Gear assembly and gear oil composition

A gear assembly comprising at least one pair of meshing gears situated inside a gear case having a sump portion and a wall portion, and a gear oil mixture disposed in said sump portion;

• at least one of said gears being immersed at least partially in said mixture and said mixture comprising a base oil, and a coolant having an endothermic liquid/vapor transition between the lower and upper operating temperatures of the gear assembly, the coolant having a viscosity lower than the base oil, and further comprises a heat exchanger disposed in said wall portion and configured to condense the vapor of said coolant into a liquid and to return said liquid to the sump portion.

A method comprising:

• providing a gear assembly comprising at least one pair of meshing gears and a gear case having a sump portion and a wall portion constructed and arranged to provide a headspace above the sump portion;
• disposing in said sump portion a gear oil comprising a base oil, and a coolant having an endothermic liquid/vapor transition between the upper and lower operating temperatures of said gear assembly, and immersing at least one of said gears in said gear oil, said coolant having a viscosity lower than the base oil, and at least one of a heat exchanger in an interior portion of the gear case constructed and arranged to fit in the head space, or a plurality of fins extending from the exterior of the gear case.

A method comprising:

• providing a gear assembly comprising at least one pair of meshing gears and a gear case having a sump portion and a wall portion with a headspace and a heat exchanger disposed in said wall portion and configured to condense the vapor of said coolant into a liquid and to return said liquid to the sump portion;
• disposing in said sump portion a gear oil comprising a base oil, and a coolant having an endothermic liquid/vapor transition between the upper and lower operating temperatures of said gear assembly, and immersing at least one of said gears in said gear oil, said coolant having a viscosity lower than the base oil, wherein said wall portion comprising a heat conductive metal configured to condense the vapor of said coolant, conduct heat away from said assembly and return the condensed coolant liquid to said sump portion.

A method comprising:

• providing a gear assembly comprising at least one pair of meshing gears and a gear case having a sump portion and a wall portion with a headspace;
• disposing in said sump portion a gear oil comprising a base oil, and a coolant having an endothermic liquid/vapor transition between the upper and lower operating temperatures of said gear assembly, and immersing at least one of said gears in said gear oil, said coolant having a viscosity lower than the base oil, and a coil filled with heat conductive fluid fit in the headspace of the gear case.

A gear assembly comprising at least one pair of meshing gears situated inside a gear case having a sump portion and a wall portion, and a gear oil mixture disposed in said sump portion;

• at least one of said gears being immersed at least partially in said mixture and said mixture comprising a base oil, and a coolant having an endothermic liquid/vapor transition between the lower and upper operating temperatures of the gear assembly, the coolant having a viscosity lower than the base oil, and a heat exchanger disposed in said wall portion and configured to condense the vapor of said coolant into a liquid and to return said liquid to the SUMP portion, and a plurality of fins extending from the exterior of the gear case.

A gear assembly comprising at least one pair of meshing gears situated inside a gear case having a sump portion and a wall portion, a heat exchanger disposed in said wall portion and configured to condense the vapor of said coolant into a liquid and to return said liquid to the sump portion, and a gear oil mixture disposed in said sump portion;

• at least one of said gears being immersed at least partially in said mixture and said mixture comprising a base oil, and a coolant having an endothermic liquid/vapor transition between the lower and upper operating temperatures of the gear assembly, the coolant having a viscosity lower than the base oil, the coolant comprising an alcohol having an ether group.

A gear assembly comprising at least one pair of meshing gears situated inside a gear case having a sump portion and a wall portion, a heat exchanger disposed in said wall portion and configured to condense the vapor of said coolant into a liquid and to return said liquid to the sump portion, and a gear oil mixture disposed in said sump portion;

• at least one of said gears being immersed at least partially in said mixture and said mixture comprising a base oil, and a coolant having an endothermic liquid/vapor transition between the lower and upper operating temperatures of the gear assembly, the coolant having a viscosity lower than the base oil, the coolant comprising at least one of diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, dipropylene glycol n-butyl ether, dipropylene glycol methyl ether, dipropylene glycol monopropyl ether, propylene glycol methyl ether, propylene glycol n-butyl ether, propylene glycol propyl ether, 1,2-propanediol, propylene glycol phenyl ether, ethylene glycol mono-propylether, or diethylene glycol methyl ether.