Controlling Hydraulic Motors With a 3rd Function Valve

[bdhsfz6]

Although I have W&R Long 3rd function valves on both my tractors, I'm by no means experienced with their use. I have read that these valves are designed mainly for use with hyd. cylinders, not motors. Holding the valves open for extended periods of time can cause overheating both from oil flow and the electric coils that hold the valve open. The manual warns against this but doesn't give specifics.

I plan to build or buy a few implements that use hyd. motors like a sweeper, post hole digger, brush cutter and a cement mixer. Has anyone here had any experience with extended 3rd function hyd. motor use?

 

[MtnViewRanch]

Although I have W&R Long 3rd function valves on both my tractors, I'm by no means experienced with their use. I have read that these valves are designed mainly for use with hyd. cylinders, not motors. Holding the valves open for extended periods of time can cause overheating both from oil flow and the electric coils that hold the valve open. The manual warns against this but doesn't give specifics.

I plan to build or buy a few implements that use hyd. motors like a sweeper, post hole digger, brush cutter and a cement mixer. Has anyone here had any experience with extended 3rd function hyd. motor use?

If you are actually going to use these prolonged use hydraulic motor implements, do yourself a favor and get a motor spool valve as well as maintained switches. In other words scrap the Long setup and build your own. Get the right controls for the applications.

 

[CincyFlyer]

One other issue with "regular" cylinder controls is that when you release the valve whilst controlling a motor, the motor stops dead.

 

[GLyford]

One other issue with "regular" cylinder controls is that when you release the valve whilst controlling a motor, the motor stops dead.

...which can lead to pressure spikes and damage to motors, fittings, and hoses.

 

[dfkrug]

I plan to build or buy a few implements that use hyd. motors like a sweeper, post
hole digger, brush cutter and a cement mixer. Has anyone here had any experience with extended 3rd
function hyd. motor use?

I have run a hyd mixer, a couple of hyd chainsaws, and a hyd PHD in various ways off my tractor.

To run a hyd motor, you will want a motor-spool valve if the rotary tool spins fast and has significant
momentum. That applies to vehicle drive wheels and rotary mowers, but not the items I run. In
this latter case, the tools spin slowly and have very low momentum. I actually WANT them to stop
immediately when I shut them off. Pressure spikes are very low.

In the case of solenoid spool valves, I have not had any that don't have 100% duty cycle, so the coils
do not overheat if left on. You CAN get things too hot if your valves and hoses are not sized for
the flows you will be using. Case-in-point: I run my mixer continuously off my loader, using my
AUX valve. My hoses are long (12') and small (1/4"), and they do get pretty warm. But I run my
tractor at idle speed, so that is OK. Sizing calcs I ran indicated I should use 3/8" hose, but I decided
to run the 1/4" for easier hose handling.

An intermittent-use valve, as you would have with a 4-in-1 setup, can be sized smaller than a
continuous-use valve cuz of the low duty-cycle.

 

[oldnslo]

Some flow diverters are built for continuos duty so this depends on the valve you have.

Depending on how the valve is sized, hose & fitting sizes, etc. heat can definitely be an issue. Frequently the lines used on FEL's are undersize for continuous flow usage.

The run down feature can be added at the implement Vs having a motor spool.

 

[dfkrug]

The run down feature can be added at the implement Vs having a motor spool.

Sure. Here is a crossover RV that I installed inline on the work ports, limited to 2000psi. Not the same
as in a motor spool valve that connects both work ports to tank when off. But the pressure spikes of shutting
a conventional valve off are avoided.

 

[bdhsfz6]

Sure. Here is a crossover RV that I installed inline on the work ports, limited to 2000psi. Not the same
as in a motor spool valve that connects both work ports to tank when off. But the pressure spikes of shutting
a conventional valve off are avoided.

Adding a crossover relief valve, similar to yours, is what I am planning to do. I'm looking at this Prince model:

Prince DRV Relief Valve DRV-4HH - Dalton Hydraulic

The implements I have and plan to build have no momentum issues so the valve should protect the hyd. motor and circuit. For any furure implements that have heavy spinning iron, I'll run a separate set of hoses and use a rear remote.

 

[Farmerford]

The crossover relief valve works, but if all you want to do is avoid pressure spikes when closing the control valve, install a check valve instead that checks to the pump side. When you close the control valve and the pressure in the exhaust side of the motor reaches the cracking pressure of the check valve (say 5-10 psi) the check valve opens and fluid circulates through the motor until it winds down. THe only disadvantage is that you can't reverse the motor because the check valve bypasses the motor when fluid comes in the "exhaust" port.

 

[Fallon]

Adding a crossover relief valve, similar to yours, is what I am planning to do. I'm looking at this Prince model:

Prince DRV Relief Valve DRV-4HH - Dalton Hydraulic

The implements I have and plan to build have no momentum issues so the valve should protect the hyd. motor and circuit. For any furure implements that have heavy spinning iron, I'll run a separate set of hoses and use a rear remote.

I have that same valve on my bench. Planning on installing it on the 3rd function on the loader. I thought about putting it on my PHD, but can't really see any downsides putting it on the loader. It will protect any impliments there instead of just the PHD. The only other hydraulic SSQA impliment I have at the moment is my Snow plow, which already has a similar crossover relief. Thought about stealing it, but got a new one instead.

My hoses jump pretty good when is stop my PHD at the moment. Planning on setting the new valve at 2,500psi to coincide with the rest of the relief valve stem in the system. The new one should only kick in when the 3rd function is cutoff from the other relief valve.