Speed changing apparatus

A speed changing apparatus comprising:

• a rotary power input selectively rotatable in either one of two rotary directions (clockwise or counter clockwise);
• a planet gear set, comprising a sun gear, a plurality of planet pinions, a carrier arm, and a ring gear;
• wherein the sun gear is drivingly connected to the power input, the sun gear, carrier arm and ring gear being rotatable about an axis;
• a plurality of auxiliary planet pinions, each auxiliary planet pinion being rotatably fast with a respective one of the planet pinions;
• an auxiliary ring gear meshing with the auxiliary planet pinions;
• a sleeve ring mounted about the planet gear set for rotation about the axis;
• a first one-way sleeve ring clutch, operative between the sleeve ring and the carrier arm;
• and
• a second one-way sleeve ring clutch, operative between the sleeve ring and the ring gear;
• wherein the apparatus has a first clutch arrangement configured to rotationally fix the carrier arm when the power input rotates in one rotary direction and to rotationally fix the auxiliary ring gear when the power input rotates in the other rotary direction and in that the first and second one-way sleeve ring clutches are each operative to engage to transmit drive to the sleeve ring from the carrier arm and the ring gear respectively in the same rotary direction.