Atlantic's works: Portable layout - Scenic details next

[Woodcock29]

Graeme its nice to see it all up and connected together. Strange how some locos run well somewhere and then not so well elsewhere. I've never used feedback controllers but have seen some strange things happen to my locos when running with feedback elsewhere. The classic I suppose is a Portescap fitted loco that you can't stop when on a feedback controller not that you should run it on one anyway.
The newer RTR locos with coreless motors are no good on feedback.
I had the screech with a Hornby J15 back at beginning of the year when I had the Spirsby layout up at home and wanted to run BR period on it. Eventually I got it quietened down - I think it was the rear motor bearing from memory.
Andrew

[Atlantic 3279]

Thanks to both of you for those suggestions. I noticed (or was reminded of) another anomaly with the J15 when test running it again last night. I've taken steps to eliminate that. It may turn out to have been the cause of a highly misleading "screech", or I may simply have pursued a red herring. I'll let you know after another test.

[Atlantic 3279]

That other J15 anomaly turned out to be a red herring in respect of the cause of the screech. I'll go into more detail either later today, or some time tomorrow, but after a frustrating further period of tinkering with the motor and loco chassis, as much test running as I've subsequently had time and patience to perform does so far suggest that the problem may have been solved.

[Atlantic 3279]

I'll explain that red herring first. I noticed on close observation while test running on the loft layout (which has to be done with the tender attached unless one has unplugged the drawbar connector and bridged the appropriate pins in the plug so as to make the loco independently operable) that the middle wheelset of the tender was not revolving. I believe a keen observer had pointed this out to me when the loco was working on "Grantham" over a year ago, but I had forgotten to do anything about it. Analysis showed that the middle wheelset as supplied is free to sit at a slightly higher level than the other two on uneven track (sensibly enough) and that it carries no weight bar its own, but that it also has power pick-ups rubbing on the wheel backs.
I wondered if it was just about possible that I was mis-hearing, and that the screech that was evident at times was in fact simply the sound of static wheel flanges rubbing against the rails, with the tender acting as a sound-box. Ideally I did not want to remove, or loosen of the pick-ups to the point where they allowed the axle to rotate freely but failed to collect current properly. I therefore spent quite some time last evening devising and applying an arrangement by which a piece of springy nickel silver wire could bear lightly against the top of the middle axle, just enough to make the wheels grip the rails and rotate. I achieved the desired loading to cause rotation without spoiling the ride of the tender on the other wheels, and found that this had made no difference at all to the screeching, so I had to look again at the loco itself today. I'll explain tomorrow...

[Woodcock29]

I had a misfortune a few years ago with one of my Hornby J15s - I have both an LNER and BR version. I was mucking around with the LNER version - possibly lubricating it to remove a screech (?) when the plastic fitting joining the flywheel to the gearbox pinged off into oblivion - never to be seen again! What to do? Hornby couldn't supply one. Well the obvious choice was to pinch the one from the BR version as I hardly ever run my BR locos. But what if I want to run that? Studying the part closely I decided I might be able the make a replacement from a piece of plastic card - which proved to be the case. An interesting fact turned out to be that it only fitted properly in one but not the other as the distances were marginally different!

Maybe one day I'll find the missing part - better not vacuum the floor of the railway room - well certainly not without a stocking over the end of the nozzle!

[Atlantic 3279]

Luckily my Hornby J15 has so much factory-applied grease on that universal joint that it would be extremely difficult for the link to ping off.

[Atlantic 3279]

Here's the rest of the dreary fault-finding saga for the Hornby J15:

I did start out by trying to test run the loco after each individual change I had made, but as that involved having to run the loco forwards and backwards repeatedly over about 20 feet of straight and curved track in order to find out whether it would eventually start screeching, after an always quiet start, I did eventually run out of patience with the time-consuming "one thing at a time" analytical approach, and finally did a few things all at once before re-testing. Not ideal, but there it is...

What I hadn't already tried, strangely enough, was simply running without the loco body in place, so I did that next. I could still provoke the screech by further test running. I decided that it was time to get the tender quite definitely out of the list of possibilities, so in order to allow the loco to run without it I used my multimeter to work out which pairs of pins on the drawbar plug & socket would need to be bridged. Definitely not the same ones as for the Heljan O2, I discovered. Far left pin on the J15 for the left rail pick-ups, next one for the right rail pick-ups, the two on the right for the motor leads. Some experimental bridging by inserting little horseshoe shapes of 0.45mm wire into the plug revealed that bridging alternate pins gave the correct circuit for the loco to run alone in the conventional direction. Just for testing, it would do equally well to bridge the middle pair, and bridge the outer pair, so that the loco would also run, but the opposite way to normal. And, no surprises, the powered loco chassis alone would still screech without the influence of the tender...

I then un-clipped the cover from the top of the gear housing and lifted out the amply greased worm-gear plus its bearings, putting the link for the universal joint safely aside, to avoid possible loss. That made it possible to push the mechanism along by hand, with gears rotating. I pushed it briskly to and fro many times, but could not demonstrate the screech. That seemed to help to confirm that it was instead coming from one of the bearings for the motor, or for the worm gear, when those rotate at speed more than just briefly. With so much grease evident on and around the gears, I doubted that the bearings for the short worm shaft could possibly be dry, but I slid them off the shaft anyway and made sure to get grease and a little extra oil on the shaft and in each bearing before sliding them back on and refitting the worm to the top of the gear set. Although the lower gears were clearly plastic of some sort, I also took the trouble to move the grease around on those before hiding them again, so that it might have chance to coat any bits that had be left dry, once the gears rotated again. Without further testing I then decided that I ought to make further effort to get oil to that motor bearing that is always hidden by the one of the two motor retaining brackets that cannot be removed without pulling off a flywheel. With the motor released, but still very little access, I tried to run oil down a thin rod held against the face of the flywheel nearest the motor, so as to reach the armature shaft, and then tilted the motor to try to get the oil to run towards the bearing without covering the plastic retainer in oil too! That done, I refitted the motor and universal joint. I then decided to have a proper look at the axle bearings, which I had so far only oiled from the sides, with the keeper plate still in place, so I took that off the bottom of the chassis, giving me chance to see (not much) of the lower aspect of the drive gears too. Looking very closely at two of the circular axle bearings, I felt that I could see faint black streaks around the groove on the outside of each bearing, which made me wonder if those two might have been sticking on the axle at times and instead rotating in the black-painted chassis block. Unlikely perhaps, but I therefore made sure that all were free on their axles, and that there was oil between the axle and the bearing (and between the bearing and the block, even though that should not be needed).

The reassembled chassis then appeared to run screech-free no matter how many times I ran it back and forth, flat-out. Some relief at last! It was still screech free on further prolonged test running with body and tender re-attached. So has the problem really now be solved, long term, or is it just waiting to strike again at the moment that will cause maximum annoyance and inconvenience? And was the noise coming from a dry motor bearing that I had failed to reach with oil at the first attempt, or from a bearing for the worm gear which rotates at equally high speed, or is there any way it could have been one of those axle bearings

[Chas Levin]

Very frustrating, know the feeling! Best of luck...

[Mersey508138]

Hi Graeme

Looks like that was quite a mammoth task in order to eventually solve the screeching issue and well done for persevering with it. I find it is highly annoying when a loco that may have cost say £130+ has a constantly bugging noise like the screech you've been encoutering and it ends up coming down to something so easy that the manufacturers could and quite probably should have dealt with before they were dispatched to the retailers or customers who have ordered their models directly.

[Atlantic 3279]

Yes. I could have coped very well without doing the lengthy investigation. No screech from the loco, and tender wheels mounted sensibly to ensure rotation would be nice to have "as standard".

[Jim de Griz]

That led to me having to devise a method to allow me to extend the "leading" ends of the curved check rails in several points so as to start two or three timbers closer to the toe. That took care of the trouble with leading bogies.

Sorry to reach so far back into the thread, but I was wondering how you did this.

I have a few sections that would benefit from a check rail, but I can’t see a convincing way to manage it.

Jim de Griz

[Mersey508138]

Hi Jim

I have tried various ideas myself for check rails on curved track sections including turnouts, this included laying pieces of rail inside the running rail next to the moulded rail chairs, the big problem was all that did was to create absolute havoc with the driving wheels on all of my loco fleet.

Ever since the last time I tried the idea around 20 years ago, I have been stumped and not had any alternate ideas.

[Atlantic 3279]

My method, for the Peco code 100 laid directly on rigid plywood baseboard, and exploiting materials I had to hand, was as follows: I placed pieces of copper clad sleeper, sitting on additional pieces of card to add to the height, in some of the gaps between the plastic sleepers, so that the copper tops were at a sufficient height to allow offcuts of code 75 bullhead rail to sit on the copper with rail head at same height as the Peco running rails. I drilled 0.7mm holes through the copper clad and card down into the board about 2mm away from the inner edge of the running rail heads and pushed in short pieces of 0.7mm brass wire, tops level with the rails. I then placed my code 75 offcuts, with ends tidied up an suitable bent like a check rail, between the brass wires/pins and the running rails, and slid a piece of copper clad strip, on edge, between the running rail and the intended code 75 check rail. I find the thickness of the copper clad that I have is usually suitable to gauge the check rail gap. With the parts thus held in place, I finally soldered the extra check rails to the brass pins and slid out the “on edge” copper clad spacer, leaving the supporting copper clad pieces and card packing in place of course.

[Atlantic 3279]

PS: The “about 2mm from the rail” position for drilling the holes was of course determined by placing a strip of copper clad and a strip of code 75 rail along the inner edge of the rail and drilling immediately next to those...

[Jim de Griz]

Thanks Atlantic, I must admit I wouldn’t have thought of using finer scale track for the check rails. I’ll have to give it a go.

Should have thought of the brass pins myself, but didn’t Funny the things that are obvious once someone points it out to you.

Jim de Griz