Hyd experts familiar with Kubota grand L

[kennyd]

OK so here is an open center solenoid:

https://www.surpluscenter.com/item.asp?item=9-6137&catname=hydraulic

They calling this a motor spool. What specifically makes this OC valve a motor spool rather than just ordinary OC?

And here is one they call reversible.

https://www.surpluscenter.com/item.asp?item=9-7312&catname=hydraulic

What makes it reversible? Isnt the other valve also reversible because it is a 3 position directional? I guess I should read the spec on this valve because it doesnt seem to be a normal OC valve, but something special.

The first valve is for motors because both work ports are connected to the tank in neutral. That would be almost useless to operate a DA cylinder. It can reverse the motor also depending on which solenoid is powered.

The second valve has no neutral position- not what you want.


Have you thought about using the PTO to power the trencher through a gearbox? Seems like you'd have more power than dealing with the losses of a hydraulic motor, and it may be cheaper also.

 

[slowzuki]

Do you mean a hydraulic motor plugging into the remotes? Kubota doesn't even over a continuous flow detent position remote to allow continuous flow. If you mean the HST, yes that is a separate system, only a common reservoir. But even the HST doesn't like operating at relief pressure constantly.

Hi slowzuki, do you mean that the pump is not designed to operate at peak pressure? There should be no issues with the pump operatind the hyd motor continuously at full flow and normal pressure, right?

 

[J_J]

Why not use a motor spool detent valve, plugged into the loop. The work ports would then control the hyd motor. You could use the engine rpm to vary the flow, or add needle valves at the work port to limit the motor speed. Whatever the hyd motor doesn't use flows through the valve. The valve should have PB because it is feeding the 3pt. If the hyd motor has a case drain, it will go to tank.

http://www.surpluscenter.com/item.asp?item=9-6760&catname=hydraulic

Detent kit

http://www.surpluscenter.com/item.asp?catname=hydraulic&item=9-4895-D

PB kit

http://www.surpluscenter.com/item.asp?catname=hydraulic&item=9-4895-B

This is a fixed 5 GPM fixed priority flow valve.
Install it before the motor control valve whether solenoid or manual valve. These come in diferent flow rates,and if you know what rpm your motor need to run, then select the valve of your choice. The second outlet can feed the 3pt which would work.

http://www.surpluscenter.com/item.asp?item=9-4158-5&catname=hydraulic

Choices, choices, so many choices.

 

[brocas]

The first valve is for motors because both work ports are connected to the tank in neutral. That would be almost useless to operate a DA cylinder. It can reverse the motor also depending on which solenoid is powered.

The second valve has no neutral position- not what you want.


Have you thought about using the PTO to power the trencher through a gearbox? Seems like you'd have more power than dealing with the losses of a hydraulic motor, and it may be cheaper also.

I already have the trencher. It is a ditch witch hydraulic unit. I got it cheap. PTO units cost $4-5K. It is easy enough to attach to the 3PH, I just need to get the hydraulics.

 

[brocas]

Do you mean a hydraulic motor plugging into the remotes? Kubota doesn't even over a continuous flow detent position remote to allow continuous flow. If you mean the HST, yes that is a separate system, only a common reservoir. But even the HST doesn't like operating at relief pressure constantly.

Actually the intent is to use the backhoe connections, but it doesnt matter, the FEL, 3PH, aux, BH, its all powered by the same pump. I wonder what kind of wear to the pump might occur if operated continuosly to power the hyd motor.

 

[brocas]

Why not use a motor spool detent valve, plugged into the loop. The work ports would then control the hyd motor. You could use the engine rpm to vary the flow, or add needle valves at the work port to limit the motor speed. Whatever the hyd motor doesn't use flows through the valve. The valve should have PB because it is feeding the 3pt. If the hyd motor has a case drain, it will go to tank.

Surplus Center - 2 SPOOL 25 GPM RD522EEAA5A4B1 OC MOTOR SPOOL VALVE

Detent kit

Surplus Center - 660150002 3-POS DETENT KIT RD5000 VALVE

PB kit

Surplus Center - 3/4" NPT POWER BEYOND SLEEVE PRINCE 660312004

This is a fixed 5 GPM fixed priority flow valve.
Install it before the motor control valve whether solenoid or manual valve. These come in diferent flow rates,and if you know what rpm your motor need to run, then select the valve of your choice. The second outlet can feed the 3pt which would work.

Surplus Center - 5/30 GPM PRINCE PRIORITY FLOW DIVIDER W/RELIEF

Choices, choices, so many choices.

Hi JJ, you are sugesting a manual spool valve (not solenoid valve). In order to control said valve, it would have to be mounted up front, or in a spot accessable from the seat. I was thinking solenoid valve because it would be so easy to control remotely.

I still need to figure out where the BH loop is in the circuit for sure. I would think it is last in the circuit after 3PH (in this case I think using the solenoid valve is straight forward). From your previous posts, you beleive it is before the 3PH. If that's the case, then its more complicated because the valve will need to have PB and there needs to be a connection to the sump.

 

[slowzuki]

Its related to what pressure it is run at. At low average pressure, the pump is fine as that is how it normally operates. At max pressure at pto rpm flow, the pump only generates something like 7 hp of power. You may want to grab a cheap pto mounted pump off craigslist, most have a lot more flow than the built in pump therefore more power can be transmitted.

Actually the intent is to use the backhoe connections, but it doesnt matter, the FEL, 3PH, aux, BH, its all powered by the same pump. I wonder what kind of wear to the pump might occur if operated continuosly to power the hyd motor.

 

[J_J]

Trace out the hoses so you will know the flow path. Once the lines goes to the 3pt, you don't see the lines out of the 3pt as they are internal to the rear end.

The 3pt should be last, as the fluid in neutral and when using the 3pt just dumps into tank. So I believe the 3pt is definitely last valve in the circuit.

A motor spool valve will do what you want. Just plug it in at the loop outlets, and the work ports go to hyd motor. You flip the lever to fwd detent and the motor runs one direction, flip the lever rev detent, and the hyd motor runs in reverse. The HP generated by the motor will be dependent on the HP required to turn the pump , minus an efficiency loss of about 15 percent.

or

If there is a loop in the back, just add the flow control valve in the circuit. With the engine running, the valve will have fluid flowing through it. With the flow control lever at 0 rpm, the fluid is passing through the valve. At a high lever position, the flow control is sending fluid to the hyd motor and the lever regulates the speed. Any excess from the flow control valve flows out the valve into another circuit ie, 3pt or tank.
The out of the motor could go to tank.