Bevel gears, their application and manufacture

Gears are used by mankind for a long time, this way of communicating the energy of rotation is the most common in mechanics.

These mechanisms transfer movement from one shaft to another, usually with a change in the speed of rotation per unit time. The means of engagement and the immediate elements of the motion message are either wheels or slats with grooves and special shaped protrusions cut on their working surfaces.

Of two circular elements interacting in the transmission, one, larger diameter, is usually called a wheel, and the second is a gear, although, in essence, they are both gear wheels.

Depending on whether the task is put in the reducer to increase the speed of rotation or, conversely, the reduction, the driving is either a wheel or a gear.

Modern construction materials allow the creation of gears capable of successfully transforming the power to 36 million watts.

The requirements for the mechanisms are different, and therefore the variety of forms of gearing is very large. The axes of rotation can be parallel, crossed or intersecting, depending on which there are cylindrical, helical, worm or bevel gears. A feature of the latter is the ability to communicate the rotation of the shaft, located at a right angle to the leading axis. This possibility is often needed in a variety of mechanisms, for example, the transfer of mechanical energy from the propeller shaft of the car to the driving wheels is carried out precisely by such a kinematic scheme.

Most often, the bevel gear has direct radial cutting teeth (tangential). If the leading and trailing axes do not intersect, then such a reducer is called hypoid. The use of such mechanisms in the design of the rear axle is caused by the desire of developers to make the overall center of gravity of the car lower to give it more stability.

In addition to spur gear, other gears are used, for example with a spiral cutting.

In addition, conical transmissions enable the rotation to be transmitted not only under direct, but also at practically any other angle, blunt or sharp.

The technology of making bevel gears is about the same as cylindrical gears, but the workpiece has a rather complex shape. It consists, as it were, of two truncated cones with a common large base on one axis. The forming cones are at right angles. The profile of the teeth is clearly visible from the non-working side of the conical wheel, while the tooth width decreases from the periphery to the center. The material of production is a special steel, resistant to wear and very hard.

The cutting profile is an involute line, this shape provides the smoothest rotation, uniform wear and the maximum distribution of mechanical stress at the moment of contact of the teeth.

Gear transmissions with a variable profile shape are difficult to fabricate, and machine-controlled machines are used to produce them.