branches chipper chipping chipping-machine chips cover covered covering danger dangers equipment feeding helmeted helmets high-pressure improvement machine machinery maintenance men-at-work outdoor-power-equipment power-equipment protection protective-clothing protective-gear pushing risks risky safety safety-colours spray sunlight sunshine tools tree tree-branches tree-loppers tree-lopping wood-chipper wood-chipping wood-chipping-machine work ear-muffs ear-protection work-clothes workers workman workmen chain-saw grinder stumpgrinder