during last months I have been working on a new project: the BR 84-009
This new steam locomotive (8 studs wide) has a new original pistons movement and as my previous BR 94-1292 has a single long frame of 10 wheels.
This locomotive under the hood has a 9 volt battery to light up the two front lights and red rear lights; the switch is in the back masked by coal.
The real challenge with this new BR was to create a propulsion system powered by my usual cabose locomotive that would allow a synchronized speed between both of them (BR and caboose).
I have to thank once again Teddy for giving me the idea of regearing the transmission between the PF medium motor with large wheels and the RC standard train motor equipped with small train wheels.
Before continuing I’d like to share a little bit of theory:
You can find the rpm of each lego motor here: lego 9v compared characteristics than you have to know the perimeter of the wheels (ex: 9v train motor rpm x diameter x PI 3,14) so you can find the distance covered by your train in one minute.
Theoretically a standard train motor 9v (only the motor with four classic wheels and no other weight) cover 110 meter in one minute: 2000(rpm)x 1,76(cm. wheel diameter)x3,14(PI)=110,52m.
Now if you want to cover the same distance with a PF medium motor with the new lego large train wheels you have to regearing, because this combinantion cover 38 meter in one minute: 405(rpm of medium pf motor)x 3,00 (cm. large wheel diameter)x3,14(PI)=38,15m.
You can use, for example, a 24 tooth gear as pinion and a 8 tooth gear as crown wheel: 405(rpm of medium pf motor)x 3,00 (cm. large wheel diameter)x3,14(PI)x24(tooth gear)/8(tooth gear)=114,45m.
My original idea to avoid any difference in speed (after regearing) between the two locomotives is a clutch system.
To respect the original aspect ratio hiding battery, motor and clutch gear I’ve used a useful SNOT technique.
Thanks in advance to Toastie if he would publish my instructions on railbricks.
Enjoy the show!
Merry Christmas to all
Edited by LEGO Train 12 Volts, 29 December 2011 - 07:58 PM.