A stable moving platform from which articles may be measured while in motion on this platform. An endless, moving silent chain type conveyor is modified to allow a center group of links to float relative to the pins which hold the links together. A mechanical force applying means presses the chain downward to define fixed horizontal and vertical planes just as the chain is to enter an inspection zone. A magnetic force applying means under the chains holds the chain in the fixed position defined by the mechanical force applying means as the chain moves through the inspection zone.

In an arm operating device of an industrial robot, two chains are laid over the driving wheel provided in the supporting arm and the driven wheel provided in the bending arm, respectively, and are coupled through rigid transmission rods and a tension device to each other, and one of the transmission rods is rectangular in section, and is slightly pushed inwardly by a guide provided on the supporting arm, whereby the device operates positively and smoothly with being free from vibrations, and chain elongation and twist.

Inverted tooth chains particularly those used in timing drive applications. Conventional guide links are replaced by conventional sprocket engaging links for the two outermost links in the outer link rows. A thick inner link of approximately twice normal thickness is placed in the inner link row and two normal thickness regular links are placed in the outer link row. Pins are fit securely in the holes of the links in the outer link rows.