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Currently, the industry standard pump test which is used to evaluate the lubricating performance of hydraulic fluids is ASTM D-2882 [1,2]. This test, and others, utilizes the Vickers V-104 vane pump [3]. Although ASTM D-2882 has been an industry standard for many years, it does not provide the necessary correlation required for prediction of the lubricating properties of a hydraulic fluid in various piston pump operations. The objective of this paper is to detail the recently proposed Rexroth Piston Pump Test which is being proposed as an ASTM standard. A description of the proposed hardware, pump testing strategies and methods of standardized wear determination will be provided.

For many years the ASTM D2882 test method, using the V-104C Vane pump, served the industry well to evaluate the lubricating properties of hydraulic fluids at low pressures (< 2000 psi). However, at higher pressures in different types of pumps (i.e. piston pumps), this method may not be reliable enough to predict satisfactory lubrication performance in commercial applications. In this paper the V-104C pump will be evaluated in terms of vane contact force and film thickness parameters to assertain the possibility of using a modified bench test to better predict hydraulic fluid performance at higher pressures.

Hydraulic piston pump failures may be related to either hardware or fluid problems. In some cases, apparent hardware failures have been traced to various fluid problems. In this paper, selected examples of pump failures will be provided to illustrate some common modes of axial piston pump failures. In most cases, these will represent actual failures including: misalignment, insufficient fluid lubrication, particle contamination, brinelling, corrosion, and cavitation. Various examples of these and other pump failure modes are provided.

There has been an ongoing interest in replacing mineral oil with more biodegradable and/or fire-resistant hydraulic fluids in many mobile equipment applications. Although many alternative fluids may be more biodegradable, or fire-resistant, or both than mineral oil, they often suffer from other limitations such as poorer wear, oxidative stability, and yellow metal corrosion which inhibit their performance in high-pressure hydraulic systems, particularly high pressure piston pump applications. From the fluid supplier's viewpoint, the development of a definitive test, or series of tests, that provides sufficient information to determine how a given fluid would perform with various hydraulic components would be of interest because it would minimize extensive testing. This is often too slow or prohibitively expensive. Furthermore, from OEM's (original equipment manufacturer's) point of view, it would be advantageous to develop a more effective, industry accepted fluid analysis screening.