Abstract: An employee of a tree service company was operating a rented Promark stump grinder (Model No. 94007). Warning labels (in English) at the grinder's controls and rotating cutters admonished the operator not to get near the cutters. Rental company employees indicated that they tell all grinder renters not to leave the controls because there is no clutch. However, the employer had not trained the employee in the proper operation of the grinder. The grinder was designed so that the weight of the 6.8- to 13.5-kilogram cutting head will cause the motor to stall if the operator releases the handle. The employee left the controls to walk to the cutting end to pick up a shovel, leaving the rotating cutters exposed and 600 to 900 millimeters off the ground. Unfortunately, the grinder did not stall as it was designed to do. The employee turned toward the grinder, and his left hand and forearm contacted the rotating blades, which cut tendons, skin, bones, and tissue. He was hospitalized for his injuries. The employee probably lost the use of two or three fingers on his left hand and was left with a deformed left arm.