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.