Rocker arm

A rocker arm is used to change the direction of a force.

In internal combustion engines used to transfer movements of a cam curve of the cam shaft to the intake and exhaust valves. The rocker arm works like a seesaw. The rotary or tilting axis is, depending on the version, in the middle between the outer ends. One end of the lever is operated by the bumper and the other end operates the valve. In the design most commonly used presses the valve spring as soon as the camshaft has rotated further, the rocker arm in its initial position. Rare designs use a separate spring to return the lever to its original position.

To adjust the valve clearance, a set screw is available at many rockers. This is a grub screw and on the side, which is operated by the bumper is screwed. To prevent an adjustment while the engine is running, the threaded pin is secured with a lock nut. The lower end of the adjusting screw is embodied spherically, and is engaged with the counterpart of the bumper. Instead of an adjusting screw and an automatic compensation element may be present. Although these hydraulic or mechanical elements minimize maintenance, however, is the rocker arm - the oscillating mass - even much more difficult. Therefore, the hydraulic compensation element is usually arranged stationary and move the pivot point of the rocker arm, similar to the case of engines with an overhead camshaft. If the tilt axis, the pivot point shifted or twisted in the manner of an eccentric, the relative height of the rocker arm to valve changes. Displacement / rotation of the tilt axis in the longitudinal direction of the rocker arm changes the lever ratio by a small amount, and hence the valve lift.

At past opposing two-stroke engines with a crankshaft rocker transmitted the power from the crankshaft and to the flask Sekundärpleuel Primärpleueln above.