slow running bachmann locos

This is a well recognised problem from the time this model was introduced. Unless the previous owner has done any work on it, the leading bogie is oversprung and lifts the front end, the leading coupled wheel is softly sprung, the loco isn't that heavy so the driving wheels slip all the time, and it's really only the rear coupled wheels that are providing traction. And then the final problem, it is geared 40:1 with a 'fat' worm which makes the drive draggier than it needs to be, and the higher than usual gearing malkes it great for slow speed control, but limits maximum speed.

What to do.
Take body off, remove front bogie, cut about one sixth off the bogie spring, and just use that small piece slightly stretched to lightly spring the bogie. (Keep the rest of the spring, it's good in pieces for other locos which have no bogie spring fitted!) Now the leading coupled wheel, take the sprung saddle out and either stretch the spring to near double the length, or find and fit a stiffer spring. On the chassis remove the plastic doodad for a decoder, and if you feel so inclined remove the decoder socket and the cast attachment points it sits on, hardwire a decoder which can go into the smokebox, and use the resulting void over the coupled wheels to pack in lead for weight to improve adhesion.. (A faster motor, the Mashima 1426 can be substituted - if you can now find one - there are doubless alternatives but I cannot identify one. You do need a good worm puller as Bachmann worms are on TIGHT!; I broke my old worm puller the first time out on another Bachmann loco... There is though another simpler way if using DCC)

You are now into the hell of putting the body back on, holding the various detail parts under the body void apart, as you slide it onto the mechanism; and the dire process of adjusting the speedo cable so the loco doesn't run like a three legged dog. (Bachmann dropped this speedo cable detail after this model and the BR Std4 2-6-4T, due to customer feedback on the difficulties it caused; as it was essential to disconnect and reconnect if taking the body of for maintenance, or decoder fitting.)

This mechanical adjustment will enable the loco to both pull much better and achieve scale for 70-75 mph. Still not fast enough for me, so I used the DCC feature of increasing track voltage, so that there is 15V at the motor terminals, and that has it capable of scale for 95mph. Consult your DCC system manual to see if this feature is available. This does the job on this loco and several other 'slugs' that I own, and I have operated this way for well over ten years now with not a hint of trouble.

For extra traction, mine also has lead sheet on the cab floor and curved to fit under the cab roof, which is not visible in operation with the tender coupled on. (I needed a little more traction to ensure a reliable restart with a full class 5 trainload standing on the 1 in 80 gradient of my layout.)

34C said:

This is a sound working principle, which I support in intent: I will not accept any downside.

Firstly this loco wasn't alone in being 'shy' of maximum speed, just the slowest I had thus far encountered; this was shortly after converting to DCC, and early in my acquisition of the new RTR OO models emerging from China.

Then there's economy - I aim to pursue model railway on a 'beer budget'. Purchase replacement motor or complete motor and driveline, or do the job using the DCC track voltage adjustment capability? The latter was attractive in economy - after considerable thought and research I had lashed out the £200 for the Lenz 100 - and it had the capability to adjust from a nominal 11V to 22V, and the decoders were rated to handle this.

So this method was trialled, proved to work; and there was no downside then, or in the seventeen years since.

Click to expand...

I dropped the track voltage (also on a Lenz 100) from 16V to 14V in order to accomodate a ModelTorque fitted loco. By making that adjustment, all my other locos ended up slowing down, most to unacceptable levels.
If you increase the track voltage, the opposite will happen - everything will go faster and you will find that some locos may not go as slow at shunting speeds as you might want them to.

Also consider that 16V is probably the most commonly used track voltage, so by default, most people will be using it. If you move locos to or from your layout (ie you take your locos to other people's layouts or they bring their locos to yours) you will find that your locos probably won't perform well on their layouts and their locos probably won't perform well on your layout because other people have most likely set their locos up on a system at 16V.

I'm not saying that increasing track voltage won't work - it does work - but I am just pointing out that there are caveats which people should be aware of before changing track voltage without realising the implications.

Personally, I prefer fixing core problems rather than symptoms and to me, a single loco which doesn't perform is the problem that needs fixing. Increasing track voltage is fixing the symptoms and it comes at the price of affecting all locos. If you are happy with scalextric speeds <G>, that's fine but it isn't for me!

I was curious about what Bachmann might get up to on the BR Std 5MT reissue, and have gone grubbing about on Bach's site to see what they might be showing.
So there it is, 73118 shown with the proper 'roll over' of the BR1F upper tender side (good) but with the speedo drive representation still in place.

Also on view, the very curious - well overwidth at 18mm! - representation of the firebox under the footplate, resulting in 'arches' to clear the centre and rear coupled wheels. (If you are really attacking your 5MT, then these can sawn away to make flush to the rest of the chassis casting.) My assumption was that the designer realising that more weight was required at the rear of the model, 'bolted it on' in this location. Whatever, this was early in Bachmann's foray into RTR OO steam models, and I don't believe it has been repeated on subsequent introductions to their range.

At the date of introduction, RTR OO steam tender locos with the drive wheels actually driven were a rarity; so for those of us that wanted this, the shortcomings were happily worked on to make it conform to our ideas. I have a feeling it may get a rougher reception this time around, what with competent loco drive now standard on tender locos, in a choice of 90+ classes available and announced...