Diesel engine QTB  

updatetd:  2008-08-27  Back

Prototype Model Building the model More pictures Videos of the model and the prototype

Photos, if not else specified: Olle Frykmo


Photo: Martin Oscarsson  See more of his pictures at:    http://www.swedishrails.com

QTB - A multipurpose engine with a built in surprise

These engines are primary constructed for keeping the snow away from the lines in northern Sweden.
The export route via rail from Kiruna to the harbour in Narvik is the main task for the Qtb engines.

The Qtb engine is a quite unique engine built in a more American way than the ordinary engines in Europe.
It powered by a General Motors EMD 12-645E engine and has ploughs both in front and on the sides.
And what more, it is the only loco in the world with built-in jack-up turntable with a possibility to turn the hole engine around on the track and settle for homebase if it gets stuck in to heavy snow.

Summer duty
During the rest of the year it is a heavy hauler of working trains of the construction sector (Banverket).
Its often seen in front of the ballast trains along the lines. 

The model
The model shows the the engine at summer duty and I have not even tried to model the built in turntable.
That has been done by a swedish H0 modeller - Rutger Friberg

Delivery years: 1969-1970
Manufacturer: NOHAB Sweden
Engine:  General Motors EMD 12-645E
Built number : 10

Lenght:        16.6 meter
Wheelbase:        2,4 + 9,3 meter
Axel config:  BoBo
Total weight  88 tons
Model  N scale  --  building from scratch

The modelling work is still going on, this is how far Ive come to now (2003-06-15)

The first prototype model is almost finished, only the handrails 
and a few details are missing:

On this page you can follow the construction of the model - from styrene sheet to finished body

Building the model 
Preparations The idea to model this engine came up when modelling a body to a railcleaning wagon. The cleaning wagon was disguised to a workmens wagon that follows the hopper wagons in an ballast train. And the Qtb-engine is a common puller of these trains.

And as protoype for modelling it is almost ideal, straight sides and angular corners
The prototype is built more like an American engine than an ordinary European engine wich means that the chassis to build the model on ought to be from an Amrican diesel. And among my N-scale engines at home I had an Atlas GP40 that really was at no use at a Swedish layout.
The GP40 is a good runner in front of heavy trains so I decided to give a first try with that chassis.
Unfortunately the chassis is about 10mm too long (Which really means 1.6 meters in 1:1) but just adding one more row of doors on the hood will make that look enough accurate to my needs.

A better chassis to use would be the Atlas GP35, not more than 3-4 mm too long.
The next body will be fitted to a GP35 chassis if everything works as planned (but you know it seldom will)



First body protptype made of cardboard

With the computer and the printer I made the first simplified model in cardboard to have a first look at how to continue.


On this model I will only fit couplings at the rear end.

I will try a system from Tomix,
Scharfenburgs couplings, really intended for multiple units. They are much smaller than the ordinary N-scale couplings and could easily be fitted on the body.
Tomix coupling for body mount
Same type of couplings installed as
exchange part for ordinary couplings  


Body - step by step

The body will be built with different type of styrene sheet.

The ground framework is a rather ugly looking box that is built tight around the chassis with 1mm sheet.

Here a few more parts cut out to form the heavy buffer beam.

And some experimental arrangments for the front lights.
It worked well at the upper headlights but not so good for the lower ones. For the next body I will try with fibre optics instead.

The hood sidings are cut out of plain 0.5 mm sheet with a "cut out" for the grating that is made of  0.5mm Car siding - H0 scale 3-1/4" spacing.

The rear end is covered with a sheet with drilled holes for the rear lights. The sheet is 0.75mm.
The buffer beam is made of two 0.5 mm sheet which makes it easier to form the sheet compared to do it in a single 1 mm sheet.

The sheets was intentionally made slightly to wide.
With enough cement or solution the different styrene sheets are "bonded" to be almost homogen and is then easily filed to soft corners.  



The cabin

The only part that is a little bit tricky to model on this engine is the cabin with its rather odd constuction

Another cardboard mockup is made to try out all the angles.


Walls made of  0,5+0,75mm

Front sheet 0,75mm

The tilted walls made of 0.5 mm
Here with the faulty rear walls that was exchanged as on next picture.

This is how the cabin looks when ready.
The warped sheet below the rear window is relly a bit  too big, but some compromises had to be done...




The doors that will be fitted to the hood is cut out  of 0.25mm sheet. On the right picture you can se all the doors lined up beside the body.


A picture that shows the roofing made of cut out 0.7mm plates


The roof for the cabin is made out of a 0.125mm sheet.

You have to be careful when gluing such thin sheets:
Too much glue makes the sheet soft.

Now with doors and the cabinroof fitted.

The rear and side bridges are made of 0.75mm sheet i

. top


The only change Ive made to the original chassis is to file down the details on the boogies to give place to the strange shields covering the boogies.

   The cut out shields (0.75mm) placed beside the body.
   Two small holes now drilled for the buffers.


The shields on place on the outside of the boogies.
Be aware of to give enough space to let the boogies swing.

The headlights are made out of a 1.6 mm styrene rod.
A 0.5mm hole is drilled out of the rod
Then the rod is cut into thin slices.

 Some will be good looking, some warped and funny looking. Out of 25 slices I got 12 good looking and there was a need for 10 pieces, so that was good enough.


Im not at all comfortable with metal work. Ive grown up with the  Airfix plastic model kits. But some time you will have to overcome some aversions.Here a few deviations from my plastic world:

The lower hold for the snow ploughs is made of a couple of copper pieces from an old Arnold switch, glued to tha chassis with epoxy.

The blades of the snow ploughs are made of styren and the hold is a styrene tube, 2,4 mm dia, with a cut along the tube where the blade is fastened. Through this tube I have put a rod of brass with a tiny head soldered on top.
The plough is mounted between a hold on the hood and the metal holders. The ploughs can be dismounted when needed.


The exhaust pipes are made of brass, tube 2mm, which also was used to make the head on the plough holders.


Click to enlarge Click to enlarge

The model, a bit pale but with all details on place, excpet for the handrails.

Soon its time for painting an lettering.



Windows, lettering

The windows and the lettering will be made of Supercal water slip decals printed on a Color in printer.

The picture shows the first try out printed on plain paper.
There is a need for a few corrections.

The model is now painted and the windows and lettering is on place.



More pictures 

Click to enlarge

Click to enlarge

Two pictures of the prototype 

The engine is Banverkets DLL 3106 in front of a ballast train
at Vsters in May 2003.

Click the pictures to enlarge.

photo: Olle Frykmo

Videoclips showing both the model and the protoype         
more from
 Mads website