Claire RJ Posted January 20, 2018 Share Posted January 20, 2018 After running beautifully and smoothly for a good while over a period of several months (not continuously but for an hour or so once a week on a running night, the 4 CEP power unit has started running erratically (sluggishly) in one direction while being okay in the other direction Has anyone else had a similar experience and can anyone suggest how to rectify this? We have removed the body from the underframe as per the Bachmann instructions, but have gone no further for the moment. Claire Link to post Share on other sites More sharing options...
RMweb Gold RFS Posted January 20, 2018 RMweb Gold Share Posted January 20, 2018 (edited) Most likely cause is one of the gear pins has come out and you are only running on one powered axle. Quite a common problem and it's happened to me on three occasions. It's easy to test if this is the case: can you rotate one of the driven axles easily with your fingers? If so that's your problem. Bachmann do sell spares for these. You might be lucky as I was on two occasions. On the first I removed the bogie side frame and found the pin had lodged in some excessive grease, and on the second a careful check round the tracks found one lying on top of the ballast. 3rd time unlucky, though, so had to fork out about £3 with Bachmann for a pack of 3 spares. Edited January 20, 2018 by RFS Link to post Share on other sites More sharing options...
Claire RJ Posted January 22, 2018 Author Share Posted January 22, 2018 Most likely cause is one of the gear pins has come out and you are only running on one powered axle. Quite a common problem and it's happened to me on three occasions. It's easy to test if this is the case: can you rotate one of the driven axles easily with your fingers? If so that's your problem. Bachmann do sell spares for these. You might be lucky as I was on two occasions. On the first I removed the bogie side frame and found the pin had lodged in some excessive grease, and on the second a careful check round the tracks found one lying on top of the ballast. 3rd time unlucky, though, so had to fork out about £3 with Bachmann for a pack of 3 spares. Thank you very much RFS. The 4 CEP belongs to my younger son and he is quite adept at carrying out repairs but he is a busy working man and I thought this might save him a bit of time. Claire (summer saturdays in Devon loft layout and Templeford Vintage O gauge exhibition layout) Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted January 22, 2018 Share Posted January 22, 2018 But if neither wheelset is freely turning, the most likely cause is the plastic drive coupler inserted in the flywheel slipping. This often starts assymetric, only slips in one direction, until there is enough wear that it is really loose. Drop of cyano rectifies. Most likely cause is one of the gear pins has come out and you are only running on one powered axle. Quite a common problem and it's happened to me on three occasions... Is this a common event on the now quite extensive range of Bachmann BR period MU's that have same style of drive as the 4-CEP? Or are we still waiting for the evidence to come in? (Four class 105 motor units, and no such problems experienced - yet.) Is there a preventative fix, such as wrap around or attach a thin sheet metal cover to positively stop them coming out? Prefer that to a protracted search of the track... Link to post Share on other sites More sharing options...
RMweb Gold RFS Posted January 22, 2018 RMweb Gold Share Posted January 22, 2018 But if neither wheelset is freely turning, the most likely cause is the plastic drive coupler inserted in the flywheel slipping. This often starts assymetric, only slips in one direction, until there is enough wear that it is really loose. Drop of cyano rectifies. Is this a common event on the now quite extensive range of Bachmann BR period MU's that have same style of drive as the 4-CEP? Or are we still waiting for the evidence to come in? (Four class 105 motor units, and no such problems experienced - yet.) Is there a preventative fix, such as wrap around or attach a thin sheet metal cover to positively stop them coming out? Prefer that to a protracted search of the track... I have 6 4-CEPs, 4 2-EPBs, 2 MLVs and a pair of Thumpers all of which have similar drive mechanisms. But I've only had the problem with 3 of the 4-CEPs and not with any of the others. When I first spoke to Bachmann they suggested a drop of superglue to hold the pin in place, but I was wary of that seeping into the gears. Instead I've used a piece of strong, black masking tape to cover the holes and prevent the pins coming out. Not had a problem since. Link to post Share on other sites More sharing options...
Claire RJ Posted January 25, 2018 Author Share Posted January 25, 2018 I have 6 4-CEPs, 4 2-EPBs, 2 MLVs and a pair of Thumpers all of which have similar drive mechanisms. But I've only had the problem with 3 of the 4-CEPs and not with any of the others. When I first spoke to Bachmann they suggested a drop of superglue to hold the pin in place, but I was wary of that seeping into the gears. Instead I've used a piece of strong, black masking tape to cover the holes and prevent the pins coming out. Not had a problem since. Many thanks to all for your interest in this matter. RFS's diagnosis was spot on. We only searched in a somewhat half hearted manner for the missing pin, and we did not send to Bachmann, but we inserted a peco black track nail, and then put over a tiny piece of insulating tape ( as suggested in previous post) to keep the nail in place. And the 4 CEP runs well again. Claire 1 Link to post Share on other sites More sharing options...
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