The Integral Temperature Method for the evaluation of the scoring load capacity of gears is described. All necessary equations for the practical application are presented. The limit scoring temperature for any oil can be obtained from a gear scoring test.
With the publishing of various ISO draft standards relating to gear rating procedures, there has been much discussion in technical papers concerning the various load modification factors. One of the most basic of parameters affecting the
rating of gears, namely the endurance limit for either contact or bending stress, has not, however, attracted a great deal of attention.
History comes around full circle. It is interesting to talk to gear manufacturers who service the defense, aerospace, automotive and computer industries and find that their sales, production and backlogs reflect excellent and, in some cases, record breaking business.
Selection of the number of teeth for each gear in a gear train such that the output to input angular velocity ratio is a specified value is a problem considered by relatively few published works on gear design.
One of the major problems of plastic gear design is the knowledge of their running temperature. Of special interest is the bulk temperature of the tooth to predict the fatigue life, and the peak temperature on the surface of the tooth to avert surface failure. This paper presents the results of an experimental method that uses an infrared radiometer to measure the temperature variation along the profile of a plastic gear tooth in operation.
Measurements are made on 5.08, 3.17, 2.54, 2.12 mm module hob cut gears made from nylon 6-6, acetal and UHMWPE (Ultra High Molecular Weight Polyethylene). All the tests are made on a four square testing rig with thermoplastic/steel gear pairs where the
plastic gear is the driver. Maximum temperature prediction curves obtained through statistical analysis of the results are presented and compared to data available from literature.
Gear gashing is a gear machining process, very much like gear milling, utilizing the principle of cutting one or more tooth (or tooth space) at a time. The term "GASHING" today applies to the roughing, or roughing and finishing, of coarse diametral pitch gears and sprockets. Manufacturing
these large coarse gears by conventional methods of rough and finish hobbing can lead to very long machining cycles and uneconomical machine utilization.
As a result of extensive research into the vibration characteristics of gear drives, a systematic approach has evolved, by which damaging resonances can be eliminated. The method combines
finite element techniques with experimental signature and modal
analyses. Implementation of the bulk of the method can be carried out early in the design stage. A step-by-step description of the approach, as it was applied to an existing accessory drive, is given in the text. It is shown how
premature bearing failures were eliminated by detuning the torsional
oscillations of a gearshaft. A dramatic reduction in vibration levels was achieved as a result of detuning the problem gear. The proposed approach can be extended to other types of rotating machines.
What was once recognized as the unique
genius of America is now slipping away
from us and, in many areas, is now seen as a "second rate" capability. Unless
action is taken now, this country
is in real danger of being unable to regain its supremacy in technological development and economic vigor. First Americans must understand the serious implications of the problem; and second, we must dedicate ourselves to national and local actions that will ensure a greater scientific and
technological literacy in America.
Gear shaving is a free-cutting gear finishing operation which removes small amounts of metal from the working surfaces
of the gear teeth. Its purpose is to correct errors in index, helical angle, tooth profile and eccentricity.