pt-425 will not move forward or reverse

[SnowRidge]

<font color="red"> I wonder what RPS stands for. I have never found a definition in the documentation. </font>

Remote PTO Switch
Relief Pressure System

Just guesses.

 

[Sedgewood]

Bob999: <font color="red"> However, the SYMPTOMS in this post sound very similar and that was the basis of my post along with comments from both Blackwell and John Coxon suggesting that tramming problems could occur from a problem in the valve.
</font>

ca956 describes his symptoms as:

<font color="green">The machine works great except when you first start it up, it will not move forward or backward. The steering, pto and all hydraulics seem to work fine. But if I push the pedal forward or reverse it will not move. After a few minutes it will start to move very slow and it will eventually move full speed.
But when you approach a hill it slows back down and jerks it's way to the top.
After it warms up completely, it seems to be fine. </font>

These symptoms aren't quite like what I experienced. In addition to the "sticky cable" feel mine had what I would describe as a mushy feel. Acceleration was no longer spin-the-tires-sharp when you mashed a pedal but had a slower, gotta build some pressure first, acceleration. But it did accelerate though I'm not sure top speed was quite as high. It didn't change with a warmup.

I'd like to know how the system works but I don't have the time right now to try and build a logic diagram from the plumbing. It seems to me and I may be wrong, that fluid is coming to the RPS valve, in through the two ball controlled "valves", from opposite sides of the charge pump, either side of the bleed port. I gather pressure is available from one port or the other depending on which way you are tramming and the ball acts as a check valve to block reverse flow to the unpressured port. And to assure pressure in the chamber the ball shuttles through at all times. Fluid from this chamber goes to the brake tender, the draft control, and possibly elsewhere. There are two or three pressure relief valves there too. Apparently when the ball isn't doing its checking properly it affects the tramming. I don't know how.

Maybe Blackwell will chime in here and straighten me out on this. /forums/images/graemlins/tongue.gif

Sedgewood

 

[ca956]

Thanks so much for all info. Sorry it took me so long to respond. I must admit, I am above average at mechanics, but I know nothing about hydraulics.
I will try and answer some of the questions.
The engine is not bogging down when I try to move and there is no unusual noises coming from the the machine.
It absolutley will not move up a hill when it is at low idle, even with the pedal to the floor, in fact it will not move at all even on level ground. If I full throttle the engine and put forward pedal to the floor, it moves very slow but the slightest bump or hill it will stop. Once it is able to make progress up the hill,
It surges forward up the incline. Most of the time the surge is
quite harsh. It is not the engine surging , the engine is staying at a constant rpm.

 

[ca956]

I must also add that the symptoms go away after i run it for a while say 10 or 15 minutes. However, I can run the machine for a 1/2 hour or an hour and shut it off and restart it again 1/2 hour later and the symptoms are back but not as severe and they go away after i run it some more.

 

[SnowRidge]

The engine really can't make enough power to move the machine at low idle. That is normal.

But it sure sounds like a hydraulic drive problem of some sort. I hate to say this, but it sounds serious enough to warrant waiting until you can talk to Power Trac next week.

BTW, where are you located? Someone might be close enough to give you a hand in diagnosing the problem.

 

[MossRoad]

Maybe you already know this, but some of us forget...

If you are going up a steep hill and the speed of the tractor starts decreasing, you have to let UP on the treadle to get more power to the wheels. If you stomp on it going up a hill, you will actually get less power to the wheels. The treadle isn't an accellerator pedal, it is a hydraulic valve. To get maximum power to the wheels, you have to have the engine RPMs at maximum and barely push on the treadle.

If I have my unit at idle and stomp on the treadle, it just sits there for a few seconds before slowly moving. You have to run these machines at maximum throttle to get the power to the system. That's the nature of the beast.

If you are not comfortable running the machine, wait until Monday to call Power Trac. A few days wait is better than a damaged machine.

 

[Sedgewood]

<font color="green"> Once it is able to make progress up the hill,
It surges forward up the incline. Most of the time the surge is
quite harsh. It is not the engine surging , the engine is staying at a constant rpm.
</font>

I wonder if you're describing the symptoms of an air leak between the tank and the inlet to the tram pump. We've all been cautioned to carefully bleed our systems to get any air out of the circuit after a filter change (the filter is between the tank & pump) because any air there will cause nearly instantanious destruction of the pump. I think I'd talk to the factory before going much further.

Sedgewood

 

[ca956]

Hopefully it has not damaged anything, But i am fearing the worst. I am going to call PT first thing Monday.
I will keep you posted.
thank you

 

[WeedPatch]

I have a very similar problem with my new 1430 ( seee "New PT 1430 won't go") I've been trying to fix the thing for two weeks now with no success. PT sent me a new tram pump but absolutely no instructions on how to swap it out. Terry said that it was a 30 minute job... after four hours we manged to get the original one unhooked only to discover that the new one is different and doesn't fit! I am absolutely exasperated with PT . Buyer beware!

 

[dturnmire]

" <font color="blue"> </font> after four hours we manged to get the original one unhooked only to discover that the new one is different and doesn't fit!"

I had a problem with flat tires mowing with the brush cutter because the inside valve stem kept getting torn off so Terry sent me a couple of valve plugs after I called and gave him the model number of my tractor. Believe it or not I received the wrong sized plugs and just went to a hardware store and bought one for 24 cents. What is amazing is the valve stems are standard size that fits on any car tire yet I'm given the wrong ones. This inattention to detail is certainly uncalled for since little things like that leave a bad impression on any customer.

Don't get me wrong. I'm very happy with my PT-180 and it is everything and more than what I expected but customer support should be one of their highest priorities.