Cooling a ranging arm gear case on a longwall shearer

A longwall shearer including

• a floor-mounted track,
• an elongated mobile frame supported on said floor-mounted track,
• arms on each end of the elongated frame, and
• rotary driven toothed drums, each of which is operably supported on one of said arms for winning mining material as said mobile frame passes back and forth along said floor mounted track,
• wherein each arm includes a gear case for transmitting rotational power from a drive to said rotary driven toothed drum,
• said gear case including an elongated housing,
• a plurality of single gears mounted in a row within said elongated housing, with one gear at one end of the row being drivingly connected to the drive, and another gear at another end of the row being drivingly connected to the driven member, each single gear mounting including a longitudinal gear axle having a mounting axis extending longitudinally along said gear axle,
• lubricating oil surrounding said single gears and contained within said housing, and
• a cooling system for said gear case, said cooling system including a coolant injection system in each of said single gears, each coolant injection system including
• a longitudinal opening in said gear axle, extending a substantial distance along said mounting axis,
• a coolant injection tube mounted inside said longitudinal opening, extending a substantial distance from one end of said longitudinal opening inside said longitudinal opening, said coolant injection tube having a diameter smaller than the diameter of said longitudinal opening,
• a coolant supply line connected to and in communication with said coolant injection tube, and
• a coolant outlet connected to and in communication with said longitudinal opening adjacent said one end of said longitudinal opening, so that coolant leaving the end of the coolant injection tube travels back along the coolant injection tube and then out of the gear axle thereby removing heat from the single gear.