7mm BR Derby Type 2 x2

[daifly]

If I interpret this correctly, you will need to ensure that the two idler gears mesh with the motor drive gears on opposite sides of the motor shaft (looking from above or below) otherwise you will end up with the scenario that Jeff highlighted in post #12 where the axles would contra-rotate! I.e. the left-hand side of the plan view must be both mirrored to the right AND flipped top to bottom.

 

[ZiderHead]

A thought: you could raise the motor and bevel gearsets so they arent visible under the bogie frames - they dont have to be in line with the axles. You could then hide a higher ratio bevel set too if required.

 

[SteveO]

If I interpret this correctly, you will need to ensure that the two idler gears mesh with the motor drive gears on opposite sides of the motor shaft (looking from above or below) otherwise you will end up with the scenario that Jeff highlighted in post #12 where the axles would contra-rotate! I.e. the left-hand side of the plan view must be both mirrored to the right AND flipped top to bottom.

Absolutely. I showed it that way so you can see the double gears on that spindle from both views.

A thought: you could raise the motor and bevel gearsets so they arent visible under the bogie frames - they dont have to be in line with the axles. You could then hide a higher ratio bevel set too if required.

I have a cunning plan which requires that the axles are in line with the motor shaft. I don't think there's any other way around it unfortunately.

 

[ZiderHead]

OK, this is pretty left field ... but bear with me

If you're not going to go down the route of Pugsley-style individual axle-hung traction motors, what you are actually replicating is a diesel hydraulic type layout, where one or two powerful motors transfer their power to the axles by gearboxes.

So, instead of trying to hide motors within the bogies, why not do it the same way as eg. a warship or hymek?


A single large motor mounted low centrally in the chassis frame, projecting below the chassis if you can hide it within the fuel tanks and underframe gubbins. As there is so much space available you can use as large a motor as you like, and there is space for a big flywheel and the main reduction gearbox. Larger motor means lower rpm, more efficiency and less gear noise. Plus you get a nice low CofG.

A cardan shaft running just above or level with the frame to a small intermediate spur gearbox fitted to each bogie. This just transfers power down to inside the bogie frames, although you could build in reduction here.

A cardan shaft from the intermediate gearbox to a bevel gearbox on each axle, which are available off the shelf for RC cars in a range of quality and durability.


This arrangement should be quiet, efficient and visually unobtrusive, adaptable for different chassis/bogie sizes by just using different length cardan shafts, suitable for any type of springing/compensation, and you could get away with only having to build the intermediate gearboxes - everything else is available off the shelf.

Jon

 

[SteveO]

Thanks Jon, I don't think it's left-field at all, it's actually quite sensible and I had already thought about it. It's only the desire for me to keep everything self-contained, neat and tidy that has kept me on this track. I thought I'd be opening up too many areas for the possibility of fault at all the major junctions, so kept on with this idea. I'm still hoping that Steph can pull something out of the bag so I don't have to think more seriously about this.