US 5,201,692 A · Rider transaxle having hydrostatic transmission

A transaxle including a hydrostatic transmission for use in a vehicle to convert rotational power from the vehicle engine to output axle means, comprising

(a) a housing for said transaxle providing a sump cavity and separate axle cavities;
(b) a hydrostatic transmission including:
(1) a first hydraulic displacement unit mounted in said sump cavity and having a rotatable cylinder block containing a plurality of chambers for holding reciprocal pistons and receiving a displacement unit mounted in said sump cavity and having a rotatable cylinder block containing a plurality of chambers for holding reciprocal pistons and engaging one end of a rotatable drive shaft to drive said rotatable drive shaft, said rotatable drive shaft supported and arranged within said housing so as not to extend through said thrust bearing;
(2) a center section mounted in said sump cavity and having means for rotatably mounting said first hydraulic displacement unit and said second hydraulic displacement unit, said means including means for hydraulically connecting said first and second hydraulic displacement units, a first running surface positioned to rotatably mount said first hydraulic displacement unit, a second running surface positioned to rotatably mount said second hydraulic displacement unit and a bottom face, porting means for hydraulically connecting said first displacement unit to said second hydraulic displacement unit integrally formed therein, and bearing means integrally formed in said center section for receiving and fully supporting said rotatable drive shaft;
(3) a thrust bearing mounted in and fully supported by said housing so as to engage said reciprocal pistons of said second hydraulic displacement unit;
(4) means for reducing the speed of said rotatable input shaft, wherein at least a portion of said speed reduction is accomplished through said porting means and said piston chambers of said first and said second hydraulic displacement units;
(5) a check valve mechanism comprising valve openings formed into the bottom face of said center section and extending to s id porting means, a plate mounted on said bottom face of said center section and plurality of plate openings formed therein and corresponding to said valve openings, a raised annular surface formed on the top surface of said plate around each said plate opening, said raised annular surface acting to form a seal between said plate and said bottom face of said center section, a plurality of balls, one of said balls being mounted in each of said valve openings and said plate openings, and means for releasably securing said balls against said plate openings;
(c) a differential gear mechanism connected to said rotatable drive shift comprising a ring gear engaged to and driven by said input drive means, a plurality of planet gears securely connected to said ring gear in a manner to allow rotation of said planet gears around an axis perpendicular to the axis of rotation of said ring gear, a plurality of bevel gears engaged and driven by said planet gears, said bevel gears being mounted on and driving said output axle means;
and clamping means for securing said bevel gears such that said bevel gears are solely supported by said planet gear unit and said clamping means, said output axle means being connected to and driven by said
(d) means for diverting said hydraulic fluid out of said porting means and said first displacement means and said second displacement means to enable said vehicle to be moved with minimal resistance from said hydraulic fluid;
and
(e) said sump cavity containing said hydraulic fluid for said hydrostatic transmission and said output drive means, and said axle cavities formed within said housing separate from said sump cavity for enclosing said output axle means and a lubricating fluid for said drive axles.

9 more elements

A hydrostatic transmission for use in a vehicle to convert rotational power from the vehicle engine to output axle means of said vehicle, comprising

(a) at least one hydraulic displacement pump located in said housing and having a rotatable cylinder block containing a plurality of chambers for holding reciprocal pistons, and receiving a rotatable input shaft;
(b) at least one hydraulic displacement motor located in said housing and having a rotatable cylinder block containing a plurality of chambers for holding reciprocal pistons, and engaging and driving a rotatable drive shaft;
(c) mounting means for rotatably mounting said hydraulic displacement pump and said hydraulic displacement motor;
(d) porting means integrally formed with said mounting means for hydraulically connecting said hydraulic displacement pump to said hydraulic displacement motor;
(e) hydraulic transfer means including said piston chambers of said hydraulic displacement pump, said piston chambers of said hydraulic displacement motor and said porting means;
and
(f) means for reducing the speed of said input shaft, wherein at least a portion of the speed reduction of said input shaft is accomplished through said hydraulic transfer means.

4 more elements

A transaxle including a hydrostatic transmission for use in a vehicle to convert rotational power from the vehicle engine to output axle means, comprising

(a) a housing for said transaxle providing a fluid sump;
(b) a first hydraulic displacement unit located within said housing and having a rotatable cylinder block containing a plurality of chambers for holding reciprocal pistons, and receiving a rotatable input shaft;
(c) a second hydraulic displacement unit located within said housing and having a rotatable cylinder block containing a plurality of chambers for holding reciprocal pistons, and engaging and driving a rotatable drive shaft;
(d) a center section mounted in said housing and having
(1) a first running surface positioned to rotatably mount said first hydraulic displacement unit, a second running surface positioned to rotatably mount said second hydraulic displacement unit and a bottom surface;
(2) porting means integrally formed therein for hydraulically connecting said first displacement unit to said second hydraulic displacement unit;
(e) a check valve mechanism comprising
(1) valve openings formed into the bottom face of said center section and extending to said porting means;
(2) a plate mounted on said bottom face of said center section and having a top surface and a bottom surface, a plurality of plate openings formed therein corresponding to said valve openings, and a raised ridge means formed on the top surface of said plate around each said plate opening, said raised ridge means acting to form a seal between said plate and said bottom face of said center section;
(3) a plurality of balls, one of said balls being mounted in each of said valve openings and said plate openings, and means for releasably securing said balls against said plate openings;
and
(f) means for connecting said rotatable drive shaft to said output axle means to drive said vehicle.

9 more elements

Rider transaxle having hydrostatic transmission

Life of this patent

Rider transaxle having hydrostatic transmission

Life of this patent

Abstract

Claims26