Chain Bar Arm/4-Bar Linkage

A chain bar arm is a special type of multi-axis arm that involves chain hard-bolted to a bar. The purpose of a chain bar arm is to make an extension such that the outer bar always keeps the same angle in reference to the ground. This means that if the outer bar is parallel to the ground in the stow position, it will remain parallel to the ground at all points in the extension of the arm. This is especially important if, for example, you have a claw to pick up an object, and you want the claw to remain parallel to the ground.


If your sprockets are of different lengths, you can mechanically rotate a between two desired angles without needing to expend a servo slot.

Chain bar arms can provide the >24” optimal extension needed to be competitive in games, but it also has disadvantages. It is much harder to control than a linear slide, since a chain bar arm has momentum. Thus, it is very difficult to be precise with a chain bar when stopping the arm quickly.

8103's chain bar to move the relic in Relic Recovery
8103's chain bar to move the relic in Relic Recovery

8103 Null Robotics, Relic Recovery