Charge pump and auxiliary pump for hydrostatic transmissions and integrated hydrostatic transaxles

Abstract

A hydrostatic transaxle having a housing forming a sump containing hydraulic fluid, a charge pump or auxiliary pump in flow communication with the sump for creating high pressure hydraulic fluid from the hydraulic fluid, a center section having hydraulic porting formed therein, a hydraulic pump and motor, connected to the hydraulic pump through the hydraulic porting. A differential and output axles are also mounted in the housing with a drive train connecting the hydraulic motor output shaft and the differential. The drive train comprises a counter shaft secured to the housing and having a first gear engaged to the motor output shaft and a second gear engaged to both the first gear and the differential.

What is claimed is:  
     
         1 . An axle driving apparatus comprising: 
 a housing;    a hydrostatic transmission disposed in said housing and forming a sump, said hydrostatic transmission including a hydraulic motor having a motor shaft;    a charge pump disposed adjacent to the external surface of said housing and hydraulically connected to said hydrostatic transmission;    axles disposed in said housing;    a differential gear unit disposed in said housing for differential connection of said axles; and    a drive train disposed in said housing between said hydrostatic transmission and said axle, said drive train comprising: 
 a counter shaft supported at both ends in said housing so as to be disposed between said motor shaft and said axles;  
 a first gear rotatable relative to and provided on said counter shaft for driving said differential gear unit; and  
 a second gear driven by said motor shaft, said second gear not rotatable relative to and mounted on said first gear, wherein said second gear engages with teeth of said first gear.  
   
     
     
         2 . An axle driving apparatus comprising: 
 a housing;    a hydrostatic transmission disposed in said housing and forming a sump, said hydrostatic transmission including a hydraulic motor having a motor shaft;    an auxiliary pump in flow communication with said sump disposed adjacent to the external surface of said housing;    axles disposed in said housing;    a differential gear unit disposed in said housing for differential connection of said axles; and    a drive train disposed in said housing between said hydrostatic transmission and said axle, said drive train comprising: 
 a counter shaft supported at both ends in said housing so as to be disposed between said motor shaft and said axles;  
 a first gear rotatable relative to and provided on said counter shaft for driving said differential gear unit; and  
 a second gear driven by said motor shaft, said second gear not rotatable relative to and mounted on said first gear, wherein said second gear engages with teeth of said first gear.