EE WAS OPERATING A PERSONNEL CARRIER GOING DOWN TO PIT. WHEN NEARING THE PIT, HE APPLIED BRAKES AND WHEN DOING SO HE PUT THE CARRIER INTO A SPIN AND HIS LEFT HAND WAS ON THE SIDE RAIL WITH FIN GERS ON THE UNDER SIDE. THE RING FINGER APPARENTLY CAUGHT A ROCK BETWEEN BOTTOM AND UNDER CARRIEAGE OF PERSONNEL CARRIER. EE WAS PLACED ON RESTRICTED DUTY.