It's every gear manufacturer's nightmare. Your company had been named as a defendant in a product liability suit - one involving serious injuries and death. You're facing endless court appearances, monumental legal fees, and, possibly, seven figure settlements our of your coffers. The very existence of your business could be on the line. The question is, how do you prevent this nightmare from becoming a painful reality.
The design of any gearing system is a difficult, multifaceted process. When the system includes bevel gearing, the process is further complicated by the complex nature of the bevel gears themselves. In most cases, the design is based on an evaluation of the ratio required for the gear set, the overall envelope geometry, and the calculation of bending and contact stresses for the gear set to determine its load capacity. There are, however, a great many other parameters which must be addressed if the resultant gear system is to be truly optimum.
A considerable body of data related to the optimal design of bevel gears has been developed by the aerospace gear design community in general and by the helicopter community in particular. This article provides a summary of just a few design guidelines based on these data in an effort to provide some guidance in the design of bevel gearing so that maximum capacity may be obtained. The following factors, which may not normally be considered in the usual design practice, are presented and discussed in outline form:
Integrated gear/shaft/bearing systems
Effects of rim thickness on gear tooth stresses
Resonant response
A few months ago at the AGMA management seminar, I was surprised by the feverish note taking that went on at a presentation on marketing. The sight reminded me that while many of us in the gear industry are good engineers, designers, and mangers, we are often not as familiar - or comfortable - with less concrete concepts, such as marketing.
Dear Editor:
In Mr. Yefim Kotlyar's article "Reverse Engineering" in the July/August issue, I found an error in the formula used to calculate the ACL = Actual lead from the ASL = Assumed lead.
October is the time. Detroit is the place. AGMA Gear Expo '91 is the event. Cobo Center in downtown Detroit is where you will want to be in October if you have any interest in gear products, manufacturing, or research.
AGMA's Gear Expo '91, "The World of Gearing," opens Oct. 20-23 at Cobo Conference & Exhibition Center, Detroit, MI. Gear Expo '91 will provide 35,000 square feet of exhibits by 91 companies from around the world.
Dictatorships can be stifling. In an autocratic organization, employees seldom participate in decisions that affect them. By establishing a collaborative environment, you allow everyone to play a role in making your organization a success.
AGMA's Gear Expo '91, "The World of Gearing," opens October 20 and runs through October 23 at the Cobo Conference & Exhibition Center in "The Heart of the Manufacturing Industry," Detroit, MI. Gear Expo '91 is "the largest trade show ever specifically organized for the gear industry," according to Rich Norment, AGMA's Executive Director.
Spur gear endurance tests were conducted to investigate the surface pitting fatigue life of noninvolute gears with low numbers of teeth and low contact ratios for the use in advanced application. The results were compared with those for a standard involute design with a low number of teeth. The gear pitch diameter was 8.89 cm (3.50 in.) with 12 teeth on both gear designs. Test conditions were an oil inlet temperature of 320 K (116 degrees F), a maximum Hertz stress of 1.49 GPa (216 ksi), and a speed of 10,000 rpm. The following results were obtained: The noninvolute gear had a surface pitting fatigue life approximately 1.6 times that of the standard involute gear of a similar design. The surface pitting fatigue life of the 3.43-pitch AISI 8620 noninvolute gear was approximately equal to the surface pitting fatigue life of an 8-pitch, 28-tooth AISI 9310 gear at the same load, but at a considerably higher maximum Hertz stress.