Tram Issue on 1845

[marrt]

I think you have an issue with your tram control. I assume you have the hydraulic foot pedal and not the cable. I think there is a way to detune the reaction of the Tram control. I have to adjust mine one of these days as i creep forward when stopped. Terry says it is an easy adjustment.

To keep from hijacking the other thread, I started a new one.

I have an older machine with the cable. I can watch the cable move on the pump. So, I'll push the cable forward slightly (or backward, doesn't matter) then stop, in about a second, the machine will lunge. It's almost like pressure has to build. Of course, if I floor the tram, it moves almost instantly.

And here's the kicker...this doesn't happen every time I change direction or stop and start. Further, if I engage the tram and don't get an immediate response, I can usually engage in the other direction, then back to the original direction and it will not lunch. For example, if I'm trying to go forward and it doesn't immediately move, I'll reverse the tram direction (still not moving) then go back to forward and it will usually move forward smoothly.

The sounds exactly like a shuttle ball type issue. However, I'm not sure my machine has the shuttle ball. I asked Terry about it a few weeks ago and he didn't seem to think it was the shuttle ball (although he didn't confirm or deny my machine has the shuttle ball...not all had them apparently).

 

[marrt]

Ok, I thought I'd post a couple videos. Never done it before, so here goes:

In this video, I reach down with my hand and pull up on the forward tram side so you can see everything without my foot in the way. Notice the camera (and my head) slam into the steering wheel.

https://www.youtube.com/watch?v=VzdFkVHL6EU

Another shot:

https://www.youtube.com/watch?v=3mVjgC4k-CM

Here's a shot using my foot to tram properly. Pretty much the definition of a tipping point.

https://www.youtube.com/watch?v=jio9GdxEn5g


Tom

 

[woodlandfarms]

Thats crazy.......

 

[marrt]

Yep. You can see, in a couple video, that the machine will tram smoothly back and forth right after it occurs. But, if you come to a full stop and wait a couple seconds, the surge is there again.

 

[SpringHollow]

Since the wheel motor circuit is semi-closed, is there any chance it is because of air in the lines?

Ken

 

[marrt]

I suppose anything is possible. But you'd think there would be additional symptoms...strange noises or pump cavitation or periods of hesitation while underway. Something.

 

[SpringHollow]

What made me think of it was that you said it only happens when you stop for a bit which would possibly allow fine bubbles to gather. But definitely a long shot and I would think the pump would have issues by now if it was.

Ken

 

[marrt]

Terry seemed to think the problem is in the tram cable linkages. He said I could put the Tractor on blocks, disconnect the tram cable then tram the pump by hand to be sure. I'm going to try this next since it should be fairly easy to do.

 

[marrt]

So close. I put the tractor on blocks and disconnected the tram cable. I found Power Trac had attached the 1/4 inch swivel for the cable through a 3/8 inch hole on the pump. And, the swivel was not very tight so I assumed it would slip from time to time. Further, when I would tram the pump by hand, everything was smooth (with the wheels in the air though). I was SO sure I'd found the problem. I fixed the issue with the swivel and reassembled everything and...it didn't make any difference at all. Rats.

However, I did notice something. The pressure on the brake tender will vary quite a bit. When the pressure is 1500 or below, I'll get the "surge." When the pressure is 1700, no surge. You can see this clearly in the third video above. After the initial surge, I can stop and go smoothly if the pressure is 1700 or so. Not sure what is causing this pressure variation but I think this is the root cause of my problem.

 

[SpringHollow]

Glad to hear you are narrowing down the problem. Problems like these can be frustrating. Hopefully you solve it soon.

Ken

 

[MikeOConnor]

The "pressure on the brake tender will vary quite a bit" thing has me interested. First off, I'm struck by how absolutely steady your pressure is. Mine has always varied, depending on what I'm doing (steering, lifting, turning on PTO, whatever). And a couple hundred PSI (up to 1700) happens all the time on mine. Heck, if I want to, I can run that pressure up to 2500 PSI just by going to full-lock on the steering. Does yours tend to stay absolutely pegged at 1500 PSI the way it mostly was in the video? That's in the "really interesting, but not necessarily helpful" department.

The second interesting thing is that the pressure appears to jump up *after* you've gone through the surge and then drops back to 1500 PSI over the next few seconds. That kind of variation (both the increase to 1700 and the gentle drop back to 1500) is normal behavior on my 1850 (which has hydraulics rather than cables, so your mileage may vary). If I were guessing, I'd think that the pressure-change is coming from something else, and the brake-tender behavior is the charging-valve/accumulator doing it's thing and bringing pressure back down to normal.

That surge is pretty spectacular. I loved your swivel theory. Your forehead-based test-instrument looked painful.

 

[ponytug]

Marrt,

Did you run the surge by Terry? It sounds to me like a charging valve/accumulator issue. Does this happen when you have the engine at mid to high rpm?

All the best,

Peter

So close. I put the tractor on blocks and disconnected the tram cable. I found Power Trac had attached the 1/4 inch swivel for the cable through a 3/8 inch hole on the pump. And, the swivel was not very tight so I assumed it would slip from time to time. Further, when I would tram the pump by hand, everything was smooth (with the wheels in the air though). I was SO sure I'd found the problem. I fixed the issue with the swivel and reassembled everything and...it didn't make any difference at all. Rats.

However, I did notice something. The pressure on the brake tender will vary quite a bit. When the pressure is 1500 or below, I'll get the "surge." When the pressure is 1700, no surge. You can see this clearly in the third video above. After the initial surge, I can stop and go smoothly if the pressure is 1700 or so. Not sure what is causing this pressure variation but I think this is the root cause of my problem.

 

[marrt]

Did you run the surge by Terry?

I did but haven't had a chance to check his recommendation yet. Terry says to take a look at the shuttle valve. Fortunately, Sedgewood still has some excellent pictures up. I'll try to get to it this weekend.

Tom