三点式钻柱扩眼器
three point string reamer
可调式扩眼器
adjustable expanding reamer
可换头式钻头
twist drills with exchangeable drill tips
变压器三点差动保护
tri-poim style differential protection of transformer
并联三点式
Parallel three point form
补偿式三点悬挂连接机构
Compensation three-point hitch linkage