Tag Archives: Hump Shunting

The Master and the Slave (pt3)

Today I ignored the dark and wet weather outside and focussed on making sure my Class 13 would be a strong runner on digital control.


As discussed in part 2, I will be installing two DCC decoders (one in each unit) and setting them to the same address.

IMG_5558LRI first modified the chassis casting of the slave and master units. Cutting away the lugs that formerly supported a small circuit board (now surplus to requirements).  This modification allows just enough space for a Bachmann 3-function decoder. Granted it is not quite enough space, thus a lot of the decoders soft outer shell needs cutting away to help it fit in the gap.

IMG_5573LRI then soldered the decoders into position and covered joins with shrink tube. This was my first time using shrink tube and I feel much more confident that my wires will not break apart as I move the loco and motors around.

Having built another model with a similar pick-up, motor and decoder arrangement I was keen to avoid a certain pitfall: If both motors and decoders pick-up from the same wheel sets, it is difficult to make separate adjustments to the decoders (without disconnecting the pick-ups).

IMG_5560LRTo avoid this problem, I wanted to build the Class 13 with some kind of pick-up connector, which would allow me to separate the pick-up’s for each unit (when needed). While wondering if I had such a connector I noticed the surplus circuit board from the Bachmann 08 includes just the thing!

I super glued the little plastic connector beneath the master unit chassis and wired the two pick-up sets together. The pick-ups are disguised as two hoses that are present on the prototypes buffer beams. All tension between the two units is focussed on the spring-loaded screw link coupling, thus these wires are loose, but kept in place by the 08s outer chassis.



The Class 13 is now one of my best runners. The slow speeds I can get out of the two motors are quite impressive.

Next on the agenda is some filling and sanding.

The Master and the Slave (pt2)


Change of plan…

I have just tested the Class 13’s ability to manoeuvre around short radius curves and over point work (which it manages wonderfully). I think this is mostly due to the large buffers I have used (preventing buffer lock). However, the master unit (with the motor) sounds like it is straining to pull the rather weighty slave unit. It would be a shame if the engine cannot pull a long train in the future because of my decision to remove one of the motors, so I have just reinstalled the motor into the slave unit.


My layout is DCC so this will mean a further modification to the front of the slave unit chassis (to accept a second decoder). For engines with two motors I use two decoders programmed to the same address. This takes the strain off an individual decoder and also allows each motor to be fine tuned separately.


The pick-ups on the Bachmann class 08 are a tad primitive. They are set up on the top surface of each wheel. When the model is brand new this is not too much of a problem. Unfortunately, as time cracks on, the pick-ups collect all the dust and dirt from the wheels until they no longer carry any volts to the motor. They can be cleaned up, but you need to take the wheels out.

As I was already deconstructing the 08s I decided to cut away all the pick-ups and install a new arrangement based on methods I have seen used on RMweb. I superglued two pieces of copper-cladding to the chassis plate and soldered together some new pick-ups from fine copper strip.

So far I am very pleased with this modification. Once I have wired the loco to pick up off all 12 wheels, it will become a very difficult loco to stall.


The Master and the Slave (pt1)

I have always been a big fan of diesel shunters. I loved watching little shunters moving around Bescot Yard and the various industrial complexes in the Midlands.

BR Class 13 Diesel Shunter

BR Class 13 at Tinsley. Copyright Mark Addison (from wikipedia)

One shunter I never had the privilege of seeing was the BR Class 13. The Class 13 was a special locomotive, designed to operate over the ‘hump’ in the large marshalling yard at Tinsely. Each one looked like two locos stuck together (which is exactly what they were). Two BR Class 08s were used to create each Class 13 loco. One of them had the cab cut away and was linked, via multiple-working gear, to the other. Thus only one driver was needed to operate these two locomotives; the cabless one being the slave and the cabbed version being the master.

The class 13 was also fitted with large buffer plates which helped counter balance these Siamese locos. Only three were ever created, each with various differences in detail. I saw a model of one on the Rail Express stand at Warley show a few years ago and was eager to try my hand at creating one out of the RTR class 08 models currently available.

First considerations

While visiting the Mickleover Model Railway Show in 2010 I was discussing with a fellow visitor my plans to build a class 13, and how wonderful it would be, having two motors and all, but the chap quickly countered: ‘why use two motors?’ he said ‘wouldn’t it be easier to take one of the motors out’? I must admit, the chap had a good point. I decided that life would be easier if one of the motors was removed, but thought it would be nice to keep the model picking up across both wheel sets.

The two best models to undertake this conversion with are the Hornby and Bachmann 08s. It is apparently easier to modify the Hornby 08 (as it is easier to remove the cab area). Plus the Hornby version is regarded as a superior model. Unfortunately, superiority comes at a price out of my budget range, so I stuck with the Bachmann models.

In October 2010 I came across the perfect donor locos in the form of x2 Bachmann models (08623 and 08672), and so armed with a photocopy of an old Rail Express article on creating a class 13 (Feb 04, No.93) I set to work.


Converting the Bachmann 08 into the slave unit.

I started by removing the motor from the slave unit. I soon discovered that if I wanted the slave unit to continue running smoothly I would need to retain the large cast weight that sits under the motor. The motor really, really didn’t want to be parted from the metal casting and became the most difficult job of this project, particularly removing the motor from the small plastic harness surround (see below).


I then began attacking the slave unit cab. Now it is important to know that the cab is in fact a separate moulded item and actually slides off the Bachmann body (with difficulty). This does leave a chunky area of plastic and interior detail in the location of the cab that needs removing with a small hack saw.


Once the cab plastic was removed it was then time to remove a chunky section of metal-chassis casting which sits in the cab area. Once this was removed with a suitable metal hack saw, it was clear that my 08s were starting to resemble a class 13.

I then used modelling putty to fill in the gap in the cab floor and sanded it to a smooth surface, while also smoothing the cut edges of the bonnet. I then removed the buffers and detail from the buffer beams and sanded them down flat (so they could be used to stick the new ‘meaty’ buffer beams to).

Modelling made easy

It was at this stage that 2011 took me off in another direction and although the new buffer beams were designed and made out of plasticard, I never fitted them. The thought of designing the cab bonnet area on the slave unit put me off.

And so by coincidence RT Models decided to create a class 13 conversion kit out of resin, white metal and nickel-silver parts. I quickly purchased the conversion kit and then got back to work on the loco.

The RT Models conversion kit is easy to put together and was quickly glued into the cab area of the slave unit. I decided to use the new buffer beams supplied with the conversion kit because they already have the holes punched out of the casting for buffers and vacuum pipes.


Stability issues

After refitting the wheels to the now motorless slave unit, I realised that my removal of the cab weights meant that the metal cast no longer fixed to the rest of the chassis (I had cut away the screw holes). I solved this issue by adding a motor harness from an old brass kit to the inside of the bonnet (which provided some rigidity to the body and frames).



It is worth noting that although there were only three Class 13s (now long scrapped), my Bachmann models include conflicting mouldings to any of the three prototypes. The main offender being a tool box (or radiator) on my slave unit that was never included on any of the three real locos. I opted to solve this problem by creating a fictional forth loco (rather than scarring the loco with modelling knives). This also allowed me to be more flexible with livery choice and detail. I have also fitted the larger buffers seen on some of the class 13s, which I think give the model a nice ‘chunky’ appearance. I want to model the engine in approximately 1968 condition, so I plan to keep it in BR Blue, but with the number 4503, which will put the loco in the period just before it was renumbered into the TOPS system as the fictional 13004.

What’s next?

I have linked the master and slave units together with a screw link coupling (managing to make the one on the front of the master fully sprung!), so I need to next test how the loco operates over short radius curves and point-work.

In the mean time, here is a video of the 13’s trial run.