Abstract: A coil former allows transposition between layers of turns in a coil to be accomplished without damage. The transpositions can be made in a short side of the coil. The former has finned portions which guide the wire into the correct locations during winding. When the coil is wound, the former is disassembled and the end portions are pulled towards the center of the former and turned through 90° to be removed. A method of using the former is described.

Abstract: A coil former allows transposition between layers of turns in a coil to be accomplished without damage. The transpositions can be made in a short side of the coil. The former has finned portions which guide the wire into the correct locations during winding. When the coil is wound, the former is disassembled and the end portions are pulled towards the center of the former and turned through 90° to be removed. A method of using the former is described.

Abstract: A mining machine haulage transmission includes an overload protection arrangement comprising a torque sensing device which monitors the torque transmitted and brings about decoupling of one or more clutches to disconnect the transmission output from its input, in the event that the transmitted torque exceeds a predetermined threshold.In one preferred arrangement, the torque sensing device produces electrical output signals dependent upon the transmitted torque to control operation of the clutch or clutches. In an alternative arrangement or in addition, a source of motive power is connectible to operate the clutch or clutches and control means are provided, responsive to the torque sensing device, to control connection of the power source to the clutch or clutches so as to bring about decoupling in the event of a torque overload.

Abstract: A longwall mining machine incorporates breaking apparatus comprising an underframe which may be an integral extension of the main underframe of the machine and which is mounted on the conveyor for movement therealong, such that the breaking apparatus is rigidly secured to, and comprises an integral part of, the mining machine. The breaking apparatus also comprises a rotary breaking element drivably carried by the breaker underframe and a reaction plate, for example, on the same underframe, which is spaced from an adjacent periphery of the breaking element. In use, material, such as coal and rocks, on the conveyor passing between the rotary element and the reaction plate is broken against the reaction plate by the rotating breaking element. In this way, the coal and rocks are broken down to a sufficiently small size that they will not become jammed under the main underframe of the mining machine.

Abstract: A mining machine includes drive unit means for driving a haulage winch and a cutting tool of the machine, the drive unit means comprising a multi-phase induction motor with a wound rotor. In order to control the motor speed, the motor is provided with a circuit connected across the rotor windings and means for varying the effective impedance presented by the said circuit to the rotor windings.