An apparatus for raising and lowering a window shade having: a clutch assembly with a clutch core having a shaft; springs having pairs of load bearing members, the springs being circumferentially positioned along a length of the shaft, the pairs of load bearing members being circumferentially spaced around the shaft such that there are no two orthogonal planes along a longitudinal axis of the shaft about which a load applied to a load bearing member of each pair is symmetrically distributed; a pulley defining openings, each of the openings being configured to receive at least one pair of load bearing members; and a housing comprising a plurality of keys, each key being configured to fit between at least one pair of load bearing members received by the openings.