Topcat2018 Posted June 7, 2023 Share Posted June 7, 2023 I have a Mainline J72 tank engine. This is a split-chassis design where the wheels on one side are connected to those on the other side via insulating axles. The problem is that the wheels have become misaligned so that when the con rods on one side are at top dead centre those on the other side are not at the mid position, because the wheels on one side can be set at any angle to those on the other side, unlike some Bachmann split-chassis locos which have square ends on the axles. Easy to fix, but can anyone tell me, when the con rods on the right side are at top dead centre, should the crank pins on the left side be facing forwards or backwards? Link to comment Share on other sites More sharing options...
508006 Posted June 7, 2023 Share Posted June 7, 2023 The question I have to ask here is which side are you referring to where the wheels are at the top dead centre or 12 o'clock position on their rotation ?.From referencing pictures of a Bachmann chassis for a J72 locomotive, it looks like the wheels on the right hand side of the loco ( fireman's side ) are 1/4 turn ( 90° ) ahead of those on the left hand side ( drivers side, looking from the rear of the loco ).Based on this, it suggests that if the wheels on the fireman's side are at the 12:00 position, the wheels on the drivers side would be at the 3:00 position ( based on the loco standing on its wheels ).Hope this helps. Link to comment Share on other sites More sharing options...
DC-345471 Posted June 7, 2023 Share Posted June 7, 2023 RH at the top LH towards the rear. Touch of superglue on either end of the axle joiner sleeve on the centre axle and a slower drying glue like an epoxy so you have time to tweak the other two to match, but ideally a quartering jig of some sort is needed as much more than a slight tolerance difference between the three axles may give a jerky perfomance. Make sure the back to back is spot on as well as once glued there is no adjusting it.They usually are pretty good when pressed fully home into the joiner sleeve. Link to comment Share on other sites More sharing options...
Topcat2018 Posted June 7, 2023 Author Share Posted June 7, 2023 Thanks to both for your replies! Link to comment Share on other sites More sharing options...
Rana Temporia Posted June 8, 2023 Share Posted June 8, 2023 I think Peters Spares has had some new mid-axle insulators made for this loco. Lots of Mainline locos around with the same problem. Link to comment Share on other sites More sharing options...
Topcat2018 Posted June 8, 2023 Author Share Posted June 8, 2023 @RTThanks for your reply. I'm hoping that all the existing components can be re-used once they are cleaned up, but I will take a look at Peter's Spares to see if they have any motor brushes as I want to replace these as well. Link to comment Share on other sites More sharing options...
threelink Posted June 8, 2023 Share Posted June 8, 2023 The nylon type axles on these locos are notorious for their tendency to split, thereby releasing the wheels to rotate and upset the quartering. In my experience there is no adhesive that will fix a split axle and replacement is the better option. Peters Spares has been recommended as a source of replacement axles. Link to comment Share on other sites More sharing options...
Topcat2018 Posted June 8, 2023 Author Share Posted June 8, 2023 @THAs mentioned in my original posting, the wheels in this loco are free to rotate anyway, as the axles are circular in cross section, unlike some Bachmann locos that have square ends to the axles. It's only friction that keeps them properly aligned.The nylon axles appear to be in good condition so I don't intend to change them. Link to comment Share on other sites More sharing options...
threelink Posted June 8, 2023 Share Posted June 8, 2023 @Topcat. If the axles are in good order, that's good news - avoids the costs of replacement and makes DC's repairs recommendation entirely feasible. Good luck in achieving the desired result. Link to comment Share on other sites More sharing options...
Topcat2018 Posted June 9, 2023 Author Share Posted June 9, 2023 Still having problems with wheel alignment. Despite the wheels being a good push fit on the nylon axles the wheels still seem to get misaligned and jam. Half the problem seems to be that the drive is applied to the rear wheels so drive to the centre and front wheels is via the connecting rods which are in two parts. With this drive arrangement It would seem to make sense to have single piece con rods so that, although the wheels on one side could get out of phase with the wheels on the other side, the wheels on one side could not get out of alignment with each other.I do have a useful tip for cheap brush and spring replacement. Rather than paying £15 plus postage for a set of brushes (which are out of stock anyway), take some brushes for a Hornby ringfield motor and file off the tapered part to make them the correct length. If new springs are needed cut the the Hornby brush springs in half as they are stronger than the Mainline ones. Works a treat. Link to comment Share on other sites More sharing options...
ellocoloco Posted June 9, 2023 Share Posted June 9, 2023 Everytime I run my Mainline Jubilee and Collet Goods I expect the axles to have gone and they'll get retired to the scrapline. Such a shame as they are lovely looking models.Peters spares have the J72 axle set in stock as RT suggests and I reckon that would be your best bet. Link to comment Share on other sites More sharing options...
atom3624 Posted June 10, 2023 Share Posted June 10, 2023 Bachmann generally have nearly every spare you need 'off the shelf', and prices are surprisingly reasonable!If not able to locate online, Jenni is a great help by email.Al. Link to comment Share on other sites More sharing options...
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