Nick Dunhill's Workshop - JLTRT LMS 10001

[simond]

Botany. It’s a branch…

 

[Yorkshire Dave]

Apparently I have a model of 10000 (16, there's the science gags again, come on keep up) to build soon (double-bubble), and each will have one power bogie and one unpowered. This of course makes fitting a decoder a doddle. Each loco can have a Loksound V5 in it, as there's loads of headroom in the decoder's rectifier with only one motor (plus a mini motor for the fan.) I pre assembled all the components of the decoder with a speaker upgrade. I know JLTRT locos often have 2 motors fitted. The motor in this loco is the same as would be fitted inside a pacific steam loco, so I often wonder why a second motor is desirable? Makes fitting a decoder much more difficult.

In an ideal world and if the kit was designed properly it would be arranged for a central motor drive to the trucks via a cardan shaft to provide an all axle (or at least an A1A-A1A) drive - which would be my preference.

As for two powered trucks in diesels - I would hazard a guess this would be more down to weight distribution and traction for haulage capacity.

In a diesel or electric loco the weight is generally evenly distributed along the length of the body. Therefore in a single truck powered model some of weight applies downward forces to the drive truck and some on the trailing truck, ergo the driving truck has to not only pull itself but the 'deadweight' trailing truck as well. The answer is a redistribution of weight towards the driving truck. With two powered trucks or two trucks driven with a centrally mounted motor via cardan shafts the weight distribution issue doesn't arise.

In a pacific steam loco as you've alluded to the wheelbase is a lot longer and the boiler allows for a greater weight to be located above this to provide more traction.

I suppose at the end of the day it's the modellers choice whether they want a single or twin powered truck drive and what the loco will be used to haul.

Having said all that my 7mm Met Bo-Bo has a single truck drive except I used the SDMP/Finney 7 gearboxes and slung the motor within the drive truck. And similarly with my 7mm NER ES1 I have arranged for the outer axles in each truck to be driven by a central motor via cardan shafts and SDMP/Finney 7 gearboxes.

 

[richard carr]

Nick

One motor bogies is perfectly fine to haul prototype length trains. It's far more important to have sufficient weight in the body to ensure adequate traction. I like the ABC supplied 6 watt maxon motors, they run really well with a decoder.

The Loksound version 5s are perfectly adequate to power the motor, however, there isn't a lot of power for sound, so I much prefer the the Loksound V5L with twin speaker outputs. Are you fitting any lights ?

Richard

 

[Clarence3815]

Poweful enough for 16 coaches including 12 wheel dining car on a 1:72 gradient?

Bernard

 

[mickoo]

Poweful enough for 16 coaches including 12 wheel dining car on a 1:72 gradient?

Bernard

Probably (almost certainly) not, you'll have to follow real life practice and use the empty stock tank engine as a banker up the grade.

Actually to be fair, I don't think 10000/1 could pull 16 coaches on the flat, they were only 1600HP and that's only a type 2, it's like asking a class 25 (steam equivalent would probably be something like a Stanier Mogul) to haul a 16 coach express, pretty much impossible at any meaningful speed.

Paired up they were 3200 HP and now you're getting into type 5 territory which is more akin to Princess Coronation HP and Deltics, the Class 50 was only 2700 HP and a type 5 and even they were paired up for the biggest expresses north of Crewe. This is why the class 40's were an abject failure on the WCML on heavy expresses, they were only 2000 HP and struggled with the biggest expresses.

Frequently the biggest expresses had pilot engines, even with a Princess coronation on the front, Liverpool boat trains were sometimes heavy weights and took a pilot.

I like it when people apply bigger and bigger motors and more and more weight to pull heavy weight trains, equivalent to something like 8000HP and then complain there's not enough power.

 

[Dave Holt]

I'm not sure it translates into 7 mm, but my experience with single power bogie 4 mm diesels is that the haulage capacity varied dramatically depending whether the powered bogie was leading or trailing (can't remember which was the better) despite maximum weighting over the drive end. The problem wasn't motor power but traction.
I'd certainly recommend twin power bogies, either with twin motors or central motor with Cardan shaft drive to both bogies.
Dave.

 

[Clarence3815]

Many thanks both.

It was a naughty question as I was thinking of the Merseyside Express which of course would have a Princess equivalent at least up Camden Bank.

The chances of recreating it in 7mm model form on that grade must be very slim, unless anyone knows differently?

Bernard

 

[Nick Dunhill]

This is a interesting conversation. I have a lot more experience of making smaller steam locos, and the customers I build for usually don't expect a 2-4-0T loco from 1880s to pull 12 bogies. It's physically impossible to fit a massive motor in one, so something akin to a 1833 is your best shot. It needs electronics, say a V5, a stay-alive unit and a sugar-cube type speaker, which doesn't leave much room for ballast. I try to shoot for 750g (total mass) and that way the loco will comfortably pull a couple of coaches, as it did in real life.

I suspect the second motor is to pull the mass of lead added to give you the adhesion. Why not look at your stock? A well known modeller I once built a Princess for had coaches that were not very free running (poor/no bearings) and each coach weighed in at around a kilo. Perhaps that could also be part of the problem.

I suspect that there are modellers running 10000/1 in a consist of 4 motors (plus roof fans, hefty speakers, lights etc) needing a small sub-station to supply the amps?

Bernard, here's a Princess I made hauling a massive train up PW's steep hill.

 

[simond]

The Folkestone club 0 gauge track is level, but it's a tiny 4-4-0, with decoder and speaker and as much lead as I could squeeze in. The rolling stock does not have ball bearings, just standard brass. As are most of the coach bodies...

And this was my Duchess before I refitted the valve gear (incorrectly ) on a 1 in 100 on a corner, with 7 bogies and two smaller vehicles. Again, pretty standard garden railway stock, mix of plastic and brass with plain bearings.

 

[OzzyO]

the Class 50 was only 2700 HP and a type 5 and even they were paired up for the biggest expresses north of Crewe.

Hello Nick, Mickoo,

the class 50 was a type 4 (type 4, 2000 - 2999 hp.). There was two reasons for the twin power units north of Crewe. One was to keep to electric times and acceleration from station stops. Two was in case they got a peg stop on the clime to Shap. One loco could do the job but not the acceleration that was timed for the electric schedule.

ATB

OzzyO.

Ps. Type 5 3000+ HP.