Hydraulic Flow Control Advice Needed

[Monster5601]

I need to know how to go about adding, or actually restricting, the hydraulic flow going to my Curtis hydraulic angle snow blade. The snow blade, mounted to my Kubota RTV, uses the same hydraulic circuit for the dump bed but I only want to slow the speed of the angle adjustments on the snow blade. The hydraulic control does not lend itself well to feathering.

Pictured is the snow blade attached to the front of the RTV. The hydraulic circuit connects to the front of the RTV and then into a pilot-check valve (all Kubota factory). I'm assuming the proper place to position flow control is in the circuit between the RTV and the check valve.

Do I need to add a flow restrictor on one hydraulic line or both?
Were is the proper location for the flow restrictor(s)?
Any recomendation on type of flow control, say washer versus adjustable valve?

Thanks

 

[5030]

Put the restrictor in one of the feed lines or the return line, really don't matter. I make my own actually.

 

[Tx Jim]

Several yrs ago I put an adjustable flow control valve on a Kubota M4900 FEL to control boom lowering speed when handling 4X5.5 rd bales. With adjustable FC valve cylinder speed can be fine tuned. I agree valve can be installed on either pressure or return line

 

[Rich B1]

You can restrict either flow or return, but IME, restricting return works best. You create back pressure in the cylinder and prevent over running due to lack of oil available when restricting the pressure side.

You can braze a fitting shut and drill it to create an orifice. This allows you to play with the size to get the speed you want. Start with a 1/32” orifice and go from there.

Or add the adjustable flow restrictors.

 

[Tinhack]

If you only put one in, make sure the control is bidirectional. Some of those control valves (shown above) have control in one direction and free flow in the other. Sometimes you want this, sometimes you don't. In your case, I think you'd want bidirectional.

Edit: Well, Rich beat me to it.

 

[ericm979]

You can restrict either flow or return, but IME, restricting return works best. You create back pressure in the cylinder and prevent over running due to lack of oil available when restricting the pressure side.

This is what I did on my backhoe's boom cylinder which was way too jerky, probably due to inexpensive valves. I put a one way adjustable valve on both ends, restricting the flow out. I wanted separate adjustments for each end because the rod end needs less fluid to move the same distance, and also gravity acts on the boom.

 

[Monster5601]

Thank you for the advice but it leads to another question.

Since the angle blade is bidirectional, how can I determine which line is pressure and which one is return since they have to exchange roles depending on the blade direction?

 

[Rich B1]

Do you have a schematic? My best guess is you need the adjustable type adjuster that allows free flow in one direction, restricted flow in the other on the lines to your plow from your vehicle.

 

[Tinhack]

Thank you for the advice but it leads to another question.

Since the angle blade is bidirectional, how can I determine which line is pressure and which one is return since they have to exchange roles depending on the blade direction?

Both lines are alternating pressure lines depending on which way you move the valve. The line that's "not pressurized" gets dumped to the tank. That's why if you use a single flow restrictor, you want a bidirectional restriction. (It will slow flow in either direction.) The rod side of the cylinder will still move a little faster since the cylinder volume is less.

 

[ericm979]

Bidirectional flow control valve: 1/4 NPT 5 GPM Needle Valve Wolverine by Prince Mfg WNV-400 | Wolverine by Prince Mfg | Brands | www.surpluscenter.com

Single direction: 1/4 NPT 5 GPM Prince WFC-400 In-Line Flow Control | Prince Mfg | Brands | www.surpluscenter.com

I'd put the bidirectional control on the piston end of the cylinder as that end flows more. When compressing the cylinder it will be pushing oil out past the control. When extending, oil will be pushing through the flow control into the cylinder. You can plumb it in between the relief valve and the hose to the appropriate end of the cylinder where its easy to get to.

I think that since there is no gravity involved (it's pushing side to side not pushing or pulling up) a single control would work fine.

I'd use a low gpm valve like these 5 gpm ones to get the best adjustment range.