Atlas o 2rail gp60 front truck locking up

Yeah, actually I have, but that was after I removed the motor from the truck and then reattached it. Or, so I thought it was properly attached.

If the worm is not completely mated with the drive gear in the truck block the wheels will rotate about one full revolution in either direction then lock up. The motor will work its way up from the block which obviously should not happen.

Anytime I have to remove a motor then reattach I make sure to spin the flywheel by hand to make sure the wheels spin smoothly in both directions.

If it worked OK before now then it's possible that a gear tooth was sheared off an idler gear or spur gear.

@Ian Pinckney posted:

My front trucks are locking up in forward and reverse after moving about a foot. Loco in dcc w/ soundtraxx tsunami 2 tsu-4400 decoder. Already checked everything I could with decoder and disassembled the sides of the truck and cleaned gears. Had some grit and small piece of insulation from wire fall out. Tried running a few more times but same result. I am not at all experienced enough to tale the truck completely apart.  Anyone have this happen? Suggestions? TIA.

Short of a complete truck disassembly, the wheel sets can be easily removed and the gears inspected for an obstruction or damage. Just remove the bottom plate under each axle by turning back the four small screws and the wheel sets will lift out. Hopefully you still have some grit that just needs removing. To reinstall the wheels just reverse the process, making sure the flat face on the bearings is seated against the flat area where they reseat in the truck block. Unlike a complete truck disassembly to access the worm gear on Atlas diesels, this step is truly easy and worth a try.  Good luck.

RM

You can try what Rich suggests and pull the wheel sets. I would suggest that while you have them out, you give them a good cleaning. If the engine is old and has sat, whatever lubricant Atlas used has a tendency to gum up and the axles can get stuck in the bearings.  A little alcohol or acetone and some wiping to clean everything up goes a long way. Then re-oil everything when you reassemble. All of the bearings have a flat side on them. This has to be positioned properly in the truck housing for everything to mesh. It is almost too easy to have the bearing be slightly off of straight and then things dont work right. 

I find that the easiest way to work on these trucks is to pull them out of the engine and just work on the truck itself.  If you have to pull out the motor, make sure the brass thrust bearing below the worm is properly positioned and that the plastic spacer is positioned between the worm and the thrust bearing. The bearings on the cross shaft have to be properly oriented as well. It seems easier to get the shaft and worm meshed in the upper housing (with the motor) and then place that into the truck block.  It takes some care to make sure nothing rocks around when you join the 2 halves.  When you put the screw back in to lock it all together, make sure everything is flat on top of the truck. If its tilted, the screw may still go in, but it wont mesh right. I then test the truck on a set of rollers by just hooking up DC power to the motor leads. Let it run a bit before re-installing.