Gearbox Express

Articles About Gearbox Express


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1 U.S. Wind Power Blowing Hot as New Installations Flourish (October 2017)

A look at recent installations, plus interviews with some wind industry insiders.

2 Theoretical and Experimental Study of the Frictional Losses of Radial Shaft Seals for Industrial Gearbox (June 2015)

The improvement of the energy efficiency of industrial gear motors and gearboxes is a common problem for many gear unit manufacturers and end-users. As is typical of other mechanical components, the radial lip seals used in such units generate friction and heat, thus contributing to energy losses of mechanical systems. There exist today simulation tools that are already helping improve the efficiency of mechanical systems — but accurate models for seal frictional losses need to be developed. In this paper SKF presents an engineering model for radial lip seal friction based on a physical approach.

3 Space Shuttle Rudder-Speed Brake Actuator (October 2015)

The U.S. Space Shuttle fleet was originally intended to have a life of 100 flights for each vehicle, lasting over a 10-year period, with minimal scheduled maintenance or inspection. The first space shuttle flight was that of the Space Shuttle Columbia (OV-102), launched April 12, 1981. The disaster that destroyed Columbia occurred on its 28th flight, February 1, 2003, nearly 22 years after its first launch.

4 How to Get the Most Realistic Efficiency Calculation for Gearboxes (April 2015)

In recent years the estimation of gearbox power loss is attracting more interest — especially in the wind turbine and automotive gearbox industry — but also in industrial gearboxes where heat dissipation is a consideration as well. As new transmissions concepts are being researched to meet both ecological and commercial demands, a quick and reliable estimation of overall efficiency becomes inevitable in designing the optimal gearbox.

5 Gear Fault Diagnosis by Motor Current Analysis: Application to Industrial Cases (February 2015)

The use of motor current signature analysis (MCSA) for motor fault detection — such as a broken rotor bar — is now well established. However, detection of mechanical faults related to the driven system remains a more challenging task. Recently there has been a growing interest for detection of gear faults by MCSA. Advantages and drawbacks of these MCSA-type techniques are presented and discussed on a few industrial cases.

6 Finite Element Evaluation of Bearing Instrumentation Method (December 2014)

This paper presents an evaluation of measurements being taken on a 750 kW wind turbine gearbox being tested by the National Renewable Energy Laboratory (NREL). High-speed stage gears and bearings have been identified as critical components of the gearbox; during gearbox testing, these components were instrumented and tests were developed to evaluate loads on high-speed tapered roller bearings (TRBs). In this paper an advanced finite element-based contact modeling procedure has been applied to model the high-speed stage with the bearings fully modeled in order to evaluate strain levels. A major conclusion is that the strains of the slotted grooves are at such a level that they have acceptable signal-to-noise levels. This was verified by the results of the initial experiments presented here.

7 Effect of Assembly Errors in Back-to-Back Gear Efficiency Testing (December 2015)

As gear efficiency is improved in small steps, it is important to be able to distinguish actual improvements from scatter that can occur while testing. An FZG back-to-back gear test rig was used to investigate how the assembly and re-assembly of the same test setup affects the measurements. A spread in torque loss between one assembly and another of the same test setup were observed. Rig conditions also affected the spread in input torque. With knowledge of how the spread in torque loss varies due to assembly, test results could be distinguished between changes due to assembly and actual differences between tests.

8 The Modified Life Rating of Rolling Bearings: A Criterion for Gearbox Design and Reliability Optimization (March 2015)

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.

9 Two-stage Helical Bevel Gearing (February 2016)

Gearing is an essential component in conveyors. The material handling industry appears divided between those who favor high-end three-stage helical bevel gearboxes and those who rely on less expensive worm gearing. But there’s an often over-looked alternative, the two-stage helical bevel gearbox.

10 Determination of Load Distributions on Double Helical-Geared Planetary Gearboxes (June 2017)

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.

11 Product News (March 2018)

The complete Product News section from the March 2018 issue of Power Transmission Engineering.

12 Thrust Cone Bearings Provide Increased Efficiency for Helical Gear Units at Moderate Speed Levels (June 2018)

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.

13 Calendar (February 2017)

The complete technical calendar from the February 2017 issue of Power Transmission Engineering.

14 An Open-And-Shut Case: Greases for Gear Applications (September 2016)

For the lubrication of open gear drives used in different industrial applications such as cement and coal mills, rotary furnaces, or where the sealing conditions are difficult, semi-fluid greases are often used in preference to fluid oils. For girth gear applications the greases are used with a splash or spray lubrication system. The selection of such greases influences pitting lifetime and the load-carrying capacity of the gears, as well as wear behavior

15 Gear Design Effects on Performance of High-Speed Helical Geartrains as Used in Aerospace Drive Systems (March 2016)

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.

16 FZG Gearboxes Lubricated with Different Formulations of Polyalphaolefin Wind Turbine Gear Oils (August 2016)

In order to analyze the different gear oils suitable for the lubrication of wind turbine gearboxes, five fully formulated ISO VG 320 gear oils were selected. In between the selected gear oils, four PAO base oils can be found: PAOR, PAOM, PAOC and PAOX. A mineral-based oil (MINR) was also included as reference.

17 Premature Bearing Failures in Wind Gearboxes and White Etching Cracks (October 2014)

Wind turbine gearboxes are subjected to a wide variety of operating conditions, some of which may push the bearings beyond their limits. Damage may be done to the bearings, resulting in a specific premature failure mode known as white etching cracks (WEC), sometimes called brittle, short-life, early, abnormal or white structured flaking (WSF). Measures to make the bearings more robust in these operating conditions are discussed in this article.

18 Wind Turbine Field and Test Rig Testing as Part of the Design Process for Gearboxes (September 2014)

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.

19 How Green is Your Gearbox (February 2009)

Rising energy costs and concerns about global warming are at the forefront of today’s news. Turn to local or national TV programming, browse the internet or read the paper and one can find numerous stories about the seemingly irreversible energy costs and the subsequent impact that these costs have on simply doing business. As a result, we as individuals are becoming increasingly aware of the cost of energy and we are being introduced to a variety of methods and/or products that will minimize the impact of these costs.

20 Designing for Static and Dynamic Loading of a Gear Reducer Housing with FEA (February 2010)

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.

21 High-Capacity Bearings Carry the Load for Chinese Gearbox Manufacturer (December 2008)

Th e signing of a contract for more than 5,000 sets of SKF’s latest high-capacity cylindrical roller bearings (HCCRB) for wind turbines will impart added load-carrying capacity, more reliability and longer life to the Nanjing Gear Company’s (NGC) line of gearboxes for wind generation applications.

22 How to Determine the MTBF of Gearboxes (April 2008)

Mean Time Between Failures is a very frequent and broadly used reliability measure of components, systems and devices used mainly in conjunction with electrical and electronic equipment.

23 Rolling-Element Bearing Analysis (June 2013)

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.

24 Trends in Industrial Gear Oils (April 2013)

With today's smaller, hotter - and overloaded - machinery, specifying the correct lubricant is vital.

25 Gear Drive Selection Process for the Parcel Handling Industry (August 2011)

This article is designed to help describe the selection process of a reducer to be used in the parcel handling industry. It will go over the different applications for which gearboxes are used throughout parcel handling facilities such as UPS, FedEx and DHL.

26 Up in the Air - Aerospace Gears (April 2013)

Volatile aerospace market keeps gear manufacturers guessing.

27 Best Practices for Gearbox Assembly and Disassembly (March 2014)

In most applications, gearbox reliability is critical to the productivity of the overall plant operation. So it follows that when industry is looking at the best ways to increase efficiency, reduce downtime, and increase profitability, gearbox performance and reliability are key factors. Designing for repair, and writing effective repair procedures, can speed the service time, and provide a quality refurbishment. The best practices listed in this article are proven, effective methods used to install and remove bearings, seals, gears, couplings and shafts within a gearbox.

28 Investigations of Bearing Failures Associated with White Etching Areas (WEAs) in Wind Turbine Gearboxes (March 2014)

A critical problem for wind turbine gearboxes is failure of rolling element bearings where axial cracks form on the inner rings. This article presents field experience from operating wind turbines that compares the performance of through-hardened and carburized materials. It reveals that through-hardened bearings develop WEA/WECs and fail with axial cracks, whereas carburized bearings do not. The field experience further shows that a carburized bearing with a core having low carbon content, high nickel content, greater compressive residual stresses, and a higher amount of retained austenite provides higher fracture resistance and makes carburized bearings more durable than through-hardened bearings in the wind turbine environment.

29 Musical Gearboxes (October 2013)

Dave Soma, the mechanical supervisor at Leland Olds Station, a coal-fired power plant near Stanton, North Dakota, says he and his maintenance team care deeply about keeping the plant running and providing people electricity, especially in the dead of winter.

30 Considering Energy-Efficient Motors: Don't Forget the Gearbox (February 2013)

The mechanical components of your drive system play a major role in overall system efficiency. Don't cut corners.

31 Gearbox Bearing Service Life: A Matter of Mastering Many Design Parameters (April 2012)

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.

32 Gears and Gear Drives Product Focus (February 2013)

Our product focus includes the latest technology in gears and gear drives from the leading manufacturers.

33 Gear Lubrication: Long-Term Protection for Wind Turbines (April 2014)

The chemical and physical properties of gear oils may change, depending - more or less - upon their formulation and the environmental conditions under which they are used. This is why - after three years of use in a wind turbine - a gear oil was examined to determine if indeed changes were evident and if the protection of the gears and rolling bearings still met the same requirements as would be expected of fresh oil. Our findings revealed that the existing gear oil - as well as its ability to protect the gears and rolling bearings - had degraded very little compared to fresh oil.

News Items About Gearbox Express

1 Gearbox Express to Open Doors Early 2012 (November 7, 2011)
Three power transmission and wind energy veterans have banded together to create Gearbox Express, an independent business focusing on the...

2 Gearbox Express Opens 75,000-Square-Foot Wisconsin Facility (May 9, 2016)
Gearbox Express (GBX) recently celebrated the official grand opening of its new 75,000-square-foot facility in Mukwonago, Wisconsin. &qu...