OHV distribution: What type of valve distribution is it?

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OHV timing is a type of piston combustion engine valve timing where the valves are located in the cylinder head, and the camshaft is located in the engine block. The designation of this type of distribution is derived from the English name Overhead Valve.

With this type of distribution, there is a relatively large distance between the camshaft and the valves. In the case of OHV distribution, the valves are therefore operated using metal lifters, lifting rods, and cams from below.


How does the OHV distribution work?

Thus, compared to other types of distribution, the OHV distribution contains many parts that adversely affect the entire aggregate, manifested by large inertial forces.

On the other hand, the advantage of the OHV distribution is the simple design solution of the camshaft drive. Due to the convenient location of the camshaft close to the crankshaft, the distribution drive can be implemented with a simple gear wheel.

The distribution drive must be designed in such a way as to enable precise adjustment of the relative position of the crankshaft and camshaft, which does not change during engine operation. However, the gear wheel fulfills all this.

Where is OHV distribution used?

The OHV distribution is mainly used for four-stroke engines. This means that the camshaft rotates 2x slower than the crankshaft because a four-stroke engine completes one work cycle during two crankshaft revolutions.

For example, engines with this distribution were installed in Škoda cars, more precisely in models 105, 120, 130, Favorit 135, 136, or Fabia and Octavia.

Video animation showing OHV distribution