A hydraulic mechanical transmission includes a first hydraulic unit having a first shaft and a second hydraulic unit having a second shaft. The second hydraulic unit is connected in hydraulic fluid communication with the first hydraulic unit by high and low pressure lines. A valve having a variable orifice is positioned along the high and low pressure lines, and at least one of the first and second hydraulic units has a variable displacement. A mechanical torque transfer arrangement transfers torque between the first shaft of the first hydraulic unit and a rotatable component of the second hydraulic unit. In use, one of the first and second hydraulic units operates as a hydraulic pump and the other of the first and second hydraulic units operates as a hydraulic motor.

A hydraulic mechanical transmission includes a first hydraulic unit having a first shaft and a second hydraulic unit having a second shaft. The second hydraulic unit is connected in hydraulic fluid communication with the first hydraulic unit by high and low pressure lines. A valve having a variable orifice is positioned along the high and low pressure lines, and at least one of the first and second hydraulic units has a variable displacement. A mechanical torque transfer arrangement transfers torque between the first shaft of the first hydraulic unit and a rotatable component of the second hydraulic unit. In use, one of the first and second hydraulic units operates as a hydraulic pump and the other of the first and second hydraulic units operates as a hydraulic motor.

A control system includes a transmission with a directional clutch and control assembly clutches coupled together and configured for selective engagement to transfer power. A controller is configured to selectively actuate the directional clutch and the control assembly clutches with clutch commands to implement a first split mode in which combined power is transferred to drive the output shaft, a first direct drive mode in which power from only the engine to drive the output shaft, and a first series mode in which power is transferred from primarily the at least one motor to drive the output shaft. The controller is further configured to implement a transient boost function within at least a portion of the first series mode in which the at least one directional clutch is partially engaged to supplement power from the at least one motor with power from the engine to drive the output shaft.

A transmission arrangement for a travel drive, in particular a mobile machine, includes a first hydraulic machine configured to be coupled to a drive machine, and a second hydraulic machine having an adjustable second expulsion volume, the second hydraulic machine configured to be connected fluidically to the first hydraulic machine via a first working line and a second working line of the transmission arrangement. The second hydraulic machine configured to be coupled or is coupled to a manual transmission of the transmission arrangement. The manual transmission has at least two transmission stages, and coupling of the second hydraulic machine to the manual transmission has the result that a torque can be transmitted. The transmission arrangement further includes a control apparatus configured to reduce to zero or to nearly zero the second expulsion volume at least during a changeover from one transmission stage to another transmission stage of the manual transmission.

A transmission arrangement for a travel drive, in particular a mobile machine, includes a first hydraulic machine configured to be coupled to a drive machine, and a second hydraulic machine having an adjustable second expulsion volume, the second hydraulic machine configured to be connected fluidically to the first hydraulic machine via a first working line and a second working line of the transmission arrangement. The second hydraulic machine configured to be coupled or is coupled to a manual transmission of the transmission arrangement. The manual transmission has at least two transmission stages, and coupling of the second hydraulic machine to the manual transmission has the result that a torque can be transmitted. The transmission arrangement further includes a control apparatus configured to reduce to zero or to nearly zero the second expulsion volume at least during a changeover from one transmission stage to another transmission stage of the manual transmission.

A check valve for use with a hydraulic drive apparatus includes a check ball disposed in a cage portion for engaging a valve seat to close the valve. The cage portion has a plurality of flexible ribs composed of a flexible material which permits the check ball to be inserted into to ball retaining area during assembly and to be retained in the ball area after assembly. A filter housing connected to a mounting member has a pair of openings formed in a first surface, and a pair of deformable lips surrounding each opening. A filter screen permits hydraulic fluid to enter a filter housing from a sump. A pair of check valves are disposed in a pair of check valve ports. An external surface of each check valve is engaged to one of the deformable lips to sealingly engage the check valve to the filter housing.

A check valve for use with a hydraulic drive apparatus includes a check ball disposed in a cage portion for engaging a valve seat to close the valve. The cage portion has a plurality of flexible ribs composed of a flexible material which permits the check ball to be inserted into to ball retaining area during assembly and to be retained in the ball area after assembly. A filter housing connected to a mounting member has a pair of openings formed in a first surface, and a pair of deformable lips surrounding each opening. A filter screen permits hydraulic fluid to enter a filter housing from a sump. A pair of check valves are disposed in a pair of check valve ports. An external surface of each check valve is engaged to one of the deformable lips to sealingly engage the check valve to the filter housing.

A hydraulic transaxle includes a transaxle casing including an upper transaxle housing and a lower casing, hydrostatic transmission (HST), and an axle. The HST has a hydraulic pump and a hydraulic motor that are fluidly connected to each other. The hydraulic motor has a motor shaft that is drivingly connected to the axle through a reduction gear train that is disposed between the hydraulic pump and the axle. Reduction gear train has a gear shaft supported by the upper transaxle housing via a ball bearing. At least a part of the upper transaxle housing is formed by a gear top cover made of metal and covering the reduction gear train. Ball bearing is supported by the upper transaxle housing and the gear top cover.

A hydraulic transaxle includes a transaxle casing including an upper transaxle housing and a lower casing, hydrostatic transmission (HST), and an axle. The HST has a hydraulic pump and a hydraulic motor that are fluidly connected to each other. The hydraulic motor has a motor shaft that is drivingly connected to the axle through a reduction gear train that is disposed between the hydraulic pump and the axle. Reduction gear train has a gear shaft supported by the upper transaxle housing via a ball bearing. At least a part of the upper transaxle housing is formed by a gear top cover made of metal and covering the reduction gear train. Ball bearing is supported by the upper transaxle housing and the gear top cover.

A vehicle transmission housing has first and second axle housings pivotably connected to opposite ends of the transmission housing and a stand-on platform may be connected to the assembly. A first gear train in the first axle housing drives a first axle having a first axis of rotation. A second gear train is disposed in the second axle housing drives a second axle having a second axis of rotation collinear with the first axis of rotation. The axle housings are both capable of pivoting about the transmission housing about a third axis that is parallel to the first and second axes. The first and second axle housings may also be separately rigidly or flexibly connected to one another. This assembly permits adjustment of the ground heights of the platform with respect to a vehicle frame.