Regarding 3rd function valve sticking

[Gordon Gould]

It does not make sense that they would offer a product that is basicly non-functional like that. I can see why you guys are upset. After reading this post I am glad (and very lucky) that I added a second a manual spool valve for my grapple control. I can feather the grapple just like the FEL. If any of you want to do the same there are several threads on how. Search teg or me or 3rd function.

 

[brocas]

With a high volume valve, and a small cyl, you can expect fast action. About the only way to decrease the speed is to reduce volume by restrictors, diverting some of the flow, and use of the feather ability. . The solenoid valve is full on or or off unless you want to add those proportional valves that only provide as much volume as needed.

Is your needle valve in front of the solenoid valve.

Option, install a larger cyl for more down force, and slower speed of activation.

The flow control valves (they are restictors that restrict flow in on direction) are after the solenoid. I dont think they could be placed before the solenoid as I think the 3rd function valve is plumbed from the FEL PB port and I'm also guessing the solenoid valve also has PB to contiue the circuit to the 3PH.

I dont think adding a second cylinder is an option (its a small grapple) and a bigger cylinder I dont think would be enough. Honestly I dont think on/off with such large flow is suitable for rthis application. It not just fast, its jolting fast.

Full feathering would be nice but I would settle for 2 speed. In fact even for the FEL that has the feathering, I think a HI/LOW selection would be really nice for really precise movement.

I am seriously considering adding this HI/LOW function not just for the grapple but for the FEL too.

I Imagine adding a "speed" control valve righ after the pump and before the FEL block. The speed valve would divert some of the flow back to the sump in one setting, and full flow in the other setting. Some details would have to be worked out on how the speed valve would be controlled.

 

[brocas]

What about putting a reducer on the hydraulic line. The would slow the flow down and that would slow down the cylinder.

That's what the flow control valves are. They restict flow in one direction. They do exactly what is expected. The problem is, if the flow is restricted to a level that gives good speed, the 3rd function valve starts sticking. It is possible that the 3rd function valve (its a solenoid valve) doesnt like too much restriction (needs a certain minimum flow to operate properly).

 

[brocas]

What size hoses are you using?

I wonder if moving the flow control near the grapple would help?

The hoses are 3/8. The flow control valves (restrictors) are right on the grapple.

 

[brocas]

I also have the WR Long. In fact, when I bought the L3240, the Kubota dealer recommended it over the factory Third Function. Mine is used solely for a Construction Attachments grapple and there have been no problems at all. I liked it enough I had them move it to my newer Kubota.

The kubota 3rd also seems to work fine. The problem I have is the flow is too high. When I try using restrictors to reduce the flow, the valve sticks.

Perhapps the solenoid valve needs some minimum flow to operate properly, or perhapps its a crappy valve.

 

[brocas]

A 2 in cyl ,1 in rod, 10 GPM, = 12.3 ips ext, and 16.3 ips retract.
-----------------------5 GPM = 6.1 ips extend---------8.2 retract ips

A 3 in cyl, 1 in rod, 10 GPM, = 5.4 ips extend----------------6.1ips retract
-----------------------5 GPM = 2.7 ips extend----------------3.1 ips retract

So volume and cyl size will affect the grapple speed.

I was well aware of this. Like I said, plan B was to restrict the flow. Your calculations are just for cylinder speed, not even accounting for the lever amplifications.

I cannot describe how fast the grapple moves. One touch of the button and the grapple flies and stops with a big shock, totally unusable and nerve shattering at full flow.

 

[brocas]

It does not make sense that they would offer a product that is basicly non-functional like that. I can see why you guys are upset. After reading this post I am glad (and very lucky) that I added a second a manual spool valve for my grapple control. I can feather the grapple just like the FEL. If any of you want to do the same there are several threads on how. Search teg or me or 3rd function.

I wouldnt say its totally non functional, but I would say its non functional with my grapple.

 

[brocas]

It does not make sense that they would offer a product that is basicly non-functional like that. I can see why you guys are upset. After reading this post I am glad (and very lucky) that I added a second a manual spool valve for my grapple control. I can feather the grapple just like the FEL. If any of you want to do the same there are several threads on how. Search teg or me or 3rd function.

I hear you about adding a spool valve, but the attraction of the 3rd function is that there is only one lever. You can raise, curl, and clamp at the same time with a single hand. You gotta admit, that's pretty sexy.

 

[teg]

...or perhaps its a crappy valve.

Oh no way...

How long have you had this valve? If it's not too long ago and it's causing the sticking problem... I would see what the dealer says about fixing their problem valve. That just should not happen.

Not sure if going to 1/4" lines would help or not...

 

[J_J]

Do you have a picture of your grapple set up?

If the geometry is not correct, you will have fast speed. Do you need high volume of fluid for normal FEL operations? You could run the engine at 1/4 speed, decreasing the volume by 4 . If you had 12 GPM, you now have 3 GPM.

This is a priority flow divider valve, the priority circuit uses 3 GPM, and the rest can go to tank, or to another valve.

Surplus Center - 3/30 GPM PRINCE PRIORITY FLOW DIVIDER W/RELIEF

What appears to have happen here is a flaw in the design of the grapple geometry, the cyl used and the valve used. This is where the engineers are supposed to figure all this out before it gets installed. If it doesn't work, the technician then comes in and fixes it.