Sauer-danfoss Inc.

Sauer Gmbh

Jim D Ryken

Jeffrey A Baldus

David D Dirks

Steven H Gluck

Scott D Meyer

A loop flushing circuit for a hydrostatic transmission module includes a three position, three port pilot pressure operated loop flushing valve having a first inlet port fluidly connected to the first system pressure line, a second inlet port fluidly connected to the second system pressure line and an outlet port fluidly connecting the loop flushing valve to the case drain through a drain line having a drain orifice therein. A loop flushing and lubrication line fluidly connected to the drain line upstream of the drain orifice extends within the casing and has an open end directed toward the rotating elements of one of the pump and motor. The three position valve has an intermediate position operatively located between the opposite end positions. System pressure from at least one of the first and second system pressure lines is always routed to the loop flushing and lubrication line through the valve regardless of which of the three positions the valve is in. Thus, lubricating for the rotating elements is insured, even when the hydrostatic transmission module is in neutral.

Loop flushing circuit for lubricating rotating elements in a hydrostatic transmission module

An improved apparatus for retaining slipper holddown pins radially in a hydraulic unit includes a cylinder block having a plurality of holes therein for respectively receiving a corresponding plurality of elongated slipper holddown pins, each having a maximum transverse width. The holes are adjacent to and communicate with a center bore of the cylinder block to form respective throats. The throats have a maximum width that is less than the maximum transverse width of the pins such that the pins cannot be radially displaced through the respective throats. Each hole has a side wall that extends more than 180.degree. around its central axis. The side wall defines the throat between the hole and the center bore. The shaft can be inserted into driving engagement with the center bore of the cylinder block. The slipper holddown pin has a maximum transverse width greater than the maximum width of the throat. Thus, the pin is radially constrained in the hole without applying external forces and cannot move radially outwardly through the throat. The bore of the cylinder block and the holes for receiving the pins can be simultaneously formed with a single broaching bar.

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Roland, IA, United States of America

Jim D Ryken