A high ratio double helical planetary transmission, for application as a helicopter main rotor drive, has been designed, fabricated and tested under the sponsorship of NRTC-CRI. The anticipated improvements offered by this new planetary transmission are reduced weight, reduced noise and improved fail-safety. This paper summarizes the design, fabrication, assembly and initial test results for the planetary transmission. Typically, the final stage in helicopter main rotor drives consists of one or two simple planetary stages which are composed of a sun gear, multiple planet gears (typically between 3 and 6) and an internal gear which is generally the fixed member of the epicyclic gear system. The main rotor transmission is the most critical and usually the heaviest assembly in the drive system for any rotary wing aircraft, be it a single or tandem rotor helicopter or a tilt rotor vehicle. The subject high ratio planetary design utilizes a compound planetary configuration with a 17.5:1 reduction ratio which would replace a two stage planetary configuration with conventional planetary gears. The new design uses ultra-safe design principles such as split-torque paths and high combined contact ratio gearing. Double helical gears in the planet/ ring meshes balance axial tooth forces so that thrust bearings are not required. The spur gear sun/planet meshes are staggered to achieve a relatively compact spatial arrangement. This concept brings together a large number of individual gear system innovations which, taken together, yield improvements in reduced weight, noise and performance combined with improved reliability and fail-safety. Fabrication and assembly of the components for this transmission are more complicated than standard planetary systems. The grinding process for the helical gears must use small diameter wheels due to the proximity of the adjacent helix, since the gears in this configuration are integral with the shafts. Assembly procedures also require special consideration because of the integrated design and double helical gears. Test results are presented to support the goals of this project, including, concept verification, weight reduction, and operating characteristics of the test transmission.


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    Title :

    Design, fabrication, assembly and test of a double helical planetary gear system for helicopter applications


    Additional title:

    Entwurf, Fertigung, Montage und Test eines doppelt gewendelten Planetengetriebsystems für Anwendungen im Hubschrauber


    Contributors:


    Publication date :

    2008


    Size :

    13 Seiten, 6 Quellen


    Type of media :

    Conference paper


    Type of material :

    Print


    Language :

    English




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