Toothed belt. Timing belt profiles

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The belt drive, which uses a toothed belt, is one of the oldest mechanical inventions. However, despite the fact that this method of transmission was invented a long time ago, it is still actively used today.

Section of belts

It should be said that there are many different belts that can be used in a belt drive. Depending on their section, the belts are divided into:

• flat;
• wedge;
• poly-wedge;
• round;
• toothed.

It can also be added that there are many manuals and other sources that describe V-belts or flat belts in detail. But with toothed belts, everything is a little worse, since this particular type of device came into use not so long ago. Although back in the days of the USSR, OST 38 - 05114 - 76 and OST 38 - 05227 - 81 were developed. These documents clearly prescribed what the dimensions of the named part should be, as well as how exactly it is necessary to carry out calculations for toothed belts and toothed belt drives.

Benefits of belts

Its wideIt was this type of belt that became widespread due to the fact that it had certain positive characteristics. These benefits include:

• The load capacity of these belts is high.
• The product has small dimensions.
• The slip of these belts is completely absent due to their design.
• These belts allow for high gear ratios.
• The speed characteristic of timing belts is also very high - up to 50 m/s.
• Due to the small initial belt tension, the impact on the shaft and axle is small.
• Quite a small amount of noise.
• Very high efficiency - up to 98%.

It is also important to understand that the production of belts is carried out with certain requirements that it must meet. These requirements include:

• oil resistance;
• belt operating temperature range (it must be between -20 and +100 °C);
• ozone resistance;
• not sensitive to weather conditions.

Shape of straps

Currently, toothed belts can be divided into several groups depending on the shape of the teeth it has. There are teeth with a semicircular shape or with a trapezoid shape.

The advantage of semi-circular teeth is that they provide a more even distribution of stress in the belt, increase the limit of possible loads that it canshifted by 40%, as well as smoother meshing of the teeth. If we talk about such belts in general, then the cost of regular and semi-circular teeth is the same, but the performance of the second type is clearly higher.

These devices consist of several elements:

1. Directly the teeth, as well as the top layer of the belt.
2. Composite carrier cord.
3. The bottom layer of the belt made of polyamide fabric.

Belt arrangement

Currently, timing belts are quite widespread in the engineering industry. This product is considered very durable, but at the same time it has the necessary elasticity.

These products consist of three layers. The first layer is the load-bearing layer and also determines the maximum load that the belt can withstand and its strength. The production of this layer is carried out from cord, which is made of either fiberglass or Kevlar.

The second layer of timing belts is made of polyurethane or rubber. It must provide the necessary flexibility and elasticity of the entire belt. The last, third layer, is made of nylon or any other durable synthetic material. In order to combine all three layers into one and create a drive belt, a vulcanization process is used.

Advantages of driven products

The first and most important advantage of this type of belt is its highestcoefficient of performance, that is, efficiency. Most often, drive belts, whether they are made of polyurethane or rubber, are used to achieve higher speeds.

Such products adhere very well to the pulley, taking the necessary shape, which provides all the necessary indicators. Another of the parameters worth highlighting is the very high flexibility of the belt. In order to reduce the risk of breaking the belt in those places where there is the highest voltage, it is supplied with special shaped teeth.

Another fact to pay attention to is the distance between the shafts when using belt gears. During the use of drive belts, a small distance between the centers of the shafts is allowed, which ensures an increase in the speed of its elements, and also contributes to an increase in the power that the belt is capable of transmitting. It is also worth noting that their use greatly reduces the vibration of the elements even in the case when loads of intermittent type are carried out, and slippage is not observed in the system itself.

PU straps

The use of polyurethane timing belts opens up more possibilities for their use. Due to the wide variety of design options and the large number of uses for such devices, they can be used in a wide variety of industries.

Because of their properties, polyurethane timing belts have found theirapplication among linear and transport equipment. In addition, they can be used in various lifting mechanisms or even in washing installations. The use of toothed belts of this type is possible when installing gates or doors that open automatically, they can even be used in robotics. It can be added that polyurethane belts can be both single-sided and double-sided. In addition, they may have a non-standard coating or an unusual shape of the teeth.

Toothed belt profiles differ in the shape of the teeth. The following types are distinguished:

• trapezoidal profile;
• semicircular profile;
• toothed double-sided.

Toothed belt repair

You can consider the process of replacing a toothed belt using the example of a five-cylinder engine. It is worth starting with the fact that in order to perform this operation on this type of engine, you must have a special tool from V. A. G.

In order to remove the desired part, it is necessary to loosen the vibration damper fasteners. It is mounted on the front of the crankshaft. After removing the belt, you need to re-tighten them using a special nozzle, which is designed for a torque wrench. If the engine is four-cylinder, then the replacement process is as follows:

1. The piston is being installed in the first cylinder in V. M. T.
2. Belt cover removed.
3. The strap is loosened and removed.
4. A new belt is being installed.

It is worth noting that if the cylinder head was removed when replacing the belt, then the gas distribution phases will have toregulate.