Join Date: May 2008
Location: Australia, S.E suberbs of Vic
I also in my designs figured that if I create the pivot perfectly inline with the pivot point of my univeral joint then there would be minimal shaft movement. However there still has to be some as having any sort of castor angle introduces that. This was my longest running design problem and right now I am pretty sure I have the solution. I plan on get a peice of high tensile bar (or a big arse bolt!) and machine it ot have 12 sides, drill the middle out and thats one side covered, for the other side I would machine the non drive part of a socket (from a socket set) and weld it to the inside of a pipe, this would slide over my 12 sides shaft and effectively be a spline.
So I understand what your using at the ends, but makes up your actual driveshafts?
For myself I am planning on going for a very different approach that yours in that I am going to have a hollow kingpin type design with external shafts. However your design is in my eyes is ingenious and its appealing to me in that it allows for a straight arms for the wheel supports and also protected drive shafts. I will do some designs for myself and see if I can get it to work for me.
Your very right that I might have the equivolent of torque steer with the ratcheting shaft design. I have ridden an upright tricycle that only powered one of the two outside wheels and when it would do a sharp turn in the same direction as the powered wheel it because very hard to peddle. I am accepting this compramise though as it gives me the following advantages: modified off the shelf bits, light, tough, more ground cleanence, relativley easy to put together and it allows for me ot have an under-drive. You see I plan on having the gears on one shaft with a single 13T sprocket at the other end, and this then powers the twin ratchets with an 18T sprocket that are all located on their own shaft lower down inline with the center of the wheels. This is hard to explain but I think I have it all figured out.
I think that you having a machine like that with those sort of parts weighing in at 24kg is no where near as heavy as I expected, its like as you said you used heavy parts, tubing, everything in the build. I would be really interested to see how you put that diff together as I think its an increadible effort.
I am doing every last trick in the book to make this thing light as, its hard going but I think it will work out for me. For example the shaft for my sprocket cluster has an OD of 20mm and I am drilling out the inside larger where it needs less strength and vice versa. I want to have my final weight without an electrics at 17kg or so, my current trike was 15 last time I checked. I would use only Cro-mo tube unlike the mild steel previously.
So whats the specs of your electric drive system?