Axle driving apparatus

An axle driving apparatus comprising:

• a housing having a first oil sump formed therein;
• a hydrostatic transmission (HST) contained in said housing and immersed in said first oil sump;
• an input shaft of said HST projecting substantially vertically outwardly from said housing;
• a cooling fan provided on said input shaft external to said housing;
• and
• a second oil sump disposed underneath said cooling fan for regulating the volume of oil in said first oil sump such that said second oil sump is partially overlapped by said cooling fan, wherein oil flows in both directions between said first and second oil sumps.

An axle driving apparatus comprising:

• a housing;
• a first oil sump formed in said housing, said first oil sump being separated from the atmosphere;
• a hydrostatic transmission (HST) contained in said housing and immersed in said first oil sump;
• a second oil sump in communication with the atmosphere for regulating the volume of oil in said first oil sump;
• and
• a siphon allowing oil to flow in both directions between said first and second oil sumps.

An axle driving apparatus comprising

• a housing;
• a hydrostatic transmission (HST) contained in said housing;
• an oil reservoir disposed on an outer wall of said housing for regulating the volume of oil in said housing, wherein said reservoir is provided with a first fixture and said housing is provided with a second fixture corresponding to said first fixture;
• and
• a coupling disposed above said first fixture which connects to the interior of said housing to provide fluid flow between said oil reservoir and an interior of said housing.

An axle driving apparatus comprising:

• a housing;
• a first oil sump formed in said housing;
• a hydrostatic transmission (HST) contained in said housing, said HST being immersed in said first oil sump;
• an input shaft of said HST projecting outwardly from said housing;
• a cooling fan provided on said input shaft external to said housing;
• an oil passage in communication with said first oil sump, said oil passage being disposed in an air-cooled area of said cooling fan external to said housing;
• a pumping means disposed between said oil passage and said first oil sump, said pumping means being driven by said input shaft, wherein said pumping means circulates oil between said oil sump and said oil passage;
• second oil sump in communication with the atmosphere for regulating the volume of oil in said first oil sump;
• and
• a siphon allowing oil to flow in both directions between said first and second oil sumps.

An axle driving apparatus comprising:

• a housing forming an oil sump therein;
• a hydrostatic transmission (HST) contained in said housing and immersed in said oil sump;
• an input shaft of said HST projecting outwardly from said housing;
• a cooling fan provided on said shaft external to said housing;
• an oil passage in communication with said oil sump, said oil passage being disposed in an area of said housing which is air-cooled by said cooling fan;
• a pumping means disposed between said oil passage and said oil sump, said pumping means being driven by said input shaft, wherein said pumping means circulates oil between said oil sump and said oil passage;
• an oil reservoir disposed on an outer wall of said housing for regulating the volume of oil in said housing;
• a first fixture provided on said reservoir;
• a second fixture corresponding to said first fixture, provided on said housing;
• and
• a siphon providing communication between said oil sump and the interior of said reservoir.