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Gears in nature: The Issus develops working gears in response to selective pressure.
Many gear companies make parts, build assemblies...and stop there. But, some don't stop; they go a step further and create end-products. Three gear companies have taken that step, and taken on nature with their creations.
This issue of Addendum is dedicated to gears that have served their country. There have been many, but among the most significant are surely those at work during the Civil War, when their application changed the nature of naval warfare forever. It's time to recall that role, namely, powering the revolving turret of the U.S.S. Monitor, one of the first "ironclad" vessels.
Every once in a while something happens to fundamentally change the nature of your business. Despite the best of intentions and the most careful planning, there's no way we can anticipate every event. What do you do, for example, when your two biggest competitors merge, when the economy collapses in the region that imports your products or when key employees leave your company? Your reactions may make the difference between success and struggling to survive.
Surface-hardened, sintered powder metal gears are increasingly used in power transmissions to reduce the cost of gear production. One important problem is how to design with surface durability, given the porous nature of sintered gears. Many articles have been written about mechanical characteristics, such as tensile and bending strength, of sintered materials, and it is well-known that the pores existing on and below their surfaces affect their characteristics (Refs. 1-3). Power transmission gears are frequently employed under conditions of high speed and high load, and tooth surfaces are in contact with each other under a sliding-rolling contact condition. Therefore it is necessary to consider not only their mechanical, but also their tribological characteristics when designing sintered gears for surface durability.
Have you ever watched the odometer on your car as you approach 100,000 miles? Something about human nature compels us to watch the odometer roll over. It may be just a fascination with numbers: Seeing all those nines line up is rare, and we don't want to miss it. but it may also have to do with the feeling of being on the verge of something that won't come again.
Audits of the heat treating department are a vital part of any good quality program - either as part of a self-assessment or ISO program for a captive shop or - of equal importance - as part of an evaluation of the capabilities of a commercial heat treat supplier. In either case, the audit process needs to be formal in nature and follow specific guidelines.
Gear pitting is one of the primary failure modes of automotive transmission gear sets. Over the past years, many alternatives have been intended to improve their gear surface durability. However, due to the nature of new process development, it takes a length of time and joint efforts between the development team and suppliers to investigate and verify each new approach.
New freedom of motion available with CNC generators make possible improving tooth contact on bevel and hypoid gears. Mechanical machines by their nature are inflexible and require a special mechanism for every desired motion. These mechanisms are generally exotic and expensive. As a result, it was not until the introduction of CNC generators that engineers started exploring motion possibilities and their effect on tooth contact.
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
It may not be widely recognized that most of the inspection data supplied by inspection equipment, following the practices of AGMA Standard 2015 and similar standards, are not of elemental accuracy deviations but of some form of composite deviations. This paper demonstrates the validity of this “composite” label by first defining the nature of a true elemental deviation and then, by referring to earlier literature, demonstrating how the common inspection practices for involute, lead (on helical gears), pitch, and, in some cases, total accumulated pitch, constitute composite measurements.
At its location in Roscoe, IL, the Forest City Gear facility is surrounded by wildlife splendor. Fruit trees, nature walks and the occasional cute and furry animal sighting create an unlikely landscape for a manufacturing site. Of course, cavorting with the cute and furry does have its drawbacks.
The large gears found in mining, steel, construction, off-road, marine and energy applications—massive and robust in nature—need to tackle the greatest production demands. This, in turn, means that a special emphasis must be put on the heat treating methods used to increase the wear resistance and strength properties of gears this size.
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.
These lines, interesting enough, are from the notebooks of an artist whose images are part of the basic iconography of Western culture. Even people who have never set foot in a museum and wouldn't know a painting by Corregio from a sculpture by Calder, recognize the Mona Lisa. But Leonardo da Vinci was much more than an artist. He was also a man of science who worked in anatomy, botany, cartography, geology, mathematics, aeronautics, optics, mechanics, astronomy, hydraulics, sonics, civil engineering, weaponry and city planning. There was little in nature that did not interest Leonardo enough to at least make a sketch of it. Much of it became a matter of lifelong study. The breadth of his interests, knowledge, foresight, innovation and imagination is difficult to grasp.
This paper addresses Austempered Ductile Iron (ADI) as an emerging Itechnology and defines its challenge by describing the state-of-the-art of incumbent materials. The writing is more philosophical in nature than technical and is presented to establish a perspective.
The phenomena of deterioration of surfaces are generally very complex and depend on numerous conditions which include the operating conditions, the type of load applied, the relative speeds of surfaces in contact, the temperature, lubrication, surfaces hardness and roughness, and the compatibility and nature of materials.
News Items About nature
1 Cimcool Presents Oak Signature Metalworking Fluids (November 18, 2011)
The Oak Signature brand of metalworking fluids integrates science and technology to help customers become more efficient in the manufactu... Read News