As the song goes “Don’t fear The Reaper”...

This is a De Facto 2.5 inch gauge loco, so why am I a Gauge ‘3’ lover -looking at building this loco? I have a small(ish) son and a wife. My son would love to be pulled around the garden by a loco and my wife would benefit from it too. Not being pulled around but using it as a mobile “trug” and garden slave... So I had to sit down with my books and try and find something that all the parties involved would like. I was the builder, so I got to choose -naturally it had to be narrow gauge and articulated. However all the con rods etc ruled out a steam or steam outline loco near plants. It had to be a “diesel” then... It had to be big and blocky and really easy to build and be cheap enough the be able to replace things that got “oops-ed”. If any of you remember the “JACK” 6 wheel locomotive once sold by IP Engineering you will get some idea of what it looks like -except in its original form it was a B+B. My version of it is a B0-B0 -using chains. Yes once again the NZ Lokey strikes back!!! My son gets to choose the sound system used by the locomotive and my wife gets to choose the colour scheme and make the cushions for the trailer... (“Be Afraid -Be Very Afraid”)

See Picture 1.

The motor that I intend to use is a 3 pole 12 Volt 150 Watt that develops 0.49 Newtons Metres of torque when consuming 50 Amps of juice. Something tells me this baby is going to need rubber gloves and some pretty potent circuit breakers during “testing”!!! The MOD 1 reduction gears are all steel and the 6mm pitch chain is of the type used for motor cycles -so it should take some hammer. The motor assembly will be mounted above the bogie and the final drive to the bogie taken through the floor of the loco the twist of the bogie being absorbed by the chain. This keeps the gears away from the nasty grit and stuff and makes the bogie lighter and easier to remove and if needed -“fiddle with”. The step down is only 16:1 which is a little higher than I would like -but I cannot see how I can get it any lower without drastically altering the dimensions of the model. This is by the way an EIGHTH scale model. It may be the smallest gauge model at 18 inches but it by far the largest one at 70cm long by 20cm wide. OK I will admit that it doesn’t “quite” scale out to 63.5mm gauge but I can accept it!

See Picture 2.

This is the highly “niced” drawing in which all the “ugh!” dimensions have been converted into suitable sizes that are easy to produce and find/replace. The bodywork will probably be made from 6mm mahogany ply -not for looks but for the simple fact I do have rather a lot of it lying around. The corners will probably be re-enforced with 10mm sq Pine -for pretty much the same reason. The louvre -air intake grills will be made from left over scraps of plastic mesh from building my “Krokodil” -which itself was itself mostly made from left overs (?)

See Picture 3.

That picture shows the drawing for the steel chassis -mostly made from 10mm square box section tubing and 3mm stock plate. After some “heart searching” I decided to install a traction bar as used by a Meyer between the two bogie pivots. This is coupled with the use of a TGOJ style “Troll Bar” which takes the traction directly from the pivot point -thus none of it goes through the chassis per se! The bogie will sit under a large ball race of the “turntable” type and there will be ball races at the pivot points -a little over kill maybe...

The main problem I have at the moment is the fact that I have no idea what a “trailer” should look like. I have asked someone who is more au fait with 2.5 inch traction than I am to look around and send me some details of some designs. The major self developed idea that I have at the moment is to build a trailer that spans two tracks of Gauge ‘3’ rail. This is based on the transporter for an R-7 launch rocket(!) This will involve fitting bearings in the wheels and a double straddle bogie. The straddle arms will be “Y” shaped and fitted “back to back” so that there is one pair of bogies on one track and a single bogie on the other, with a total of three bogies on each track.  It sounds complex -but I got the idea from a tram sleeper that is also “Y” shaped and made from pressed steel.

The design is not even at the “shopping list” stage and already there is trouble!!! The motor that I had decided to use is no longer available... So, what I am going to have to do is to look around and rejig my drive array. The obvious first stop for a motor is MFA and I have high hopes for the “Torpedo RE-850 “ motor that they sell. According to the spec sheet it is actually more powerful than the motor that I original went for -but its torque is in the wrong place... This added to the fact that the shaft from the motor is 6.35mm i.e a quarter of an inch. To be honest with you I don’t think that I HAVE an imperial drill set -even the ones left over from my late father were mostly metric -although there are some “interesting” Whitworth sizes. I have “handed down” an ex-MCR 4 inch BSW spanner for doing up locomotive nuts -what I will use it for I have no idea but I refuse to be parted with it!!!

I had originally decided to “go” with 10mm 1.6mm wall square steel tube. Only to find that this is an item that you pay through the teeth (and then some) for.... So I have decided to use 10mm by 20mm 1.5mm thick rectangular section steel tube -which is 20% of the cost of the other(???) The result is that the chassis is now twice as deep as it was and the “nice” re-enforcing truss under the centre section of the loco now looks slightly cramped. But due to the deeper section of the chassis rails it will be quite a bit stronger than it would have been -and thus (hopefully) more suited to heavy garden use.

The next problem on the horizon is the joining of all the cut metal lengths to build the chassis. I will be the first to admit that I am a terrible welder.... The options available to me are; to use 45A AC and 1.5mm rods, 90A Argon MIG it -or to use bronze welding. The latter is by far my most “attractive” method of joining steel. I use the SIF process and I have to admit it does produce a rather smooth joint -despite my best attempts to ruin it!!! I use a twin carbon arc torch fed from an AC welding plant rather than Oxy-Gas.

After an evening of going steadily mad -I am am nearly at my wits end... I know that I am not very good with gearbox design but there are times when I would cheerfully attack my draughting pad with an axe!!!! The motor that I had originally started out with, was beautiful, it had some quirks in the cable dept -but on the whole it was lovely. The RE-850 is also lovely -but it is obviously not the “correct” motor for this loco... It has a 6.35mm shaft -or if you prefer a 1/4 inch one. This is proving to be a complete pigs ear of a work around. The only thing I can think of doing it is this way, (deep breath...)

The first gear is a 15 tooth MOD 1 bored out from 6mm to 6.35mm

The second gear it drives is a 60 tooth MOD 1 which has a bore of 12mm.

This then drives a 15 tooth MOD 1 gear. The width of the boss of the gear is 12mm -this then fits inside the bore of the 60 tooth MOD 1 gear -forming a spur gear The two are united via a crown weld on the inner bore of the 60 tooth gear. The net result is that we have a 60 tooth gear with a bore of 6mm.

This then drives a second 60 tooth MOD 1 gear with a bore of 12mm.

On the same shaft is a 16 tooth 6mm pitch sprocket bored out to take a 12mm shaft.

There is then a chain drive to the  axle and it has a 27 tooth sprocket.

There is then a connecting 27 tooth sprocket to the other axle.

The sides of the gearbox are made from 6mm thick polycarbonate and all the shaft run on ball races.

It is evil!!! It is hideous!!! The only saving grace that it has -is that it will work...