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Engineer's Toolbox:
Retaining rings replace nut-and-bolt fasteners in rocker arm assembly

High-performance rocker arms add horsepower to an engine, and retaining rings have played a role in their development.

Rocker arms are used in combustible engines and are important to engine performance. Standard engine rocker arms or roller-tipped rocker arms are the most common. They are made from stamped steel and bolted to the block. Rocker arms are connected pushrods inside the block, which are connected to valve springs that are under extreme pressure.

High-performance rocker arms or shaft-mount rocker arms are used in high-performance engines. They are mounted on a shaft for extra rigidity, reduction of vibrations, and have less chance for uncontrolled valve-train motion at high RPMs. They feature a trunnion (a pivot point) along with a bearing inside the arm to reduce friction and wear. The bearings and trunnion are held in place by an SH retaining ring on each side of the rocker, and the rings mount directly on the shaft. This replaces the conventional "nut and bolt" rocker arm assembly found in standard engines.

View the full Rotor Clip catalog here. You can download the catalog too.

 

 

A pre-cut groove in the shaft firmly secures the retaining ring in place, pressed up against the rocker arms and bearing, which aims to further reduce wear of the rocker arms caused by vibrations and extensive use. If the rocker arm becomes damaged and needs to be replaced, the ring can be easily removed and the rocker arm can slide off the shaft. Racing enthusiasts go to great lengths to reduce weight without sacrificing power and ease of access for replacement in the field. The rocker arm and retaining ring combination is an excellent example of how this is accomplished.

Source: Rotor Clip Company, Inc.

Published November 2013

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