we are starting a project with the year 9 students to do shopping trolleys
this is the basic wheel they will be using .
I am 3D printing at the moment and then they will construct their designs, after working them on Creo. This was my first model/Design on Creo 3,
and I found it quicker and easier to use.
Jeremy, well done getting to grips with latest version, Creo just keeps getting better. 
Your castor reminded me of something Razor, the aluminium scooter company, recently launched. They call it the Crazy Cart. The launch video was a spoof of the Ken Block rally car ace which went viral. The car is really simple with the front wheel electrically driven and doing the steering on a vertical axis so the car always goes where the driving/steering wheel is pointing. The rear wheels are castors on a pivoting bar.
In the default position, the rear castors act like normal wheels following where the front wheel goes. The rider has a lever like a handbrake that rotates the bar allowing the castors to rotate. If the car is cornering when the lever is lifted the rear drifts wide. Crazy Cart is a simple idea but the effect is amazing and driving the cart huge fun. I'm waiting for a school to start making them, what a great project for engineering courses...
