Running a Hydraulic Motor - Valve Question

[sequoyah101]

I'm not too lazy to go to the Prince manual to look but I am seeking confirmation / support. I'll go back to trying to figure out what Prince says and if they have anything like that.

I need to run a motor Reverse, Neutral (ports blocked to hold), Forward and then Free Spool. Imagine this sequence in the order listed as you move the control handle. Pulling back would be reverse and pushing all the way forward would be Free Spool. Being free spooling in Neutral is unacceptable since I need to hold a load in that position and passing through the Neutral slot while not being able to hold the load would be a problem.

What type of valve should I use?????

No direct knowledge of the JD valves, but in general...

When running a hydraulic motor, you have to remember that it is really a pump in disguise. So, if there is a lot of rotational momentum (like a rough cut mower), the motor will keep turning from that momentum. You stop the flow of fluid to the motor it can't instantly stop. It will then start acting like a pump, but the lines will be deadheaded with no relief. If the momentum can provide enough instant engery, the pressure can get very high very fast and "bad things" may happen.

Motor spool valves allow for free wheeling in neutral. Standard spool valves don't. At a guess, the "deluxe" valves may have a relief built in? You may want to add a relief valve between the inlet and outlet of the motor for protection.
Fairly cheap and easy to do. Parts from surpluscenter.com.

 

[RickB]

A standard 4 way valve with a crossover relief in the work lines will do what you want.

 

[J_J]

It would appear from your statement that you need a single spool valve with float.

You could get a loader valve which will match the GPM or this one spool valve with float.

http://www.surpluscenter.com/Hydrau...INCE-RD512GG5A4B1-OC-VALVE-W-FLT-9-6701-F.axd
Relief valve.

http://www.surpluscenter.com/Hydrau...00-3000-PSI-HYD-CUSHION-VALVE-9-4019-50-H.axd

Reverse, hold in neutral, fwd, and float/free wheel. Allows motor to turn with a load, or force the motor to turn manually.

Hydraulics:
Type: open
Capacity: 10.3 gal [39.0 L] (9-speed)
11.5 gal [43.5 L] (12-speed)
12 gal [45.4 L] (24-speed)
Pressure: 2860 psi [197.2 bar]
Valves: 0 to 3
Pump flow: 18.7 gpm [70.8 lpm]
Total flow: 25.3 gpm [95.8 lpm]

 

[RickB]

The importance of a crossover relief or some component filling that role cannot be overstated.

 

[sequoyah101]

Thanks and thanks as well to RickB. I was headed in that direction but wanted support and illumination. I plan on running this off of one of my three ways. Not much volume is needed since the motor application is SLOOOOW RPMs. The hydraulic cylinders will need a lot of speed either.

 

[thirdroc17]

A related question.

I'd like to put hydraulic rotation on the snow blower chute on my sub compact Kubota. It already has a standard loader valve. 2 spools, one with float. The one with float raises and lowers the snow blower, one without float is not currently being used and I'd like to use this to power a hydraulic motor to turn the chute.

To me, that means a reversible motor, and a couple of hoses, or over $800 to buy the same from Kubota.

Odds are, the motor will run way too fast for the application, so I'll have to slow it down. Looking at flow control valves, I see there are ones that restrict one way, and full flow the other, as well as restrict in both directions. Which would be most appropriate? The single, both way valve would be a lot cheaper, but that would put the valve upstream of the motor in one direction, downstream of the motor in the other. I don't now if this would be harmful or not, or just less desirable or no difference whatsoever. The one way type valve would require one on each side of the motor.

I should be able to get parts required, except the mounting bracket I'd have to build, for about $200 from Surplus Center. A vast savings over Kubota's price, which I simply can't really afford.

Before you say use an electric motor, I have my reasons for wanting hydraulic. Everything from trying to waterproof everything, and frying it anyway, to no good location to put a switch. The joy stick on the loader valve is right there, in my hand, doing nothing. Logic would dictate using it.

 

[J_J]

If you are trying to slow a hyd motor, find a washer restrictor or a fitting with a small orifice and insert it into one of the motor fittings.

 

[RickB]

I would install two one-way restrictors oriented so as to limit the flow TO the motor regardless of direction of rotation and allow free flow AWAY from the motor regardless of direction of rotation. Limiting flow or otherwise raising pressure in a motor return path can shorten the shaft seal life significantly.

 

[J_J]

The washers are cheaper and you only need one.

The fluid has to pass through the orifice coming and going.

Select the orifice for the speed.

Can also use a needle valve to adjust flow.

 

[RickB]

The washers are cheaper and you only need one.

The fluid has to pass through the orifice coming and going.

Select the orifice for the speed.

Can also use a needle valve to adjust flow.

Style is irrelevant, function isn't. I disagree on the quantity required for the reason I stated. Your mileage may vary, but I'm not going to risk an orbit motor for the price of a one way restrictor. You can choose to do so.