and back down to drive wheel 120 the arrows shown on drive wheel 120 and the follower wheels indicate the rotational direction of the follower wheels with respect to the drive wheel belt 114 is wound as such to ensure that follower wheels 126 and 128 rotate in opposite directions although follower wheels 126 and 128 rotate in opposite directions belt 114 synchronizes them to rotate at the same speed sheave 110 is generally cylindrical in shape and is rigidly mounted to shaft 138 shaft 138 is a rotational axis for sheave 110 sheave 112 is generally cylindrical in shape and is rigidly mounted to shaft 136 shaft 136 is a rotational axis for sheave 112 follower wheel 128 shaft 138 and sheave 110 all rotate in unison and in an opposite direction of follower wheel 126 shaft 136 and sheave 112 which also rotate in unison because follower wheel 126 and 128 are synchronized to rotate at the same speed in opposite directions it follows that sheaves 110 and 112 are also synchronized and rotate at the same speed in opposite directions in the preferred embodiment sheave 110 and follower wheel 128 rotate at the same rpm as sheave 112 and follower wheel 126 as shown in fig2 4 and 6 sheave 110 in a preferred embodiment of the present invention is made up of four integrally formed coaxial grooves 202 204 206 and 208 in alternate embodiments the total number of grooves on each sheave varies depending on the depth of the.