How added suspension to my railmotor

A couple of years ago, I constructed a two-car railmotor based on a couple of Andel resin freelance coaches (see How I constructed a railmotor). Since her construction, she has been through quite a few reincarnations as I have sorted-out a series of problems. Whilst this has at times been frustrating, the solutions have also provided me with opportunities to develop knowledge and experience in a range of different fields.

Problem: Erratic radio control

Initially, she was controlled with a keyfob controller using a circuit from a gadget for dimming LEDs.

Solution: After trying various modifications, I eventually discarded this control system and installed a Deltang receiver/controller (see An evaluation of the Deltang r/c system)


Problem: Lack of power
 Initially, the railmotor was powered by an IP Engineering motor and gearbox assembly. The 16:1 gearing on this mechanism meant that there was insufficient power from the motor running on 12 volts to take the power car and trailer up the 1:40 gradients on the railway.
Solution: The original motor/gearbox was discarded an MFA gearbox motor was mounted beneath the chassis powering the wheels through bevel gears. (see  Progress Report 48)

Problem: Regular derailment
Whilst sometimes she would run round the track without problems, on other occasions she would regularly become derailed as she negotiated some pointwork.
Solution 1: My first diagnosis was that she needed more weight over the front wheels - to keep her nose down. Some strips of lead flashing were trimmed to fit into the cavity beneath the bonnet and, with fingers crossed, I gave her a trial.

Some sets of points she negotiated without problem, but others she refused to take without derailment. Close scrutiny of her progress showed that one wheel was riding up over the check rail, thereby causing the other to foul the frog.

 Solution 2: My next attempt was to widen and deepen the flanges of the Tenmille wheels with plasticard as I had done successfully with other finer-flanged wheels (see How I improved the compatability of IP Engineering wheels with LGB pointwork)

Tenmille wheels

Plasticard 'washers' roughly shaped

Superglued to the back of the wheels before being filed to shape

Testing.

 Whilst this has been successful with other rolling stock, this was not so with the railbus. I then tried some LGB spoked metal wheels which have wider treads and deeper flanges and of course are designed to be compatible with LGB pointwork. No success. Clearly the problem was more deep-rooted.

I studied her closely again as she went through the points and realised that, as her wheelbase is quite long (in comparison to most of my other locos), she was unable to flex her chassis if the rail dropped slightly. This meant that in certain places, not all four wheels were in contact with the rail. Whilst this was less of a problem on straight track, it was disastrous on the curves of points which were not perfectly level.

Solution 3: What was needed was some simple form of compensated suspension - to allow the leading wheels to follow the contours of my uneven trackwork. After considering (and rejecting) a range of complex hinged systems, I eventually opted for the simplest - a U-bracket which was loosely mounted so it could rock from side to side.

 A bracket was made from 64thou brass strip, with two fixing-holes along the centre-line.

Between these holes a short length of 2mm diameter brass rod was soldered.

The bracket was then bent into shape and fixed in place with self-tapping screws as, unlike nuts and bolts, these could be screwed-in without me having to dismantle the bonnet assembly (a fiddly process).

Another test-run showed that this solution was successful. The wheels now remained in contact with even my most irregular trackwork.

A few more test-runs showed I needed to adjust the back-to-back distances on the wheels on the powered axle, but the railmotor will now trundle around the railway at a sedate pace with only the occasional mishap - usually explained by overhanging vegetation or twigs which have fallen on to the track.

I spruced her up by giving the radiators and headlamp surrounds a couple of coats of brass paint and painted the underframes and steps with matt black.

And then, of course, she needed extensive test-running ......

And then, although she will never need to traverse R1 pointwork (the only R1 points I now have on my railway are in the copper mine sidings), I decided to see how she would fare through the most challenging trackwork on my railway.

No trickery involved (apart from editing out the manual changing of the points) - I even tried her flat-out through the points without mishap. However, she struggled to get through two R1 points connected in tandem to form a cross-over. But this was because the buffers between the two cars locked rather than any problem with the suspension system.

So, I feel very pleased with my applied problem-solving in this instance. This is one of the reasons I find railway modelling so rewarding - each day presents a new challenge which requires ingenuity and sometimes dogged persistence to overcome.

How I constructed a cattle wagon from an IP Engineering Kit

Having previously scratchbuilt two cattle wagons based loosely on Welshpool and Llanfair originals (see How I made two cattle wagons from plasticard), I decided to make my next pair from IP Engineering wooden kits.

The kits included everything needed, including laser-cut wooden parts, whitemetal fittings, steel wheels a pre-curved steel roof and various oddments.

The underframe
Following the instructions, two lines were drawn 30cm either side of the centre line on the base to later position the solebars for 45mm gauge.

In addition, I marked the position of the axles, 50cm either side of the centre line. I have found from experience that this is useful to help ensure the axles are square and parallel.

Rather than fitting the solebars first as per the instructions, I firstly glued the buffer beams in place.

I then glued the solebars between them.

 The body
Back to the instructions, holes were drilled in the corner posts and door posts to take the bars across the van openings. Lines were drawn 62cm from the base to guide the fitting of the side panels.

The side panels were then glued in place .......

 ..... as were the lower planks.........

 ....... on all four side units.

The vertical frames were then glued to the end panels.

The side units were then joined to the doors. Rather than fitting the doors flush with the inside edges of the door frames as per the instructions, I decided to glue the doors flush with the outside edges. I felt this would be more realistic, particularly when fitting the hinges.

The top rails were then glued to the top of the door frames and between the end posts.

At this point I glued the framing for across the centres of the side panels. To help with alignment, I drew marks either side of the frame.

The sides and ends were then glued to the base.

 The roof
I decided to fit roof support panels to the ends of the wagon. The roof was used as a template to mark out the profile for the roof panels on 2mm plywood.

The panels were then marked out and trimmed to fit between the corner posts.

They were then glued in place, using the roof for correct alignment.

Rather than gluing the roof in place, I decided to make it removable. The roof was used as a template to mark out framing for inside the ends of the roof.

These were then cut out with a craft knife and glued with expoxy to the underside of the roof.

The framing for the sides of the roof were made from offcuts from the kit fret.

Detailing
The hinges were then superglued to the doors and wagon base.

 The brass bearings were pressing into the axle guards in the vice.......

 

 ....... before the axle guards were epoxied to the solebars, using the lines drawn earlier as guides.

The bars for the windows were then cut and fixed in place in the holes drilled previously with superglue.

Then the buffers were screwed to the buffer beams.

 

Rather than finishing the kit at this point, I decided to add cosmetic brake gear. A brake lever was fashioned from a lolly stick, 105mm long, tapering from 4mm to 2mm and rounded at each end with sand paper.

 

A 10mm x 10mm triangular bracket was cut from a lolly stick together with a mounting plate.

 

 The mounting plate was glued to the back of the solebar ......

 ..... and the bracket was glued to it.

Two pieces of offcuts from the kit's fret were cut to a length of 25mm and two small pieces of lolly stick were cut to act as spacers. Holes were drilled at 3mm intervals in one of the brackets.

 The hanger was glued together - one end being rounded with emery paper.


The hanger was glued to the solebar, and the lever was inserted into it and glued to the bracket.

The wagon was then ready for painting.

Two coats of Halfords grey primer were applied and then rubbed down with fine emery before a final coat was added. The underframe and hinges were then picked out with black acrylics. The roof was primed with grey primer and then given a coat of acrylics - an equal mix of black and silver.

I have found that the steel roof makes the wagons somewhat heavy, which may not prove to be a problem for live steam locos, but my 0-4-0 electric locos struggle with them in a train. I intend to replace the roofs with plasticard at the earliest opportunity (See Progress Report 41)

UPDATE (15/8/12) - The wheels originally supplied with the kit proved to be incompatible with LGB R1 points. I solved the problem by fixing plasticard washers behind each wheel (see How I made IP Engineering wheels compatible with LGB pointwork).