Air cooled gear housing

A spur-gear mechanism, comprising:

• a drive shaft for transmitting a driving power from a motor, said drive shaft defining an axis;
• a split housing surrounding transmission stages of the spur-gear mechanism and including an upper housing portion and a lower housing portion;
• an axial fan wheel fixedly disposed on said drive shaft and drawing air axially from the motor to force the drawn air to flow in a direction of the axis through the split housing in substantial parallel relationship to the drive shaft;
• a split spacer flange formed in one piece with the upper and lower housing portions, respectively, and including first openings extending at a slant to outwardly direct a flow of air drawn in by the axial fan from the motor to flow across inclined outer base surfaces of the housing;
• first cooling ribs disposed on side surfaces of the housing in flow communication with second openings of the spacer flange and bent inwards towards the second openings;
• second cooling ribs disposed on the base surfaces of the housing in flow communication with the first openings of the spacer flange and bent inwards towards the first openings;
• and
• reinforcing ribs formed on the spacer flange between the first and second openings.