Research Papers

A High Ratio Power Dense Planetary Drive for Rotorcraft Applications

[+] Author and Article Information
Xiaolan Ai

Fellow ASME
Timken Technology Center,
The Timken Company,
Canton, OH 44706
e-mail: xiaolan.ai@timken.com

Curtis Orkin

Engineering Manager
Timken Aerospace Transmission,
The Timken Company,
Manchester, CT 06045
e-mail: curtis.orkin@timken.com

Randy Kruse

Precision Gear Specialist
Timken Technology Center,
The Timken Company,
Canton, OH 44706
e-mail: randy.kruse@timken.com

PowerGear is gear analysis software developed by Drive System Technology, Inc.

WindowsLDP is a Window based Load Distribution Program for gear analysis, developed by Ohio State University Gear lab.

Contributed by the Power Transmission and Gearing Committee of ASME for publication in the JOURNAL OF MECHANICAL DESIGN. Manuscript received November 14, 2012; final manuscript received August 23, 2013; published online December 18, 2013. Assoc. Editor: Avinash Singh.

J. Mech. Des 136(2), 021010 (Dec 18, 2013) (10 pages) Paper No: MD-12-1558; doi: 10.1115/1.4025967 History: Received November 14, 2012; Revised August 23, 2013

Epicyclic geartrains are known to provide high power density and have become the geartrain of choice for the main power flow in virtually all rotorcraft designs. This paper presents a unique compound planetary design targeting a helicopter main gearbox transmission application. The design significantly improves power density over conventional geartrains through its innovative planet gear load-sharing configuration along with the utilization of high-performance materials for gears and bearings. Design studies were conducted comparing the power density of this new design to a baseline gearbox design. The results of these studies demonstrate an estimated 38% power density improvement over the baseline configuration. Of the total improvement, 86% is attributed to the novel load-sharing configuration while 14% is attributed to utilization of advanced materials and processes.

Copyright © 2014 by ASME
Topics: Stress , Bearings , Design , Gears
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Lestine, J., and White, G., 1970, “Advanced Technology VTOL Drive Train Configuration Study,” Sikorsky Aircraft, USAAVLABS Technical Report No. 69-69, U.S. Army Aviation Material Laboratories, Fort Eustis, VA.
Bruyne, N. D., 1974, “Design and Development Testing of Free Planet Transmission Concept,” Curtiss Wright Corporation, NJ, Report No. USAAMRDL TR-74-27, Eustis Directorate, Fort Eistis VA.
Drago, R. J., Lenski, J. W., Jr., and Robuck, M. J., 2005, “High Ratio, Reduced Size Epicyclic Gear Transmission for Planetary Wing Aircraft With Improved Safety and Noise Reduction,” U.S. Patent No. 6,966,865 B2.
Brown, F. W., Robuck, M. J., Roddis, G. K., and Beck, T. E., 2004, “Design of a High Ratio, Ultra-Safe, High Contact Ratio, Double Helical Compound Planetary Transmission for Helicopter Applications,” American Gear Manufacturers' Association 2004 Fall Technical Meeting, Milwaukee, Wisconsin.
Brown, F., Robuck, M., and Kozachyn, M., 2009, “Design, Fabrication, Assembly and Test of a Double Helical Planetary Gear System for Helicopter Applications,” The Boeing Company, American Helicopter Society 65th Annual Forum, Grapevine, TX.
Robuck, M., 2009, “Epicyclic Gear Transmission for Rotary Aircraft” U.S. Patent No. 7,507,180 B2.
Ai, X., Orkin, C., Kruse, R., Forbes, R., and Wilmer, M., 2011, “High Ratio Epicyclical Gear Transmission With Improved Load Carrying Capacity,” PCT patent application WO/2011/100499 A1.
Ai, X., Orkin, C., Kruse, R., Forbes, R., Wilmer, M., and Chiavaroli, N., 2011, “Gear Transmission Load Sharing Mechanism,” PCT patent application WO/2011/112930 A1.
Ai, X., Orkin, C., Kruse, R., Forbes, R., Wilmer, M., Smith, B., and Chiavaroli, N., 2011, “Load Split Mechanism for Gear Transmission,” PCT patent application WO/US2011/130352 A1.
Gilbert, R., Craig, G., Filler, R., Hamilton, W., Hawkins, J., Higman, J., and Green, W., 2008, “3400 HP Apache Block III Improved Drive System,” The Boeing Company, Redstonr Arsenal, American Helicopter Society 64th Annual Forum, Montreal, Quebec, Canada.


Grahic Jump Location
Fig. 1

Compound double planetary concept (from Ref. [5])

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Fig. 2

Gear train diagram of TPD MGB (BP1, BP2: bevel pinion 1 and bevel pinion2; BG: bevel gear; DS: drive sun gear; IS: idler sun gear; LP: large planet gear; SP: small planet gear or simple idler planet gear; PC: planet carrier; RG: ring gear)

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Fig. 3

Gear train assembly of TPD MGB

Grahic Jump Location
Fig. 4

Force balance diagram, (a) the reference design, force balance diagram, (b) TPD MGB design with complete floating small planet in the compound planet gear, and force balance diagram, (c) TPD MGB design with partially floating small planet in the compound planet gear

Grahic Jump Location
Fig. 5

First configuration of TPD MGB design, single point pivotal support of compound planet gears.

Grahic Jump Location
Fig. 6

Second configuration of TPD MGB design, two-point flexible support of compound planet gears

Grahic Jump Location
Fig. 7

Planet carrier structural design and FEM results for the first configuration

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Fig. 8

Planet carrier structural design and FEM results for the second configuration




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