Had my USAT Alco S4 on plow duty today and it started making weird noises then a high pitched whine. I pulled it off the track for inspection and I can move one axle with a little pressure with my finger. I took the motor cover off expecting to find a cracked gear but no. The worm gear appears to be made out of metal and looks fine. Taking the bad axle out I grasped the gear and tried to wiggle the wheels but it didn’t move so there goes the theory of a split gear. Can the teeth on the axle gear be worn down? This loco doesn’t have alot of hours on it.
How do I fix this?
Thanks
Todd
Hi Todd, Sorry to hear of your problem, Have you tried to power that one MOTOR BLOCK to determine where the noise is coming from? To me it sounds like a DRY BUSHING or BEARING.
Keep us posted on the results.
Good Luck
I have had USA diesels “whine” right out of the box. Complete disassembly of the truck and applying power to the motor alone showed the whine was in the motor itself. I replaced the offending motor blocks with new ones from USA. Two out of Three USA engines had this issue with one truck. May not be what you are experiencing but it sounds like a replacement block is needed. Beautiful runners once you quiet them down.
After further checking one of the axles is slipping while the motor is turning. I would say the whine was from the gear not engaging and slipping and the motor just spinning. So with it back together one wheel turns and the other stutters and makes terrible noises.
If the gear is not split what can be slipping? Can the metal worm gear be junk or can the axle gear be worn so it doesn’t engage? I might have to dig in deeper to see if there is actually anything broken.
This is my 3rd USAT engine so I guess 2 out of 3 ain’t bad.
Sounds like you got a plan…Worth fixing. I don’t recall exactly what I paid but I know USA has a good parts department and I recall the motor blocks were pretty inexpensive. I love my SD-40’s!
The Scoop. I took the bum motor block off tonight and removed the top cover then examined the gears. It does look like the bad axle gear has a slight “U” shape to it VS the other axle gear is straight. With my finger pressing down the motor I applied power to it and everything worked with no slipping. I put it back together and tried it again with power to the loco and the wheels spinning I put pressure with my finger on the bad axle and it kept moving without slipping SO does this mean it is fixed? Could something had been loose in the block?
Next time I’m running trains I will put it back on the track and take it through the paces. Somehow I might have dodged a bullet in having to replace the block and saved $50 . I will keep my fingers crossed.
Thanks
The big test today and the Alco S4 ran like a brand new engine even pulling a heavy train. I wonder what was making the axle slip? When taking it apart I didn’t notice anything loose but putting it back together must have fixed it. Maybe when I opened the block I let the gremlin out?
Next is to fix the pickup wire I broke then to the paint shop.
Thanks guys for the help.
Todd
If the plastic axle gear is not straight across, then failure will occur.
USA does sell axles with wheels and gears, and whole motor blocks.
They used to be a good deal, but now are $50 and above. I got 2 at York several years ago for $27, but those days/deals are now gone.
I would get the whole block as you will use the parts sooner or later and it is nice to have a spare motor and axle.
Sometimes the axles are installed improperly, the brass bushing on the axle can be positioned 90 degrees “wrong” which will cause problems.
An axle that does not run true is either a bent half axle (rare) or a split plastic gear casting where the axle is not held securely.
Greg