SEmG

Bachmann N Class Tender Modifications
to Improve Running Reliability

Various people have reported problems with Bachmann N Class tenders derailing. What follows is how I fixed mine plus a couple of other friends' examples with a few simple tweaks.

Modified N Tender

photograph by Jeff Lynn

Above is a photo, taken on Jeff's layout, of one of his N class locos with a modified tender as per this article (the first one he did, in fact). The tender mods are, of course, invisible in the photo! He has not renumbered it but has heavily weathered it and put some real coal in the tender.

Firstly I separated the locomotive and tender by undoing the two screws on the drawbar retaining plate on the tender front underside (being careful not to lose the very small screws!). Then I separated the body from the base - two self-tapping screws here but beware, on all of the tenders I have dealt with one of these screws didn't want to turn and I nearly stripped out the head slots. Remove the brake rodding if you have previously fitted it.

Now for the real work: firstly I removed the centre wheels and elongated the axle holes upwards with a 1mm drill in my mini-drill (see Figure 1), to allow the centre axles to float - half of the original problem seems to be that the tender can rock back and forth, pivoting on that centre axle. I tried to keep the slot vertical as I didn't really want any fore-and-aft play on the axle. I then replaced the wheels and axle when ready and tested the chassis on the track. As you do this step, check and fix any back-to-back dimensions.

Secondly, I added a little lead weight into the front half of the tender body to give a slightly better balance.

Thirdly, I filed a very slight, shallow crescent into the underside of the front footplate where the drawbar passes under - this allows the loco and tender a little more free up-and-down movement and also eliminates any chance of the front of the tender resting on the drawbar and lifting the weight off the leading wheelset. This step may not be really necessary but it is easy enough to do while you have the body and chassis separated.

For the flat-sided tender, this was all the work needed. I reassembled the tender chassis and body, then carefully put the drawbar, retainer and screws back. Test again and, hopefully, all should now be well.

For the slope-sided tender, I found that there was also too much side-play on the leading and trailing axles, causing a noticeable crab-wise movement when there was a load behind the tender, so I bushed these with some very small pieces of plastic rod, retained in the axle holes with just a tiny spot of glue (not too much or you'll gum up the works!). The tender can now be reassembled as above, and, again hopefully, it should now run more reliably.

 
Figure 1
Figure 1
(a) Looking from inside the tender frames, the original centre axle hole;
(b) As modified.
Figure 2
Figure 2
Front of tender footplate: file shallow curve under here.
 

Good luck with this - it's really not difficult and probably takes just as long to describe as to actually carry out the mods.

Jeff Lynn,
Melbourne, Australia.

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This page was last updated 15 September 2007

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