Can PT-425 handle Sabre Saw?

[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.