Abstract: A crust breaker and ore feeder device for electrolytic aluminum smelting employs an in-line three-position pneumatic cylinder capable of moving the plunger shaft to a fully raised position, to a fully lowered position, and to an intermediate, partly lowered position. The full stroke is used for a conventional combined ore dispensing and a crust breaking operation; a partial stroke between the fully raised position and the intermediate position permits ore dispensing without a crust breaking; and a partial stroke between the intermediate position and the fully lowered position permits crust breaking operation without ore feeding. The cylinder can take form of a tandem cylinder having upper and lower axially aligned cylinder portions, with rods not connected to one another.

Abstract: A crust breaker and ore feeder device for electrolytic aluminum smelting employs an in-line three-position pneumatic cylinder capable of moving the plunger shaft to a fully raised position, to a fully lowered position, and to an intermediate, partly lowered position. The full stroke is used for a conventional combined ore dispensing and a crust breaking operation; a partial stroke between the fully raised position and the intermediate position permits ore dispensing without a crust breaking; and a partial stroke between the intermediate position and the fully lowered position permits crust breaking operation without ore feeding. The cylinder can take form of a tandem cylinder having upper and lower axially aligned cylinder portions, with rods not connected to one another.

Abstract: A reservoir for holding pre-fill hydraulic fluid is connected at its bottom to the power input side of a hydraulic motor. A stand pipe within the reservoir is connected to a hydraulic fluid drain outlet for expulsion of excess volume hydraulic fluid. Compressed air is introduced to the reservoir at a level above the top of the stand pipe. Valving in the compressed air line is operable to three states: opened between the compressed air source and the reservoir; opened between the reservoir and the atmosphere and closed. A valve connected in the drain outlet may be opened or closed. A check valve between the reservoir and the hydraulic motor is held opened by pilot operation during return of the hydraulic fluid to the reservoir and checked closed during high pressure input to the hydraulic motor.