Topic: adult tricycle design

[piersdad]

I had built several of these with steerable front wheels that just clip on to the front forks of an ordinary cycle.

the steering shaft threads through the front forks and these remain bolted to the frame
the steering shaft runs freely in the center  of the forks and attaches to the front assembly and a lever attached to the shaft turns the wheels.
correct ackerman angles and steering geometry is essential

briefly the ackerman angle  is where the center of the king pin and the  center of the steering arm joint  both point to the center of the rear axle
this system enables the inner wheel of a circle to steer  further than the outer wheel and so each wheel is turning in a correct circular path.
the king pins are also inclined inwards at the top and this has the effect of causing the front assembly to rise up a fraction as the wheel is turned so that when the wheel is turned  the weight of the vehicle tends to straighten the wheels to straight ahead.



to update to a new cycle body means just unbolt the assembly and replace the cycle with a new one.
i made one for a IHC boy who at 20 yrs was not able to balance a 2 wheeler and was not really interested in a tricycle as sold today.
   So when i made the front wheel steering one he was wrapped and 6 years later i saw him still cycling around with updated cycle attached to the old front assembly.

so here are some pics of tricycles i have made


leaning into the corner on 2 wheels is thrilling same as a 2 wheeler here


2 more with details of frame



and an abandoned one
 

see also my invalid reclining tricycle i made my wife

here

http://www.storydad.com/forum/index.php/topic,459.0.html