Search results
Results from the WOW.Com Content Network
Although an overhead camshaft (OHC) engine also has overhead valves, the common usage of the term "overhead valve engine" is limited to engines where the camshaft is located in the engine block. In these traditional OHV engines, the motion of the camshaft is transferred using pushrods (hence the term "pushrod engine") and rocker arms to operate ...
This reduced inertia in OHC engines results in less valve float at higher engine speeds (RPM). [1] A downside is that the system used to drive the camshaft (usually a timing chain in modern engines) is more complex in an OHC engine, such as the 4-chain valvetrain of the Audi 3.2 or the 2 meter chain on Ford cammers. Another disadvantage of OHC ...
The most common use of a rocker arm is to transfer the motion of a pushrod in an overhead valve (OHV) internal combustion engine to the corresponding intake/exhaust valve. In an OHV engine the camshaft at the bottom of the engine pushes the pushrod upwards. The top of the pushrod presses upwards on one side of the rocker arm located at the top ...
Pushrods are long, slender metal rods that are used in overhead valve engines to transfer motion from the camshaft (located in the engine block) to the valves (located in the cylinder head). The bottom end of a pushrod is fitted with a lifter, upon which the camshaft makes contact. The camshaft lobe moves the lifter upwards, which moves the ...
The lobed camshaft rhythmically presses against the lifter, which transmits the motion to the engine valve in one of two ways: through a pushrod which actuates the valve via a rocker mechanism (in an overhead valve (OHV) engine); via direct contact with the valve stem or rocker arm (in an overhead camshaft (OHC) configuration).
Most modern pushrod engines have two valves per cylinder, while many OHC engines can have three, four or even five valves per cylinder to achieve greater efficiency and power. Recently, however, GM has begun offering a pushrod V6 with VVT, and Cummins' ISB is a 4-valve pushrod straight-6. The GM 3900 was the first mass-produced pushrod engine ...
As engine speeds increased through the 20th century, single overhead camshaft (SOHC) engines— where the camshaft is located within the cylinder head near the top of the engine— became increasingly common, followed by double overhead camshaft (DOHC) engines in more recent years. For OHC and DOHC engines, the camshaft operates the valve ...
The technology allows the intake and exhaust valves being positioned for optimum engine performance, which offers lower resistance for the air/fuel mixture flow. Overhead Cam engines also have fewer moving parts and produce less mechanical noise than competitive technologies. They also offer better cooling performance to combat overheating. [2]