Abstract: A drive system (10) for an aircraft, operable for selectively enabling ground movement, and in particular taxiing movement, of the aircraft without requiring the aircraft to be moved by a ground vehicle. The drive system (10) comprises a power system (25) and a mechanical transmission (23) for delivering rotational drive to landing gear (13) of the aircraft. The mechanical transmission (23) comprises an input (41) for receiving drive from the power system (25), an output (43) for delivering drive to the landing gear (13), and a gear mechanism (45) operably coupling the input and output to transmit drive from the input to the output. The gear mechanism (45) is configured to accommodate some misalignment between the input (41) and output (43).

Abstract: The present invention provides a pressure roller for use in semi-autogenous comminution of maters. The roller has an outer face (11) accommodating a set of wear resistance inserts (13) in a spaced array over the outer face. The inserts are embedded in the surface of the roller and extend into an outer section of the roller. Each insert is spaced inwardly from or is flush with the outer face of the roller.