They can be used in hiavily dust - pol - luted awful environments , the occasions with no attached lubrication and sealing to the mechanism , medium & low rotating speed . it has large rotating torque and low use cost 使用在有重度粉尘污染的恶习劣环境.机构不需附带润滑及密封,中低转速的场合.转动扭矩大,使用成本较低