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Circular pitch gives me the size of the teeth in my mind, but diametral pitch does not. What is the purpose of the diametral pitch concept? Does it merely avoid pi in calculation?
A four-point contact ball bearing makes it easy to simplify machine designs that combine radial, thrust and moment loads, because it can handle all three simultaneously. They are primarily used for slow-to-moderate-speed applications, or where oscillatory movement is predominant.
Spiroid and worm gears have superior advantages for hightorque and miniaturization applications. And for this reason they are particularly preferred in aerospace, robotic and medical applications. They are typically manufactured by hobbing technology, a process with a typical overall lead time of 4 to 14 weeks.
Today’s competitive industrial gear marketplace demands products with excellent reliability, high capacity and low noise. Surface-hardened, ground tooth gearing predominates, but the legacy tooth forms handicap further improvements in capacity and noise generation. Vehicle and aircraft equipment use tooth forms not found in the standard tables to achieve better performance — with little or no increase in cost. This paper will propose adopting these high-contact ratio forms to industrial use.
Experts gathered at the 9th CTI Symposium to discuss the challenges of reducing noise, improving energy efficiency and meeting the changing demands of the marketplace
Engineers typically learn that the bearing L10 life can be estimated using the so called “C/P method” — or the “basic rating life” of the bearing, a method rooted in the 1940s. Major developments have since led to the “modified rating life,” released in ISO 281:2007, which includes the aiso life modification factor. In this paper a succession of equations used for bearing life ratings are reviewed, and current bearing life rating practices are discussed in detail. It is shown that — despite the introduction more than 30 years ago of the adjustment factor of the basic rating life, and the standardization in 2007 of the aiso modification factor — use of these improved calculation methods are not practiced by all engineers. Indeed — many continue referring to the old model as a way of seeking compliance with existing, established practices.
One of our goals at Power Transmission Engineering is to help you understand, identify and select the best technology for your mechanical power transmission or motion control applications. With every project, you have to decide which components to use, and which suppliers, based on functionality, quality and price. We aim to help you make those decisions informed by providing the latest information on current technology, especially when it comes to mechanical components.
University lab's motor eliminates pricey rare-earth magnets.
The Calendar for events happening in the industry
According to the Department of Energy (DOE), more than half of all electrical energy consumed in the U.S. is used by electric motors. To address this, several years ago, the DOE conducted a technical study as to what could be done to raise the efficiency levels of “small” motors. After years of study and litigation, the Small Motor Rule (SMR) was passed that covers two-digit NEMA frame single- and three-phase ¼ through 3 horsepower motors in open enclosures.
When comparing bearing suppliers, engineers are often left with few options other than to compare dynamic load ratings and corresponding life calculations. Of course, we can look at steel and manufacturing quality; but if we are comparing sources of similar quality, those items may not provide a large contrast. It often surprises people to learn that bearing capacities are calculated values, not tested values. Lately, however, a trend is emerging for bearing suppliers to increase their ratings for higher performance bearings that have premium features such as higher quality steel and specilaized heat treatment. Bearing companies are under intense competitive pressure to make every feature add to the dynamic capacity of their bearings because it is very well understood that an increase in capacity adds to the bottom line.
Tooth contact analysis (TCA) is an important tool directed to the determination of contact patterns, contact paths, and transmission errors in gear drives. In this work, a new general approach that is applicable to any kind of gear geometry is proposed.
In this paper, the influences of various gear parameters on the mesh stiffness are systematically investigated by using the finite element method. The comprehensive analysis shows that contact ratios are the key factors affecting the fluctuation value of mesh stiffness.
Does the definition of specific sliding mean the same between ISO 21771:2007 and AGMA 917-B97? In ISO, specific sliding is the ratio of the sliding speed to the speed of a transverse profile in the direction of the tangent to the profile. In AGMA, specific sliding is ratio of gear tooth sliding velocity to its rolling velocity.
I need help determining the diametral pitch needed to achieve the closest center-to-center distance for 2 spur gears. The 1st gear is a 34-tooth and the 2nd gear is a 28-tooth. The center-to-center distance between the gears needs to be as close to 2 1⁄8" as possible.
Standardized calculation methods such as ISO 6336 and DIN 3990 already exist to determine the load distributions on gears inside a planetary gearbox, but by their very universal nature, these methods offer varying results depending on the gearbox design. Double helical gears, in particular, can benefit from more specific, complex algorithms to reach a maximum level of efficiency. Double helical gears interact with the rest of the gearbox differently than helical or spur gears, and thus benefit from different analytical models outside the standardized methods. The present research project describes the algorithm to determine the load distribution of planetary gearboxes with double helical gears.
A reader is looking for the best reference materials with formulas for gear measurements over pins.
Our expert explores standard vs. optimized gears, as well as high contact ratio gearing.
Slow speed operation of fan systems within the air handling industry is generally performed due to two reasons: a coast down operation is required for hot (induced draft) fans to cool down before shutdown (often by using a turning gear), and operational efficiency improvements can be achieved during non-peak periods by slow speed operation using a VFD. In either case, when these fans are supported by hydrodynamic bearings, it is the oil film thickness developed from the bearing-shaft interaction that limits the minimum speed that can be maintained without causing premature wear and bearing failure. This paper will present a brief overview of lubrication theory and critical design parameters to achieve slow speed operation.
In this century’s complex, ever- changing world of manufacturing, such capabilities as hardware and software expertise, effective location and distribution, business savvy and yes, even luck, are some of the cardinal requirements for running a successful business.
Is there a gear software package out there that will calculate the design of spur, helical, worm, and planetary gearsets? Also, we would like a program that calculates stresses and material selection. Finally, we would like to have the program calculate bearings loads, too. Thank you for your help.
This paper provides a mathematical framework and its implementation for calculating the tooth geometry of arbitrary gear types, based on the basic law of gear kinematics. The rack or gear geometry can be generated in two different ways: by calculating the conjugate geometry and the line of contact of a gear to the given geometric shape of a known geometry (e.g., a cutting hob), or by prescribing the surface of action of two gears in contact and calculating the correspondent flank shapes.
The performance of high-speed helical geartrains is of particular importance for tiltrotor aircraft drive systems. These drive systems are used to provide speed reduction/torque multiplication from the gas turbine output shaft and provide the necessary offset between these parallel shafts in the aircraft. Four different design configurations have been tested in the NASA Glenn Research Center, High-Speed Helical Geartrain Test Facility. The design configurations included the current aircraft design, current design with isotropic superfinished gear surfaces, double-helical design (inward and outward pumping), increased pitch (finer teeth), and an increased helix angle. All designs were tested at multiple input shaft speeds (up to 15,000 rpm) and applied power (up to 5,000 hp). Also two lubrication, system-related, variables were tested: oil inlet temperature (160–250° F) and lubricating jet pressure (60–80 psig). Experimental data recorded from these tests included power loss of the helical system under study, the temperature increase of the lubricant from inlet to outlet of the drive system and fling-off temperatures (radially and axially). Also, all gear systems were tested with and without shrouds around the gears.
Asymmetric tooth gears and their rating are not described by existing gear design standards. Presented is a rating approach for asymmetric tooth gears by their bending and contact stress levels, in comparison with symmetric tooth gears, whose rating are defined by standards. This approach applies finite element analysis (FEA) for bending stress definition and the Hertzian equation for contact stress definition. It defines equivalency factors for practical asymmetric tooth gear design and rating. This paper illustrates the rating of asymmetric tooth gears with numerical examples.
The complete Industry News section from the September 2014 issue of Power Transmission Engineering.
Beginning with a brief summary and update of the latest advances in the calculation methods for worm gears, the author then presents the detailed approach to worm gear geometry found in the revised ISO TR 10828. With that information, and by presenting examples, these new methods are explained, as are their possibilities for addressing the geometrical particularities of worm gears and their impact upon the behavior and load capacity of a gearset under working conditions based on ISO TR 14521 — Methods B and C. The author also highlights the new possibilities offered on that basis for the further evolution of load capacity calculation of a worm gearset based on load and contact pressure distribution.
During the qualification campaign of the NIRSpec (near-infrared spectrometer) instrument mechanism, the actuator could not achieve the expected lifetime that had been extended during the development phase. The initial design could not be adapted to the requested number of revolutions during that phase. Consequently the actuator needed to be modified so that the function of the mechanism would not be endangered or, by extension, the overall function of the NIRSpec instrument. The modification included a change of the overall actuator design—internal dimensions, tolerances, materials, lubrication and assembly process—while keeping the interface to the mechanism, mass and function.
One of the driving forces behind the industrial revolution was the invention—more than a century ago—of the electric motor. Its widespread use for all kinds of mechanical motion has made life simpler and has ultimately aided the advancement of humankind. And the advent of the inverter that facilitated speed and torque control of AC motors has propelled the use of electric motors to new realms that were inconceivable just a mere 30 years ago. Advances in power semiconductors—along with digital controls—have enabled realization of motor drives that are robust and can control position and speed to a high degree of precision. The use of AC motor drives has also resulted in energy savings and improved system efficiency. This paper reviews the development and application of inverter technology to AC motor drives and presents a vision for motor drive technology.
Energy-challenged industries--and countries--can benefit from improved motor design and materials.
Motion control systems engineers work chiefly in two well-defined areas: 1) new designs and 2) redesigns or retrofits. This article examines the best approach for each option.
The availability of high-strength shaft materials, in combination with bearings with high carrying capacity, allows use of slimmer shafts. However, the modulus of elasticity remains the same, so seat design for bearings and gears must be given close attention.
The latest offering by machine design experts J.R. Hendershot and T.J.E. Miller is an 822-page brushless permanent-magnet (PM) machine design book that serves as a worthy follow-up to their 1994 work.
This paper describes the development of an educational program centered on electric motor and electric vehicle technology at the MIT (Massachusetts Institute of Technology) Edgerton Center.
This article describes how more sophisticated modeling techniques allow the latest software to identify design issues with bearings, shafts, gears and complicated multi-body systems.
Today, better fuel economy is a main objective in the automotive development process. It remains top-of-mind with the auto industry and consumers because of costs and environmental impacts. Because the industry’s average fuel-economy standard is required to increase by 40 percent by 2020, manufacturers and engineers are working to develop fuel-efficient, environmentally friendly and reliable designs for vehicles.
OEMs can minimize the cost of ownership by using highly efficient motors and recognizing when unreliable motors are driving up the operating costs of their applications.
A recent trend has been a movement to more user-friendly products in the mechanical power transmission industry. A good example of such a product is a high-horsepower, right angle, shaft-mounted drive designed to minimize installation efforts. Commonly referred to as an alignment-free type, it allows the drive package mounting to be quicker, more cost effective and require less expertise during installation. This facilitates the use of the drive in applications such as underground mining, where there is little room to maneuver parts. The most common application for the alignment-free style drive is for powering bulk material handling belt conveyors.
The use of motor structures which can concentrate magnetic flux allows ferrite PM motors to achieve performance and power densities that approach those of PM motors using rare earth magnets, but without the cost penalties and supply source concerns of rare earth magnets.
You may have noticed that the magazine looks different this issue. The new look is part of an overall effort to refine our focus. We wanted to make clear to potential subscribers and advertisers how this magazine is different, why its content is important and where it fits in the marketplace.
When software goes bad, what do we call it? System failure? Human failure? A virus? A number of words will work. How about this? Glitch. It has that onomatopoeic quality that fairly screams, Downtime! And with good reason -- software-generated miscalculations can have very expensive -- if not perilous -- repercussions.
When designing spur teeth, is there a formula/guideline/design guide for determining the amount of crowning?
A reader asks what are the required parameters to properly specify a gear.
How does one draw and mesh involute gear teeth in AutoCAD?
Following is a presentation of a gear design based upon a theoretically perfect gear technology, for which an overview is offered for consideration. What follows is a report on the design's testing and subsequent manufacture of a hypoid gear pair for a 1999 Ford Mustang.
This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability.
The mechanical components of your drive system play a major role in overall system efficiency. Don't cut corners.
The ball screw drive is an assembly that converts rotary motion to linear motion and vice versa. The ball screw drive consists of a ball screw and a ball nut with recirculating ball bearings...
This article presents the first kW-Class, 3-phase GaN-based inverter. Hard-switched at 100-kHz PWM, its heart is a 6-in-1 power module with 600-V GaN power HEMTs, achieving a new efficiency of 98.5%, a more than 2% improvement.
When it comes to gear design software, the learning curve never ends. The leading vendors offer various training programs to keep their users well-informed.
A reader asks for clarification on last issue's Ask the Expert column about ball screw sizing.
The growth of worldwide energy consumption and emerging industrial markets demands an increase of renewable energy shares. The price pressure coming from coal, oil, nuclear and natural gas energy - combined with enormous worldwide production capacities for components of wind turbines - make wind energy a highly competitive market. The testing and validation of gearboxes within the test rig and the turbine environment attract a strong focus to the needs of the industry. The following contribution sums up the typical process requirements and provides examples for successful system and component verifications based on field measurements.
News Items About Matrix Design
1 Matrix Design Opens Indianapolis Sales Office (February 5, 2016)
Matrix Design, LLC has announced the opening of their Indianapolis sales office. The new sales office will be lead by Tim Fenner, who rec...