I've done this. Two friends and I formed a production company to provide full service stills/motion and creative services. More important than the gear were the pooling of our iPhone contacts lists. In any case, we formed an LLC. We each contributed gear, including a Red set up, a few Leaf backs, and some Cannons, as well as grip/strobes/HMIs/computers, etc. The agreements stated that upon dissolution we would keep the gear we contributed as a set off against our share value. It was also agreed that the company's business came first, so any booking of equipment for personal projects/outside business was subordinated to the company's booking. We each had to buy a bunch of crap and pitch in operating capital, including a Dodge Sprinter and a ton of Drobos, and lenses for the Red. We had a few issues with double booking but created a tracking program that made sure we did not double book any gear. When we amicably disolved (we each went, creatively, in different directions) the property was distributed as intended. It worked nicely, but we had lawyers draw everything up and we have known each other for years, so we all felt secure in the arrangements.
Bottom line: don't do it without an agreement, in writing.