benjy14 Posted October 9, 2020 Share Posted October 9, 2020 Hi there, I am really hoping that somebody out there will be able to help me. I own a MTH HO Big Boy and have discovered that one of the driveshafts is kaput: As you can see, three of the pins that engage with the motor and gearbox have totally worn away. I have made contact with MTH but they no longer supply this part. I have also contacted the sole retailer that they suggested may carry stock but alas, they don't. I am therefore need to find an alternative way to replace (or repair?) this driveshaft and I am wondering if anybody on RMweb could suggest a way that I could do this? I don't know if 3D printing would be an asnwer but it is a very small component (just 15.6mm long), so I don't know if this would be an option. Any advice, help or suggestions would be really appreciated. Many thanks, Ben Link to post Share on other sites More sharing options...
RMweb Gold Joseph_Pestell Posted October 10, 2020 RMweb Gold Share Posted October 10, 2020 Many other locomotive models have similar driveshafts. Just a matter of finding one the right size. 1 Link to post Share on other sites More sharing options...
RMweb Premium boxbrownie Posted October 10, 2020 RMweb Premium Share Posted October 10, 2020 If no alternative can be found it might/should be possible to remove the drive lugs and drill and insert nylon/brass rod to repair the shaft. 1 Link to post Share on other sites More sharing options...
298 Posted October 10, 2020 Share Posted October 10, 2020 Can you post the dimensions please? (Ball diameter, prong length and thickness). NWSL do/did spares for a variety of applications and I think I brought a DIY kit from Hollywood foundry. It may also be possible to cannibalise something from another manufacturer, or adjust the length by cutting into two and joining with a plastic sleeve. But what might work for my locos that only have to pull a couple of reefers may not stand up to the demands of such a loco, hence the wear issue in the first place. Replacing them with a brass component may fix that point only for something else to wear. Link to post Share on other sites More sharing options...
benjy14 Posted October 10, 2020 Author Share Posted October 10, 2020 Thank you for all of your replies. 12 hours ago, Joseph_Pestell said: Many other locomotive models have similar driveshafts. Just a matter of finding one the right size. Yes, definitely an option to explore. Would you be able to recommend a manufacturer to look at? 11 hours ago, boxbrownie said: If no alternative can be found it might/should be possible to remove the drive lugs and drill and insert nylon/brass rod to repair the shaft. Yes, trying to repair the driveshaft is definitely something I am going to try. 10 hours ago, 298 said: Can you post the dimensions please? (Ball diameter, prong length and thickness). NWSL do/did spares for a variety of applications and I think I brought a DIY kit from Hollywood foundry. It may also be possible to cannibalise something from another manufacturer, or adjust the length by cutting into two and joining with a plastic sleeve. But what might work for my locos that only have to pull a couple of reefers may not stand up to the demands of such a loco, hence the wear issue in the first place. Replacing them with a brass component may fix that point only for something else to wear. The shaft is 15.7mm long, the ball diameter is 2.6mm and the prong thickness is 1.1mm. I am not entirely certain what the prong length should be as I don't know how badly worn they are but I would estimate at least 2mm. I have had a look at the NWSL website but I am not entirely certain what they offer, so I will try contacting them on Monday. Paul Martin of EDM Models (a friend through the Ffestiniog) has very kindly offered to make me two new driveshafts from brass and he warned, as you do, that this might cause other parts to wear. I am not sure though how much of a choice I have; if I can't repair the shaft and can't source a replacement plastic part, using brass ones is going to be the only option. Thanks again for your help and any further advice would be most welcome! Link to post Share on other sites More sharing options...
RMweb Gold Joseph_Pestell Posted October 11, 2020 RMweb Gold Share Posted October 11, 2020 Most manufacturers these days build their diesel / electric locomotives with a central motor and driveshafts to gears on the bogie. So just a question really of which manufacturer offers the best spares availability. It may be better to replace not just the shaft but the two "cups" at each end. So the motor shaft diameter is a critical dimension as well. 1 Link to post Share on other sites More sharing options...
benjy14 Posted October 11, 2020 Author Share Posted October 11, 2020 12 hours ago, Joseph_Pestell said: Most manufacturers these days build their diesel / electric locomotives with a central motor and driveshafts to gears on the bogie. So just a question really of which manufacturer offers the best spares availability. It may be better to replace not just the shaft but the two "cups" at each end. So the motor shaft diameter is a critical dimension as well. Thank you! I will make some enquiries and see what I can find. I have the dimensions, so will see if I can find something that matches. I have now at least three avenues to explore, so I'm sure that one of them will come off! Link to post Share on other sites More sharing options...
298 Posted October 12, 2020 Share Posted October 12, 2020 2.6mm sounds like the part was under-specified by the designer for this use, I'm sure I've seen some bigger sizes in 4mm and for comparison the Bachmann underground Ernie parts are 2.4mm. I'd take Paul up on his offer as it sounds like a plastic replacement is only going to wear out again. Link to post Share on other sites More sharing options...
meil Posted October 12, 2020 Share Posted October 12, 2020 Available from Ultrascale: https://www.ultrascale.uk/eshop/products/view/CAT028/476 1 2 Link to post Share on other sites More sharing options...
benjy14 Posted October 13, 2020 Author Share Posted October 13, 2020 8 hours ago, 298 said: 2.6mm sounds like the part was under-specified by the designer for this use, I'm sure I've seen some bigger sizes in 4mm and for comparison the Bachmann underground Ernie parts are 2.4mm. I'd take Paul up on his offer as it sounds like a plastic replacement is only going to wear out again. 7 hours ago, meil said: Available from Ultrascale: https://www.ultrascale.uk/eshop/products/view/CAT028/476 Thank you both so much for your posts; that is extremely useful information, much appreciated! Ben Link to post Share on other sites More sharing options...
AndyID Posted October 13, 2020 Share Posted October 13, 2020 It's also possible to make your own from some basic components. https://www.rmweb.co.uk/community/index.php?/topic/157598-motorgearbox-for-djh/&do=findComment&comment=4097629 Link to post Share on other sites More sharing options...
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