Crowning

GEAR TALK WITH CHUCK | 2018-03-13

Bevel Buzzwords

Does technical lingo confuse you? If so, welcome to the bevel gear sector and its special kind of hell. The same “system” that benefited from stand...

GEAR TALK WITH CHUCK | 2017-11-02

Swag of the Expo Awards

My last blog covered the motivation for the Swag of the Expo award and my inspiration in creating it. Top contenders that did not quite qualify for...

TECHNICAL ARTICLES | 2016-06-01

Worm Gear Efficiency Estimation and Optimization

This paper outlines the comparison of efficiencies for worm gearboxes with a center distance ranging from 28 - 150 mm that have single reduction from 5 to 100:1. Efficiencies are calculated using several standards (AGMA, ISO, DIN, BS) or by methods defined in other bibliographic references. It also deals with the measurement of torque and temperature on a test rig — required for the calibration of an analytical model to predict worm gearbox efficiency and temperature. And finally, there are examples of experimental activity (wear and friction measurements on a blockon- ring tribometer and the measurements of dynamic viscosity) regarding the effort of improving the efficiency for worm gear drivers by adding nanoparticles of fullerene shape to standard PEG lubricant

GEAR TALK WITH CHUCK | 2016-02-18

Something to Look Forward to

With Super Bowl 50 behind us, the sporting public can turn its attention to basketball and hockey while baseball teams start spring training. Those...

FEATURE ARTICLES | 2013-08-01

Leading the Way in Lead Crown Correction and Inspection

Forest City Gear applies advanced gear shaping and inspection technologies to help solve difficult lead crown correction challenges half a world away. But these solutions can also benefit customers much closer to home, the company says. Here's how…

FEATURE ARTICLES | 2012-05-01

Gear Software - Without it, Hardware Goes Nowhere

It’s a brave, new hardware-software world out there. Players in the worldwide gear industry who don’t have plenty of both run the risk of becoming irrelevant—sooner than later.

FEATURE ARTICLES | 2012-03-01

The Plastic Gear Pay-Off

Eliminating noise, weight and wear proves valuable in 2012.

TECHNICAL ARTICLES | 2011-06-01

Drive Line Analysis for Tooth Contact Optimization of High-Power Spiral Bevel Gears

In the majority of spiral bevel gears, spherical crowning is used. The contact pattern is set to the center of the active tooth flank and the extent of the crowning is determined by experience. Feedback from service, as well as from full-torque bench tests of complete gear drives, has shown that this conventional design practice leads to loaded contact patterns, which are rarely optimal in location and extent. Oversized reliefs lead to small contact area, increased stresses and noise, whereas undersized reliefs result in an overly sensitive tooth contact.

TECHNICAL ARTICLES | 2010-08-01

Crowning Techniques in Aerospace Actuation Gearing

One of the most effective methods in solving the edge loading problem due to excess misalignment and deflection in aerospace actuation gearing is to localize tooth-bearing contact by crowning the teeth. Irrespective of the applied load, if the misalignment and/or deflection are large enough to cause the contact area to reduce to zero, the stress becomes large enough to cause failure. The edge loading could cause the teeth to break or pit, but too much crowning may also cause the teeth to pit due to concentrated loading. In this paper, a proposed method to localize the contact bearing area and calculate the contact stress with crowning is presented and demonstrated on some real-life examples in aerospace actuation systems.

TECHNICAL ARTICLES | 2010-07-01

Effects of Profile Corrections on Peak-to-Peak Transmission Error

Profile corrections on gears are a commonly used method to reduce transmission error, contact shock, and scoring risk. There are different types of profile corrections. It is a known fact that the type of profile correction used will have a strong influence on the resulting transmission error. The degree of this influence may be determined by calculating tooth loading during mesh. The current method for this calculation is very complicated and time consuming; however, a new approach has been developed that could reduce the calculation time.

VOICES | 2010-03-01

Crowning: A Cheap Fix for Noise and Misalignment Problems

Fred Young, CEO of Forest City Gear, talks about sophisticated gear manufacturing methods and how they can help solve common gear-related problems.

TECHNICAL ARTICLES | 2001-09-01

What "Ease-Off" shows about Bevel and Hypoid Gears

The configuration of flank corrections on bevel gears is subject to relatively narrow restrictions. As far as the gear set is concerned, the requirement is for the greatest possible contact zone to minimize flank compression. However, sufficient reserves in tooth depth and longitudinal direction for tooth contact displacement should be present. From the machine - and particularly from the tool - point of view, there are restrictions as to the type and magnitude of crowning that can be realized. Crowning is a circular correction. Different kinds of crowning are distinguished by their direction. Length crowning, for example, is a circular (or 2nd order) material removal, starting at a reference point and extending in tooth length or face width.

TECHNICAL ARTICLES | 2001-09-01

Face Gears: An Interesting Alternative for Special Applications - Calculation, Production and Use

Crown gearings are not a new type of gear system. On the contrary, they have been in use since very early times for various tasks. Their earliest form is that of the driving sprocket, found in ancient Roman watermills or Dutch windmills. The first principles of gear geometry and simple methods of production (shaper cutting) were developed in the 1940s. In the 1950s, however, crown gears' importance declined. Their tasks were, for example, taken over by bevel gears, which were easier to manufacture and could transmit greater power. Current subject literature accordingly contains very little information on crown gears, directed mainly to pointing out their limitations (Ref. 1).

TECHNICAL ARTICLES | 1995-11-01

Determining Spline Misalignment Capabilities

Introducing backlash into spline couplings has been common practice in order to provide for component eccentric and angular misalignment. The method presented here is believed to be exact for splines with even numbers of teeth and approximate for those with odd numbers of teeth. This method is based on the reduction of the maximum effective tooth thickness to achieve the necessary clearance. Other methods, such as tooth crowning, are also effective.

INDUSTRY NEWS | 1993-07-01

Gear Tip Chamfer and Gear Noise; Surface Measurement of Spiral Bevel Gear Teeth

Could the tip chamfer that manufacturing people usually use on the tips of gear teeth be the cause of vibration in the gear set? The set in question is spur, of 2.25 DP, with 20 degrees pressure angle. The pinion has 14 teeth and the mating gear, 63 teeth. The pinion turns at 535 rpm maximum. Could a chamfer a little over 1/64" cause a vibration problem?

INDUSTRY NEWS | 1992-03-01

Our Experts Discuss Hobbing Ridges, Crooked Gear Teeth, and Crown Shaving

Question: When cutting worm gears with multiple lead stock hobs we find the surface is "ridged". What can be done to eliminate this appearance or is to unavoidable?

TECHNICAL ARTICLES | 1988-09-01

Crowned Spur Gears: Optimal Geometry and Generation

Involute spur gears are very sensitive to gear misalignment. Misalignment will cause the shift of the bearing contact toward the edge of the gear tooth surfaces and transmission errors that increase gear noise. Many efforts have been made to improve the bearing contact of misaligned spur gears by crowning the pinion tooth surface. Wildhaber(1) had proposed various methods of crowning that can be achieved in the process of gear generation. Maag engineers have used crowning for making longitudinal corrections (Fig. 1a); modifying involute tooth profile uniformly across the face width (Fig. 1b); combining these two functions in Fig. 1c and performing topological modification (Fig. 1d) that can provide any deviation of the crowned tooth surface from a regular involute surface. (2)

TECHNICAL ARTICLES | 1988-05-01

Tooth Root Stresses of Spiral Bevel Gears

Service performance and load carrying capacity of bevel gears strongly depend on the size and position of the contact pattern. To provide an optimal contact pattern even under load, the gear design has to consider the relative displacements caused by deflections or thermal expansions expected under service conditions. That means that more or less lengthwise and heightwise crowning has to be applied on the bevel gear teeth.

TECHNICAL ARTICLES | 1987-07-01

Longitudinal Load Distribution Factor for Straddle- and Overhang-Mounted Spur Gears

A pair of spur gears generally has an effective lead error which is caused, not only by manufacturing and assembling errors, but also by the deformations of shafts, bearings and housings due to the transmitted load. The longitudinal load distribution on a contact line of the teeth of the gears is not uniform because of the effective lead error.

FEATURE ARTICLES | 1987-03-01

Crowning: A Cheap Fix for Noise Reduction and Misalignment Problems and Applications

Noisy gear trains have been a common problem for gear designers for a long time. With the demands for smaller gear boxes transmitting more power at higher rpms and incumbent demands for greater efficiency, gear engineers are always searching for new ways to reduce vibration and limit noise without increasing costs.