the amide linkages are attached directly to two aromatic rings have been designated as aramids by the federal trade commission first the aramid fibers in addition to being stronger are more flexible this makes a wheel which includes this fiber as a reinforcement more resistant to shear and in the event of damage to the wheel the fiber will better be able to hold the wheel together until the defect is detected this is especially true in a cutoff wheel as shown in u s pat no 3 487 589 to binkley which is pinched in a cut and flexed to the extent that numerous bond posts are broken the aramid fabric being much more resistant to shear will show this advantage second this quality makes it possible to utilize more of the inherent tensile strength of aramid fibers to hold the wheel together at higher rotational speeds these facts are born out by an over speed test which was run on 10 inches u00d7 3 32 inch u00d7 5 8 inch wheels of identical structure namely the only difference between the two above described test wheels was the type of reinforcing fiber used one used fiberglass while the other used aramid fiber prd 49 such aramid has the following properties specific.