Hydraulics valve question

[Anonymous-0]

Hello,

Have a hydraulic question for you.

Have a 15 gpm pto pump. Need to spin a hydraulic motor. Also need to lower the spinning hydraulic motor at the same time via a cylinder. Do they make a priorty valve so the motor keep spinning and the cylinder will lower at the same time. I don't think the motor will keep spinning with regular open center valves.

I am making a hydraulic post hole digger with down pressure on a tractor with no 3ph and it has a mounted post driver on the front.

thanks,

 

[Bob]

You need a "flow divider".

 

[JMS MN]

Look into a priority valve like those used on power steering tractors/combines. They pull away maybe 3gpm to run the steering motor, leaving the rest for other demands. Purpose is to always have steering, no matter what other demands are. Probably a lot of combine valves are crunched in salvage yards- not a big demand for them compared to pumps, motors, cylinders. Not hard to spot- little casting between the pump and hydro steering unit. I scarfed a few from JD and IH combines- same unit, different color.

 

[Rusty wheel]

You can install flow control valves in the cylinder ports. Always control the flow on the exhaust port to prevent drifting. If you only want to control the speed of the cylinder going down, you only need one control valve. The oil would be free flow to the cylinder going up. RW

 

[rrlund]

Can't you simplify the whole process by using a 2 spool valve? One side for the motor,the other for the cylinder.

 

[RodinNS]

I've never found that you need to lower the auger at the same time as you run the motor. I always just put some down pressure on the bit and then let it dig. I run them on a skid steer and never had any trouble like that. Actually, I don't think you'd want to be forcing it down too much. It should dig it's own way down.
If you were intent on doing that you would want a priority flow control valve. I think they're more commonly refered to as a pressure compensated flow control. The controled flow would go to the motor and the excess flow to the cylinder.

Personally I'd just go with a basic two spool valve. You don't even need a motor spool for this because there's basically no inertia in an auger.

Rod