The Dynamic Behavior in line contacts between the vane tip and camring in an oil hydraulic vane pump with intravanes has been investigated. Variations of the radial acting force of a vane were calculated from previously measured results of dynamic infernal pressure in four chambers surrounding a vane, and variations of the behavior were estimated in both the rotational speed range from 1200 to 2700 rpm and in the delivery pressure range from 10 to 21Mpa. The results indicate the variations of the radial acting force. Under the standard operating condition (to 14 Mpa, 1800 rpm), the radial acting force on the vane is governed by internal dynamic pressures, but it is more influenced by rotating speed at higher than 2000 rpm relatively.