By providing in a carcass saw an easily accessible switch and associated blade-reversing means, serious jamming of the saw-blade and related jumping of the blade out of its guides in the saw are avoided and a return to normal saw operation in minimal time and with minimal damage is assured....http://www.google.com/patents/US4502184?utm_source=gb-gplus-sharePatent US4502184 - Reversible carcass saw
