The Bison is certainly an interesting vacuum. It is obviously a copy of a Kirby, as its design is heavily influenced by them. I love the look of it. the headlight lens makes it look like an evil monster or assasin, especially when it is lit.
From what I know, the company was started in Ocala, Florida by a Baptist preacher named Dick Shaefer, who had a job selling Kirby's through college. He later decided that he could improve upon the Kirby, and he started his own company (he got the name Bison because he saw a herd of them while on vacation in South Dakota).
When they worked, they were very effective at carpet cleaning. However, they had tons of problems, many of which were still not worked out by the time they went out of business. VCCC club member Clay Floyd ran a Bison service center in Colorado in the 1970's, and has told lots of stories regarding the company.
At one point, Shaefer had a very successful company, until Kirby saw what was happening and sued him for copying their design. The lawsuit carried on for almost ten years. When all was said and done, The settlement he ended up having to pay Kirby was so large, it cost him his company, and he went out of business in 1982. The owners manual gives you an idea of just how blatantly eveident it is that it is a copy. For example, the height adjuster is called the "rug jack", the spray gun is called the "mist-o-matic", and the sani emptor is called the "emptomatic."
Shaefer did have some great ideas, and did make several improvements to the Kirby on his machine. He did away with the belt lifter, and made the nozzle release lever activated. He added a variable speed control, and utilized a powerful GE built motor (which was also incredibly loud!).
From what Clay has told me, Shaefer was charged with murdering a girl, and is currently doing time in jail.
By the way, the Bison that I am shown with in the "oh no, not another people picture thread" is one that I bought off of eBay about a year and a half ago. The one I am shown assembling in the "NE wash in attendees" thread is one that I bought from a retired vac shop owner in Chicago, brand new, out of the box.
Evan