SUPERVISOR WAS TRYING TO PULL BELT OVER WHILE PULLING ON IT WITH A ROPE & SHEAVE. HE GOT HIS FINGERS IN THE SHEAVE WHEEL. CAUSE OF THIS INJURY WAS AWARENESS & AN UNSAFE ACT. COMPLIANCE WITH RU LES/REGS WAS A FACTOR; PERSONAL SAFETY EQUIPMENT WAS A FACTOR; MINER PROFICIENCY & ATTITUDE WAS A FACTOR; MINING SYSTEMS IS A FACTOR.