Guide for gear designers, consisting of theory, calculations, charts, curves and references, explains lubrication requirements for gears to insure maximum performance. Mechanical and service variables are considered in order to obtain optimum gear performance under severe operating conditions

Townsend, D. P.

English

NASA Technical Reports Server

1972	 B7210136 
NASA TECH BRIEF 
Lewis Research Center 	
-4r 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Lubricant Selection for Gear Designers 
A guide for gear designers, consisting of theory, cal-
culations, charts, curves, and references, has been written 
that considers the lubrication requirements for gears to 
insure maximum performance. Mechanical and service 
variables are considered in order to obtain optimum gear 
performance under severe operating conditions. 
The lubricant in gearing prevents failure under several 
modes of operation, such as boundary lubrication, mixed 
lubrication, and full elastohydrodynamic (EHD) film 
operation. In EHD lubrication, the contacting surfaces 
under high loads such as those obtained in gears and 
bearings, elastically deflect. These surfaces are separated 
by a thin EHD lubricant film, which is a few micro-
inches thick. 
Gears operating under boundary and mixed lubrication 
require added protection. This protection is provided by 
extreme pressure and anti-wear additives to prevent 
failures. 
The predominant mode of failure in gears that must 
operate at high speed and transmit high loads is scoring. 
Basically, scoring results from a breakdown in the lubri-
cant and/or boundary film separating the load carrying 
members. At the operating load and speed, the lubricant 
is expected to provide an unbroken film between the 
teeth or load-carrying members, and cool the gear so that 
the film of lubricant does not become too thin. Factors 
that can affect the start of scoring are described in the 
guide. 
In many applications, gears operate with a full EHD 
film. The method of EHD film formation and how the
lubricant properties affect the film are presented and dis-
cussed. An analytical method for determining EHD 
film thickness and how the film affects gear failure are 
also reviewed. Using the principles and theory discussed 
in the guide, design procedures for EHD application have 
been outlined. 
Notes: 
1. The following documentation may be obtained from: 
National Technical Information Service 
Springfield, Virginia 22151 
Single document price $3.00 
(or microfiche $0.95) 
Reference: NASA-TM .X-52942 (N71-14785), 
Lubrication Considerations in Gear Design 
2. Technical questions may be directed to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio 44135 
Reference: B72-10136 
Patent Status: 
No patent action is contemplated by NASA. 
Source: D. P. Townsend
Lewis Research Center

(LEW-1 1483) 
S
Category 04 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States 	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19720000136 2020-03-17T03:30:42+00:00Z


Lubricant selection for gear designers

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server