Reconfigurable power spindle

A gear train for coupling a rotational input to first and second rotational outputs, comprising:

• a sun gear rotatable about a center axis;
• a ring gear independently rotatable about the center axis;
• one or more first planetary gears, each meshingly engaged with the sun gear;
• one or more second planetary gears meshingly engaged with the ring gear and with one of the first planetary gears;
• and
• a carrier rotatable about the center axis and supporting the first and second planetary gears for rotation about their respective axes,
• whereby the rotational input is selectively coupled to one of the sun gear, carrier and ring gear, the first rotational output is selectively coupled to a different one of the sun gear, carrier and ring gear, and the second rotational output is selectively coupled to the remaining one of the sun gear, carrier and ring gear.

A machine tool spindle having N input shafts, with N≧3, and one output shaft, comprising:

• (N−1) gear trains arranged sequentially as a plurality of intermediate gear trains terminating in a last gear train, each gear train having two inputs and an output, and each gear train being capable of achieving a desirable contribution of power among the inputs, including an equal contribution of power associated with each input, wherein:
• a) the output of each intermediate gear train is coupled to one of the inputs of the next gear train in sequence,
• b) the N input shafts are selectively coupled to the other input of each gear train, and
• the output of the last gear train is coupled to the output shaft.

A machine tool spindle having N input shafts, with N≧3, and one output shaft, comprising:

• (N−1) gear trains, each gear train having two inputs and an output, each gear train being capable of achieving a desirable contribution of power among the inputs, including an equal contribution of power associated with each input, the gear trains arranged in two rows, each row comprising a plurality of in-series intermediate gear trains terminating in one common last gear train, so that the two rows are coupled in paralell through the last gear train, wherein:
• a) the output of each intermediate gear train in a row is coupled to one of the inputs of the next gear train in sequence,
• b) the N input shafts are selectively coupled to the other input of each gear train, and
• the output of the last gear train is coupled to the output shaft.