Transmission (mechanics)

A transmission (or conversion element ) is a machine element can be changed with the movement variables. Sometimes the change of a force or torque plays a crucial role. The movement is to be changed often to rotate.

When out of the manual transmission automobile known or the gear train of a clock are mainly to gear transmission, which are only one of several types of transmissions.

• 3.3.1 Open Frame
• 3.3.2 Closed design

• 4.1 cam gear
• 4.2 linkage 4.2.1 Crankshaft

Gear types

Transmission with fixed-fixed components (ie solids ) are called Mechanical transmission. With participation of fluids is fluid transmission or hydraulic transmission. The control of electrical generators and / or motors sometimes causes so-called electric or electronic transmission.

The oldest transmission system comes from Franz Reuleaux from the 19th century. He shared the mechanical transmission as follows:

• Crank mechanism (see linkage )
• Cam gear
• Wheel gear (see gear and friction gear )
• Roller gear (see traction drive )
• Screw gear (see helical )
• Blocking transmission

Definition of Terms

Transfer gearbox and convert:

• Torques
• Directions of rotation
• Speeds

In accordance with VDI guideline VDI 2127:

They are usually mechanical means (one machine ), but can also hydraulic, rare based on pneumatic or electromagnetic principles. They consist of at least three members, each a moving input and output member, and the machine frame.

Terms for those units change rotational motion:

• The most common task is to adjust a transmission of a given input speed, such as the speed of electric motors, to a required output speed, for example, for a tool. Examples: the shaver to speed the round knife or car engine speed ( 6000 rpm ) at the transmission input to the output gear 1000 rpm have ( to realize other ratios, automotive transmissions have several courses).
• The translation is the ratio between the input and output speed. The gear ratio is greater than one occasion (no DIN standardized term ) called reduction.
• The gear ratio is fixed or changeable only in stages: manual with several courses constant rotational relationship.
• The gear ratio is infinitely variable: continuously variable.
• The ratio of the maximum to the minimum ratio is the range of adjustment of the transmission.

Transmission with uniform translation ( for rotary motion )

The transmission is usually between a driving engine (motor) and a working machine (or machine part ). With two, it is connected via a fixed or detachable clutch.

Gears are divided according to different criteria:

According to type

• Fixed gear - speed ratio and torque converter can not be changed
• Adjusting mechanism can be divided into stepped and continuously variable transmission. Gearbox: speed and torque can be connected graded. The function can also be located in a direction of rotation in the form of a reverse gear. ( Typ. use in motor vehicles. ) Traction drives, see Continuously variable transmission (CVT ) chain transmission
• Rigid chain gear with thrust belt

• Wälzkörpergetriebe
• Traction drives, see Continuously variable transmission (CVT ) Belt transmission ( flat belts, V-belts )

By type of power transmission

Mechanical transmission

Positive gear

Frictional Gear

Hydraulic gear

In hydraulic transmissions ( see flow transmission ) are the input and output side with a fixed components ( wheels, belts, etc.) connected to each other. The drive shaft is a liquid in the interior of the move, which drives the output shaft. A distinction is made between hydrostatic (with external pressure generation ) and hydrodynamic (integrated pressure generation ) transmissions.

Electric transmission

An electrically controlled combination of a generator and an electric motor is often referred to as an electric gear. The definition of the transmission as a compact machine element is no longer true for such combinations. One older example is the Leonardsatz. In modern combinations electronically controlled hybrid power generators and electric motors adjacent to diesel engines, gas turbines, and spark ignition engines are involved.

After design

Open design

Open design means that the elements of the transmission are freely accessible. Often, however, they are covered for safety reasons. Examples: belt transmission, (formerly called transmission)

Closed design

For gear units with closed housing no sand or dust get into the Meschanismen, which is important for low wear. Lubrication is by fat or a closed oil circuit. In simple transmissions, it is sufficient for lubrication of often when a gear is partially immersed in an oil bath and on spraying when operating oil mitschmiert the other gears. The case also serves the noise protection and security. Examples: motor vehicle transmission, differential gear

Transmission with a non-uniform translation

To take account of the position dependence of the transmission on the respective position of the drive to use the transfer function. This records the position of the power take-off from the position of the actuator.

Cam gear

As cam gear mechanisms are referred to, in which the shape of a moving curve of a scanner picked up and forwarded to other transmission elements ( rotary or linear ). The scanning usually takes place on one side, that is, the scanner is running on the curve to which it is pressed, but are too large lifting forces, it can also withdraw from the curve. To avoid this, different solutions for the forced guidance of the scanners have been developed.

Cam can transfer their curve by rotation or longitudinal displacement on the scanner. Often cam be used formed as a circular segment, and only for the purpose of scanning therefore swing back and forth, according to the reciprocating motion of flat cam.

Cam gears are widely used in automation to operate switch, or to perform complicated movements. The most prevalent is the use in internal combustion engines where cam gear ( camshaft) control the opening and closing of the valves. From there, the problem of lifting the scanner is known ( flutter valve ).

The synthesis of cam gears usually goes hand in hand with the synthesis of coupled gears, which are usually forward the sampled movements and reshape. There are special waveforms to optimize the scanning behavior:

• Optimal speed
• Optimal acceleration
• Optimal power
• Minimizing noise

For this purpose, inter alia, correspondingly inclined sinoids are generally used.

Linkage

Coupling gears are gears which convert rotational movement into linear or oscillating motion, and vice versa. They are characterized by the coupling of at least two of the movable elements with a paddock.

Linkage are unevenly translated transmission.

The coupling is usually an engine part in the form of a connecting rod, a connecting rod, a coupling rod or a sliding block.

Crankshaft

In the group of linkage part, inter alia, also the crank mechanism. It is a rotary (rotating ) movement in a translational ( linear ) movement or vice versa. Application it is used for example in steam engines or piston engine. (see also crankshaft )

Step gear

Step gear set a continuous rotation into an intermittent rotary indexing. Between each step, there is a pause before the next step begins. Step transmission can be realized with almost everyone Transmission.

Step gears are used to convert continuous movements in progressive movements with momentary or latching temporal as well as with back-step ( short backward movement). Step transmission can be realized, including through gear train (eg Sternradgetriebe ), wheels linkage or linkage, but also by cam gear and transmission of special designs.

The best known design of stepper drives is the Geneva mechanism, in which the dominant transmission part (depending on severity ) may take the form of a Maltese cross. They were for example used in film projectors and cameras to perform the stepwise movement of the film material, but are also very widespread.

Phrase " sand in the gears "

Due to the function of a gear, there is the colloquial expression spanner in the works, if something works slow or just disturbed. Sand in the transmission provides increased wear, a transmission can also block or destroy. Its origin may have the phrase in racing as well as other competitions, as done for example in bidding. It will happen sometimes that actually sand is in addition to other sabotage measures introduced in gear units and motors in order to give the competitors disadvantages. Even were and are not all gear sealed casing, whereby sand and dirt can get into the gearing, as in bicycle, farm machinery or a concrete mixer.