The screw jack has tremendous force, but the internal components installed are very precise. Even a small red limit line on the lifting sleeve of the jack is not a dummy, and it is of great help to the lifting work of the jack. Observing the lifting sleeve of the jack, we can also find a circular small hole at the top of the sleeve. What is the function of this small hole?

A screw jack is a lifting equipment that drives the screw pair through manual transmission, and transmits the lifting force of the screw and nut to the lifting sleeve. Each lifting process of the jack is a friction process between the lifting sleeve and the body. Excessive friction can easily wear down the lifting sleeve and reduce its lifting force. We can improve the wear resistance and service life between the lifting sleeve and the body by adding lubricating oil to the small circular hole at the top of the lifting sleeve.

Although screw jacks are different from hydraulic jacks in that they do not require the use of hydraulic oil, friction and wear behavior between various components still exist during operation. Therefore, lubrication of each component is required through oil injection holes.