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Technical Paper

Hydraulic System Cavitation: Part II – A Review of Hardware Design – Related Effects

1999-09-14
1999-01-2857
Cavitation erosion is one of the most important causes of loss of hydraulic pump efficiency, wear and even failure. Although cavitation process is often understood, there is typically little understanding of the joint role of the hydraulic fluid, which is a component of the system, and the operation of the hydraulic pump. In this paper, an overview is provided that describes the fluid properties that most impact on cavitation damage, the cavitation process within the pump and components and the use of computer simulation to prove improved designs that minimize hydraulic cavitation when various types of fluids are used.
Technical Paper

Biodegradable Hydraulic Fluids: A Review

1999-09-14
1999-01-2865
There is an ongoing interest in biodegradable hydraulic fluids. Biodegradable fluids are often considered to include only vegetable oils, polyol esters and diester base stocks. However, other fluid base stocks including highly refined mineral oils, poly(alpha olefins) and fire-resistant fluids such as water-glycol hydraulic fluids are also biodegradable fluid alternatives. This paper will provide an overview of the international literature on biodegradable fluids, various international testing protocol, fluid base stocks, effect of oxidative stability, material compatibility and pump performance.
Technical Paper

Root Cause Analysis of A Piston Pump Failure: A Case History

2000-09-11
2000-01-2590
In many situations, the root cause of a particular failure may be determined based on the observation of a single part, or perhaps a photograph, taken from the failed system. However, when failure analysis is conducted on the complete component, a different result often emerges. Such is the case described here for a piston pump that was operating on an anhydrous poly(alkylene glycol) - PAG at high pressure. Initial observation suggested the fluid was the root cause of the failure. However, when failure analysis was properly applied, it was learned that the root cause of the failure was due to mechanical failure caused by the motor-to-pump coupling. This analysis procedure is presented as a case history in this report.
Technical Paper

Anhydrous Polyalkylene Glycol Hydraulic Fluids

2000-09-11
2000-01-2557
There is an ongoing interest in identifying new biodegradable hydraulic fluid compositions that may be used as alternatives to mineral oil in many hydraulic applications such as mobile off-highway equipment. To date, many basestocks have been proposed including: vegetable oils, polyol esters, diesters, synthetic hydrocarbons and others. One basestock is gaining interest as alternative, biodegradable, fire-resistant hydraulic fluid; anhydrous poly(alkylene glycol) (PAG) fluids. However, the use of these fluids is not new; they are simply being rediscovered. The objective of this paper is to provide an overview of the discovery and development of anhydrous PAGs as hydraulic fluids. This discussion will include: an overview of PAG chemistry, properties and hydraulic pump performance.
Technical Paper

Hydraulic Fluid Qualification: An Overview of Critical Considerations

2000-09-11
2000-01-2541
There are numerous fluid-related performance concerns when hydraulic fluids are being qualified for use. These concerns are especially important when non-mineral oil derived hydraulic fluids are being qualified for use in unusual and critical applications. In this paper, a number of performance-related fluid deficiencies that may be encountered in use will be described.
Technical Paper

Hydraulic System Cavitation: A Review

1998-09-14
982036
Cavitation is the dynamic process of gas cavity growth and collapse in a liquid. These cavities are due to the presence of dissolved gases or volatile liquids and they are formed at the point where the pressure is less than the saturation pressure of the gas (gaseous cavitation) or vapor pressure (vaporous cavitation). In this paper, various hydraulic system design factors and fluid properties affecting the cavitation process, and bubble collapse mechanisms will be discussed. In-situ generation of cavitation, examination of the cavitation process in model hydraulic systems, material effects and test methods will be reviewed.
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