VARIABLE-SPEED TRANSMISSION SYSTEMS

摘要

1508975 Change-speed gear WILSON MILLER & CO Ltd 27 March 1975 [30 March 1974] 14223/74 Heading F2D Clutches C1, C2 connect suns S1, S2 of a planetary gear set with the output member 12 of a hydrodynamic torque transmitter T, which may be a converter with a reaction element 13 mounted on a unidirectional sprag clutch 17, as shown, or a two-element coupling, a third clutch C3 connects a planetary carrier L1 through a central shaft 28 with the input member 11 of the transmitter, as shown, or with the output member 12, a ring gear A1 is connected with the final output member 24, and carrier has pinions P1 in mesh with the ring gear and with the sun S2 and also with further pinions P2 which mesh with the sun S1. The sun S2 and the carrier have brakes B2, B1 which in common with the three clutches may be operated by oil pressure, and a unidirectional sprag clutch (not shown) may be connected between the carrier and the fixed housing of the transmission to facilitate smooth transition from first to second ratio. First ratio is established by engagement of the clutch C1 so that drive is transmitted from the member 12 to the sun S1 and thence through the pinions P2, P1 to the ring gear A1, reaction on the carrier being taken by the sprag clutch. If engine braking is required the brake B1 is applied. Release of brake B1 and application of brake B2 to hold the sun S2 establishes second ratio, and engagement of both clutches C1, C2 with both brakes released locks the planetary train to establish direct drive. If the clutch C3 is engaged also the torque transmitter is by-passed provided the shaft 28 is connected as shown to the input member of the transmitter rather than to the output member 12. An alternative mode of establishing direct drive is by engagement of the clutches C1, C3 only to divide the torque into two paths between the transmitter and the output member 24. Overdrive is established when the clutch C3 and brake B2 are applied and reverse when the clutch C2 and brake B1 are applied. In a modification, the ring gear is attached to a spur wheel situated between the clutch C2 and the planetary set and meshing with a further spur wheel driving a pair of output shafts through a differential gear. Further modifications incorporate a second ring gear in mesh with the pinions P2 and engageable by a brake to provide an additional ratio.