The standard gear module is a gear profile with an involute configuration on the sides. This gearing has a lot of advantages over analogues, teeth are easy to process and install, and gears do not require jewelry accuracy of installation. In addition, there are versions with a cycloidal form of the working profile, including Novikov's transfer. In ratchets, an asymmetrical tooth configuration is often used.
Gear Module Parameters
The considered characteristic is denoted by the letter m, indicates the strength of the gears. The unit is measured in millimeters (the higher the transmission load, the greater the modular value). In calculating the parameter, the following indicators are used:
- diameter of pitch circle;
- pitch and number of teeth;
- involute (diameter of the main circle);
- a similar characteristic of the depressions of the dark gear;
- tooth height of a dark and light wheel.
In the engineering industry, calculations are carried out according to standard values for the convenience of manufacturing and replacing gears with numbers from 1 to 50.
Spur and helical wheels
The modulus and diameter of the spur gear is one of the most popular types. The teeth are placed in radial planes, and the contact area of the pair of wheels is parallel to the axis of rotation. The axes of both gears are similarly positioned.
Helical gears are an improved variation of the above modification. The teeth are at a certain angle to the rotational axis. The engagement is smoother and quieter, which allows the elements to be operated in low-noise devices, guaranteeing the transmission of more torque at high speed. The minuses include an increased contact area of the teeth, which provokes increased friction and heating of parts. This is fraught with weakening power and increased lubricant consumption. In addition, mechanical action along the axis of the gear requires the use of thrust bearings for mounting the shaft.
Chevron modifications and analogues with internal gearing
Chevron gears can cope with the problems of mechanical axial force. Unlike the straight and helical versions, the teeth are made in the form of a letter V. The axial effect of the two halves of the device is compensated by the interaction, which makes it possible to avoid the use of thrust bearings on the shaft. The specified model is independently mounted on the axis, one of the working gears is mounted on cylindrical shortened bearings (floating bearings).
The gear module with internal gearing is equipped with teeth having a thread inside. The operation of the part involves one-sided revolutions of the drive and driven wheels. In this design, less friction is spent, which contributes to an increase in efficiency. Such devices are used in mechanisms limited in overall dimensions, as well as planetary gears, special pumps and tank turrets.
Screw, circular, sector versions
The screw type gear module is a cylinder with teeth, which are placed in a helical direction. Such elements are mounted on disjoint shafts located perpendicular to each other. The alignment angle is 90 degrees.
A sector gear is a part of any gear used in gears where the main element does not need to rotate a full revolution. Such a detail makes it possible to save valuable space in the dimensions of a full-fledged analogue.
The gears modulo and the number of teeth with a circular arrangement differ contact contact at one point of engagement located parallel to the main axes. The second name of the mechanism is Novikov’s transmission. It provides good driving performance, smooth and silent operation, increased engaging ability. At the same time, the efficiency of such parts is slightly lower than analogues, and the manufacturing process is much more complicated. These parts have a significantly limited industry due to their characteristics.
Bevel gear module
This type of gears has various varieties that differ among themselves in the configuration of the tooth lines: straight, curved, tangential, circular elements. Similar parts are used in units to transform the movement of a mechanism by transmitting the effect of movement from one shaft to another. For example, in the differentials of cars in the transformation of torque from the power unit to the wheels.
Bevel gears modulo and number of teeth are divided as follows:
- The rake structure is characterized by an infinite radius of the dividing part of the circle. As a result, such elements are parallel lines with an involute profile. This characteristic is most important in the manufacture of gears. With a rack, the transmission is called rack or rack. This type is used to transform revolutions into translational rotation and vice versa. The main scope is rail.
- Star wheel. It is used in most chain transmissions, which allows it to be combined with a flexible part that serves to transmit mechanical stress.
- The diameter of the gear according to the number of teeth and the crown-shaped modules is a special type of impellers. The teeth in this version are located directly on the side surface. This part functions in aggregation with a spur or drum counterpart, which includes special rods in the design. A similar unit is used in the mechanisms of the tower clock.
How to calculate the indicator?
The definition of the gear module is fixed by the following formula:
- m = d / z = p /.
- The height of the tooth head and a similar parameter of the leg are marked with the symbols Hfp and Hap, the ratio is Hfp / Hap = 1.24.
- How to determine the gear module in another way? m = da / z + 2.
Often, engineers are faced with the task of evaluating the gears in real execution for replacement or repair. Sometimes the documentation for the part is compiled formally, which complicates the conduct of these manipulations. Among the proven diagnostic methods is a break-in method. A gear wheel with known parameters is inserted into the teeth of the test element, after which a circular run-in is carried out. If the test pair is engaged, this indicates the coincidence of the step. With a negative result, the process is repeated. With helical variations, a milling cutter that is exactly the right step is chosen.
To summarize
Design drawings and schemes for gears of various configurations mainly coincide for bevel and spur versions. The main differences arise when calculating the strength. In graphic displays, characteristics based on typical overall dimensions of gears are used. Among the presented assortment on the market, it is quite possible to choose a gear wheel with the necessary characteristics and strength indicators.