Abstract: A high ratio epicyclic gear assembly comprising two high torque planetary trains through which power flows via two parallel paths in one or other of which is an intermediate star train (7) with a low torque differential train or gear which transmits the combined power in such a way that the high torque planetary trains share the total torque in a predetermined ratio.

Abstract: A torque limiting coupling including: (a) an input gear (7) and an output (8) gear interconnected by a torque limiting device; (b) gear chain (9) interconnecting the input and output gears; and (c) a torque limiting device which retains the gear train (7, 8, 9) to prevent relative rotation of the gear train (7, 8, 9) and the input (7) and output gears (8) to provide a 1:1 input output ratio below a predetermined level of input torque and releases the gear train to allow relative rotation between the input (7) and output gears (8) at or above the predetermined level whereby excess torque is dissipated.