3 Common Types Of Rocker Arm

An engine rocker arm is located between the crankshaft cam and valves. It helps convert radial movement into linear movement between the cam lobe and the poppet valve before entering into the combustion tube of the engine (such as those used in automobiles, maritime vessels, motorcycles, and reciprocating aircraft). The valve is opened from the other end.

The movement of the cam lobe on the bucket tappet causes friction. Bucket tappets are favoured for high-speed engines since they do not need an intermediary element and are low in weight. Alloy coating is fitted on the bucket tappet to reduce friction. It is becoming increasingly popular to employ the rocker arm with a roller bearing encased to minimize friction.

Types of rocker arms.

Rigid Type

This type of rocker arm has fixed joints. These types of rocker arms have a shaft that holds the arms into one place. The presence of the shaft makes the rocker arm rigid. The benefit of having a rigid engine rocker arm is that it prevents deflection of the valves. This type is used in engines of trains. Exhaust and intake valves move in the same direction at the same time. The valves are held in place by a spring, which acts as a counterweight to the movement.

How it works

This component is connected to the intake and exhaust valves using a rocker arm at one of its ends. This implies that when the camshaft cam triggers the rocker arm, one of its sides descends, enabling the valve to open and enabling the mixture of fuel and air to go into the combustion chamber.

Torsional & Bending Type

This rocker arm is composed of many parts that are joined together through bushing force. It functions similarly to a flexible body. This function is triggered if the Torsional & Bending type of Rocker Arm is selected and determines the properties of the bushings. Rocker arm bushing force decreases the vehicle’s weight by reducing the force transmitted from the wheel to the undercarriage. When a bushing is attached to a solid steel shaft, it is a hollow cylinder with a steel sleeve on the outside. Viscoelasticity is seen in the relationship between the force applied to the shaft and the relative deformation.

Beam Type

This rocker arm is composed of many components that are held together by Beam Force. It’s like a lithe, spherical body. This function is triggered if the Rocker Arm’s Beam type is specified, and it determines the properties of the beam forces. Three different internal forces might arise when a beam is exposed to transverse loadings: normal or axial, shearing, and bending moment. To forecast the behaviour of parts, it is necessary to know the intensities of these forces.


Rocker arms are very vital in engines. Different types are made to serve specific purposes. It helps in changing the direction and the amount of motion from the crankshaft cam to the valves. For maintenance purposes, ensure that you lubricate the moving parts of the engine rocker arm to prevent engine failure. They are also made from different materials; depending on the purpose of the engine, select the suitable material.

Katherine T. Burrows

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