"Improving" the Triang M7

[DCB]

I don 't know where the M7 came from.  It started as SR Green, it had been repainted BR unlined early emblem black and the cab spectacles and coal rails had been improved.  Someone had fitted Romford wheels so no magnadhesion and had fitted and wiper pickups to the bogie , which meant the wheels often failed to go round.  It derailed its leading driving wheels frequently even on 2ft radius curves and proceeded down the track at a jaunty angle swinging its backside wide on every curve.  It could just pull 3 Triang Mk1 coaches and despite 8 wheel pick up frequently stalled.

 

I finally decided enough was enough and removed the bogie pickups.  It pulled a lot better, didn't run or pick up any worse but it was still pretty bad.

 

I had a root in my scrap box and found a brass bogie around the correct wheelbase, and two axles of split axle wagon wheels, probably mainline.

 

It was easy enough to open out the axle holes in the bogie frames to suit the wheels. The wheels had pin points on the axles but a bit of work with a hacksaw or file would have sorted them but I put them in the lathe because I'm lazy

 

All I needed was some PCB to solder the bogie sides to instead of the brass spacers. Some hopes. I just couldn't get it soldered, so plan B sandwich a piece of square section plastic  with the bogie sides.  It worked but looked horrible, the securing screws had their heads on the inside and nuts on the outside.

 

So plan C, sort of square U section plastic with te screws countersunk into the bogie sides and nuts on the inside. Result. A drawbar across the top with a coupling on the end was added and it was hopeless.   Panic ensued but tightening the securing screws  so the drawbar was fixed to the bogie improved matters and a second screw made it even better. Finally I tried pivoting the bogie just in front of the leading bogie wheels which made things a lot better. My tightest curve is 3rd rauius and tightest point 2ft Radius Peco streamline small radius and she sails round with far less tail wag than before.

 

Next problem leading wheels kept derailing. a piece of PCB inside the rear chassis extension and a plastic cross piece to give only 1mm clearance on level track helped as did binning the smokebox interior detail in favour of a lead block.  As of this evening with the pickups wired she runs with all the driving wheels off the track, so the bogie pickups must be working and has been shunting 6 X Triang Mk1s up a 1 in 36 gradient. Final bodge was to add plastic sheet to hide the gap behing the cast chassis where the firebox should be.     Next job is to put a bit of filler on the screw head to disguise it a bit more.

 

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Edited August 19, 2018 by DavidCBroad

[DCB]

The M7 was designed to run on steel track and there is a magnet between the leading wheels which holds the front down as well as a springy brass plate which guides and supports the bogie. I removed the magnet and replaced it with a lump of lead, I think it was once a car wheel balance weight.

 

I also changed the motor to 5 pole, a bit of a saga.    The Airfix 5 pole X04 replacement (MW 005 ?) should have been a direct swap. Now I don't usually like 5 pole X04s as they lack torque compared to the 3 pole  and struggle up banks and let fly down the other side,  but for shunting / Banking the 5 pole gives a "Softer" power delivery  and I wanted the 3 pole for another loco.

 

The 5 pole motor simply didn't fit.     It had an X04 worm on but the mesh was horrible.  Close examination showed the "Ears" on the motor front plate which engage the chassis were slightly different to the X04. A root in the scrap box's X04 bits section found several other front plates on which the ears varied.   I decided easiest way is swap armatures so I stood the X04 on its magnet, so the worm was uppermost and heated the worm with a blow lamp until it pulled off the shaft. I carefully removed the magnet, eased the pole pieces apart popped out the rear bearing diaphragm and pulled the armature out noting which way round the spacers went [would have been sensible but I forgot] and did the same with the 5 pole armature, before swapping 5 pole armature to 3 pole frames and easing the worm back on to give about 5 to 10 thou end float 0.005" - 0.010"

 

She is now a lot smoother and quieter.   

Edited August 19, 2018 by DavidCBroad