Maintenance-free electric cylinder with long service life

A sealed cavity is formed among a cylinder barrel, a gear box and a speed reducer, a ball screw connected with the gear box is arranged in the cylinder barrel, a flow channel communicated with the sealed cavity is formed in the ball screw, the ball screw comprises a screw rod connected with the gear box, and the screw rod is connected with the gear box. The lead screw is connected with the push rod through a lead screw nut. When the electric cylinder stretches and retracts in a reciprocating mode, a core transmission part is lubricated and cooled through oil exchange between the gear box and the lead screw, and the service life of a product is prolonged. After the electric cylinder is installed, a proper amount of oil liquid is injected at a time through the oil inlet, the oil liquid circularly flows between the gear box and the cylinder barrel along with the change of pressure under the reciprocating motion of the electric cylinder, frequent oil adding is not needed, and the purpose of long-term stable work