oscillating forces and moments ex- erted on the swash plate. The pump and motor performance fora given displacement for a machine required a simulation model that de- scribed the flow of a compressible and viscous fluid fromtheports through the valve plate to the displacement cham- ber. It also considered the gap flow through the lubricating gaps that seal the displacement chamber as pres- sure changes occur in the displacement chamber resulting from the moveable parts of the rotating group. Once the Maha Fluid Power Research Center was certain of its findings, it validated these predic- tions with a prototype valve plate manufactured in Germany with a waved surface profile that was deter- mined by the prior simulation work. Efficiency measurements of a vari- able displacement unit running with both the prototype and standard valve plates were compared. The measurements of the pump running with the prototype valve plate showed an increase in total pump efficiency of 2 to 10%, dependent upon operat- ing parameters. While the increased load-carrying ability of the fluid film was discovered, the group looked further into the shape of the structure’s surface and the potential it would bring. It was shown that at partial operating loads, the gap between the cylinder block The cross-section of an axial piston ma- chine of swash plate design.
Air-Fuel Ratio Controls Altronic Inc. has announced its EPC 50 air-fuel ratio controllers for low-horsepower, carbureted natural gas- fueled engines operating at or near a stoichiometric air-fuel ratio and with three-way catalytic converters. An oxygen sensor is used in the exhaust stream to sense O2 content, and a thermocouple input signals when proper exhaust temperature has been reached. A system fuel control valve installed in the fuel line to the carburetor is adjusted by a stepper motor under microprocessor control to maintain the correct O2 content in the exhaust. The EPC 50 also incorporates a thermocouple input and a ded- icated output for implementation of catalyst over-temperature protection.
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Cylinder Liner And Engine Overhaul Kits IPD, Torrance, Calif., has introduced its first en- gine overhaul products for the Detroit Diesel 60 series engine with two-piece articulated steel crown/aluminum skirt pistons. This new release utilizes the IPD patented cylinder liner with a par- abolic cooling groove.
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and valve plate alone contributed from 60 to 70% of all power losses associated with the lubricating gaps. The relatively high losses at partial load conditions (i.e., low pressure and low displacement operating condi- tions) limit the overall machine effi- ciency at these operating conditions. By applying a wave-like microstruc- ture to the pump’s internal valve plate surface, the load-carrying ability of the film fluid was significantly in- creased while reducing energy loss. By using the waved surface, a power loss of 60% was demonstrated. Dr. Ivantysynova said that going forward, the discovery and beneficial results obtained through waved-sur- face has the potential to significantly improve existing pump and motor effi- ciencies in a wide range of operating conditions. dp
Eaton Re-Engineers MatchMate Hoses Eaton has re- engineered its Aeroquip Ma t ch Ma t e Global braid- ed and spiral h y d r a u l i c hose prod- ucts to have higher work- ing pressures, temperature ratings and covers for abrasion resistance. Included in the product offering are the Aeroquip GH120, GH663, GH781, GH793 and GH493 hose products. The products are designed to meet or exceed a variety of SAE and EN standards. Eaton said its hoses have an average 29% higher pres- sure rating than comparable hoses, along with a 260°F temperature rating.