Articles About gear design
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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.
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.
Our expert explores standard vs. optimized gears, as well as high contact ratio gearing.
Power density is a key factor in gear design. Increasing the power density enables engineers to use smaller gears for their applications which lead to smaller and lighter gear boxes. The benefit for example for the automotive industry is less moving load in the vehicles and therefor a reduction of fuel consumption and subsequently a reduction of CO2 emission. The limiting factor for the increase in power density of gears is the material strength in regard to the critical failure mode.
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.
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.
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.
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.
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.
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 â” 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.
When designing spur teeth, is there a formula/guideline/design guide for determining the amount of crowning?
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.
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?
Todayâ™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 â” with little or no increase in cost. This paper will propose adopting these high-contact ratio forms to industrial use.
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.
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 (160â“250° F) and lubricating jet pressure (60â“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.
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.
Artist Tom Longtin adds completely non-circular planetary gears to his unique portfolio.
Cylindrical gear design can be divided into three steps. In the first step, rough gear pair dimensions such as center distance and face width are being estimated. Center distance and face width are directly linked to the available space (housing dimensions) and influence the overall size, weight and cost of the gears.
In this centuryâ™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.
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.
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.
News from around the industry
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.
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.
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
Here's what one supplier is doing to take advantage of the mobile phone in your pocket.
Engineers typically learn that the bearing L10 life can be estimated using the so called âœC/P methodâ â” or the âœbasic rating lifeâ of the bearing, a method rooted in the 1940s. Major developments have since led to the âœmodified rating life,â 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 â” 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 â” use of these improved calculation methods are not practiced by all engineers. Indeed â” many continue referring to the old model as a way of seeking compliance with existing, established practices.
The load carrying capacity of gear transmissions depends strongly on design, material and operation conditions. Modern analysis methods, e.g. finite element analysis (FEA), consider the above parameters with more or less sufficient accuracy. Yet it remains an ongoing challenge to account for backlash and manufacturing errors, despite a definite need to do so.
Modern aircraft, missiles and space vehicles employ a large number of electric motors and actuators. While the basic design of these motors is in many respects very similar to that of their automotive and industrial counterparts, motors for aerospace applications differ significantly in some areas.
In a research project at the Vienna University of Technology, the KISSsoft design software was used to check a new drivetrain concept and the micro-geometry of the bevel gear stage for a UAV (unmanned aerial vehicle).
How one gearbox manufacturer took an existing design and transformed it to meet the needs of this demanding environment.
In the general context of the reduction of energy consumption and polluting emissions, gearbox efficiency has become a major issue.
When it comes to a steel-gear mesh, there are several common standards and design rules on how to reduce noise emissions in the mesh. But if plastic gears are involved, this is no longer the case. The topic of this presentation is to highlight some of the differences between metal-and-plastic gear meshes, i.e. which design strategies can be stated as valid for metal as well as plastic and which are not?
The complete Product News section from the October 2018 issue of Power Transmission Engineering.
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.
Thrust cone bearings are an elegant option to handle the axial forces generated by the torque transmission in helical-toothed gear stages. They have proven as an efficient and reliable bearing concept for integrally geared compressors but are nearly unknown in other fields of gearbox engineering. The presented investigations consider three aspects which appear relevant to extend the field of possible applications for thrust cones towards gearboxes constructed with roller bearings.
The complete Industry News section from the June 2018 issue of Power Transmission Engineering.
Gearboxes are important assemblies within mechatronic systems. During the design phase of such systems it is essential to know the gearbox behavior under consideration of dynamic interactions with its environment. Holistic system simulation helps the engineer to understand this and to improve, adjust, or optimize gearboxes and their application.
It is hard these days to find any device that is not IoT-compatible or WiFi-connected. I recently had a new well pump installed that requires an iPhone for setup, which makes it hard for me to check or change the setup since I do not own an iPhone. In Olden Times, you had potentiometers or RS-232 connections - and that was fine.
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.
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.
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 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.
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...
Energy-challenged industries--and countries--can benefit from improved motor design and materials.
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 designâ”internal dimensions, tolerances, materials, lubrication and assembly processâ”while keeping the interface to the mechanism, mass and function.
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.
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.
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.
One of the driving forces behind the industrial revolution was the inventionâ”more than a century agoâ”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 semiconductorsâ”along with digital controlsâ”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.
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.
A reader asks for clarification on last issue's Ask the Expert column about ball screw sizing.
The complete Industry News section from the September 2014 issue of Power Transmission Engineering.
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 âœsmallâ 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.
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.
How does one draw and mesh involute gear teeth in AutoCAD?
The mechanical components of your drive system play a major role in overall system efficiency. Don't cut corners.
This paper summarizes the chemical, metallurgical and physical aspects of bearing steels and their effect on rolling bearing life and reliability.
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.
A reader asks what are the required parameters to properly specify a gear.
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.
News Items About gear design
1 New Brevini High Power Series Combines Epicyclic Gear Design with Modularity (March 2, 2007)
Brevini's new ?High Power? Series combines the highly efficient epicyclic gear design of Brevini's recently introduced ?S? Series...
2 Excel Gear Designs, Prototypes Navy Gun System Gearboxes (September 10, 2009)
Roscoe, IL-based Excel Gear has transitioned from prototype to production of 38:1 ratio gearboxes designed for positioning the gun mount ...