RMweb Premium 21C123 Posted November 15, 2015 RMweb Premium Share Posted November 15, 2015 Hi all Like others I've been seduced by the Dapol terrier, which is yet to arrive here in NZ. I'm planning a small layout and have started buying second-hand wagons and a built LSWR B4 kit. The loco is a brass kit, no idea from what maker, and has a couple of issues that I'm hoping someone may be able to help me with. Generally it runs fine - backwards. Going forwards there is a tight spot in the drive train. I've taken the connecting rods off and found two things. The slide bars are of square section, one set is diagonal when looking along the loco <> and the other roughly square [ ], the sliding parts bind a bit on both so the first question is should they be set so that the square section is horizontal ? the piston rods are also bent slightly which probably isn't helping. The next discovery is that the gear wheel on the driven axle is not at 90° to the axle, there is a wobble in it and there doesn't appear to be a grub screw so I assume it's pressed on. Any ideas on how to cure that one ? The motor worm drives directly on to the gear and seems to be at 90° to the axle. Any suggestions would be gratefully received, Roger Link to post Share on other sites More sharing options...
Simond Posted November 15, 2015 Share Posted November 15, 2015 Not a specialist in this loco, nor the kit of course, but can suggest... The "backwards but not forwards" suggests that the quartering and coupling rods are basically ok. If you can remove the motor and worm, rolling the chassis by hand can be an easy way of detecting a tight spot. The slide bars should certainly be square on, the upper and lower faces should be horizontal. If it's "only a bit out" I suspect it will not be the cause of your problem, and I would look for something else first, particularly as it will be a cosmetic pain to fix. The worm gear should definitely be at right angles to the axle, it should not wobble as it rotates. It is unlikely to be pressed on, in fact, the wobble is often caused by the bore being a little too big, and the grub screw pushing the wheel over to one side. Possibly an old toothbrush, & some meths and a good scrub in the area, you might find that there is a screw hiding in there. If so, you might want to try removing it, cleaning thoroughly, and gluing the wheel to the axle. If you do this, you will be relying in the surface tension if the "glue" to centre the wheel on the axle - I'd recommend one of the Loctite retainers (601 from memory, but please check) and you will need to support the wheel, with the axle vertical, and the motor & worm out of the way, so they do not cause it to be pushed over as the glue solidifies. You also need to ensure that the retainer is dripped in, and thoroughly wets the axle & bore all round, by spinning the wheel with your fingers, and jiggling it up & down slightly. Let it drop back into the temporary support and leave for a couple if minute, it should be fine. That it runs ok backwards but not forwards is interesting. The load on the motor shaft reverses as the direction, so when it's going backwards, it's trying to pul the motor shaft out of the motor, and when it's going forwards, it's pushing the motor shaft into the motor. It could therefore be that your motor is damaged (unlikely, but possible) or that the worm itself is catching on the outside of the motor case. You will be able to see this if you look at the worm and motor and try to turn the wheels one way or the other. There will be a little end float in the armature shaft but the worm shouldn't touch the motor case. You don't say whether the problem occurs once per revolution of the wheels, or just generally going forwards - if it is once per rev, I'd suggest that you look for a polished or bright spot on the rods, might indicate an unwanted contact which can be resolved by adding a washer, or a bit of judicious filing. Another point of contact can be the crosshead at end of travel, but this would usually cause a problem going either way. Not sure if the wheels are Slaters'. If so, the boss is slightly proud of the crank web, and I have found it necessary to put a washer behind the coupling rods, to prevent a "snick". Again, I'd expect that to be an "either way" problem. The wipers are quite short - I'm guessing this is not an electrical issue, but it might be worth ensuring they are clean and are all in contact, as a slight wobble on a driver might lose contact on an 0-4-0 quite easily. If you connect the controller direct to the motor with croc-clip leads and hold the chassis off the track, does it run smoothly both ways? Turn the speed right down and examine it from every angle... You might see the problem! Hoping this helps to diagnose your problem, once you know what's wrong, you're well along the road to fixing it! Do post up what you find, Best Simon Edit - the over enthusiastic smellchecker "helped"... Link to post Share on other sites More sharing options...
Marshall5 Posted November 15, 2015 Share Posted November 15, 2015 It's probably an old Vulcan kit, later marketed by Adrian Swain (of ABS) under his Zero Zephyrs label. Good luck with your project. Ray. Link to post Share on other sites More sharing options...
N15class Posted November 15, 2015 Share Posted November 15, 2015 Hi Simon is right about the horizontal slide bar. I would check to see if the cross head is catching the coupling rod. As for the running problems I would say the it is all to do with the gear set. As it wobbles it needs to be replace with a new gear and worm, a pair that fit the axle and motor shaft. When putting together if the gear is screw fitted to the axle file a small flat on the axle. This way you tighten the screw onto the flat, it then does not need to be overly tight as the flat stops the gear turning and the gear will also not be pushed out of square. asfor the worm put a washer between it and the motor and tighten the worm against making sure there is minimal end float. The washer then acts as a thrust washer reducing any drag. The gear and worm should be set so that the gear wheel has minimal back and forth movement when meshed, a fag paper between the mesh.two while the screws are done up. Both centre lines must also line up. You also need zero side to side movement on the driven axle, if there is the worm and gear will constantly coming out of correct. Link to post Share on other sites More sharing options...
RMweb Premium 21C123 Posted November 16, 2015 Author RMweb Premium Share Posted November 16, 2015 Hi all thanks for the replies, gave me some things to try. Yes, the tight spot was in one place consistently. I took the connecting rods off the crankpins and found that one of the screwed bolts was loose in the wheel, I think it was protruding a bit and catching the whitemetal spring ? Anyway once cleaned and put back together it is working fine. The gear wheel is still not true, and it has no grub screw, it appears to have been drilled through and a pin soldered in place. As it is now going I'll leave it alone until I have some time to replace the gear and worm. Thanks for the help Roger Link to post Share on other sites More sharing options...
Simond Posted November 16, 2015 Share Posted November 16, 2015 Ah, great news, glad you sorted it. If the gear is pinned to the axle, that's good. If it's running sweetly, don't change anything!!! A crankpin sticking out of the back of the wheel, catching on the frames/spring would make perfect sense. Best Simon Link to post Share on other sites More sharing options...
Guest Isambarduk Posted November 17, 2015 Share Posted November 17, 2015 I agree with all the above; it is a kit from former Eric Underhill Models - Vulcan Model Engineering and the wheels and the gears can be a bit of a 'challenge'. I built my B4 from this stable when they first became available (I would guess 1983/84), it was a very good kit in its time and I would say that it's still a good place to start if you're after a B4. As far as I can remember - it was a long time ago! - the wheels, hornblocks and worm gear came ready assembled (please correct me somebody if I am wrong) and the wheels, which are plastic centred, are a push-fit on the axles; I don't know if they were Slater's wheels but they were included in the kit. As in many kits of the day, I was able to make the steel worm and brass worm wheel run nice and smoothly but not quietly. Fortunately, I soon discovered Ultrascale gears and I fitted replacements, which I can thoroughly recommend (see: www.ultrascale.com/eshop/products/CAT015#WWGS4 ); they are inexpensive at around £7 per set and, thanks to the self lubricating qualities of the Nylatron (carbon filled nylon-type polymer) worms, they require no oiling and they are as quiet as you could wish for. (Don't worry about the cautionary note on long delivery times, I think these are for more specialist items as I have found that gears arrive within a few days in the UK). I can add more detail on ratios, Type 1 or Type 2 and so on, if you wish. David More details in captioned pictures at: www.davidlosmith.co.uk/Honfleur.htm Link to post Share on other sites More sharing options...
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