Problems with our new GMD-1

[Puddington]

If not taking the Leafs seriously is a criteria for failure then units shipped anywhere near 90% of their own fanbase this year should be failing.

I am curious though Mike...you said Dan worked on the units for hours. What needed so much work? That sounds like serious tinkering which sounds like a "fiddly"  (rather than robust) design. In my experience, design margin (lattitude) is needed for production to run smoothly. If something fails QC you swap out a whole assembly *or ship the customer a new unit* rather than spending the time tweaking it. Tweaks have a bad habit of moving over time and unit to unit. And some times you just have to accept that a lemon will come off the line, especially if the design spec is really tight, and the lemons need to be scrapped as bad yield rather than trying to patch them.

Just curious...


Md

I agree however if we don't figure out what the root cause is then we'll never get a fix.. Without having spoken with Dan I am sure he laboured over the units, confident he could find the issue as opposed to just grabbing another unit or two; that's Dan... he never says die.... I will be speaking with him Monday and we will go over the process.

[jdcolombo]

When I got my sound-equipped GMD-1, the wheel gauge was narrow, but it ran beautifully, particularly after tweaking some of the ESU LokSound's BEMF parameters.  Then I gauged the wheels, and started having the same sypmtoms that Mark Dance had. 

I took the engine off the track, and noticed that after re-gauging the wheels, the wheels seemed "tight" in the trucks; they no longer had the slight bit of back-and-forth free play they did before the gauging.  After some trial and error, what I concluded is that the plastic truck sideframes were pushing in on the bearing strips, and gauging the wheels made the axles just enough longer (as a result of moving the wheels outward to get the gauge correct) that two of the wheelsets (on the front truck) were now binding.  When I pushed the wheels back in, they were fine.  So what I did was take a pair of flat tweezers and tried to ever-so-slightly bend the bearing cups outward.  That fixed my problem - at least for now.  But, what I fear is that the plastic truck frames will continue to exert pressure on the bearing cups, causing them to bend back in, and that eventually the wheels will start binding again.

What I think I'm going to have to do to make a permanent fix is take the trucks completely apart, and scrape off a bit of the plastic on the inside of the truck frame where the frame contacts the wheel bearing strips, then bend the cups out ever-so-slightly to provide more side-to-side "play" in the wheelsets when properly gauged.

My observations might be consistent with what happened to Mark's units - they might have run fine after Dan's adjusting, but if the plastic truck sideframes are exerting inward pressure on the bearing cups, then over time these cups would tend to bend back inward, causing binding and causing the motor to burn up if one tried to run them at sustained high speed.

Mike, if you haven't checked this possibility, do so.  I might be wrong about it (it won't be the first or last time), but it seems to be what I observed with my own unit.  And if I'm right, then the cause would be the plastic truck frames being just a hair too small (narrow), which in turn exerts pressure on the bearing cups.  When the wheels are gauged narrow, all is fine, but if you gauge them correctly, the expanded length causes issues.

John Colombo

[mark dance]

When I got my sound-equipped GMD-1, the wheel gauge was narrow, but it ran beautifully, particularly after tweaking some of the ESU LokSound's BEMF parameters.  Then I gauged the wheels, and started having the same sypmtoms that Mark Dance had. 

I took the engine off the track, and noticed that after re-gauging the wheels, the wheels seemed "tight" in the trucks; they no longer had the slight bit of back-and-forth free play they did before the gauging.  After some trial and error, what I concluded is that the plastic truck sideframes were pushing in on the bearing strips, and gauging the wheels made the axles just enough longer (as a result of moving the wheels outward to get the gauge correct) that two of the wheelsets (on the front truck) were now binding.  When I pushed the wheels back in, they were fine.  So what I did was take a pair of flat tweezers and tried to ever-so-slightly bend the bearing cups outward.  That fixed my problem - at least for now.  But, what I fear is that the plastic truck frames will continue to exert pressure on the bearing cups, causing them to bend back in, and that eventually the wheels will start binding again.

What I think I'm going to have to do to make a permanent fix is take the trucks completely apart, and scrape off a bit of the plastic on the inside of the truck frame where the frame contacts the wheel bearing strips, then bend the cups out ever-so-slightly to provide more side-to-side "play" in the wheelsets when properly gauged.

My observations might be consistent with what happened to Mark's units - they might have run fine after Dan's adjusting, but if the plastic truck sideframes are exerting inward pressure on the bearing cups, then over time these cups would tend to bend back inward, causing binding and causing the motor to burn up if one tried to run them at sustained high speed.

Mike, if you haven't checked this possibility, do so.  I might be wrong about it (it won't be the first or last time), but it seems to be what I observed with my own unit.  And if I'm right, then the cause would be the plastic truck frames being just a hair too small (narrow), which in turn exerts pressure on the bearing cups.  When the wheels are gauged narrow, all is fine, but if you gauge them correctly, the expanded length causes issues.

John Colombo

thx John...the change in running resistance you point out that could be caused by tight side frames/axles would be consistent with the auto-calibrate routine *not* being able to properly set the PID parameters, especially if the control system's design latitude is very small.  This in turn could lead to the high pitched whine from the PWM as it tries its best to control the motor as well as possibly jerky running when it can't control things. 

To clarify the motors on my units have not burned up as they take off like a shot as expected when I run auto-calibrate.  They just don't run afterwards on track other locos have no problem running on.  So I take this as a likely decoder issue.  Perhaps the decoders overheated?

md

[Puddington]

John: Thanks; that makes sense.... It's weird but it makes sense.... I will get Dan to check that in the morning (I'm still not well enough to get to the office) but I can see what you are saying and it makes some sense... now the question; was the truck made to spec (and if so, then we get to beat on the guy who worked on the design...um..ah... I wonder who that could be..?)

I will get back to you guys.

[Jeff AKA St0rm]

I have been running my 2 GMD-1's with the sound off and listening to the motor sounds. There is a very high pitch noise that is consistent from 0-50% or 30 SMPH. I dont know if this is normal as i have gaged my wheels and never listened to it before i did the wheels. I do notice that the cups are angled out on one of my units but not the other, and both make the noise. Mine look like they are running unimpeded but it is hard to tell. Let me know if you want me to run any tests.

Jeff

[Joetrain59]

Z905's are a perfect fit, just use screws that come with couplers. N scale couplers will need trip pin cut back to clear pilot. Post pix later today.
 LET'S GO ISLANDERS!!!! 
 Joe D

[shark_jj]

Mike, I kicked this back to the top to see if Dan had discovered anything about the width of the truck side frames since the you indicated on Feb 22nd that you were going to ask him to check it out.

[Puddington]

We did; the truck frame is to spec and although it has the potential to rub, it only does so on the out of gauge axles. We are manufacturing new axle sets and will send them free of charge to anyone who asks us. We'll be posting a You Tube video on how to swap them out as well. I'm hoping that we'll have the new axle sets within three weeks.

[jdcolombo]

We did; the truck frame is to spec and although it has the potential to rub, it only does so on the out of gauge axles. We are manufacturing new axle sets and will send them free of charge to anyone who asks us. We'll be posting a You Tube video on how to swap them out as well. I'm hoping that we'll have the new axle sets within three weeks.

Ah - so my observations were correct, but the conclusion was wrong.  The problem is axle sets that are a tiny bit too long when properly gauged, not truck frames that are a tiny bit too narrow.  I hadn't even considered that - I just assumed that the axles were fine.  Live and learn.  I've ordered new wheelsets per your instructions in the other thread, although right now mine seems to be running OK since my last "tweaking" session.

John C.

[Joetrain59]

Any update on when new axles will arrive?
 Joe D

Sorry, I'm asking too soon. Don't know how to delete a post here.

[Puddington]

Any update on when new axles will arrive?
 Joe D

Sorry, I'm asking too soon. Don't know how to delete a post here.

No worries; they are working on them and as soon as they are ready we'll air freight them here - as soon as we've got em the local gentry will know.....

[Joetrain59]

I need to send an end flap from jewel box, right?
 Joe D

[Puddington]

I need to send an end flap from jewel box, right?
 Joe D

Yep.... thanks!

[shark_jj]

Mike:  any updates on the arrival of the wheelsets.  It is well past 3 weeks.

[Puddington]

Jason just got back from the factory in China Friday where they worked on the wheelset issue. Without getting into the nitty gritty the problem became a tad more complex than we'd imagined; thus Jason's visit and working in person with the engineers was timely to say the least. The wheelsets are in production; I don't have a specific time frame but am hoping to have more information mod next week. They will be air freighted here so transport won't be an issue.

Sorry for the delay in getting to this; been otherwise occupied for last week or so.