Hollow Shaft Gearboxes
Articles About Hollow Shaft Gearboxes
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Approximately one quarter of all servo motors around the world require some type of gear reduction in their applications. From large satellite dishes to precision medical devices, gearboxes boost torque and reduce speed for servos in order for them to be sized more efficiently. While gearbox fundamentals haven't changed much over the past 20 years, their effectiveness has improved significantly, driven mostly by the need to accommodate advancements in servo technology.
Gear drives focus on longevity, quality and customization.
Schaeffler Touts System Solutions and Electrification Advancements at Detroit Symposium
With the increasing mechanical power capacity of gearboxes, the thermal power limit tends to become the limiting factor. To achieve a balanced system, the gear unit needs extra cooling. Using a fan that is mounted to a fast rotating shaft is a common solution. For this solution an optimal design is investigated.
The proof of the reliability of a gear drive is now an additional requirement. In Europe, the acceptance authorities for wind turbines are requesting a system reliability proof from gearbox manufacturers. The AGMA committee reviewing the AGMA 6006 standard for wind turbines is considering adding a chapter about design for reliability. However, reliability considerations are not new; NASA, for example, was in the 1980s using reliability concepts for gear drives.
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.
Modern drivetrains with voltage-source inverters not only offer advantages like, for example, variable speed operation, increased efficiency and higher dynamics, but also an increase in failures caused by induced parasitic currents.
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.
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.
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
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.
In this study, a finite volume CFD simulation model of a single-stage injection-lubricated test gearbox was applied to investigate its oil flow and no-load power loss. The results provide physically plausible information on the oil supply and its distribution.
Worm, bevel, and parallel shaft gear units were installed at two breweries to provide the necessary process control.
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Rolls-Royce is pioneering the UltraFan engine family architecture containing a planetary gearbox in a power range of 15 to 80 megawatts. To increase the efficiency of the UltraFan, a planetary gearbox is introduced between fan and intermediate pressure compressor. This enables running the turbine to rotate faster and allows a reduced fan speed.
The presented method offers a possibility or the quantitative evaluation of the operational behavior of integrated transmission systems.
Bearing subsystem life and reliability explained.
Research has shown that the phasing of the planets in an epicyclic system can have a significant impact on the dynamic characteristics of the gearbox.
Condition Monitoring Technology Evolves for Gear Drives, Gearmotors and Gearboxes. Here's a look at what some leading manufacturers are offering.
PTE Examines Gearmotor and Gear Drive Technology
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.
In this paper, the models for different power loss sources in transmissions from literature are applied and compared, which form the two methods - ISO 14179-2 and the joint model to estimate the power losses in a transmission. A 2-speed transmission in an electric vehicle is used as a case study to compare the two methods and validate them with experimental data.
Prototype and Process Development Ensuring Stable Quality at the Highest Level
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 thereâ™s an often over-looked alternative, the two-stage helical bevel gearbox.
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.
Sustainability is becoming one of the most important aspects within the power transmission business. Users demand low-maintenance drive systems with as little disruption as possible, and expect lifetimes of more than 10,000 hours. Approximately 40 percent of long-term gearbox leakages can be traced back to poor interaction between the radial shaft seal (RSS) and the lubricant. Thus, it becomes essential to analyze the tribological system as a whole, which includes the gear oil, seal grease (if required), elastomer material and design, and the shaft.
SKF Product Investigation Center Troubleshoots Critical Rotating Equipment Applications with Analysis, Research and Testing Procedures.
FVA Offers FE Shaft Calculations in the FVA-Workbench
With today's smaller, hotter - and overloaded - machinery, specifying the correct lubricant is vital.
Th e signing of a contract for more than 5,000 sets of SKFâ™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 Companyâ™s (NGC) line of gearboxes for wind generation applications.
I'm not able to get a good connection between the pulley and shaft in my drive assembly. Could you explain the various ways of connecting a pulley to a shaft to prevent the pulley from slipping?
U.S. manufacturers, such as food processors, face an unprecedented competitive environment and must look for ways to be profitable without negatively affecting the quality of finished products.
Most manufacturers of shaft-mounted speed reducers offer torque arms for their products. However, in some situations, a machine designer may be required to design his own.
S.S. White Provides Twisting, Turning Power Transmission with Flexible Shafts
A new preventive maintenance program at a leading New England Ivy League university demonstrates how the push for more sustainable "green" building management has led to a growing awareness of a chronic, widespread problem with HVAC motors—electrical bearing damage and failure.
All major manufacturers of 3-phase AC induction motors offer "inverter-duty" or "inverter-readyâ models, but while these motors have inverter-rated insulation to protect the windings, the bearings--their most vulnerable parts--are too often ignored.
Volatile aerospace market keeps gear manufacturers guessing.
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.
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.
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.
In recent years the estimation of gearbox power loss is attracting more interest â” especially in the wind turbine and automotive gearbox industry â” 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.
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 â” 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.
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.
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.
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.
Our product focus includes the latest technology in gears and gear drives from the leading manufacturers.
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.
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.
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.
You need to transmit a rotary motion where no straight line is possible. Or, you need to allow for some uncontrollable misalignment. How about transmission taking place between moving components? What if you need to control something in hazardous locations where you cannot directly handle the application, such as high-temperature environments, under hazardous conditions or in clean room applications? Functionally designed flexible shafts can meet all these challenges.