HST Unit

Abstract

An HST unit includes a first hydraulic motor unit for operatively driving one of a pair of driving wheels; a second hydraulic motor unit for operatively driving the other one of the pair of driving wheels; a hydraulic pump unit operatively connected to a driving power source, the hydraulic pump unit configuring a traveling hydrostatic transmission in cooperation with the first and second hydraulic motor units; and an attachment frame for supporting the first hydraulic motor unit, the second hydraulic motor unit and the hydraulic pump unit, the attachment frame being attachable to a vehicle frame.

1 . An HST unit applied to a working vehicle including a vehicle frame that has a pair of right and left main frames, a driving power source and a pair of first and second driving wheels that are positioned on right and left sides, respectively, the HST unit comprising:
 a first hydraulic motor outputting rotational power toward the first driving wheel through a first motor shaft;   a second hydraulic motor outputting rotational power toward the second driving wheel through a second motor shaft;   first and second hydraulic pumps that have first and second pump shafts and form first and second HSTs in cooperation with the first and second hydraulic motors, respectively; and   an attachment frame detachably mounted to the vehicle frame so as to connect the pair of main frames to each other,   wherein the attachment frame includes first and second motor supporting surfaces that extend substantially vertically and are respectively positioned on one side and the other side in a vehicle widthwise direction with a state where the attachment frame is mounted to the vehicle frame as a reference,   wherein the first hydraulic motor is supported by the first motor supporting surface so that the first motor shaft extends along the vehicle widthwise direction, and   wherein the second hydraulic motor is supported by the second motor supporting surface so that the second motor shaft extends along the vehicle widthwise direction.   
   
   
       2 . The HST unit according to  claim 1 , wherein the first and second hydraulic pumps are directly or indirectly supported by the attachment frame so that the first and second pump shafts extend along a vehicle lengthwise direction.