Showing papers on "Pressure angle published in 1974"

An Evaluation of Stresses and Deflection of Spur Gear Teeth Under Strain

Abstract: This paper aims at an evaluation of the stresses induced by a static load applied to gear teeth. For spur gears of different ratios with 20-deg pressure angle and standard addendum proportions, the stresses and deflections are computed by the finite element method. Formulas are drawn allowing a simple calculation of the maximum stresses, and the results are compared with what is given by ISO and AGMA standards related to the strength of gear teeth.

High torque gearing

Abstract: Novikov gearing obtains its exceptional tooth surface load capacity by using concave-convex circular arc profiles of nearly the same radii, so that the contact area between mating teeth is very large and the Hertzian stress low. Because the centers of these arcs are very close together, a small error in center-distance produces excessive changes in pressure angle and overloads the tips of the concave teeth. The subject invention eliminates this problem by using profile curves having a radius of curvature that increases with distance from the pitch circle. The discrete arc centers of Novikov gearing are replaced by continuous evolute curves which are positioned to be tangent to the pressure line near the point where it passes through the pitch point. This allows much closer profile conformity for a given center-distance error, reducing surface stresses and increasing torque capacity.

High capacity gearing

Abstract: A type of gearing that significantly increases the torque capacity of high reduction gearing. This is accomplished by utilizing on the larger of a pair of mating gears a larger pressure angle than that of the smaller gear, and also in some cases a circular arc profile that has a shorter radius than that of an involute profile. The effect of these profile characteristics is to shift the principal tooth load away from the region where the line of action is tangent to the base circle of the smaller gear. Since this is the region where the relative radius of profile curvature is at a minimum, it is the place where tooth surface stresses tend to be a maximum. Relief of the surface stresses in this region therefore allows the gear set to carry greater torque without being subject to failure by surface pitting.

Planar gear train

Abstract: A driving and a driven spur gear, lying in a common plane, are operatively coupled with each other through the intermediary of an idler gear in mesh therewith, the idler gear being radially shiftable against a resilient force in the common plane of rotation. The tangent to any tooth flank of both the driving and the driven gear at its point of contact with a tooth of the idler gear includes a pressure angle α with the common diameter of the meshing gears; the angle δ between the two common diameters should be so chosen that the two tangents are substantially perpendicular to each other, with δ - 2α = 90° for rotation in one direction and δ +2α =90° for rotation in the opposite direction.

Gear with non-involute tooth flanks - has pressure angle varying from minimum to maximum at opposite ends

Abstract: The flanks of the gear teeth deviate from the involute, i.e. there are variations to the profile and in the lengthwise direction, it being particularly for use as a gear-type tool for cold-rolling gears. The pressure angle varies along the flank over the width of the tool so as to be at a maximum at one end and a minimum at the other. A modification can be carried out to the flank along which the angle alters, and a profile modification can also superimposed on it. The corrections made possible meet all the requirements encountered under extreme conditions of service of the gear teeth.

Differential Reducers Using Internal Gears with Small Tooth Number Difference : The First Report, Fundamentals of Design

Abstract: A planetary differential reducer using internal gears with small tooth number difference is described : Essential points of the design are considered and an example of the reducer is manufactured. The idea is used that an internal gear with small tooth number difference has theoretically a contact ratio less than unity owing to trochoidal interference, but it is practically available under suitable condition. In case that the tooth number difference of the input-side gears is not the same as that of the output-side, such an especially high reduction ratio as 1/10, 000 is obtained. The calculation methods for strength and efficiency are given and the experimental value of efficiency is shown to agree with the theoretical one. The cost down of reducers with high reduction ratio is expected from using the above reducers which can be easily manufactured with standard pinion cutters of pressure angle 20°.

Bending Fatique Strength of Gear Teeth under Random Loading : Part 2, Program test under gamma distributed 16 steps Loading

Abstract: This report presents the test results about bending fatigue strength of gear tooth under two kinds of repeated 16 steps program loads which are gradually increasing or decreasing. Load frequencies are gamma distributed. Materials of test gears are normalized S38C and carburized SCM21. Each of test gears has module 4mm, pressure angle 20 degrees, number of teeth 27 and width 8mm. Miner's cumulative damage theorem is statistically tested and the following facts have become clear : (1) Factor of loading sequence and load frequency distribution are not significant. (2) Factor of material is significant. (3) Fatigue life has a trend that the longer the program load cycle period is, the longer is the fatigue life in comparison with the values calculated from Miner's theorem. (4) Frequency of stress which is higher than fatigue limit strength has little correlation to C. (5) The scatter of Miner's constant C is mainly due to the scatter of fatigue life, and C itself is rather deterministic.