Can PT-425 handle Sabre Saw?

[SPYDERLK]

You need some sort of flow divider. It seems to me that nearly any of them would work, be they priority, proportional, or rotary. JJ would better know the finer points of choice between them. Without knowing why not:confused2: I would choose the proportional or rotary, sized appropriate to your total flow. These split the incoming flow into 2 equal portions. If your PT was at full rpm this would be 4 and 4gpm. You would use one of these flows for the Samurai and back off the rpm just a little to get 3 and 3gpm. This ploy would allow you to use engine rpm from midrange up to 3/4 maximum to vary the speed of your cutter. [higher would overspeed it a little] ... Now, a priority divider would send its priority flow to the cutter at any engine rpm where at least that much flow was available from the pump. This would keep the cutter speed constant until fairly low engine rpm where the pump could not deliver the priority flow. You can access Surplus center dividers from JJs link in post 14
larry

 

[Clumber]

Thanks SPYDERLK, I am begining to get it. I just read on the Surplus Center site that Rotary dividers are used to sync two cylinders, and proportional dividers are used for hydraulic circuits or motors that operate at same speed. Integral check valves allow free return flow through valve in reverse. I don't umderstand this last sentence...

So I think the priority divider is more appropriate in this case... So the one JJ suggested seems a good choice:
https://www.surpluscenter.com
/item.asp?item=9-4158-4&catname=hydraulic

I would just leave the pressure relief setting at factory default of 1500 PSI.

 

[SPYDERLK]

That one is a 4gpm priority. Thats more flow than the Samurai wants, I thot. They sell a 3gpm priority of the same thing tho. Another thing to consider is the 30 gpm input capacity of that valve. Thats so far above what youre feeding it I would be concerned how well it would operate and would seek advice.
larry

 

[J_J]

Here you go, 0-8 GPM, with relief.

https://www.surpluscenter.com/item.asp?item=9-064-38&catname=hydraulic

Instructions for the valve.

https://www.surpluscenter.com/adspecs/AS9-064-38.pdf

This is similar to what I use on my older PT. Mine is 0-13 GPM. Most of the newer PT's, use a PTO solenoid on/off hyd valve.

You could probably use the Aux hyd. I think I would try that first.

 

[Clumber]

That one is a 4gpm priority. Thats more flow than the Samurai wants, I thot. They sell a 3gpm priority of the same thing tho. Another thing to consider is the 30 gpm input capacity of that valve. Thats so far above what youre feeding it I would be concerned how well it would operate and would seek advice.
larry

I was thinking of backing off the throttle to lower the GPM, but now I see that the priority divider delivers 4 GPM at any engine RPM. So it won't work.

 

[Clumber]

Here you go, 0-8 GPM, with relief.

https://www.surpluscenter.com/item.asp?item=9-064-38&catname=hydraulic

Instructions for the valve.

https://www.surpluscenter.com/adspecs/AS9-064-38.pdf

This is similar to what I use on my older PT. Mine is 0-13 GPM. Most of the newer PT's, use a PTO solenoid on/off hyd valve.

You could probably use the Aux hyd. I think I would try that first.

Thanks JJ! I was looking for a fixed setting to avoid accidental movement of the lever, but I may not have a choice. Also, I was going to use the PTO to drive the cutter and the AUX to drive a cylinder telescoping boom like the one in the photo. But I think I am getting ahead of myself for now. I will draw up a configuration of hoses, fitting and connectors to implement this. I will then ask for a sanity check.

 

[FAZTRAC]

Clumber
JJ has picked the right valve for you. Both control of flow and pressure are integrated in one valve.You can set either pressure or flow from O to full flow and 0 to 3000 psi. The cutter uses a 3 cubic inch dispacement per revolution motor, so 3.3 GPM produces 254 theoretical rpm which is their ideal speed. In actuality they allow you up to a maximum of 400 rpm on their motor so you actually have quite a bit of leeway in setting the speed/flow.
The flow adjustment lever has a locking device on it once you set it you just tighten the knob and it stays. The same is true for setting the pressure, there is an allen head screw under the cap with a locking jam nut, it will not move once adjusted either. Flow is motor speed & Pressure is motor power in simplistic terms. That's a great looking cutter. Hedge trimmer on steroids, go for it. I can lend you a flow and pressure meter to set your speeds and pressures if you do this.

 

[J_J]

On the subject of rpm for the hyd cutter. If the sickle bar blades are on top of each other, this situation will give the widest opening, and dictate the width of the cut object.. The correct rpm will vary for the thickness of limbs/branches/twigs, etc, to provide an efficient cut. At a fast rpm, the timing of the cutters may be that it will only allow, say a small stem to be cut cleanly, and if cutting large branches at the same time, the teeth will eventually grind/chew through the material. If the rpm is slow enough to allow the full thickness, say 1 in, to drop into the valley of the teeth, the teeth can make a clean cut in one cycle.

I would say try it at different rpm's for certain material and you will get a feel for the correct rpm. I have many many hours using a gas hedge trimmer. Slow rpm is good sometimes, and at other times fast cycle time is good. Keep it slow for the larger stuff.

The torque is going to be there at any speed, if the motor is running, and it will not be constant. . Torque is also based on cu in and psi. So a 2.8 cu in hyd motor developing the full 2500 psi, will have a force of 1116 in lbs or 92.9 ft lbs of force. If cutting small stuff the torque will be low, as the pressure developed by the hyd motor will be low.

No idea where they come up with the 500 psi, without a pressure reducer, as the load dictates the pressure.

 

[Clumber]

Clumber
JJ has picked the right valve for you. Both control of flow and pressure are integrated in one valve.You can set either pressure or flow from O to full flow and 0 to 3000 psi. The cutter uses a 3 cubic inch dispacement per revolution motor, so 3.3 GPM produces 254 theoretical rpm which is their ideal speed. In actuality they allow you up to a maximum of 400 rpm on their motor so you actually have quite a bit of leeway in setting the speed/flow.
The flow adjustment lever has a locking device on it once you set it you just tighten the knob and it stays. The same is true for setting the pressure, there is an allen head screw under the cap with a locking jam nut, it will not move once adjusted either. Flow is motor speed & Pressure is motor power in simplistic terms. That's a great looking cutter. Hedge trimmer on steroids, go for it. I can lend you a flow and pressure meter to set your speeds and pressures if you do this.

Thanks FAZTRAC, for the insight and offer to loan the gauges. Before I take you up on that, can you or anyone suggest the gauges that I could purchase (i really should have them if I'm going to get involved in this and other projects). Also, please elaborate on the process, for example, where the gauges should be connected etc.

 

[Clumber]

Thanks to all of you for the guidance provided here. It is much appreciated.

I will be beginning the project soon and will keep yall appraised of the progress.

I do have two areas that I'm a bit fuzzy about. Not clear on what the pressure setting should be. 500 psi seems ridicules. I will probably leave it set at the factory default, i.e., 1500 psi, and see how that works.

The other is the t-fitting or valve used to connect the excess flow line to the return hose. Is a special t-valve needed to ensure the direction of the flow?

Thanks again.

Patrick

 

[J_J]

When you install the tee for the return, the flow will find the path of least resistance, which is usually to the reservoir/tank.

Flow gage and pressure gage setup.

To check for pressure and flow, add the setup in series with what you want to test. For instance, if testing a hyd motor, install the flow gage and pressure gage in series, and with the motor running, the flow gage will show GPM's, and the pressure will show the pressure developed by the motor.

It may not show max pump pressure, because it depends on the resistance the motor has to work against. If the motor was about to stall, the pressure would be up very high, and the flow decreasing. With a light load on the motor, flow would be up to the pump volume, and the pressure would be low.

 

[J_J]

There is no psi statement in the manual other than the 500 psi. Although the motor is rated for 2300 psi. The selector valve I suggested, has a factory setting of 1500, up to about 2500. So if you don't use the selector valve, the only relief will be on the PTO valve, which may be to high for the pruner.

It also says that the pump used can be up to 10 GPM's, They seem kind of vague on things, like they never tested the unit with gages attached under min and max conditions.

 

[FAZTRAC]

Clumber:
Purchase a 3K PSI, bottom mount, hydraulic pressure guage and a 0 to 10 GPM flow meter, which is a small cylinder about a 10 in. long, typically with half inch female pipe thread at each end, with an arrow indicating flow. A donut ring rides up and down inside the tube scale, indicating in gallons per minute/ litres per minute how much oil is flowing through the tube. Next install a half inch "t" fitting on the "out" end of the flow meter and install your pressure guage into the branch of this "T". On the other end of your "T" you attach a high pressure ball valve that is in line with the flow meter (your guage is attached at 90 degrees in the T branch)
I like to install a short jumper hose about 2 feet long at the inlet end of the flow meter. This gives you flexibility in installing your flow meter and press. test into almost any circuit on the tractor for additional trouble shooting down the road. In this case you will install your inlet test hose into the controlled flow port of your combo flow control/presure relief valve. The hose between the CF port and your cutter you attach to the ball valve at the "out" end of the flow meter. Initially I would put a male jic by male jic fitting between the two hoses that connect to your cutter motor so it doesnt run during your testing, and then you are ready to test. You will set your flow control lever to "0" on the valve scale. You are now by- passing all the oil back to the tank through the EX port of the valve. You then take the cover nut off the pressure relief adjuster, loosen the jamb nut, and then back out the big screw thing until it feels loose. In reality you are backing off tension against a spring holding a ball or plunger. You are now at 0 flow and 0 pressure in your motor drive circuit. First step is to set the flow. Turn on the PTO circuit and set your flow at 4.5 gallons per minute using the lever with the ball on it. Lock down the flow control lever when you reach required flow. Your flow should barely change on the guage no matter how fast you run the engine. Next you slowly close the ball valve (your flow will go to 0) and start turning in the big allen screw on your pressure adjuster, you will see the needle on the pressure guage start to rise. When you reach the factory pressure setting recommendation, (whatever it is !), you will tighten the jam nut and reinstall the cover cap nut. Your adjustments are now complete. Open the ball valve, remove tester from circuit and reconnect the hoses to your cutter motor. Put caps and plugs on your tester or hook one end to the other after you remove it from the system. Treat all hydraulics like open heart surgery, everything must be kept sterile at all times.:thumbsup: Use JIC 37 degree swivel fittings for all new hoses and fittings just like PT does, easy to connect and remove for service.

 

[J_J]

The solenoid control PTO GPM is 8.

The 425 can not set the GPM's unless he runs the engine at a lower engine rpm, and in normal operation, the engine is normally run full open for cooling, hill climbing, ditch work, etc.

The relief pressure is already set on the solenoid PTO valve for the PTO attachments. However if you are talking about the additional flow control valve with relief, then he would set that valve to whatever relief the system needs for the motor, and the lever on the side of the valve determines the GPM to the hyd motor from 0 to 8.

Manual says 3.3 GPM, producing a certain motor rpm, but could be variable according to the material you are cutting.

 

[J_J]

If you want to go less money, the Aux circuit at full engine rpm will provide 4 GPM, and if that provides the correct sickle bar speed, then use it. Again, the pressure in the Aux circuit is dictated by the material you are cutting, and if you want to see the pressure, just add a pressure gage in the Aux circuit.

 

[Clumber]

If you want to go less money, the Aux circuit at full engine rpm will provide 4 GPM, and if that provides the correct sickle bar speed, then use it. Again, the pressure in the Aux circuit is dictated by the material you are cutting, and if you want to see the pressure, just add a pressure gage in the Aux circuit.

So, if I used the Aux circuit then I don't need the divider. I can control the flow from 4 GPM to approx 3.3 GPM, required by the sickle, by reducing the engine rpm just a tad from full. The effect on engine cooling should not be significant. This is the method suggested by the vendor.
"You are correct you could control the speed the cutter operates by varying the rpm of your tractor. You just need to make sure the cutter knives can be seen with the naked eye, if they are going faster and are a blur to the eye than you are outside the operating range."

 

[MossRoad]

If you use the AUX circuit, you have to find some way to direct the flow. It currently uses the lever down by your knee. You don't want to be having to hold that lever on all the time. And you may not want to be able to accidentally reverse the flow by pushing the lever in the wrong direction. Just some things to think about.

 

[Clumber]

Thanks MR, I forgot about that lever control. Well, I guess its back to the divider on the PTO circuit alternative.

 

[Clumber]

FAZTRAC, thanks for the very useful details you provided in post #33. It gave me a firm grasp of what I need to do.

 

[J_J]

If you use the AUX circuit, you have to find some way to direct the flow. It currently uses the lever down by your knee. You don't want to be having to hold that lever on all the time. And you may not want to be able to accidentally reverse the flow by pushing the lever in the wrong direction. Just some things to think about.

I don't think the sickle bar unit cares which way the motor is turning, as the blades just slide back and forth. Just looking at the blades, you can not tell which direction the hyd motor is turning. The motor is reversible.