OHC, SOHC, and DOHC are abbreviations that stand for different types of engine configurations in motorcycles, specifically regarding the placement and operation of the engine's camshaft(s). Here's what each abbreviation stands for:
OHC (Overhead Camshaft): In an OHC configuration, the camshaft(s) is positioned in the cylinder head above the combustion chamber. It uses a system of cam followers, often called rocker arms or tappets, to open and close the valves. The camshaft is driven by a timing belt or chain from the crankshaft. OHC engines are known for their compact design, reduced weight, and ability to rev higher due to lower valvetrain mass.
SOHC (Single Overhead Camshaft): SOHC engines have one camshaft located in the cylinder head, positioned above the combustion chamber. This single camshaft operates both the intake and exhaust valves. It is also driven by a timing belt or chain from the crankshaft. SOHC engines are simpler and less complex than DOHC engines, but they generally have fewer valves per cylinder.
DOHC (Dual Overhead Camshaft): DOHC engines have two camshafts positioned in the cylinder head, one for the intake valves and one for the exhaust valves. This configuration allows for better control over valve timing and lift, resulting in improved engine performance. DOHC engines tend to have a higher number of valves per cylinder, which enhances the engine's breathing capability and increases power output. The camshafts in a DOHC engine are also driven by a timing belt or chain.
Overall, the choice between OHC, SOHC, and DOHC configurations depends on various factors, such as engine size, performance requirements, cost considerations, and design preferences. Each configuration has its advantages and trade-offs in terms of complexity, weight, power output, and manufacturing costs.