Push pull linkage

From RC Helicopter Wiki

A method of delivering torque from a servo to a bellcrank, using a pushrod on either side of the servo horn. This way, there will always be one rod pushing, and one rod pulling (hence the name). Push-pull linkages greatly reduce the amount of slop in a linkage, by spreading the load over both push rods (so reducing horn bending) and allowing a tiny amount of tension to exist in the linkage.