Importance

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Abstract

A multistage gear pump assembly includes first and second gear pumps that use common shafts and are axially separated by a spacer plate secured within a common bore and secured to the housing. Pressurized bearings are provided at opposite axial ends of the first and second gear pumps. The second gear pump handles cruise and idle operations of the aircraft while the first gear pump stage assists in meeting higher demand modes of engine operation. Otherwise, the first gear pump is maintained at a minimal pressure to reduce energy consumption and still provide desired stability and eliminate issues associated with bearing oil whirl associated with prior known arrangements. However, when additional assistance is required, such as during takeoff, climb, or windmill relight, the first gear pump advantageously contributes to the increased pressure.

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First Claim