Tuesday, 22 June 2010

R6.E1. Front foot self leveling system

Posted by PicasaI have been asked by a few people to discuss my front foot leveling system in a bit more detail, so here it is.
The idea is very simple. The front foot is unlocked and allowed to pivot, this keeps both front casters on the ground and stops wobble and also makes the turning very fast. When an obstical is encountered, without the springs the foot will tip up and everything stops. Normally you would over come this by locking thr front foot with blocks or whatever system you chose. The problem I found with that is first the casters not running true because they are not level all the time and also the stress transmitted up through the ankle when bumps are hit.
This is where the springs come in. The first system picture with the coil spring sort of speaks for itself but looks very messy. A spring is fitted front and back on the front foot and this keeps the foot level. When a bump is encountered the spring compresses absorbing the shock but both wheels stay on the ground. When uneven ground is crossed or the rear feet are higher or lower than the front the springs will compress or expand to keep the front foot level.
To make the system look better I eventually dropped the coil spring and instead went for a leaf spring made out of some type of very springy metal that rebound very nicely.The power of the spring does not need to be that much at all because generally the front foot runs level. If a very large obstical is encountered the front wheels will not cross it anyway so the spring does not even come into play.
The pictures show the leaf spring before it was fitted with the pins to lock it in psootion and it aslo has not been painted. I found a nice flexible white paint so when it is finally fitted you hardly notice it in place.
When I first moved over to the leaf spring I initally fixed the spring in with heavy duty double sided tape and amazingly it held in placed and worked. Short term this might be OK but heavier fixings, bolting on, would be needed. The tops of the bolts do show but no-one really notices once all painted up.
This self leveling system combined with the 72mm skate wheels fitted on casters is a brilliant combination and runs well on a variety of surfaces and best of all virtually silent.

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