HST system driving apparatus

A driving apparatus for a tractor, comprising:

• an axle;
• a differential gear unit for driving said axle;
• a speed change mechanism;
• a transmission mechanism for transferring power from said speed change mechanism to said differential gear unit;
• a casing, said casing comprising a case lid and a case body attached to said tractor for housing said differential gear unit and said transmission mechanism, wherein said transmission mechanism comprises at least one shaft, said shaft having a first end rotatably supported by said case body and a second end rotatably supported by said case lid, said case body and said case lid interface substantially at one end of said shaft of said transmission mechanism;
• a loading surface provided on an outside surface of said case body for mounting said speed change mechanism;
• means for detachably securing said case body and said case lid together, said detachably securing means including means for detaching said case lid from said case body for servicing said driving apparatus so that said differential gear unit and said transmission mechanism remain housed within said case body;
• means provided by said casing for holding oil used by said speed change device wherein said oil serves to lubricate said transmission mechanism and said differential gear unit;
• and
• means provided by said casing for receiving an oil filter for filtrating said oil.