Vane Pump

The A5S 360R uses a vane pump to provide the transmission main line oil supply for operation and cooling requirements. See Fig 1 . The pump rotor is mechanically driven by the torque converter oil pump drive tangs at 1:1 engine speed rotation providing pump operation. The rotor with 13 vanes is located in a recess on the rear surface of the bell housing covered by the pump cover plate. The rotor and vanes are placed inside a slide mechanism. As the rotor spins, the vanes "sweep" the oil from the pump intake to the output along the mating surface of the vane ends and the interior surface of the slide. The slide is mounted on a pivot pin. As it pivots, it changes the eccentricity of the rotor to slide mating surface changing the pump output volume. The slide's position is influenced by a calibrated spring and hydraulic input pressure from the main pressure regulator solenoid in the valve body. The benefit of changing the slide position is to optimize pump output volume to meet the needs of the operating conditions. See Fig 2 .

• Max volume during engine startup. This condition provides a fast priming action of the pump for immediate lubrication and hydraulic pressure for operation.
• Regulated output volume for varied driving conditions. Maximum volume is not required at all times.

Fig 1: Identifying Vane Pump Components

Courtesy of BMW OF NORTH AMERICA, INC.