Abstract: An expansion chamber for a hydrostatic transaxle to provide for expansion of the hydraulic oil during operation of the transaxle, where the expansion chamber is formed as part of the housing inside the main sump by ribs or other members extending from the housing and is closed by a cap to form a sealed chamber. A siphon tube may be secured to the cap or integrally formed therein, or formed by additional cast ribs or similar features formed into the housing and also sealed by the cap.

Abstract: A pair of zero-turn, hydrostatic transaxles (HZTs) that may be joined to form an integrated, zero-turn, hydrostatic transaxle. Each of the hydrostatic transaxles are further comprised of a casing carrying a hydraulic pump driven by an input shaft, a hydraulic motor driven by a the hydraulic pump through porting contained within a center section, and an axle shaft driven by the hydraulic motor. The hydrostatic transaxles are joined along an interface extending generally perpendicularly to the axle shafts.

Abstract: A center section for a hydraulic pump and motor mounted in a transaxle casing. The center section has a protuberance formed thereon, a pair of flat surfaces separate from the protuberance and at least one fastener opening formed in the center section for receiving a fastener engaged to the casing. The protuberance is adapted to mate with a center section locator formed in the casing to establish an X-Y orientation for a central axis while the fastener provides a Z-axis locator for the center section.

Abstract: In a hydrostatic transmission or integrated hydrostatic transaxle having a housing forming an oil sump and a hydraulic pump and hydraulic motor mounted in the sump and connected through hydraulic porting, a filter housing or other structure defining an internal volume is mounted adjacent to the check valves for the hydraulic porting. Oil passing into this internal volume is filtered to prevent the introduction of contaminants into the hydraulic porting. A himney is formed as part of the filter housing and extends upwards therefrom, and is open to the internal volume. The chimney also includes an opening to permit air to escape to the oil sump, to reduce the risk of air being introduced into the hydraulic porting through the check valves.

Abstract: An expansion chamber for a hydrostatic transaxle to provide for expansion of the hydraulic oil during operation of the transaxle, where the expansion chamber is formed as part of the housing inside the main sump by ribs or other members extending from the housing and is closed by a cap to form a sealed chamber. A siphon tube may be secured to the cap or integrally formed therein, or formed by additional cast ribs or similar features formed into the housing and also sealed by the cap.

Abstract: A pair of substantially mirror image, zero-turn, hydrostatic transaxles (HZTs) that may be joined to form an integrated, zero-turn, hydrostatic transaxle. The control arm and brake mechanism associated with the HZTs can be mounted on either the inboard or outboard side of the HZT casing. In one embodiment, an integrated, inboard brake mechanism is provided for the joined HZTs.

Abstract: A bypass mechanism for a hydrostatic transaxle comprising a casing in which is carried a hydraulic motor that rotates on a motor running surface of a center section. The bypass mechanism includes a bypass actuator having a first end that extends from the casing and a second end that extends through an opening in the center section adjacent to the motor running surface. Connected to the bypass actuator is a bypass arm that is adapted to rotate the bypass actuator to lift the hydraulic motor from the motor running surface of the center section. A first retaining ring attached to a first groove formed in the bypass actuator adjacent to an exterior surface of the casing and a second retaining ring located in a housing bore adjacent the first retaining ring maintains the position of the bypass mechanism relative to the transaxle components.

Abstract: In a hydrostatic transmission or integrated hydrostatic transaxle having a housing forming an oil sump and a hydraulic pump and hydraulic motor mounted in the sump and connected through hydraulic porting, a filter housing or other structure defining an internal volume is mounted adjacent to the check valves for the hydraulic porting. Oil passing into this internal volume is filtered to prevent the introduction of contaminants into the hydraulic porting. A chimney is formed as part of the filter housing and extends upwards therefrom, and is open to the internal volume. The chimney also includes an opening to permit air to escape to the oil sump, to reduce the risk of air being introduced into the hydraulic porting through the check valves.

Abstract: A filter assembly for a hydrostatic transaxle comprising a hydraulic pump and a hydraulic motor in fluid communication via porting formed in a center section. The filter assembly includes an upper filter member having a generally horizontally oriented filter media adapted to be positioned adjacent to the center section. A lower filter member is attached to the upper filter member to form a filter housing having an interior area such that make-up fluid enters the interior area substantially via the filter media. A conduit places the interior area of the filter housing in fluid communication with the porting of the center section through which make-up fluid is allowed to enter the porting of the center section.