Third function dirverter valve vers True 3rd function valve

[k0ua]

I suppose you could say there are some "brand new rocks". When Lava (molten rock) flows out of the earth's crust, and solidifies and cools. I suppose that igneous rock is "new rock". You could also argue the molten rock has been in the earth for a really long time too.. I suppose you could say some rock is older than others, Metamorphic rock (like granite for example) has change over eons of time. And sedimentary rock has formed slowly over time from sedimentary deposits laid down little at a time.

So long story short... well most rocks are pretty darn old.. And some dirt is probably older.:laughing:

 

[k0ua]

I also think I need to try to clarify something.... Correction if needed is appreciated.

So, tractor running, no hydraulic requirement. Pump pushes fluid thru the FEL valves, thru the 3rd function valves (if equipped), thru the rear remotes, thru the 3pt and dumps back to the tank. No pressure established. Open flow. This cycle can go on indefinitely and create minimal heat because there is virtually very little resistance.

When a valve is activated, regardless of where it is in this chain, it first closes the "open" path. Then it diverts this flow to whatever function is desired. Let's say lifting the FEL. Suddenly the relaxed open flow of fluid has been disrupted. Now we begin to build pressure. Whatever pressure required to lift the FEL is exerted. No bypass is required. Suddenly we reach the end of the FEL lift cylinder's stroke. Now the PB in the FEL valve is activated. All excess pressure is pushed down the line. If no other action is required, it quietly dumps into the tank. Let's say we have also activated the 3rd function. Now the pump provides pressure to the FEL lift, it bypasses down the line thru the PB because the lift cylinder has reached it's max stroke, now the 3rd function has the pump's full ouput. Action will be quickly completed. Now the PB in the 3rd function valve is activated. All excess pressure is pushed down the line. If no other action is required, it quietly dumps into the tank. This process continues as long as a valve is activated. When us operators are done required pressure the whole system goes back to the relaxed state and fluid is simply dumped back into the tank. If this makes no sense or if I'm in error please let me know. I think it's beneficial for everyone to understand how this works.

There is a little more:.. When the operator raised the FEL for instance and doesn't let the valve center when the cylinder reaches the end of the stroke, the pressure maximizes to what ever the PRV (Pressure Relief Valve) is set for. It opens a new path to the tank or otherwise the pump would just keep on pumping into a "deadhead" and the pressure would keep on rising until something possibly breaks. That could be a hose, a hard line, the pump (and its associated gears) or even possibly the engine could stall... But thankfully all of those bad things dont happen because the PRV opens and the pressure spike is "relieved". At the very least things are going to get pretty hot fairly quickly and fluid flowing over the PRV will generate lots of heat too.

The same thing can happen to a "rear remote" if left in detent or the operator does not let it center so the fluid can flow to the tank.

 

[ovrszd]

Yep. With no use, there's no pressure created. That's the part that's often misunderstood.

 

[k0ua]

Yep. With no use, there's no pressure created. That's the part that's often misunderstood.

Agreed. Many people think the fluid comes out of the pump at somewhere around 2500 psi, but pumps make flow not pressure. The fluid does not become pressurized until it runs into something.

 

[N2DFire]

There does not appear to be a port at the loader control valve either. Perhaps I am not looking correctly. Ill call Bobcat tomorrow and check. I dont see any exposed tubing as everything appears to be bolted directly to the trans housing

SSdoxie's reply is spot on.

The Power Beyond port on your loader valve is on the inboard side of the valve nearest the transmission - there is a hard line painted the same color as the rest of the under carriage (not a rubber hose or tubing - hard metal line - looks like a large diameter rod about the size of a mans finger) with a "banjo fitting" style head - that hard line runs toward the rear of the tractor then turns upward and bolts into the rear end with another banjo fitting under the seat. This would be forward and further inboard of where the rear remotes bolt up.

Please go back to my post on the first page (#7) and see the thread I referenced on my 3rd function build as I am sure the pictures will help explain. I would link them here but I'm at work & they block photobucket so I can't get links to post the pictures here (or even see the pictures on my old thread, just the text).

Edited to add that based on the text I *think* the picture in post #11 on the second page of my thread will be the most helpful in finding the PB port on the loader valve.

Thanks & Good Luck.

 

[AKfish]

No. If installing a thumb, it should be designed to give similar power/force at the tip of the teeth as the bucket. That way neither one can "overcome" the other.

If you have a thumb with too small of a cylinder, when clamping down on something by using the bucket, you can blow hoses off your thumb cylinder or damage the cylinder.

If the power/force between the thumb and grapple are roughly the same, you have a stale mate between the hydraulic forces, and maximum clamping ability.

I'd have to disagree.. The working pressure rating for the thumb on my JD110 TLB is 2,500psi. The system relief pressure for the bucket curl function is 3,000psi.

So, when using the thumb and bucket to grab something, continuing to curl the bucket will roll the thumb right back up towards the dipperstick.

You don't want a "stalemate" situation.

 

[LD1]

I'd have to disagree.. The working pressure rating for the thumb on my JD110 TLB is 2,500psi. The system relief pressure for the bucket curl function is 3,000psi.

So, when using the thumb and bucket to grab something, continuing to curl the bucket will roll the thumb right back up towards the dipperstick.

You don't want a "stalemate" situation.

Then your system has some sort of relief valves built in. You cannot compress a cylinder via external source without relief

 

[downsizingnow48]

Agree with AKfish. System pressure for my B21 is 2100lbs. I set the relief for the thumb at 1200lbs. Depending on position, sometimes the bucket pushes the thumb back against its relief, sometimes the thumb pushes the bucket back against its relief. Either way there is plenty of clamping force. But without the reliefs, something would bend or blow.

 

[powerscol]

Thanks folks. To get this back on track I'll be taking a few pictures of the tube SSdoxie mentioned. Dennis - is there a valve that you know of that will fit without cutting the tube either at the front or the back. My ability to cut something and put it back together is nill, and I believe this tube see max hyd pressure, correct?

PS As I am older than dirt too, does that not make us priceless. I dropped in an antique store the other day, and found out the furniture I bought way back when 2nd hand is worth a whole lot more now that when I bought it. After all at my age I say I am getting wiser, not older. I just find more ways to use power tools than doing hand work.

Pictures later

 

[powerscol]

View attachment Joystick Valve GROUP(HST)_CT235.pdf

It appears tube 38 in the Bobcat parts catalog is what your referring to. If there is room would replacing the single banjo bolt with a double one work to get supply? Then I would need another double banjo bolt for line 33 which I assume is the return line?

Thanks for any thoughts.