A vane motor consists of a housing with an eccentric bore, in which runs a rotor with vanes in it that slide in and out.

The force differential created by the unbalanced force of the pressurised fluid on the vanes causes the rotor to spin in one direction. A critical element in vane motor design is how the vane tips are machined at the contact point between vane tip and motor housing. Several types of “lip” designs are used, and the main objective is to provide a tight seal between the inside of the motor housing and the vane, and at the same time to minimize wear and metal-to-metal contact.