Martin B. Treuhaft

Wear Measurement of a Large Hydraulic Fluid Power Pump Using Radioactive Tracer Wear Technology

Real-time wear measurement is possible in fluid lubricated components utilizing radioactive tracer technology (RATT). This technology has been applied to internal combustion engines since the 1950’s, but has only recently been applied to hydraulic components. This paper presents the application of radioactive tracer technology to measure wear rate of pistons and slippers in a large variable displacement, high pressure, axial piston pump under various operating conditions. To apply this technology, new piston and slipper assemblies were exposed to thermal neutrons in a nuclear reactor to produce characteristic radionuclides (isotopes) in the slippers and pistons. These isotopes act as tracers, which when worn off in an operating pump can be measured by monitoring the gamma-ray activity in the circulating fluid. The accumlation of wear particles in the unfiltered circulation loop is monitored continuously as the pump is operated under various transient and steady state conditions. The steady state wear rate is determined by the rate of accumulation of radioactive wear particles in the loop over a period of time, usually less than a few hours. This first time application of RATT for wear analysis in a large hydraulic pump has shown positive results. This technology can be applied to determine wear sensitivity of hydraulic pump parts for an endless array of factors, such as speed, pressure, displacement, temperature, contamination level and composition, and duty cycle. Break-in, start-up, and transient wear affects can also be observed. Comparisons can also be made between the wear of different design features and materials.Copyright

Engine durability, emissions and fuel economy studies with special boundary lubricant chemistry

A unique combination of boundary lubricant and surfactant chemistries has produced significant benefits in ring and bearing wear control. This chemistry is added as an engine treatment to current quality engine lubricants. Microscopic wear studies employing radioactive tracer and metal surface analysis techniques have helped define optimum chemistry for enhanced bearing and ring wear control in a running engine. These studies have also served to further our understanding of the wear protection mechanism. Results from macroscopic engine wear studies, carried out in Sequence IIIE engines/stands using modified ASTM IIIE protocols, paralleled data obtained from the radioactive wear studies. They confirmed the positive wear protection benefits of this unique chemistry. Vehicle emission evaluations using the Federal Test Procedure (FTP) for light duty vehicles with this unique chemistry showed no detrimental effects either as added pollutants or catalyst degradation. Initial fuel economy data have also indicated a subtantial benefit for this chemistry, especially under engine conditions emphasizing boundary lubrication. The paper will describe and discuss the test methods employed in evaluating this unique chemistry and the relevance of the resulting data to improved engine durability, emissions and fuel economy. 18 refs., 15 figs., 15 tabs.