Hydrualic Logic

[Spiffy]

I posted in another thread, but realized this belongs in it's own thread.

Maybe it's just us 24XX guys, and maybe the most recent models are different too, but I'm positive that the PTO switch doesn't turn on the flow so much as turning off a bypass line (requires a simpler, cheaper, and less space consuming valve).

So, why do I care? Because on the 24XX the rear (i.e. BH) and front PTO hydraulics are on the same line, so:

(1) There's always just enough pressure on the quick connects that they aren't very "quick" until you shut the machine off (or have the BH attached).

But if the couplers for the BH are attached:

(2) you have plenty of volume up front until your stumper touches a stump or trencher dirt ect.....at which point the laws of least resistance take over and most of it goes through the BH.

So, the solution: leave BH coupled, but I have a high pressure ball valve (hydraulic shop - not box store!) in line with my BH quick connect. Now, when changing front attachments or using the BH: valve open [the extra path is just enough to eliviate my connecting woes]; after changing an attachment, I reach down as I climb back on and BH vavle closed [no power loss].

I have no idea about the (1)4XX machines, suspect the former problem, but obviously not the latter. If it is an issue, than your solution is just a bit simpler yet: valve in line with the front quick connect, off while connecting, on while operating.

No pictures....yet.

 

[Spiffy]

Pictures!

Still dirty at that! /forums/images/graemlins/wink.gif

 

[Spiffy]

Closer view.

 

[Spiffy]

Oh that someday list keeps getting longer, but I'd love to have a three way valve and a 3 postion toggle (in place of the two position now), but very limited $$$, space (it's just tight enough in there, that I'd want it well thought out first), and time required this work for now. /forums/images/graemlins/smile.gif

On a similar note, I have pretty fast leak down in both the front and the BH even more so. Anybody else? Is it the cylinders or the valves (sure looks like PT knows cylinders, but maybe)? The old farmhand keeps a loader bucket in the air for a week before you notice any drop (ok she's getting a bit weaker these days, but still holds better than the PT [bucket: overnight w/o a load, faster loaded; backhoe: as you speak). Weird "safety feature", side effect of a specific design, sloppy valves, I need to rebuild all my cylinders? Questions, Questions....... /forums/images/graemlins/tongue.gif

 

[J_J]

On the subject of quick connect fittings, their are some fittings that are designed to connect under pressure, and some are not, like on our Pt's. The quick connect fittings that connect under pressure, cost more.

On a full pressure line, it is a good idea to connect the return line first so as to not dead head the attachment.

Dead head means the hyd fluid has nowhere to go

An example of this is when someone turns on the PTO with no attachments. The relief valve starts whining, and it may stall your engine.

 

[J_J]

I don't think that PT purchased the really good valves, which have built in load checks. There is also the tolerance on certain valves, which will keep a loaded bucket from dropping too fast. On some, you can watch the bucket move. Do not trust that bucket in the full up position to remain in place. Use some kind of bracing when working under hyd buckets.

 

[Sedgewood]

<font color="red"> Do not trust that bucket in the full up position to remain in place. Use some kind of bracing when working under hyd buckets.
</font>

Or mowers.... /forums/images/graemlins/tongue.gif

And be darned sure your brace won't break or slip when the cylinder leaks down and loads it with the full weight of the bucket. It'll drop to the point it would have leaked down to. Huh? What did I say? In other words, if time enough has passed for the bucket to have dropped 3 feet, when the brace lets go the bucket will drop 3 feet. In my case the 700lb? roughcut mower dropped from 6 feet and stopped a foot off the ground. It came down so fast I'd wager PT puckered when it stoppied! After I found and untwisted the glasses the mower swiped off my head and I had trampled in the commotion, I cleaned my drawers and swore off braces entirely. If I don't have 'em I can't get lulled into trusting 'em. I now let 'er hang and stand in such a way that it can't hit or trap me if a hose breaks while I'm fiddling around under there.

Wondering what experience I'll learn from last,
Sedgewood

 

[cqaigy]

<font color="red"> swore off braces entirely. </font>

Me too. I chain the mower up in the air. Just make sure your hanging your chain from something that can take the load.

 

[J_J]

These true stories are just some of the reports that other PT operators should be aware of. If someone has had an experience like the above, go ahead and state the facts, and what you did to solve the problem.

One of these I can add, is to never let your feet hang out of the PT. It will crush it very thin. This problem was solved by keeping feet in the treadle area.

 

[Spiffy]

Not sure it's physically possible to dangle your feet into a pinch spot on the 2445. Sure be easy to crush your whole body though, so I always turn it off before getting near the joint area.

Good point about dead-head JJ! Even with my valve open at the BH, it still helps to connect the return first (unless not running). Any progress on that steering pump? I'm starting to wish that I had a fully independant steering pump too, don't think I have room in the rear, even if there is a shaft [doesn't look like there is].

Also, JJ you mentioned (in another thread) having a machine with simple valving for the steering, I have to wonder how much I'd regret switching to something like that. Reason: I think that'd be simpler to integrate a rear joystick (BH work almost screams for something like that).