Belt (mechanical)#Vee belts
V-belts are power transmission belt of belt drives, which have a trapezoidal cross-section.
The friction of the edges of the belt in a wedge-shaped groove is considerably higher than with a flat support. This fact take advantage of the V-belt. They are made of rubber with a textile or steel wire core and are manufactured endless. You can transmit much greater torques than flat belts in the same space. Due to the higher friction, the forces on the bearing significantly reduced. Compared to the flat belt efficiency is somewhat lower.
One can also arrange side by side multiple V-belts. Because V-belts gradually expand during use, but it is important that for drives with multiple parallel belts all belts at the same time replaced.
In practice, four different types V-belts are mainly used.
- Classical V - V-belts, which are sheathed with a fabric layer and are produced in the profiles 5, 6, 8, 10, 13, 17, 20, 22, 25, 32 and 40. They are characterized by a very high operational reliability. The use is very regressive.
- Spacesaver - also covered, but with improved power transfer. Used in the SPZ ( 9.7 ), SPA ( 12.7 ), SPB ( 16.3 ), SPC (22 )
- Raw edge V-belts - belts with open flanks ( FO) with advantages in wear behavior, the accuracy and the frictional force. Profiles: XPZ, XPA, XPB, XPC
- Formgezahnte V-belt - like the edge V-belts, but with additional formgezahnter inside ( FOZ ). This type is preferred for new drives, due to a longer maturities, lower energy consumption and higher power transmission.
The belt is probably the best known representatives of the drive belt. He finds in motor vehicles using to drive the alternator, often the fan and the water pump or the hydraulic pump ( power steering pump ) for the power steering. Also it is used in the household washing machines for rotating the drum.
Typically, V-belts running on pulleys with a fixed diameter. However, one can also push two conical discs together or further apart, so that the belt continues to run inside or outside. The result is a continuously variable transmission. One of these designs, which depends on the speed adjusts itself, is also known under the name VARIOmatic and is used in scooters.
While flat belts are not standardized, V-belts are largely standardized, so that they can be used and vendor-neutral swapped. Since there are different standards, DIN 7753 Part 1/ISO 4184 European and RMA / MPTA American, a conversion factor Ld La ( see below) is used.
Since a belt is relatively high (large ), it arrives at the deflector to a compression in and thus to the heating. You can teething the V-belt to allow smaller wheel diameter or to reduce the losses. However, a toothed belt is still a V-belt, as it frictionally operates by the wedging action on the sides.
The V-ribbed belt ( also ribbed belt ) is a further development of the V-belt. V-ribbed belts combine the advantages of the flat belt ( small radii ) with those of the V-belt (lower wrap or greater friction ). The belt having ribs extending in the longitudinal direction. The pulley has corresponding grooves. V-ribbed belts are increasingly for example in so-called serpentine drives of engines for several ancillary components ( such as cooling water pump, air compressor, alternator, power steering pump from motor vehicles ) but lately used in washing machines. V-ribbed belt with a plurality of units can be driven by a belt, for example by the smooth outer surface is used. V-ribbed belt drives in cars can be designed for a service life of 160,000 km. You need as opposed to the V-belts, which is often under static, automatic tensioning systems to under all operating conditions to ensure constant belt force as possible.
The usage number of the V-ribbed belt ( on each V-ribbed belts noted) provides information on number of ribs, belt profile and the reference length. " 5PK940 " So has five ribs, the PK profile and a reference length of 940 mm.
A chain-belt ( V-belt slats )
A chain-belt ( V-belts, disks ) are finite V-belts made of individual elements ( blades ) are made ( by the meter). The individual elements are connected by steel pivot rivets ( drive belt ) and a T-bar end ( high- conveyor belt ), and consist of polyurethane elastomers which are reinforced with a plurality of layers of polyester cloth. Transferred services and pulleys used correspond to the classical V-belt or wedge belts of rubber tissue.
The structure of the link belt allows a few simple steps to assemble any required length of the belt itself. The design proves beyond with internal drives ( or transport routes ) as advantageous as the chain-belt can be closed in the drive ( endless) and thus partly account for complex disassembly. When you install may ̣ chain-belt - as opposed to rubber-fabric belts - will be skipped because they are flexible due to the material composition of polyester / polyurethane.
These properties allow specific drives on the inside to construct and to refrain from clamping devices.
Lifetime intervals of chain-belt are due to the material composition when compared to rubber fabric V-belt systems - especially in difficult environmental conditions, such as Temperatures ( from -40 ° C to 116 ° C ), oil, water, steam, chemicals, abrasive media - greatly increased.
Interpretation of belt drives
Calculation of V-belt ( also of timing belt ) is based on decades of experience in the practical application of belt drives.
Industrial V-belt drives with Duri high-performance V-belts are designed for constructive information. The calculation of belt drives is based on standard international method for actuator sizing.
The drive calculation includes the geometric and performance parameters. First, the geometric boundary conditions are considered. In these, the belt profile ( Classic V-belts, wedge belts, etc.), the pitch length Lw and the center distance and wheel diameter defined. In the second step, the performance parameters, the service factor and the daily stress duration are determined.
Based on this information, the maximum transferable power of the belt is determined based on the data sheets Duri drive technology. The total number of necessary belt results from the quotient of the input power and the power value of each belt.
The power value of the belt and the underlying length, width, operating and angle factors are crucial for an economic calculation of the drive. Typically, the life of the belt at 25,000 hours is dimensioned for industrial use.