Chain drive

Chain transmission are flexible drive mechanism. They transmit rotational forces with fixed or interchangeable gear ratios via chain. They usually work on sprockets and are among the interlocking gears. A slat chain transmission used a chain that is laterally moveable slats have form-fitting with two grooved blunt conical disks. Frictional designs are rare, just push chain transmission.

An arrangement of drive and driven gears with a revolving chain is called a chain drive. Chain drive with interchangeable in translation stages are used for example in bicycles with derailleur used, but even earlier in some of Richard kitchens constructed motorcycle models. Slat chain transmission are variable transmission. The sizes of the chains are normalized and are governed by the [ customs ] - moderation.

Positive chain drive

Positive chain drives are the most common embodiment. The drive chain, the so-called roller chain is mainly used. The inner link plates are pressed onto sleeves, which causes a higher resistance to wear. As noise and wear reduction hardened and ground rolls are stored on the sockets. While frictional movement transfers ( eg belt or rope drive ) always occurs some degree of slip, the drive and output shaft move when chain drive always completely in sync with each other. ( A new chain experienced in operating a chain elongation of about 2%, which may be adjusted by clamping elements. ) Therefore is in the automotive technology, the camshaft, which must always be at a fixed angle relative to the crankshaft, usually via a chain or a timing belt driven.

Compare positive and non- positive gear

Other advantages over the non-positive power transmission:

• A chain drive requires no major friction surfaces for transmitting power such as Belt drives ( except timing belt ), so disk diameters are smaller ( dental) possible.
• There is no bias necessary, which relieves the bearings of the shafts.
• It can be transferred depending on the application much larger forces.
• Since the smaller chain looping and axial distances are hardly elastically deformed during rotation possible.
• The lifetime of well -lubricated chain drives is high compared with other transmission systems
• No maintenance required (if chain drive is integrated into the oil circuit of the motor, so lubrication is ensured, and over the life of the engine no complex control drive change such as the timing belt is required)

Disadvantages compared to the non-positive power transmission:

• Chain drives have higher operating noise.
• The chain is wrapped around the toothed pulley is not round but polygonal, so that the circulating chain segment is shorter than the circular arc described. This leads to a discontinuous transmission - the driven shaft is alternately accelerated and solved, which can lead to high strand forces. Higher numbers of teeth, this referred to as polygon - effect longitudinal oscillations can be reduced.
• Vertical standing waves can not bond well with a chain drive, because the chain straps would rub on one side of the disk face. With vertically one above the other, cross shafts mounted at the bottom of the chain wheel sag, which can have unfavorable running properties. Ideal is a slight angle offset arrangement.
• Vibrations - especially on the returning chain route - must be partially reduced by additional (partly sprung damper ) or idlers.

To avoid mutual reinforcement between chain and sprocket wear, should be used as tooth numbers primes, so do not access the same types of bolts in a tooth gap.

Drive chains on motorcycles run with better efficiency than Cardan, when they are in perfect condition. For a reliable lubrication, they are often carried out as an O- ring chain.

Chain drive of a bicycle

Positive chain drive be used on a bicycle. There the bicycle chain has ( propshaft etc. ) prevailed over all other transmissions. A disadvantage of the power transmission through the chain is the fact that the translation can not be chosen continuously. In cycling, this has mainly led to the derailleur were in demand in recent decades, especially with simple graded ring gear packages, which are now offered by the trade because of the technical development of chain and sprockets in a large selection (9 - and 10 - speed cassettes, since 2008, 11 -fold).

Frictional chain transmission

In the power transmission without tight fit so-called link chain drives are used. They usually work positively and are therefore not allocated to the chain drives, but follow the principle of operation of belt transmissions.

As an exception interlocking slat chain drives to call, such as the continuously variable PIV transmission, in which a chain having laterally displaceable tabs engages the radial Nutenzähne two conical disk pairs. Tooth and gap of a plate pair are opposite each other.

Chain drive as a removable gear

In motor vehicles, chain transmission were also used as four-stage change gear. The best known examples are the motorcycle gears of Richard kitchens in models Zündapp KS 601 ( and KS 600 ) and Victoria Bergmeister.

Continuously variable transmission chain

There are also continuous chain transmissions in which a slat chain between two conical pulleys running on the input and output side. By changing the distance between the conical discs the transmission ratio can be adjusted. The adjustment is carried out hydraulically generally; each one of the conical disks is fixed, while the other acts as a piston cylinder. They can be moved by an increase in the oil pressure in the hydraulic system.

These gears are used in automobile industry as an automatic transmission. Their main advantage is their stepless drive that allows a driving always in the most economical speed range of the engine without a jolt. A well-known representative is the multitronic Audi.

It must be considered in the interpretation that the chain can not slip because it can otherwise lead to a destruction of the gearbox. The maximum transmissible torque of a chain converter is approximately 300 Nm (end of 2003).