I also have seen one.
From the looks of it, it was a Willis jeep rear end with small wheels mounted (to slow down the spin? and height?).
The frame work was square, 4' x 4' as was the hopper.
My guess was that the hopper could carry maybe a cubic yard of sand.
Because of weight the tires had to be 6 ply and costly.
The rig actually looked to be a commercial build or a darn good amateur.
Were it not for deep snow I could attach a pix as it is still behind an old shed nearby at my friends place.
He did use it briefly but since he went onto paved roads to service snow clients he totally shredded the tires as they were not meant for highway use.
The only downsides were sand flow control plus the fact that you could not back it up to, say, a garage door.
Good however for roads or drives that had sufficient turn-a-rounds.
As I mentally picture it, I believe I could easily add control features and render it very functional for limited applications.
My friend owns a storage locker facility and occasionally he needs to sand the lanes between the buildings here due our climate.
Ideal situation as he can do all the sanding going forwards, simply weave in and out of the aisles.
He has 9 buildings thus 10 aisles to weave in and out plus a FEL CUT to load the hopper.
I would use a linear actuator to open/close the flow control and perhaps jury rig a shaker mechanism to ensure a nice flow.
Also I would extend the shaft so as to have an auger to constantly stir the sand/salt mix.
AHA, found me a fun project! (if we do it I'll take pics and post.)
