pt-425 will not move forward or reverse

tracdoc · Jul 10, 2004

Monday is right around the corner, so waiting to call Terry to get the real skinny is certainly the safest course of action at this point.

Can't help but thinking that it is an air problem in your hydraulics. When the system is down, air (somehow) gets in. When you start up , the accumulated air causes the problems you are experiencing. With use, the system gets pressurized internally, and the accumulated air gets purged/bled to the tank, resulting in resolution of the problem. When you power down, more air finds it way in, and you again repeat the problem. If this is indeed the pattern, why does the bloody air only get in during down time?

Also, if air is getting in during down time, one might reasonably expect that hydraulic fluid would squirt out the same pathway in reverse when the machine is powered up and the hydraulics are re-pressurized. Have you seen any telltale oil drips/spots??

I'll be very interested to learn the solution to this vexing problem.

Good luck, and please keep us posted here.

Sedgewood · Jul 11, 2004

Also, if air is getting in during down time, one might reasonably expect that hydraulic fluid would squirt out the same pathway in reverse when the machine is powered up and the hydraulics are re-pressurized. Have you seen any telltale oil drips/spots??


If air is getting in during shutdown I would presume the leak is above the level of the oil in the reservoir. This leak is on the suction side of the pump so it wouldn't leak oil when powered up. There might be a telltale moistening with oil around the leak though.

If yours is plumbed like mine the suction line runs from the reservoir to the hydraulic filter which is mounted quite high up, then back down to the pump. I'd check the connections at the filter first. Or maybe the spin-on filter gasket isn't sealing properly.

Good luck,
Sedgewood

J_J · Jul 11, 2004

I think I may be able to answer your question as to why air gets in the system, at down time. When every thing heats up, parts expand, and perhaps every thing is sealed up. Things may work good for a while, and then you shut every thing down. Now, as parts cool down, a vacuum is generated and therefore sucks air in to the system, and the process is repeated. I would put thread sealer in all suspected parts. It is doubtfull that a new hyd filter would be clogged up so fast. Have you looked in the hyd tank to see if bubbles were present. If you see bubbles in the fluid, you are either sucking air, or the pump is cavitating, which means it is generating its own bubbles. You do not want to see bubbles.

blackwell · Jul 12, 2004

A 425 does not have a shuttle or draft control valve.
EB

blackwell · Jul 12, 2004

Check the charge pressure, sounds like the filter has collapsed or is loose and sucking air.
EB

blackwell · Jul 12, 2004

A 1430 pump could be changed in under 30 min. I'm and old man and could remove a tram pump, disassemble it and lap the valve plates, replace the seals, reinstall on the machine and test in less than 3 hours. These things are simple and easy to repair. If you dont understand the machine, find a good mechanic close by who does.
EB

blackwell · Jul 12, 2004

The high pressure kidneys are connected to the sides of the shuttle. If the ball doesn't seal, the kidneys are connected together thus bleeding tram pressure.
EB

ca956 · Jul 13, 2004

I called PT on Monday. Terry had me change the hydro filter
because he thought the filter might be plugged.
Changing the filter had no effect on it and I see no signs of a fix. I paid for this machine and then waited 2 1/2 months to receive it !!!! And I have a machine that doesn't work.
PT says run the machine and maybe it will fix itself. I'm not kidding !!!!!

yes buyer beware !!!!!

Bob999 · Jul 13, 2004

The high pressure kidneys are connected to the sides of the shuttle. If the ball doesn't seal, the kidneys are connected together thus bleeding tram pressure. 

What are "high pressure kidneys"? Where are they located? What do they do?

tracdoc · Jul 13, 2004

ca956,

I looked at your Profile for TBN and found it basically blank. Where are you and your machine located? Perhaps there are other TBNers in your vicinity who might have the hydraulics dialed in and who could give you a hand?

I really regret that you are experiencing these problems, and with a new machine no less. I was hoping that PT would have a more satisfactory algorithm for diagnosing and fixing problems in units under warranty, especially considering that most of us can't simply load up and drive the beast to Tazewell.

Please keep us posted...

blackwell · Jul 13, 2004

Ports behind the valve plate which allow high pressure fluid in and out of a closed center axial piston pump. They are shaped like a kidney, thus their name.
EB

blackwell · Jul 13, 2004

Most hydraulic components require a 15 hr + break in period, after that they function much more efficent. This could happen in your case.
EB

eambrose · Jul 13, 2004

I really think you should send them the machine and make them fix it - they can't just deliver a machine that does not work - I don't care what their paperwork or policy says.

You should send it back and tell them you don't want it back until it is fixed

ca956 · Jul 14, 2004

I live near near Cleveland,Ohio.

ca956 · Jul 14, 2004

I have not seen any leaks. Terry also had me remove the two hoses from the tram pump and check the fittings to make certain they were not plugged. They were not.

ca956 · Jul 17, 2004

I discovered a HUGE !!! safety issue with my PT-425 in regards to the issue i am having with the forward and reverse motion or should i say, lack there of ? When the machine has little or no forward or reverse motion YOU HAVE NO BRAKE !!!
My shop has an incline approach to the door. As I was backing the machine out of the garage, (remember i have a very slow or no response tram pedal) the PT started to roll and i could not contol the speed. The brake does not work and stepping on the forward peddle has no response. So basically you are going along for the ride. How nice this would be unloading from a truck or trailer.
I called pt on Friday, they are convinced that it may still be a plugged filter. He wants me to try a NAPA filter.
I hope it is that simple. I really like the machine, it does great
work. It was exactly what i was looking for at my bussiness.

WeedPatch · Jul 17, 2004

I noticed the very same thing when my tractor had virtually no power. I rolled down a slight inclline, gaining speed, and had no way to stop. The parking brake is virtually useless because it is so difficult to engage. I have to use a length of pipe as a lever, and that is hardly a feasible maneuver when one is merrily accelerating downhill. I consider this to be a serious, potentially lethal design flaw, and one that PT could easily fix (I told Terry how!) Has anyone solved this problem?

Rip · Jul 17, 2004

This (lack of) brake issue is a serious one. I (and others) have brought it up at various times in the past. At the PT level, it is not a technical issue, but rather a cost issue.

All models from the 1445 and above do have either internal wet spring-applied/hyd pressure release or external dry Brake Tender that basicaly operates in a fail-safe manner.

In my opinion, they should equip all the smaller models with the internal wet brakes (or at the very least, offer it as an option) for the very reasons you and others have mentioned.

As I was looking specifically for a machine suited for work on very steep terrain, brakes were a primary consideration, and the Brake Tender system on the 1845 works well indeed.

A good hyd shop can replace the wheel motors ( all or at least 2) on the other models with ones with integral wet disk brakes, but it will not be cheap. On the other hand, it would be only a nominal cost at the factory level to equip them this way or offer it as an option.

I fully agree that this is a serious safety issue, and one that PT has chosen to ignore due to cost considerations. How to get them to change, I do not know. This issue has been raised numerous times before to no avail. Hopefully it won't take a serious injury or death to wake them up.

Talk to a good hydraulic shop for an estimate on upgrading your particular unit. It should not be hard to do, but may involve some modification or customization. It also may widen the wheel track somewhat, which could be a problem for some or a boon to others due to increased side-hill stability.

Good Luck whatever you do...

Rip

J_J · Jul 17, 2004

Read my post # 462047. 7/14/04 06:08 This could be a manual or electric shut off valve.

cqaigy · Jul 18, 2004

Hey J_J

 Read my post # 462047. 7/14/04 06:08 This could be a manual or electric shut off valve. 

Could you tell me how to find your post? I tried a search but only get your post to look at that post. Theres gotta be a way to find a specific post and I bet you know how /forums/images/graemlins/smile.gif

TIA