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worm gear drives - Search Results

Articles About worm gear drives


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1 Worm Gears - Ask the Expert (October 2013)

How does one determine the center of a worm and a worm wheel? Also, what are the differences between the common worm tooth forms?

2 Gears for Nonparallel Shafts (September/October 1986)

Transmission of power between nonparallel shafts is inherently more difficult than transmission between parallel shafts, but is justified when it saves space and results in more compact, more balanced designs. Where axial space is limited compared to radial space, angular drives are preferred despite their higher initial cost. For this reason, angular gear motors and worm gear drives are used extensively in preference to parallel shaft drives, particularly where couplings, brakes, and adjustable mountings add to the axial space problem of parallel shaft speed reducers.

3 Vectors in Gear Design (July/August 1999)

Friction weighs heavily on loads that the supporting journals of gear trains must withstand. Not only does mesh friction, especially in worm gear drives, affect journal loading, but also the friction within the journal reflects back on the loads required of the mesh itself.

4 Application of Miner's Rule to Industrial Gear Drives (January/February 1990)

We need a method to analyze cumulative fatigue damage to specify and to design gear drives which will operate under varying load. Since load is seldom constant, most applications need this analysis.

5 Dynamic Loads in Parallel Shaft Transmissions Part 1 (March/April 1990)

Recently, there has been increased interest in the dynamic effects in gear systems. This interest is stimulated by demands for stronger, higher speed, improved performance, and longer-lived systems. This in turn had stimulated numerous research efforts directed toward understanding gear dynamic phenomena. However, many aspects of gear dynamics are still not satisfactorily understood.

6 Standards Development: Enclosed Drives (March/April 2011)

Chairman Todd Praneis of Cotta Transmission describes the activities of AGMA's Enclosed Drives technical committee.

7 Pitting Resistance of Worm Gears: Advanced Model for Contact Pattern of Any Size, Position, Flank Type (October 2012)

An experimental and theoretical analysis of worm gear sets with contact patterns of differing sizes, position and flank type for new approaches to calculation of pitting resistance.

8 Relationship Between Wear and Pitting Phenomena in Worm Gears (May/June 1998)

Worm gears display unique behavior of surfaces because of the presence of wear phenomena in addition to contact pressure phenomena.

9 Dynamic Loads in Parallel Shaft Transmissions - Part 2 (May/June 1990)

Solutions to the governing equations of a spur gear transmission model, developed in a previous article are presented. Factors affecting the dynamic load are identified. It is found that the dynamic load increases with operating speed up to a system natural frequency. At operating speeds beyond the natural frequency the dynamic load decreases dramatically. Also, it is found that the transmitted load and shaft inertia have little effect upon the total dynamic load. Damping and friction decrease the dynamic load. Finally, tooth stiffness has a significant effect upon dynamic loadings the higher the stiffness, the lower the dynamic loading. Also, the higher the stiffness, the higher the rotating speed required for peak dynamic response.

10 Developing a Total Productive Maintenance System (May/June 1995)

There's a reason they call it catastrophic gear failure: For example, if the line goes down at a large aluminum rolling mill because a gear set goes bad, the cost can run up to a whopping $200,000 a week. Even in smaller operations, the numbers alone (not to mention all the other problems) can be a plant manager's worst nightmare.

11 Minimal Tooth Number of Flexspline in Harmonic Gear Drive with External Wave Generator (October 2013)

Wave generators are located inside of flexsplines in most harmonic gear drive devices. Because the teeth on the wheel rim of the flexspline are distributed radially, there is a bigger stress concentration on the tooth root of the flexspline meshing with a circular spline, where a fatigue fracture is more likely to occur under the alternating force exerted by the wave generator. The authors' solution to this problem is to place the wave generator outside of the flexspline, which is a scheme named harmonic gear drive (HGD) with external wave generator (EWG).

12 Gear Ratio Epicyclic Drives Analysis (June 2014)

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.

13 How Bearing Design Improves Gearbox Performance (September 2012)

Gearbox performance, reliability, total cost of ownership (energy cost), overall impact on the environment, and anticipation of additional future regulations are top-of-mind issues in the industry. Optimization of the bearing set can significantly improve gearbox performance.

14 Designing Reliability Into Industrial Gear Drives (September/October 1998)

The primary objective in designing reliable gear drives is to avoid failure. Avoiding failure is just as important for the manufacturer and designer as it is for the end user. Many aspects should be considered in order to maximize the potential reliability and performance of installed gearing.

15 Worm Gear Measurement (September/October 1997)

Several articles have appeared in this publication in recent years dealing with the principles and ways in which the inspection of gears can be carried out, but these have dealt chiefly with spur, helical and bevel gearing, whereas worm gearing, while sharing certain common features, also requires an emphasis in certain areas that cause it to stand apart. For example, while worm gears transmit motion between nonparallel shafts, as do bevel and hypoid gears, they usually incorporate much higher ratios and are used in applications for which bevel would not be considered, including drives for rotary and indexing tables in machine tools, where close tolerance of positioning and backlash elimination are critical, and in situations where accuracy of pitch and profile are necessary for uniform transmission at speed, such as elevators, turbine governor drives and speed increasers, where worm gears can operate at up to 24,000 rpm.

16 Alternative Lubrication Methods for Large Open Gear Drives (September/October 1996)

The type of lubricant and the method of applying it to the tooth flanks of large open gears is very important from the point of view of lubrication technology and maintenance. When selecting the type of lubricant and the application method, it is important to check whether it is possible to feed the required lubricant quantity to the load-carrying tooth flanks, This is necessary to avoid deficient lubrication, damage to the gear and operational malfunctions. It is important to determine the type of lubricant, which may be fluid or grease-like. The consistency of the lubricant will have a direct impact on the ability of the lubrication system to feed adequately the lubricant to the gear. The interactions between the common types of lubricant and the lubrication application methods for open gear drives are shown in Fig. 1.

17 Full-Load Testing of Large Gearboxes Using Closed-Loop Power Circulation (September/October 1991)

This method of testing large gearboxes or, indeed, any power transmission element, had numerous advantages and offers the possibility of large savings in time, energy, and plant, if the overall situation is conducive to its use. This usually requires that several such units need to be tested, and that they can be conveniently connected to each to each other in such a way as to form a closed-loop drive train. No power sink is required, and the drive input system has only to make up power losses. The level of circulating power is controlled by the torque, which is applied statically during rotation, and the drive speed. Principles, advantage, and limitations are described, together with recent experiences in the only known large-scale usage of this technique in Australia.

18 Introduction to Worm Gearing (March/April 1993)

Worm gears are among the oldest types of gearing, but that does not mean they are obsolete, antiquated technology. The main reasons for the bad experiences some engineers have with worm gearing are misapplication and misuse. No form of gearing works for every application. Strengths and weaknesses versus the application must be weighed to decide which form of gearing to use. For proper application and operation of worm gears, certain areas that may differ from other types of gearing need to be addressed.

19 Engineering Constants (May/June 1987)

Rules and Formula for worm gears, bevel gears and strength of gear teeth.

20 Contact Surface Topology of Worm Gear Teeth (March/April 1988)

Among the various types of gearing systems available to the gear application engineer is the versatile and unique worm and worm gear set. In the simpler form of a cylindrical worm meshing at 90 degree axis angle with an enveloping worm gear, it is widely used and has become a traditional form of gearing. (See Fig. 1) This is evidenced by the large number of gear shops specializing in or supplying such gear sets in unassembled form or as complete gear boxes. Special designs as well as standardized ratio sets covering wide ratio ranges and center distanced are available with many as stock catalog products.

21 Cone Drive Double Enveloping Worm Gearing Design and Manufacturing (October/November 1984)

Worm gearing is of great antiquity, going back about 2100 years to Archimedes, who is generally acknowledged as its inventor. Archimedes' concept used an Archimedial spiral to rotate a toothed wheel. Development of the worm gearing principle progressed along conventional lines until about 500 years ago when Leonardo DaVinci evolved the double enveloping gear concept.

22 Worm Gears - Higher Energy Efficiency and Less Strain on Resources (May 2011)

A very direct and effective way of increasing power transmission efficiency is a changeover from mineral-oil-based lubricants to synthetic lubricants.

23 Load Carrying Capacity of Screw Helical Gears with Steel Pinions and Plastic Wheels (July/August 2004)

There is an increasing significance of screw helical and worm gears that combine use of steel and plastics. This is shown by diverse and continuously rising use in the automotive and household appliance industries. The increasing requirements for such gears can be explained by the advantageous qualities of such a material combination in comparison with that of the traditional steel/bronze pairing.

24 The Effect of Lubricant Traction On Wormgear Efficiency (January/February 1985)

The effect of various lubricant factors on wormgear efficiency has been evaluated using a variety of gear types and conditions. In particular, the significant efficiency improvements afforded by certain types of synthetic lubricants have been investigated to determine the cause of these improvements. This paper describes broad wormgear testing, both in the laboratory and in service, and describes the extent to which efficiency can be affected by changes in the lubricant; the effects of viscosity, viscosity index improvers and, finally, synthetic lubricants are discussed. The work concludes that lubricant tractional properties can play a significant role in determining gear efficiency characteristics.

25 Improved Worm Gear Performance with Colloidal Molybdenum Disulfide Containing Lubricants (November/December 1988)

Worm gear speed reducers give the design engineer considerable options, but these gear systems present a challenge to the lubrication engineer. Heat energy generated by the high rate of sliding and friction in the contact zone causes worm gears to be relatively inefficient compared to other gear types. Because worm gears operate under a boundary or near-boundary lubrication regime, a satisfactory lubricant should contain a friction modifier to alleviate these conditions.

26 Viewpoint (November/December 1988)

Eliot K. Buckingham explains the procedure for proper measurement over wires for worm gears, in response to last issue's article.

27 Our Experts Discuss Hobbing Ridges, Crooked Gear Teeth, and Crown Shaving (March/April 1992)

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?

28 Cutting Low-Pich-Angle Bevel Gears; Worm Gears & The Oil Entry Gap (July/August 1992)

Question: Do machines exist that are capable of cutting bevel gear teeth on a gear of the following specifications: 14 teeth, 1" circular pitch, 14.5 degrees pressure angle, 4 degrees pitch cone angle, 27.5" cone distance, and an 2.5" face width?

29 Gear Inspection Chart Evaluation; Specifying Unusual Worm Gear Sets (November/December 1991)

Question: When evaluating charts from a gear inspection machine, it is sometimes found that the full length of the profile traces vary, and that sometimes they are less than the length of active profile (above start of active profile-SAP) by up to 20%. This condition could be caused by a concentricity error between tooth grinding and shaping, or by unequal stock removal when grinding. (See Fig. 1.) Is it possible that some of the variation is coming from the inspection machine? How can variation from the inspection machine be reduced?

30 Pineapples, Corncobs & Other Hobbing Matters (July/August 1991)

Two questions on hobbing cover the various types of hobs and their unusual names, as well as the importance of hob swivel angle.

31 Limitations of Worm and Worm Gear Surfaces in Order to Avoid Undercutting (November/December 1990)

The dimensions of the worm and worm gear tooth surfaces and some of the worm gear drive parameters must be limited in order to avoid gear undercutting and the appearance of the envelope of lines of contact on the worm surface. The author proposes a method for the solution of this problem. The relations between the developed concept and Wildhaber's concept of the limit contact normal are investigated. The results of computations are illustrated with computer graphics.

32 Cutting Worm Gears with Standard Gear Hobs (January/February 1994)

We make a lot of single-start worm and worm gear sets, and it always seems as though we're buying another special hob. We also do a lot of spur gear cutting, and the spur gear hobs and the worm gear hobs look alike, so we wonder why we cannot use the standard hobs for cutting worm gears too. Can we do this?