Balancer shafts: principle of operation, design features

Balancer shafts are a part of a car engine of complex design, usually a metal rod with grooves, which is designed to ensure the balance of rotating masses in the cylinders of the car engine.

Balancer shafts were first installed in Mitsubishi vehicles. Such technology was quite simply called a silent shaft. Any brand of car in any condition will be accepted for recycling here:

Today, balancer shafts are used in most car models produced under such brands as GM, Audi, Mercedes, BMW.

How balancer shafts work

The shafts are attached through two small holes on the back of the engine crankcase, making rotary movements on plain bearings.

The upper balancer shaft is connected to the lower shaft by actuators. The drive of the upper shaft has a toothed belt which engages the drive of the lower shaft by a special gear.

The shafts are installed only in pairs, symmetrically on both sides of the crankshaft. The balancer shaft always rotates in the opposite direction from the crankshaft, and its speed is doubled.

This reduces all engine vibration by mutually compensating the inertial forces of the crankshaft balancer shafts, since these forces are always directed toward each other.

The balancer shafts are secured only longitudinally by a locking plate which is attached to the annular grooves. Such locking grooves are located on each pinion of the upper and lower balancer shaft.

The principle of operation of the CRM is based on the formation of inertial forces from the interaction of all its working mechanisms and elements. Some elements, such as pistons, make reciprocating movements, and others, connecting rods, make rotary movements.

The effects of inertial forces in the engine cylinders create a strong vibration and increased noise level in the engine as a whole, which leads to overload and rapid wear of individual engine components.

In order to somehow balance the vibrations created in the engine, balancer shafts are used.

Balancer shaft drive

This drive is derived from the crankshaft and is used to provide alternating rotary motion at a preset angular velocity. The toothed belt often serves as the drive.

In order to reduce the rotational vibrations that occur during the rotational motion of the shaft, a spring-type vibration damper is used, which is installed in the sprocket on the drive.

Difficulties in balancer shaft repair

Strenuous balancer shafts are often subjected to extremely high stresses, which can cause bearing and drive unit failures. Rapid wear or failure of the components increases noise and vibration levels, resulting in a complete breakdown of the drive.

Repair work on balancer shafts is difficult and expensive. That is why many car owners prefer to simply remove the balancer shafts and close the holes with special plugs instead of expensive replacement.

Among other things, the use of balancer shafts affects the complexity of the car engine itself, as well as the cost of its maintenance.

If it is still necessary to replace the balancer shaft, a new drive chain and bottom crankshaft pinion are installed along with the new part.

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