16 and another of the inner flange portions 102 a is in contact with the inner seal surface 98 a of the shaft 16 and one of the inner seal surfaces 98 b 1 of the boss 52 a also one of the outer flange portions 102 b is in contact with the inner seal surface 98 d of the outer race 94 and the inner seal surface 98 b 2 of the boss 52 a and the other outer flange portion 102 b is in contact with the inner seal surfaces 98 b 1 98 b 2 of the boss 52 a in operation the spring 62 biases the sector gear 58 and therefore the shaft 16 and valve plate 20 towards a closed position such that the central port 14 is substantially closed or blocked completely depending upon how the assembly 10 is configured when a current is applied to the motor 38 the pinion gear 42 is rotated which causes the rotation of the intermediate gear 44 the middle gear 54 and the sector gear 58 to rotate the sector gear 58 the force applied to the sector gear 58 by the return spring 62 is overcome the amount of rotation of the sector gear 58 is.