That darn Sumpter

[Neil Robinson]

I wonder if it's something to do with the motion?
Try removing all the rods from the offending bogie and retest.

 

[Neil Robinson]

Hi Neil, had a good look at that, the quartering is bang on and when the motion is rotated without the motor everything has ample clearance and turns perfectly. It's definately binding somewhere but I'm damned if I can see it, I'm hoping another mallet user has experienced similar problems, the front drive unit is fine by the way and I'm wondering whether to do a swap over of gears, but if that one aint broke I'm tempted not to tamper. Keep thinking mate.
Kim

I think you're wise to leave the other unit alone, at least until you've located a suspect part on the rear unit. I don't doubt that the quartering is O.K. and the motion looks right, but as the rest of the mechanism also looks O.K. I still think it worth test running without the rods. There is a lot of play as standard with LGB rods and just occasionally odd things happen. I once worked on a rack loco that bent the rods from time to time. It was fixed by slackening a screw despite there being clearance with the screw tight.

 

[Philbahn]

Kim just a shot acr0ss the bows. Have you checked the quartering of the wheels. Ie are the wheels on each axle at 90 degrees to each other. It sounds as though itis locking when one wheel either leads before the other and going one way it won't lock but the other way it locks. With out the motor in it probably won't show up. Replace motor and then try turning slowly.

 

[Philbahn]

Think the best way is to assemble the bogie and drop a rule across the pins. the without moving the unit try the other side . Try both the top and ottom of the pins

 

[themole]

Kim, the axle of one of the three axles (rear unit) has moved on its spline/wheel.:Looser: I had this problem many moons ago there is a solution though, apply a small amount of super glue when you know the rear unit is NOT binding. problem solved!!!
Alyn

 

[themole]

Kim if you can it should stop the problem; but if the inner gears are moving ,with respect to the axle, then you will have to strip down check the quartering; and apply super glue to the gear/axle. Alyn PS one of the most common offenders was the electric rack loco.

 

[Neil Robinson]

Kim, the axle of one of the three axles (rear unit) has moved on its spline/wheel.:Looser: I had this problem many moons ago there is a solution though, apply a small amount of super glue when you know the rear unit is NOT binding.
Alyn

My personal preference would be to drill through the gear boss and axle and drive a roll pin in rather than use superglue. I've used this method to stop gears moving axially along the shaft.

 

[stevedenver]

given your description and other info posted -i would suspect that the gears are worn  -or there is play or some issue in the unpowered axle causing the seizing-also take out the wheels and see if they are bent-this can happen and it might be an issue

it is my experience that this wear can be almost imperceptible and yet allow slippage of the worm -this has been the problem for me in every loco i have had slippage issues-ie repeatedly quarter and then later something happens-

i might be wrong, but i believe there can be slight differences between old and new components   -

'frinstants: i had an old 2076 with slipping -replaced the axels and still had issues-then had to replace the housing in order to get things to properly seat-either due to wear at teh 'bushing area' or a slight change in the size of the old and the replacement axels

i would systematically start with replacement-the axels-do em all -perhaps another set of idlers as well

 

[stevedenver]

so what did the trick?

 

[Philbahn]

Kim Just a thought.If you have to secure the gear try a bearing retainer as opposed to super glue. The common grade is 601 (locktite) Swan bearings (Wyko) behind HMP Preston sell it.
Or if you are not in a rush I can drop you some off next time I'm passing

 

[stevedenver]

congrats and well done for your perseverance
its the stuff you think/assume is ok thats eluding