Maybe a Step 'Backwards', But Handy?

ddonnell · Dec 25, 2006

On my CUT, the pressure buildup is on the implement hoses, not the tractor hydraulics. If I screw up (which I sometimes do) and don't equalize the pressure after the engine is off with the loader still connected, or if the temp. rises while the loader sits, then the hoses to the loader sometimes retain/buildup pressure. I just use a screwdriver to push the ball on the loader's male disconnect, lose a little fluid(minimal), and I'm back to easy connection. Am I missing something here with the PT aux. line? Seems to me that you should be able stop, unhook the current attachment hydraulically, turn off the PT, wiggle the joystick every whichyway (to relieve pressure in that attachment's lines for the next time), disconnect the hydraulic lines, drop the attachment, start the PT, go pick up the next attachment and connect with it via the quick attach. If that attachment requires the auxilliary hydraulics i.e. minihoe, 4-in-1 etc., then you hookup with hydraulic locking, turn off the PT, do the wiggle-waggle thing again with the joystick, turn off the Pt, disconnect the QA lines and reconnect with the new attachment lines. If there is a problem with built up pressure in the new attachment (due to temp. etc.), the screwdriver on the male ball solves it quickly. Start up and away you go. It doesn't seem like there would be any more hassle hooking to an attachment that needs the aux. hydraulics than there would be with any other non-hydraulic attachment except for the requisite hooking up of hoses.

I'm the first to admit that I'm a novice when it comes to hydraulics, but if in fact the PT works like my CUT, I'm at a loss as to understand the need for all the accessory plumbing. I must be missing something. Please clue me in.

An aside: Has anyone made a second joystick left of the steering wheel for control of the curl and side-to-side of the minihoe? Someone in this forum talked about a second valve block? in parallel with the steering? block that would/could overide the aux. pto and steering wheel so you could run the minihoe more like a real backhoe with two control levers. I'd love a picture or description. Thanks for all your help in my decision process and a happy and prosperous new year to all.

Dave

KentT · Dec 25, 2006

ddonnell,

I'll try again to describe the hydraulics. The PT-425 has three hydraulic circuits at the front of the machine, not counting the higher hydraulic flow for the main PTO itself (which is controlled by a simple electrical on/off switch on the dashboard).

Under the dashboard on the right side (from the seat) is a 3-valve hydraulic body. The two circuits on the right side of that hydaulic body are for the bucket lift and curl. They are controlled by the long joystick type of control. (The lift circuit has float built-in, while the other two do not.) The third circuit id called the Auxiliary PTO (compared to the main PTO which is higher-flow and controlled with the electric switch described above). The Aux PTO circuit is on the left side of that bank of 3 valves, and is controlled by a short lever down next to your right knee. This was originally designed for controlling the locking mechanism that locks attachments on the front tool carrier -- the first PTs used a mechanical locking mechanism. (Now, only the PT-180 uses that less-expensive approach.) This circuit moves two short double-action rams that push locking dogs into place to lock the attachment on the tractor. This allows you to attach things like buckets without ever leaving the seat (see MossRoad's site for some great videos of this). Think of this circuit as the alternative to the awkward links and pins used to attach a normal 3-point attachment -- it is a totally different quick-attach that doesn't require you to leave your seat.

As time evolved, PT added attachments to their product lineup that use hydraulic cylinders on the attachment itself -- such as the grapple bucket, minihoe and power-angle snow/dozer blade. To use these attachments, you disconnect the hydraulic lines for the attachment lock using the hydraulic quick-connects, and use that control circuit to control the cylinders on the attachments. However, that leaves you controlling those attachments with a short, stubby lever down next to your right knee. This requires you remove your right hand from the joystick control to control the other hydraulic circuit, or awkwardly reach over with the left hand.

So, in normal compact tractor terms, we're using the equivalent of the "rear remote" circuit (actually built-in on the front of PTs) to control both the hydraulic quick attachment system and the hydraulic cylinders on the implements themselves. However, this circuit is already on the PTs and doesn't need to be added with some type of optional "Power Beyond" type of lines and controls. It's just that the control lever is a bit awkward.

Some of us have modified our PTs to change how that third circuit is controlled. Some have added electric diverter valves that allow control from a push-button that can be added to the joystick control. Others of us have designed some type of mechanical linkage that moves the control lever over to the left side of the steering wheel where it can be controlled with the left hand. Here's how I modified mine:

My Aux PTO mod

Some, like BobRip have also split the Aux PTO circuit and added short hoses with quick-connects so that you can use and control these new front attachments without disconnecting the Quick Attach locking circuit. Note that electric diverter valves will add this capability also - combining both the benefits of (1) moving the controls and (2) splitting the circuit so that you don't need to disconnect the hydraulic lines from the Quick Attach to use the grapple or minihoe.

BobRip is still controlling his modified circuits with the original short lever down by his knee, unless I'm mistaken...

Hope that clears up any confusion...

And yes, the pressure buildup in attachments is similar to what you describe. I carry a small hammer and punch in my toolbox and just give the female connector a quick tap to relieve the pressure...

SIDE NOTE: What happened to the search function here? I'm not having any luck using it to find old posts. Does it not work for any topics moved from the old forum software, or what?

J_J · Dec 25, 2006

I just tried my search mode and it worked just fine. I searched for [ slime ] in Power trac forum, and got 42 hits.

J_J · Dec 25, 2006

Spiffy said:
Forgot to note that one has about double the flow you'd need for a 4XX; I'm planning to upgrade my PTO pump from 15 to 20 someday (actually have a pump, but starting figuring numbers on my attachments and 30 was just too much).

Have you figured out the additional HP that would be required to run a larger pump? You can sometimes get away with just a larger pump, but you can not use any of the other pumps at the same time. There is a hydraulic calculator on Surplus Hydraulics that will compute the max pump flow for the HP that you have. I would like to increase my PTO pump also, but the end of my pump is 1/4 in from the hydraulic tank.

BobRip · Dec 25, 2006

KentT, I am still using the original handle and am reasonably satisifed with it. I am also very pleased with the modification. See http://www.tractorbynet.com/forums/power-trac/82642-auxiliary-hydraulics-modification-422-425-a.html

ddonnell · Dec 26, 2006

KentT,
I think I understand the basics of the PT hydraulics. I was alluding more to the disconnecting and reconnecting of hoses and equallizing pressure to do that. I was under the impression that some folks here were doing some of these plumbing modifications to eliminate the pressure buildup in hoses for easier connecting and less back and forth from seat to implement. That's what I use the screwdriver for. Obviously there is more to it than that. Thanks anyway for explaining it again. Sounds like the PT equalizes pressure pretty much like my CUT.

MossRoad · Dec 26, 2006

I've only had a locked up hydraulic connector a couple times. It was on my snow plow. I had to crack open a fitting to bleed off just a drop of fluid, then I was able to attach it to the tractor. I learned to wiggle the valve before disconnecting the hydraulic hoses on the AUX pto circuit and that pretty much eliminated the problem.

jfh28 · Dec 26, 2006

I've only had a locked up hydraulic connector a couple times.

I locked up my grapple bucket once. Last time I had used it was on a cold winter day. When I went to hook it up it was a hot spring day and no way was it connecting. Didn't feel like messing around bleeding it off so I just used the forks to stab the tree to move it. When the next cool day came up I was able to connect it with out any problems. So expansion/contraction of the fluid plays a part. I also had a hydro man tell me to wiggle the handle before disconnecting and haven't had any problems since.

Jack

KentT · Dec 26, 2006

J_J said:
I just tried my search mode and it worked just fine. I searched for [ slime ] in Power trac forum, and got 42 hits.

JJ -- it doesn't search the old topics for me. And, it looks like I'm not alone:

http://www.tractorbynet.com/forums/news-feedback/92266-search-posts-older-than-1-a.html#post1040082

J_J · Dec 26, 2006

KentT said:
JJ -- it doesn't search the old topics for me. And, it looks like I'm not alone:

http://www.tractorbynet.com/forums/news-feedback/92266-search-posts-older-than-1-a.html#post1040082

In the search date block, it comes up with the default, [any date] ---- newer than. I searched for [ bridge ] and it went all the way back to 2000. If that doesn't work, I just don't know.