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