Crown nut

The utility model discloses a crown nut belongs to beam -pumping unit technical field. This crown nut includes: nut body and at least one plunger. The utility model discloses a set up at least one through -hole on the nut body, every through -hole in at least one through -hole all with the outside intercommunication of the interior threaded holes and nut body of nut body, thereby can pour into the screw loose agent in to at least one through -hole into by nut body outside, and correspond at least one through -hole of ground shutoff through at least one plunger, prevent that the screw loose agent from volatilizing, thereby make the screw loose agent permeate into crown nut and crank pins threaded connection position by through hole, the rust at crown nut and crank pins threaded connection position is detached through the screw loose agent, and lubricate with the crank pins threaded connection position crown nut, thereby reduce the frictional resistance between crown nut and the crank pins, reduce operating personnel's intensity of labour, shorten and dismantle the required time of crown nut, rate when avoiding the influence to recover the oil.