At the end of a shift on the downhill coaster, an employee was waiting for an empty cart to arrive at the bottom so he could ride it back up the hill. The cart arrived with its seat belt safety lock engaged. The employee boarded the top of the cart and began working to disengage the lock by reaching under the cart. His right hand and two fingers got caught between the rear wheel of the cart and the coaster rail. His ring and little fingers were crushed and lacerated, resulting in surgery and partial amputation of the ring finger.