Gears

Gears are the standard element in drive technology. And gears or spur gears are without doubt precision-manufactured components. They are either mounted on a shaft or secured on an axle by bearings and enable rotational directions, forces and torques to be transmitted. The degree of accuracy achieved during the manufacturing of gears determines their subsequent noise, wear and vibration behaviour during use. The diversity of materials involved, the wealth of possible variants, the quality required and manufacturing processes all mean that gears really are a subject just for specialists. This applies just as much to standard gears as it does to individual customer-specific solutions produced according to drawings.

Gears - milled or ground

Our production portfolio encompasses gears designed for various areas of application. We manufacture gears for our customers in line with their exact specifications, either as milled or ground models. We can provide gears in various modules and with various bores: milled, skive hobbed, spur-style, helical gears, with spherical flanks or ground ones. All our ground gears comply with DIN 3962/67 4 to 7 with regard to quality of toothed systems.Special profile shape can also be manufactured, tailor-made to suit your instructions.

[Translate to English:] Stirnrad – gefräst

Spur gears – ground

In industries such as the manufacturing of pumps, requirements demanding low-noise and low-wear running and flow rate are crucial. Precision geometries of individual teeth are extremely important and these are features which cannot simply be produced by the usual method of hobbing. Such spur gears are pre-milled, heat-treated and they also undergo gear grinding and cylindrical grinding all on the premises of WIAG Antriebstechnik. Tooth flank accuracy attaining a quality level of up to Class 4 guarantees that the necessary and the expected parameters are achieved.

We grind gears up to module 12 with a diameter ranging from 35 up to 500 mm.

[Translate to English:] Geschliffenes Stirnrad

Flank quality categories

In line with DIN 3961 there are 12 qualities regarding the toothed systems of gears. These can be achieved by implementing various manufacturing methods. The number 1 signifies the finest with number 12 denoting the coarsest gear tooth quality.

Manufacturing processes:

Quality 1–6 honed
Quality 1–7 ground
Quality 5–7 scraped, (cold-rolled)
Quality 5–9 hobbed, planed, shaped
Quality 7–12 profile milled, profile shaped, broached
Quality 8–12 punched, pressed, sintered, injected

Bevel gears

Bevel gears are subjected to the most enormous strain and the most extreme conditions in gearboxes. While the axes are laid out parallelly to one another in the frequently used spur gear, in a bevel gearbox the drive shaft and the pinion shaft intersect at an angle - often at an axis angle of 90°. Contact of the tooth flanks is linear. A bevel gear drive is made up out of two components: the bevel gear and the larger crown wheel. The drive is usually brought about by the bevel gear whereby both rotation directions are possible. Quality, precision and a long service life are the priority requirements demanded of every single gear.

We can produce the right bevel gears for you to suit the most diverse purposes and applications. Whether it involves individual pieces, a series or just one special requirement - we will manufacture goods in line with customer-specific instructions.

Worm shafts and worm gears

Worm shafts: milled
If force has to be transmitted on shafts positioned crosswise to one another, then this can normally only be achieved by using worm gears and worm shafts. The spindle shape necessary in such a case places exceptionally high demands on the precision work performed during the manufacturing of these drive elements.
Worm wheels and worm shafts, i.e. worm drives, are composed of "a snail or worm" in a screw shape, which rotates and meshes with a gear, i.e. a worm gear. We produce such worm shafts and worm wheels or gears by using our precision milling techniques and procedures.

[Translate to English:] Schneckenräder und Schneckenwellen

Operating principles

A gear can be defined as a machine part in the form of a wheel fitted with evenly distributed teeth. The combination of several such gears is called a gear drive. These gears turn by means of shafts on which they are fixed or, alternatively, on axles on which they are mounted. The rotational direction changes when two gears with outer teeth mesh together; the addition of a third gear between them means the direction remains the same. As a result of the varying size of gears, the rotational speed or the torque can be increased or reduced.

Gear types

Spur gears are commonly used. The fully toothed pulley has a cylindrical shape. As a result of the parallel axes of a spur gear and its mating gear, a spur gear drive is formed.
Spur gears

have teeth cut mostly straight or helically, i.e. in a spiral
can have double helical teeth
can be combined with gear racks.

The worm gear operating in connection with a screw is another gear variant. Both components together form a so-called worm gear drive. A worm gear is implemented when the shafts are to cross but are not to intersect. So that the tooth flanks of the worm gear do not only make contact with the drive teeth at just one point but linearly, they are hollow. Because of its slanted, spirally cut teeth, the screw resembles a thread. Each tooth corresponds to one turn of the thread.

When it comes to bevel gears, the axes usually intersect at a helix angle of 90°. A truncated cone with a toothed lateral surface forms the basic shape of a bevel gear. In a bevel gear drive the tops of two matched bevel gears run together as their axes share a common point of intersection.

There exist even more types of gears such as sprockets, ellipse gears and brake gears.

Gear teeth types

Involute toothing is used in both automotive and in mechanical engineering to name but two areas and, not least because of its simple and cost-effective manufacturability, it is the most common kind of toothing system to be found. Should the distance between two gears with involute toothing slightly alter, then only the radii of the pitch circles also change. Their relation, however, remains the same. And this is one major reason why this kind of toothing is widely chosen.

In contrast to involute toothing, with cycloidal teeth slight friction occurs when accelerating from a slow speed to a fast one. The teeth with a narrower bottom enable greater transmission ratios in a small space. The manufacturing process involves a significantly greater amount of work as a special design for the teeth of the gear pair is required. Furthermore, on account of the depth of engagement, an empirical adjustment of the distances is necessary.

In the case of spur gearing, the so-called Wildhaber-Novikov gear, we see a circular arc gear. Semi-circular teeth mesh with concave inward arched spaces. The tooth space radius is in actual fact greater; only in theory does it look identical.

In contrast to involute toothing, Wildhaber-Novikov gearing is characterised by a 1.5 to 3-times higher inertia of tooth flanks. Some disadvantages here are the lower tooth root load, higher manufacturing costs and sensitivity when changing axis distances.

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