Prompted by this thread, I spent a few minutes this morning looking at the design and I think I see what is causing it, but I don't have a solution (yet). First, the effect I see is definitely not due to the skirting detail. In one sample, I measure a 4 scale inch difference between the front and rear truck sideframe, relative to the railhead (taking into account the cylinders). Not a huge deal for sure, and it's not there on all locos, but it is noticeable on several, especially given the relatively small gap between the truck and the skirting. I think it's due to the new design of the phospher bronze axle bearings that transmit current from the wheels to the wipers. In the new trucks, the center axle is sprung by virtue of this bearing design: the middle axle bearing is on a long folded arm that springs relative to the main arm that spans the outer axles. When there is no weight on the truck, the middle wheel sits lower than the outer two, and this compresses under weight. So when the loco is on the rails, this bearing is under tension, by design. But since the folded spring arm is asymmetric, this tension tries to rotate the outer axle bearings: one up, one down. If the side-frames are not rigidly attached to the bearing part, it will tend *not* to rotate with the wheels, giving the sloped appearance it has. The degree to which this happens depends on how well the side frame is connected to the bearing part. I think the main way this is managed is via dimples in the side frames mating with the cups, but the tolerances here are not very tight. If they insist on a sprung truck, it would be better for Kato to make the spring mechanism symmetric about the front and back axles - a pretty trivial thing to do. So how to fix it? I'm guessing that the old-style bearing part from an SD70M would drop in place to these trucks, eliminating this tendency, but I have not verified that. If it does fit, it's a pretty simple fix. (Of course that eliminates the sprung design, but I've never seen the need for that in the first place.) -Gary P.S. I still love these locos, and the hobby of model railroading, in case anyone doubted that.
If it bother you guys that much put the loco on a flat surface push out the rear of the truck to one side and gently push down on the back of the truck from the top this will level out the truck.
It's funny how a couple of the Kato Fan Boi's are so quick to brush this off as no big deal. If it was an Atlas, IM, or FVM loco, the torches would be blazing and the pitchforks waving. It's certainly there, it can be tweeked temporarily but seems to return over time.
I did some testing on one of my sd70Ace engines. there is nothing wrong with the truck or drive shaft. what is causing the angle problem looks to be the contact strip. on the old style frame,the strips are free to move up to where they do not put much down pressure on the truck. on the new frame,the contact strips are kept from moving to where they put alot of pressure on the truck contacts and there is not enough weight of the frame to force the truck straight. so what i did for a test is i made the contact strips float and that stopped the trucks from being angled
I am no Kato Fan Boi, but I do think this is much ado about almost nothing. If we're refusing to even pop the hoods on our locos and tweak them a little here I don't know what else to say. When someone won't even pop the hood and take a few photos, and I have none of these here to check, there isn't much I can do to help.
AS posted i did a test but my camera is not the best and i do not know how to circle a reference point. and I just tested the engine on my track for 30 min. to see if there would be a pick up problem. and did not have any issues. the engine ran great. I am not sure as to the truck falling out problem. as I have not had that problem.
I don't have one to pop open either. But Gary Hinshaw looked at his and wrote up something near a PhD dissertation on the matter just a few posts back. I think he nailed the issue exactly.
I'll snap a picture and post it when I get a chance. I'm also interested in understanding ns737's solution: could you elaborate on how you "made the contact strips float"? Thanks, Gary P.S. I'm a self-declared Kato Fan Boy (~90% of my loco fleet is Kato), but I won't hesitate to criticize them when I think they deserve it. I think this truck design is a step backwards from the excellent design they had for the SD70M (which would have worked for the ACe too). To me, the tilting detracts from the illusion that these are the massive, high-horsepower beasts; and isn't that exactly the illusion many of us are trying to achieve with our modeling? For sure, it's not a big deal - I just responded to this thread because another modeler was bothered by it, and I thought maybe we could come up with a simple solution that we could share with others. (Too bad it's not as easy as just pushing the truck back down.) If you're not bothered by it, and/or you don't want to take them time to read all the posts here, no problem! Just kindly move on to the next thread in that case. Sorry for the rant.
HI that is why i say my camera is not the best. I will try to put in words where a pic would be better. if you take the trucks off the frame you will see the contact strips run between the fuel tank and metal at the end the frame. and since i have spares i cut the strips back where they go to the end of the frame. that allows the strip to move up and down like a spring. with the truck back in place, the truck contacts engage the strip like the old style frame strips do and the pressure is not strong that it no longer forces the frame up and the truck down. hope that helps. ED
The problem is that the sprung pickup on the center axle is too strong for the weight of the loco. The center of pivot for the truck is just slightly ahead of the #2 axle so the main weight of the loco is on axle #1 and #2. The needle point pickup strip can float in the truck frame but it rocks back and forth at the point above the #2 axle where it makes contact with the leaf spring. With the loco on the rails, the weight just ahead of the center alxe causes the whole assembly to rock forward. Gary's idea of going back to an SD70 pickup instead of the sprung pickup may solve it but you will end up with a rigid truck. The older style trucks don't float at all and you end up with fewer wheels making good contact with the rails. the sprung trucks may be problematic but when they work right, the loco's pull more than any previous 6 axle loco of the same size and weight. The other solution may be to try keeping the existing pickup system from rocking, allowing the center axle to still be sprung. I think I have an extra truck laying around from my first ACE which was missing a signifigant couple gears out of the truck, Kato sent me another truck. If I an find it, I will hack a little bit and see if it helps.
Foe what it is worth, I have or worked on over 30 SD-70ACe's and have only found 3 with problems. They all pushed the center axle out when loaded, one example, 57 cars when the lead unit lost contact and stalled and the trailing unit locked up. Removing the shell and rotating the gear train in reverse cleared the jam but the truck was not properly locked in place, lower to main gear case. This might be what you are seeing, after repair no further problems. I do not think the new chassis is a problem, it has not shown up again. I do not remember if the "tilt" was there before the failure. As far as trucks falling out of the chassis, if they are not installed correctly this will happen. You just can't push them in. Bob.
skipgear i just tested that theory and i removed the center wheel set from the truck and put the truck on a engine that i did not alter yet. and the truck still tilted. I have the sd70m's with the old frame and trucks and i put one on the track. with one sd70Ace that i altered the contact strips. and now both look the same. no more tilt look on my sd70Ace. and my sd70Ace stills pull the same as before i altered it.
Guys, i think it's just the fact that the axle closest to the fuel tank has that little do-dad above it. It would appear that it's playing tricks on your eyes...
These might not be realated, but I had one truck on a ES44 that was tilted and would derail on a switch, Kato sent me a new truck, problem solved! The truck frame looked warped, IMO.
Maybe I am wrong but these two truck shots show that the frames from the center towards the inside axle is higher than the part between the center and the outside axle... http://rrpicturearchives.net/showPicture.aspx?id=723349 http://rrpicturearchives.net/showPicture.aspx?id=723359
For your enjoyment and discussion. Look at the full sized pic. The rail is straight and level. I copied out the front axle on the truck. I pasted it in front of the second and third axles. The wheels are touching the rails the same everywhere. You can definately see a differenece in the axle heights. The truck goes up on the left. It's not an optical illusion. The pic speaks for itself ;-)
