Friday, May 25, 2012

How I constructed a railmotor from two Andel freelance coach kits

Having acquired a couple of Andel's freelance coach kits I initially thought of constructing them as per the instructions to increase my coaching stock. However, after almost completing the first coach I had a change of plan.

I've always been fascinated by railmotors, particularly the early internal combustion vehicles made, for example, by the Ford Motor Company (see

I haven't discovered whether Ford Railmotors ever ran on three foot narrow gauge railways but various petrol driven railmotors ran on some Irish narrow gauge railways in the 1920s. Using the Andel coach kits as the basis, I decided I could make a representation of a petrol driven railmotor inspired by the standard gauge Ford prototypes. It would also provide me with an opportunity to experiment with battery power, something else I've been considering for some time.

Constructing the body

 In addition to the Andel kit of pre-coloured resin castings, I bought a couple of axle bearings from Garden Railway Specialists, a motor and gearbox from IP Engineering, spoked wheels and 45mm axles from Tenmille, and a radiator grille, a pair bright LEDs with resistors and a pair of headlight casings from Cambrian.

In addition, I bought some AA battery holders, a couple of slide switches and a four pole two-way toggle switch from Maplin.

 As my model was going to be a freelance interpretation of the prototype, I firstly decided how I would shorten the coach sides to determine the optimum length for the railmotor. I decided that my model would have a separate driver's compartment (whereas most Ford Railmotors had the driver sitting within the passenger compartment).

Both sides were shortened accordingly......

 ..... as was the base. A 30mm wide by 40mm long projection was left at the front of the base to house the engine compartment. The width was determined by the width of the GRS axle bearings into which the font wheels would be mounted.

 One of the ends had its coupling mounting removed to enable it to sit over the extended base.

 The inner doors and end planking mouldings were glued in place .......

 ...... and the ends and sided were then assembled on to the base using medium viscosity Superglue.

The droplight frames were trimmed to represent various open positions ...........

...... and glued into the door openings.

 The section removed from the coach sides was had a 5mm strip removed from its base and glued into place inside the body to act as a divider between the driving and passenger compartments. A small packing piece was needed to centre the panel and allow a snug fit.

Wheel bearings

 The bearings proved with the GRS axle bearers were soldered into the holes using my trusty 75watt soldering iron and some flux paste.

 The mounting was then bolted below the base at the front of the body.

Update - April 2014

 I found the running of the railbus to be unreliable - she would derail at regular intervals, particularly when negotiating some pointwork. Closer examination revealed that the combination of a long wheelbase with slightly uneven track resulted in one wheel rising above the depth of its flange.

To remedy this, the front wheel brackets on the motor and trailer cars were given a simple form of suspension to enable the wheels to pivot from side to side (see How I added suspension to the railmotor)


The engine compartment was fashioned from three pieces of 2mm thick Plasticard - its dimensions determined by the size of the Cambrian radiator grille. The upper surface of the engine compartment was made from three layers of plasticard, which was then filed into a curve to match the curve of the radiator.

 Next, two small holes were drilled either side of the bracket on the Cambrian headlight casings. The leads for the superbright LEDs were then threaded through and bent to allow the LED to point forward. The headlight lenses were then glued in place. Holes were drilled in the sides of the engine casing to take the leads ..........

 ....... which were then soldered in place with their respective resistors. The headlight casings were then glued in place with Superglue. The wires not only conduct the electricity to the LED, they reinforce these fragile fittings.

Mud-guards were fashioned from 1mm brass sheet and bolted to the front of the body above the leading wheels.

Motor and gearbox

 Once the majority of the body was completed, attention was given to the motor mounting. The IP Engineering kit includes all that is needed.

 The worm gear was pushed on to the motor shaft in a vice....

 ... and the sides of the motor mounting were assembled.

 The brass bearings were pushed into place and the gear wheel was pushed on to the axle. This was threaded into the bearings and mountings were linked together with the spacers and bolts provided.

The motor was then screwed into place and the assembly wired-up and tested to determine the ideal position for the worm-gear on the gear wheel.

The motor and axle assembly was then mounted beneath the rear of the base using a simple U-shaped bracket made from a piece of 1.5mm brass sheet.

 UPDATE: The IP Engineering gearbox was seriously underpowered and has now been replaced - scroll down to the update below

Two 3-cell AA battery boxes slung under the body, being held in place with small brass bolts. A further 2-cell battery box was fixed inside the passenger compartment, providing 12 volts of power using 1.5 volt alkaline batteries. If I decide to replace these with 1.2v rechargeable batteries I will need a further 2-cell battery box.
UPDATE: The alkaline batteries have now been replaced with a 12v Li-ion battery (see update below)

Remote control
I decided I wanted some sort of simple remote control for the railmotor. As this vehicle is experimental, I opted for a budget approach in the form of a cheap remote control LED dimmer purchased from China through a well-known online auction website.

After a few experiments...........

 ...... the circuit board from the controller was removed from its case and mounted inside the driver's compartment with a couple of brass bolts.

UPDATE: This radio control system has now been replaced with a Deltang receiver/controller - see below


Then everything was tested and wired-up.

I had always intended that I would construct two railmotors coupled back-to-back - one powered and one acting as a trailer.

 This would enable me to run them end-to-end without having to turn them at each end of the line. I also wanted the headlight LEDs to be directional (ie only the leading headlights would light). I had hoped that simply wiring them across the motor terminals would achieve this but this was not to be - and so a four-pole two-way switch was wired in keeping the lighting circuit separate from the motor circuit.

 Electrical connection between the coaches was achieved by purchasing from Maplin a three-way plug and socket used for connecting disc drives in computers.

 The wiring to the plug was replaced with thinner gauge wire to improve flexibility around curves

In addition to the headlights, I included a interior lighting in each vehicle.

 This was catered-for by fixing two copper bus-bars longitudinally across the top of each coach. Four yellow LEDs were soldered across the bars and wired through a resistor and a slide switch to the batteries.

UPDATE: The yellow LEDs  have been replaced with warm white LEDs and the railmotors rewired to make use of the Deltang receiver/controller's outputs (see below).

You'll notice from the photo above that seating was added for passengers and the driver. Although passenger seating was transverse in the original railmotors I decided to fix them longitudinally as there was insufficient width. A simple dashboard was also made for the driver's compartment ........

... and two willing 'volunteers 'were press-ganged into becoming drivers. The chap on the left was formerly part of a funeral party while the chap on the right had his arms repositioned into something more appropriate for driving the railmotor. These, together with various passengers, will be fixed in place with clear Bostik - enabling them to be removed if required.

 To represent toplights in the windows, glazing bars were made from the hanger mouldings provided with the kits.

The roof was shortened to match the length of the coach and roofing bars glued in place to help hold the roof in place. These were slotted to facilitate the lighting bus bars.

After filling and rubbing down the dints and screw holes,

......  the wheels were removed and the windows and underframes were covered in masking tape.

The vehicles were then given two light coats of Halfords grey primer from rattle cans and left for a couple of days for the paint to harden before having minor blemishes filled and then being rubbed-down with fine wet-and-dry.

Two coats of Rover Damask Red from Halfords rattle cans were left for a couple of days before the masking was removed and slight imperfections were touched-up and the underframes hand-painted with black acrylics.

 Glazing was then added to the windows using heavyweight clear plastic sheeting.

Test running
There then followed a period of test-running around the railway.

Despite the weight of the batteries, I found it necessary to add more weight to the power-car. A few strips of lead were wedged into crevices and a whitemetal passenger was added until she was able to take the line's 1:40 inclines without wheel-slip.

Now it has been completed I've realised it is somewhat under-powered. Whilst the power car runs OK on its own, when the trailer is added it struggles up the inclines unless the batteries are new. I'm now considering adding another motor mechanism to the trailing car and also using rechargeables (possibly Li-ion) to give it a bit more oomph! (see Update below).

Whilst the LED dimmer does not provide finely tuned acceleration and deceleration, it does enable me to slow and stop at the stations. Reversing cannot be done remotely, but it doesn't take a moment to flick the switch mounted beneath the power-car.

The internal lighting is somewhat dim. I may replace the standard LEDs with superbright versions, but for now, the railmotor provides a useful service during the winter months - in both the imaginary and real life of the railway.

I've learned a great deal from making this model - my first venture into battery power. Hopefully, my next project will benefit from this experience.

UPDATE (20/8/2013)

 The gearbox

After only a minimum of test-running it soon became apparent that the IP Engineering gearbox was not only seriously under-powered, the plastic gears were wearing alarmingly. The railmotor was therefore put back on the shelf until a more reliable mechanism could be sourced. After searching the internet and approaching some bespoke model railway gearbox manufacturers and being somewhat perturbed by the prices, I raised the issue on the G Scale Central forum. I was advised to invest in an MFA Como 12-24v 1:30 gearbox motor and a set of bevel gears. This set-up cost less than £15 which is far more appropriate for my modelling budget.

The gearbox motor assembly is quite compact and I found I could install it in the same position as the original motor, with a very slight adjustment to the position of the rear axle.

 A new mounting for the axle was folded-up from brass shim to accommodate the bevel gear.

As the motor is provided with its own mounting bracket. it was a relatively easy process to bolt it into place, with a few spacer washers to ensure the two bevel gears meshed. It was a lot easier to mesh the larger bevel gears than it was to mesh a worm with a worm wheel (see How I built an IP Engineering diesel (Update)).

The motor and gear assembly is quite discrete, though in time I will probably paint it black.

The railmotor was tested - finding that the new motor and gearbox arrangement provided plenty of power to move both the power car and the trailer car up the 1:40 gradients on my railway. The gears are considerably noisier than the original mechanism but this is something I can live with.


 The eight alkaline batteries which originally powered the railmotor were only a temporary measure for testing purposes and it was my intention to replace them with NiMh. However, I found a cheap Chinese source for 12v Li-ion batteries through the well-known online auction website which take up considerably less room (and provide 6.8 amp hours).

One of these was stripped from its blue cardboard case and the switch and leads discarded.

 A battery box was made from black plasticard and fixed beneath the motor car.

The battery was then fitted into the battery box and wired-up through a two-way switch - one way leading to a charge socket and the other way leading to the Deltang radio receiver/controller (see below).

 Radio control system

However, even despite the slight modification of adding a diode to the radio control board, its reliability was a bit hit and miss. For the past month I had been trialling the Deltang radio control system (see Deltang evaluation) and this seemed like an ideal opportunity to evaluate a different receiver/controller - the Rx61-22, which has eight controlled outputs in addition to the motor control.

Wires were soldered on to the relevant output pads on the receiver.....

As can be seen, the combined receiver/controller boards are very small, and so care (and a good pair of glasses) is needed to attach the wires. I used the two auto direction outputs (the red wires) for the front and read headlights and one of the switched outputs for the interior lights (grey wire).

Because the outputs can only power up to two LEDs I needed to construct a simple transistor switch to handle the added load for the eight LEDs used to illuminate the two railcars (See How I constructed a simple transistor switch).

In addition, I constructed a further two transistor switches for the front and rear headlights and then, after attaching the wiring to the receiver/controller, enclosed the receiver and the switches in some clear heatshink sleeving (so the receiver's LED can be seen).


After testing the newly refurbished railmotors, I decided the feeble orange LEDs needed to be replaced. I invested in a pack of warm white LEDs which give a diffused light. There were soldered into place and the original resistor replaced with a 150R resistor.

Having run the railmotor in the gathering dusk, I'm now wondering whether these lights are a bit too bright. I might remove two from the passenger compartments leaving them with just one to relieve the gloom.

UPDATE - 6 Nov 2015
 I've now added my own home-bashed sound system (using a modified MP3 player) - See