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Planetary Gears

TECHNICAL ARTICLES | 2024-05-10

Flexible Planet Pins for High Torque Epicyclic Gears: Experience with Design, Manufacturing, and Application

For wind turbine main gearboxes (MGBs) with about 1 MW or higher power, gearbox designs with multiple power paths are used. They handle several mega-Newton-meter of torque economically. Earlier wind turbines with lower power ratings used parallel shaft gearboxes with only one power path but soon they were superseded by planetary gearboxes having typically three to five planets per stage. This paper describes experiences using planetary gears where “Flexpins” are used to improve the load sharing between the individual planets—representing the multitude of power paths—and along the planet’s face width.

ADDENDUM | 2024-05-10

Once More Around the Sun

A gear is nothing without its counterparts. Gears work in conjunction with other components within a gear system to achieve specific mechanical functions. These counterparts work together synergistically to form functional gear assemblies capable of transmitting motion and torque, converting speed and torque ratios, and performing a wide range of mechanical tasks in various applications across industries.

TECHNICAL ARTICLES | 2024-04-09

Cross-Correlation of Design Variables for Epicyclic Systems

This paper shows a methodology to extensively evaluate different designs of epicyclic gear systems. As outlined, no choice is required on the part of the designer who is free to probe all design variables.

TECHNICAL ARTICLES | 2023-10-05

Experimental Evaluation of Wind Turbine Gearbox Structural Models Using Fiber Optic Strain Sensors

The main objective of this study is to perform an experimental evaluation of the structural model of a five-planet first planetary stage from a modern 6MW wind turbine gearbox.

TECHNICAL ARTICLES | 2022-05-19

Algorithm-Based Optimization of Gear Mesh Efficiency in Stepped Planetary Gear Stages for Electric Vehicles

The objective of this paper is to develop a method for the algorithm-based design and optimization of the macrogeometry of stepped planetary gear stages.

TECHNICAL ARTICLES | 2020-07-01

Influence of Planet Carrier Misalignments on the Operational Behavior of Planetary Gearboxes

This study deals with the modeling and consideration of misalignments in planetary gearboxes in the optimization and design process. Procedures for taking into account misalignments in cylindrical gearboxes are standardized and established in industry. Misalignments of central elements like carrier, sun gear or ring gear in planetary gearboxes, cause varying contact positions and variable loads, depending on the angular position of the central elements. This load, which is variable over the circumference, is not taken into account in the standardized procedures, despite its effects on the loads on the gears.

TECHNICAL ARTICLES | 2020-05-01

New Guideline for Determining the Reliability of Planetary/Spur Gear Units

In the wind power industry, the reliability of powertrain components plays a major role. Especially in multi-megawatt offshore applications, an unplanned replacement of drivetrain components can lead to extremely high costs. Hence, the expectation of wind farm operators is to forecast the system reliability. Under the leadership of the VDMA (Mechanical Engineering Industry Association), the standardization paper 23904 "Reliability Assessment for Wind Turbines" was published in October 2019.

INDUSTRY NEWS | 2018-08-15

IMTS 2018: A Field Guide

Chicago Preps for the Next Manufacturing Technology Extravaganza Matthew Jaster, Senior Editor

INDUSTRY NEWS | 2018-08-13

International Gear Conference 2018

Lyon, France. Mechanical transmission components such as gears, rolling element bearings, CVTs, belts, chains, etc. are present in every industrial...

INDUSTRY NEWS | 2018-04-30

EMAG Gets Smart with Mobile Analytics

Machine data has never been easier to collect, distribute and analyze. Monitoring production lines, evaluating tools and surveying tool conditions ...

INDUSTRY NEWS | 2015-05-18

Santasalo Launches Quatro+ Planetary Gears

Santasalo recently introduced their new series of planetary gear units to the global industrial market. The new Quatro+ range offers high...

TECHNICAL ARTICLES | 2014-06-01

Gear Ratio Epicyclic Drives Analysis

It has been documented that epicyclic gear stages provide high load capacity and compactness to gear drives. This paper will focus on analysis and design of epicyclic gear arrangements that provide extremely high gear ratios. Indeed, a special, two-stage planetary arrangement may utilize a gear ratio of over one hundred thousand to one. This paper presents an analysis of such uncommon gear drive arrangements and defines their major parameters, limitations, and gear ratio maximization approaches. It also demonstrates numerical examples, existing designs, and potential applications.

ASK THE EXPERT | 2014-01-01

Planet Carrier Design

With all the advantages of building float into a planetary gear system, what advantages are there to using a carrier in the first place, rather than simply having your planets float in the system?

TECHNICAL ARTICLES | 2013-11-01

Design and Optimization of Planetary Gears Considering All Relevant Influences

Light-weight construction and consideration of available resources result in gearbox designs with high load capacity and power density. At the same time, expectations for gear reliability are high. Additionally, there is a diversity of planetary gears for different applications.

TECHNICAL ARTICLES | 2013-09-01

Light-Weight Design for Planetary Gear Transmissions

There is a great need for future powertrains in automotive and industrial applications to improve upon their efficiency and power density while reducing their dynamic vibration and noise initiation. It is accepted that planetary gear transmissions have several advantages in comparison to conventional transmissions, such as a high power density due to the power division using several planet gears. This paper presents planetary gear transmissions, optimized in terms of efficiency, weight and volume.

FEATURE ARTICLES | 2012-06-01

Growing Pains - Renewables Hang on in Turbulent Energy Market

The turbines are still spinning. They’re spinning on large wind farms in the Great Plains, offshore in the Atlantic and even underwater where strong tidal currents offer new energy solutions. These turbines spin regularly while politicians and policy makers— tied up in discussions on tax incentives, economic recovery and a lot of finger pointing—sit idle. Much like the auto and aerospace industries of years past, renewable energy is coping with its own set of growing pains. Analysts still feel confident that clean energy will play a significant role in the future of manufacturing—it’s just not going to play the role envisioned four to five years ago.

TECHNICAL ARTICLES | 2011-09-01

Analysis of Load Distribution in Planet Gear Bearings

In epicyclic gear sets designed for aeronautical applications, planet gears are generally supported by spherical roller bearings with the bearing outer race integral to the gear hub. This article presents a new method to compute roller load distribution in such bearings where the outer ring can’t be considered rigid.

TECHNICAL ARTICLES | 2005-01-01

A Planetary System that Increases Power Density

Turnkey Design Services is manufacturing a planetary gear system to increase power density.

TECHNICAL ARTICLES | 1998-07-01

Effects of Planetary Gear Ratio on Mean Service Life

Planetary gear transmissions are compact, high-power speed reducers that use parallel load paths. The range of possible reduction ratios is bounded from below and above by limits on the relative size of the planet gears. For a single-plane transmission, the planet gear has no size of the sun and ring. Which ratio is best for a planetary reduction can be resolved by studying a series of optimal designs. In this series, each design is obtained by maximizing the service life for a planetary transmission with a fixed size, gear ratio, input speed, power and materials. The planetary gear reduction service life is modeled as a function of the two-parameter Weibull distributed service lives of the bearings and gears in the reduction. Planet bearing life strongly influences the optimal reduction lives, which point to an optimal planetary reduction ratio in the neighborhood of four to five.

TECHNICAL ARTICLES | 1994-03-01

Stress of Planet Gears with Thin Rims

This article discusses the relationships among the fillet stress on a thin rim planet gear, the radial clearance between the gear rim and the gear shaft, the tooth load, the rim thickness, the radius of curvature of the center line of the rim, the face width and the module.

TECHNICAL ARTICLES | 1990-07-01

Efficient Methods for the Synthesis of Compound Planetary Differential Gear Trains for Multiple Speed Ratio Generation

This article presents an efficient and direct method for the synthesis of compound planetary differential gear trains for the generation of specified multiple speed ratios. It is a train-value method that utilizes the train values of the integrated train components of the systems to form design equations which are solved for the tooth numbers of the gears, the number of mating gear sets and the number of external contacts in the system. Application examples, including vehicle differential transmission units, rear-end differentials with unit and fractional speed ratios, multi-input functions generators and robot wrist joints are given.

TECHNICAL ARTICLES | 1988-11-01

The Elementary Theory for the Synthesis of Constant Direction Pointing Chariots (or Rotation Neutralizers)

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)

TECHNICAL ARTICLES | 1988-01-01

KHV Planetary Gearing - Part II

Consisting of only a ring gear b meshing with one or two planets a, a carrier H and an equal velocity mechanism V, a KHV gearing(Fig. 1) is compact in structure, small in size and capable of providing a large speed ratio. For a single stage, its speed ratio can reach up to 200, and its size is approximately 1/4 that of a conventional multi-stage gear box.

TECHNICAL ARTICLES | 1987-11-01

KHV Planetary Gearing

Traditionally, a worm or a multi-stage gear box has been used when a large speed ratio is required. However, such boxes will become obsolete as size and efficiency become increasingly important considerations for a modern transmission. The single-enveloped worm gear has a maximum speed ratio of only 40 to 60. Its efficiency is only 30 to 60 per cent. The necessity of using bronze for the worm gear and grinding nitoalloy steel for the worm drives up material and manufacturing costs.

TECHNICAL ARTICLES | 1986-11-01

A Logical Procedure To Determine Initial Gear Size

When a gear set is to be designed for a new application, the minimum size gears with the required capacity are desired. These gears must be capable of meeting the power, speed, ratio, life, and reliability requirements.

VOICES | 1985-11-01

Industry Forum

One of the current research activities here at California State University at Fullerton is systematization of existing knowledge of design of planetary gear trains.