An employee was trying to unfasten a power utility pole secured to a ride-on digger derrick. In order to loosen the ratchet strap that secured the easement machine, he placed his right hand on the ratchet mechanism and his left hand on the metal pole rack. While he was pushing away from his body with his right hand to loosen the strap, the pole came free from the strap, shifted, and caught the employee's left hand against the pole rack. The employee's index finger was amputated from the nailbed to the tip.