spearmint100 Posted March 14, 2015 Share Posted March 14, 2015 Does anyone have any tips for the re-assembly of the valve gear on a Bachmann split chassis V2. My original intention when I took the chassis apart was to replace it with a Comet etched brass unit to be built to EM gauge with Gibson wheels. Having since decided against going the EM route I am now attempting to recreate what I started with rather than throw the whole chassis away. The main part of the valve gear remains in one piece and just requires remounting on the centre driving wheel crankpins. I have obtained replacement centre axle bushes and crankpins from Bachmann. After much trial and error the two problems I have are alignment - the pins have a hexagonal centre to engage the eccentric crank and require at least three hands to keep wheel, rods and eccentric in line - and assuming I can ever achieve alignment the pin is just push fit with no obvious means of retaining it in position. I am sure I must be missing something obvious. Any helpful suggestions would be appreciated. Link to post Share on other sites More sharing options...
relaxinghobby Posted March 14, 2015 Share Posted March 14, 2015 Use the slow acting cousin of super glue; NutLock or Loctite depending on manufacturer to fix the pins. A photo would help in showing us the exact problem. Link to post Share on other sites More sharing options...
spearmint100 Posted March 14, 2015 Author Share Posted March 14, 2015 Use the slow acting cousin of super glue; NutLock or Loctite depending on manufacturer to fix the pins. A photo would help in showing us the exact problem. Thanks for your reply. As requested I have attached a photo. The hole in the eccentric crank is hexagonal and can - with difficulty - be matched with the hexagonal top of the retaining pin. This then needs to be aligned with the bush and rods and when in position presumably pushed home. Link to post Share on other sites More sharing options...
Theakerr Posted March 14, 2015 Share Posted March 14, 2015 If my memory is correct (It is getting a bit full), the pin has a screw thread on it. Assembly is by threading the pin through the eccentric, the piston rod, the bushing and the conrod, placing the assembled bits into the hole on the wheel, pushing them in far as they will comfortably go and then use the eccentric arm to turn the pin all the way home and tight. Getting the eccentric correctly lined up with the wheel boss can be a bit of a pain but as I remember (old age caveat) the pin is in plastic and I just kept turning until it lined up. Tweezers and mini long nosed pliers were my tools. Hope this helps. Link to post Share on other sites More sharing options...
spearmint100 Posted March 15, 2015 Author Share Posted March 15, 2015 If my memory is correct (It is getting a bit full), the pin has a screw thread on it. Assembly is by threading the pin through the eccentric, the piston rod, the bushing and the conrod, placing the assembled bits into the hole on the wheel, pushing them in far as they will comfortably go and then use the eccentric arm to turn the pin all the way home and tight. Getting the eccentric correctly lined up with the wheel boss can be a bit of a pain but as I remember (old age caveat) the pin is in plastic and I just kept turning until it lined up. Tweezers and mini long nosed pliers were my tools. Hope this helps. Thanks for your reply. I think mine is an older version with a plain, non threaded pin - which also seems reluctant to push fully home. I think I will have to go with the slow acting glue suggestion after easing the driving wheel hole very slightly. Link to post Share on other sites More sharing options...
John Tomlinson Posted March 15, 2015 Share Posted March 15, 2015 At risk of stating the obvious, the eccentric is meant to face roughly towards the wheel centre when correctly positioned. You should find that the pin has a shape inside of the top that will hold the eccentric in position by fitting inside the hexagonal shaped hole. It isn't to be honest a great bit of engineering, but you may be able to get the pin further in by rotating it a bit each way as you press in. John. Link to post Share on other sites More sharing options...
spearmint100 Posted March 21, 2015 Author Share Posted March 21, 2015 Thanks for the replies. Finally solved the problem. The crankpin hexagon first required a very slight dressing with a fine file to fit through the eccentric. To overcome the need for three hands I used Castrol grease to hold the relevant rods together over the driving wheel boss with the eccentric at the correct position for 'bottom dead centre'. After an application of Araldite to the driving wheel bush with a cocktail stick the rod was finally pushed home. Job done and the V2 runs as it should again. Link to post Share on other sites More sharing options...
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