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Articles About theory


1 Got Lean, Six Sigma - Here's Another Theory (March/April 2009)

Most readers are at least familiar with continuous improvement programs such as lean and six sigma. Perhaps your shop or company is well along in the implementation of one or the other—if not both. But what about theory of constraints (TOC), introduced in Dr. Eliyahu Goldratt’s 1984 book, The Goal? Despite its rather negative-sounding name, this continuous improvement process has much to offer manufacturers of all stripes. And when combined with lean and six sigma, the results can be dramatic. Dr. Lisa Lang, a TOC consultant and speaker, explains why and how in the following Q&A session with Gear Technology.

2 Helical Gears With Circular Arc Teeth: Simulation of Conditions of Meshing and Bearing Contact (July/August 1987)

Circular arc helical gears have been proposed by Wildhaber and Novikov (Wildhaber-Novikov gears). These types of gears became very popular in the sixties, and many authors in Russia, Germany, Japan and the People's Republic of China made valuable contributions to this area. The history of their researches can be the subject of a special investigation, and the authors understand that their references cover only a very small part of the bibliography on this topic.

3 Tribology Aspects in Angular Transmission Systems, Part 1 (August 2010)

"General Explanations on Theoretical Bevel Gear Analysis" is part 1 of an eight-part series from Gleason's Dr. Hermann Stadtfeld.

4 Development of Gear Technology and Theory of Gearing (July/August 1999)

I must admit that after thumbing through the pages of this relatively compact volume (113 pages, 8.5 x 11 format), I read its three chapters(theory of gearing, geometry and technology, and biographical history) from rear to front. It will become obvious later in this discussion why I encourage most gear engineers to adopt this same reading sequence!

5 Parallel Axis Gear Grinding: Theory & Application (November/December 2000)

The goal of gear drive design is to transit power and motion with constant angular velocity. Current trends in gear drive design require greater load carrying capacity and increased service life in smaller, quieter, more efficient gearboxes. Generally, these goals are met by specifying more accurate gears. This, combined with the availability of user-friendly CNC gear grinding equipment, has increased the use of ground gears.

6 Inspiring the World Beyond the Theory of Gearing (June 2014)

Celebrating Dr. Faydor Litvin: Remarkable Scientist, Dedicated Mentor, Continuing Inspiration

7 The Elementary Theory for the Synthesis of Constant Direction Pointing Chariots (or Rotation Neutralizers) (November/December 1988)

The south-pointing chariot exhibited at the Smithsonian Institution, Washington, D.C., (circa 2600 BC)is shown in Fig. 1. Although the mechanism is ancient, it is by no means either primitive or simplistic. The pin-tooth gears drive a complex system, wherein the monk on the top of the chariot continues to point in a preset direction, no matter what direction the vehicle in moved, without a slip of the wheels.(1)

8 Optimum Shot Peening Specification - II (January/February 1992)

Following is the second part of an article begun in our last issue. The first part covered basic shot peening theory, shot peening controls, and considerations that should go into developing a shot peening specification. Part II covers optional peening methods and the relationship of shot peening specifications to the drawings.

9 Gear Noise As a Result of Nicks, Burrs and Scale - What Can Be Done (July/August 1996)

There are many different causes of gear noise, all of them theoretically preventable. Unfortunately, the prevention methods can be costly, both in equipment and manpower. If the design of the gear and its application are appropriate, in theory all that is necessary is to have a tight control on the process of producing the finished gear. In reality, there are many variables that can cause a process, no matter how well-controlled, to deteriorate, and thus cause errors, some of which will cause a gear to produce unwanted noise when put to use.

10 Evaluation of Methods for Calculating Effects of Tip Relief on Transmission Error, Noise and Stress in Loaded Spur Gears (January/February 2012)

The connection between transmission error, noise and vibration during operation has long been established. Calculation methods have been developed to describe the influence so that it is possible to evaluate the relative effect of applying a specific modification at the design stage. These calculations enable the designer to minimize the excitation from the gear pair engagement at a specific load. This paper explains the theory behind transmission error and the reasoning behind the method of applying the modifications through mapping surface profiles and determining load sharing.

11 Practical Considerations for the Use of Double-Flank Testing for the Manufacturing Control of Gearing - Part II (March/April 2014)

Part I of this paper, which appeared in the January/February issue of Gear Technology, described the theory behind double-flank composite inspection. It detailed the apparatus used, the various measurements that can be achieved using it, the calculations involved and their interpretation. The concluding Part II presents a discussion of the practical application of double-flank composite inspection -- especially for large-volume operations. It also addresses statistical techniques that can be used in conjunction with double-flank composite inspection, as well as an in-depth analysis of gage R&R for this technique.

12 Gearbox Speed Reducer Helps Fan Technology for "Greener" Jet Fuel Efficiency (August 2008)

Today’s ever-evolving global economic engine is, in many ways, a wonderful phenomenon; you know—a rising-tide-lifting-all-boats, trickle-down-theory-of-economics dynamic at work.

13 Practical Considerations for the Use of Double-Flank Testing for the Manufacturing Control of Gearing - Part I (January/February 2014)

Part I of this paper describes the theory behind double-flank composite inspection, detailing the apparatus used, the various measurements that can be achieved using it, the calculations involved and their interpretation. Part II, which will appear in the next issue, includes a discussion of the practical application of double-flank composite inspection, especially for large-volume operations. Part II covers statistical techniques that can be used in conjunction with double-flank composite inspection, as well as an in-depth analysis of gage R&R for this technique.

14 Going Lean Is One Thing (June 2007)

Google “lean manufacturing” and you will find a virtually endless font of information regarding formal lean implementation. You’ll see definitions for Japanese words such as kaizen, gemba, muda, mura, kanban, and so on. You will also find other variations or iterations of lean, e.g.: Six Sigma, Lean Sigma, TPS (Toyota Production System), TOC (Theory of Constraints), JIT (Just in Time), and others.

15 The Words and Wisdom of Sheldon Gear Ratio Brown (August 2010)

Bicyclophiles (OK—not a real word, but you get the idea) around the globe may very well know the name, but chances are good that most Gear Technology readers have never heard of Sheldon Brown, AKA—“Gear Ratio,” “Gain Ratio,” “Mouldy Oldie,” “Theory,” “Quixote,” “Fixit” and some the Addendum team probably missed.