Abstract: A tandem-belt variable-speed transmission has a pair of shafts each provided with a pair of outer disks flanking an intermediate disk forming therewith a pair of nips each receiving a respective belt. One of each of the outer disks is fixed on the shaft and the other outer disk is axially displaceable on the shaft. The intermediate disk of each pulley is rotationally coupled to one of the respective outer disks and is axially displaceable relative to both disks. An adjustment member is rotationally fixed but axially shiftable on one of the shafts and is connected via a link to the movable disk of the other shaft for varying the pitch of the pulleys. A pressure element and a formation on the movable member of the one shaft and on the adjustment member rotationally couple this movable member to the one shaft.

Abstract: A variable-speed transmission has a pair of parallel shafts each carrying a two-part pulley of which one half only is axially displaceable along the shaft while the other is axially fixed thereto; both parts are rotatable relative to the shaft. A belt or chain spans the two pulleys and interconnects the two shafts rotationally together. A pressure ring is rotatable and axially shiftable on each side of the shaft to one axial side of the pulley and operatively engages the displaceable half of the respective pulley. A pair of operatively interconnected rigid levers lying to one axial side of the belt are each pivoted on a respective pressure ring and on the housing and the two levers are directly connected together so that they can operate to displace one of the pulley halves in one axial direction while displacing the other in the opposite direction and vice versa.