At the top of the internal combustion engines, petrol and diesel engines, the distribution shaft is located at the top of the cylinder head. The classical construction of the GRM provides for the rotation of a rotational effort from the crankshaft to the crucible through the chain transfer. The GRM Chain Drive has a number of advantages and its specific drawbacks. The history of the GRM chain drive
The history of the GRM chain drive
Chain drive has a long history. The mass use of the chain (like the GRM-belt) refers to the end of the 1950s, that is, by the time of the transition to the superstructure.
The main flaw is noisy work. Main advantage-durability
In recent times, jagged chains have been increasingly being distributed, gradually replacing the roller skaters. They are more flexible and highly capable of transmission, the main one being the low level of noise at work.
Coupling structure design
Usually a single-and two-line roller circuit is used for the drive. They shall transfer efforts from an asterisk to the end of the crankshaft, with another star on the end of the roll.
The chain has an almost zero ability to stretch and contract, and there is rather limited flexibility. Therefore, in order to ensure that it has a constant tension during operation, it is necessary to use powerful hydraulic pressure, similar to the miniature oil dampers. They may be from one to three, depending on the number of bends.
To keep the chain "sitting" in its place at any turn, it literally has to be surrounded by a system of teners and sedans
Even a well-strained chain keeps the "play" property in places where there are no stars or teners. A chain structure that is developing a lot of inertia, so a chain drive requires a lot of hesitation. This task is handled by the sootters-additional spring-loaded slats. They have a steel frame covered with a layer of solid rubber. The circuits are equipped with weak springs, which allow the chains to "play", but only within limited limits. The villagers and the tranquiousers are quite effectively dampable vibration and noise. The chain-of-command prevents a limitless finger from being placed in the block or head of the cylinder block. In normal operation, the chain does not concern it.
Advantage of the GRM chain drive
The efficiency and durability of the GRM chain drive depend on the material and the quality of the heat treatment of the chain and the stars.
The accuracy of production and the purity of the working surfaces is of great importance. The main advantage of the GRM chain is its durability. On modern engines, the resource of the chain is between 100 and 200,000 kilometers of mileage. If high quality materials were used in the manufacturing of components and the correct tension and heavy lubricant was used in operation, the chain will last at least as much as the engine itself.
The collapse of the chain is rare. Deterioration of its condition can be traced to noise amplification when the engine is running.
Disadvantages of the GRM chain drive
The GRM chain end is more complicated and therefore more expensive. However, the reliability of the chain drive is often more important than the higher cost.
The chain is an attribute of expensive and powerful motors that require special design reliability
The main lack of the chain is difficult to access. The whole drive requires constant oil supply, so the mechanism is taken to the inside of the cylinder block (and, in part, inside the HC). The chain is practically free from wear, which is not to say about shoes (tranquitators) and hydraulic pressure. Even for visual inspection of these elements, not to mention a replacement, you have to deal with half the engine.
In addition to the cost and complexity of the GRM chaining, it is possible to include noise at work, greater weight. But despite these drawbacks, it is used in the motor cars of the most prestigious cars-Jaguar, Mercedes, BMW and others. This is explained by the desire of producers to provide the status buyer with expensive but reliable equipment.
