Problems with my Terrier

[John R Smith]

Good afternoon everyone

 

And I hope that you all had a great Christmas. During the festive season, I have taken the opportunity to give my rolling stock a service, but have not succeeded to improve a problem with my little Dapol Terrier, which has been the regular pilot and local goods loco at Ponteglos for the past two years.

 

Straight out of the box when I first got it, it was a very poor runner at slow speed, but I fixed this by adjusting all the pick-ups and cleaning the wheel treads. Recently, however, things have gone downhill again, so I removed the body from the chassis as per instructions, and cleaned and lubricated everything.

 

The problem is this - running forward the loco is quiet and smooth, with perfect slow-speed performance. But running in reverse, bunker-first, there is an annoying ticking sound from the mechanism and the motion is not as smooth. Checking this with body removed I can see that the 'ticks' are related to motor revolutions, with one tick per rev of the flywheel.

 

Has anyone else experienced this sort of problem with a Terrier? And did you manage to fix it?

 

 

(illustration copyright Dapol ltd)

 

 

Many thanks in advance for your time

 

John

[Mike Huxley]

Hi John,

 

I've had a similar problem with my Dapol 5700 pannier, which ran reasonably well  at first, then developed the same problem as you have experienced. Also, the circuit board started to smoke after a short time. As the model was within the 1 year warranty, I have returned it to Rails of Sheffield, who are replacing it, but if I had the option I would prefer to have another "Minerva" Pannier instead. 

 

I have a feeling that this is an ongoing problem with Dapol locos of late and as a result will not be buying any further modls from them.

 

Cheers,

Mike

[Simond]

John,

 

A “tick” per revolution of the motor suggests a damaged brush or commutator. As it’s a can motor, I suspect that it is not something you’ll be able to fix, as reassembly of a can motor is “challenging”. Replacement of the motor should be reasonably easy, assuming you can get one.

 

Alternatively, it’s not a cracked gear is it?

 

Atb

Simon

[Izzy]

 

A ticking when running in one direction can be something catching/ brushing against something else that doesn’t happen in the other one. It can often be gear related when spur gearing can move sideways under loading, and sometimes the face of the worm or wormwheel can be poor and is the cause, (since different faces will take the load depending on direction). Might even be the flywheel catching something if the motor shaft has a lot of end float.

 

Izzy

[John R Smith]

Thanks for your replies.

 

I have had a look at the DCC Supplies site, who do the Dapol spares, and they do not list a replacement motor for the Terrier. I am beginning to think more seriously about endfloat as a possible culprit, because the ticking sound can be intermittent. Can motors don't have to be rubbish, of course, back in the day some Japanese ones had a very good reputation, IIRC.

 

So far my recent adventures in O gauge (after a long absence) seem to have been bedevilled by very poor mechanical performance from the current R-T-R offerings. Makes me nostalgic for the M7 I built from a CCW kit back in the early '70s, powered by a 5-pole Pittman motor. It ran superbly.

 

Best wishes

 

John

[Simond]

I’d concur entirely with Izzy’s suggestion, particularly if it’s worse laden with a long train. Probably easier to fix too

 

Fingers crossed

Simon

[Hal Nail]

Given various reports of problems developing in terriers, panniers and jinties (don’t think I’ve read anything about 08s), I am feeling a tad wary. It’s bad enough if there is a higher than ideal chance of getting a poor one initially but at least you can test for that: apparently quite frequent faults developing after a year or two are really off putting.

 

I do hope in some shape or form this is all fed back to Dapol, otherwise they will take the view their approach to quality is sufficient.

[John R Smith]

Well, I spent most of today, on and off, working on the Terrier and getting nowhere most of the time. Very frustrating, but in the end - SUCCESS! So an explanation may be of some use to those of us who own the Dapol Terrier, Pannier and Jinty, which I suspect all have much the same mechanism.

 

I stripped the loco down to the chassis, and checked out all the things which could possibly cause poor running -

• We must be fair to Dapol. Most of the mechanical design and component quality seems pretty good, and certainly a lot better than the H****n locomotives which I have previously examined. Fit and finish is fine, the c/sunk setscrews holding everything together are good quality, and there are no obvious issues with alignment or gear mesh. 
• There is a lot of sideplay in the driving axles, which at its extremes could cause a problem with the rim pickups. However, this is necessary and forgivable because it allows the use of small radius curves.
• There is also some sideplay in the nylon gear train from the motor to the driven axle. I reduced this using some washers to shim it, but it made no difference to the running quality so I think it is of no consequence.
• There is some endfloat in the can motor drive shaft. However, it seems well within what I would consider acceptable limits, and moreover has a spring tensioner to take it up during normal running.
• You may remember that I said I had cleaned and lubricated everything, but still had this problem with ticking and poor running in one (reverse) direction. The lube point I had most trouble with was the motor shaft bearings - one end is behind the flywheel, the other below the worm gear cover. So I stripped down the PCB boards for the DCC and removed the worm gear cover.
• When I lubed before I had use Locolube synthetic oil as recommended by Dapol and sold by DCC Supplies. It occurred to me that this oil is very thin, in fact perhaps far too thin for a heavily loaded bearing. So I got out my favourite lube, Singer Sewing Machine Oil, and used that on the motor shaft bearings. One is behind the worm gear, and was now accessible. The other is behind the flywheel, and is tricky to get to. Take up the endfloat gently with a screwdriver tip, and use a thin oiling pin to drop a little oil right into the bearing.

I had been trying different things and testing them all day with no result. You can imagine the good vibes when at last after re-lubing the motor bearings I had perfect running in both directions - smooth, quiet, and down to a crawl. It looks as if those bearings are critical and need a good thick oil too. Sadly there is no felt oil pad as we had on the old 00 locos of my childhood, so perhaps this job needs doing at fairly frequent intervals. 

 

All best wishes

 

John