
