Reasons for and development of an internal combustion engine with an immediately hydraulic output are examined. The crankshaft can be eliminated by converting combustion energy through pistons to hydraulic output, and as a result there are no energy conversion losses in and out of the intervening rotary stage. The hydraulic harnessing of combustion energy permits better distribution of forces on the piston and, therefore, higher piston loading. More power can be generated for the same piston size and speed. Hydraulic output lends itself to energy storage; hydraulically-stored energy insulates the engine from the rate at which work is being done. The engine can thus be designed around its best speed without considering partial or no load conditions. Stored energy makes it possible for the compression system to respond to work demand without waiting for the engine to respond. The engine runs only when necessary. Two or more engines can be combined in systems requiring high horsepower. Hydraulics offers greatly increased design flexibility. Discussed are the hydraulic substitute for the conventional flywheel; quick and efficient starting and stopping; conversion of declining combustion pressure into constant hydraulic pressure; operation over a range of system pressure levels; and interface with a hydrostatic transmission. Applications of hydraulic prime movers include use in off-road machinery, railroad locomotives, marine equipment, standby electrical generating equipment, armored vehicles and ships. The engine may also help reduce air pollution by removing the necessity of keeping engines running when no work is needed.

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  • Supplemental Notes:
    • Presented at SAE Off-Highway Vehicle Meeting and Exposition, Milwaukee, Wisconsin, 11-14 September 1978.
  • Corporate Authors:

    Society of Automotive Engineers (SAE)

    400 Commonwealth Drive
    Warrendale, PA  United States  15096
  • Authors:
    • Ferris, J J
  • Publication Date: 1978

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00399005
  • Record Type: Publication
  • Source Agency: National Highway Traffic Safety Administration
  • Report/Paper Numbers: SAE 780748, HS-025 573U
  • Files: HSL, USDOT
  • Created Date: Aug 31 1985 12:00AM