An accessory drive system is used to power the accessories of an internal combustion engine. The accessories typically include an air conditioning compressor, a power steering pump, and an alternator. A front end accessory drive belt is trained around pulleys to supply power from the crankshaft of the engine to the accessories. Front end accessory drive belts are sensitive to misalignment. Pulley to pulley misalignment of only a few degrees can result in increased system noise, belt wear, and imposes an offset load on the pulleys potentially causing a premature failure of the drive belt system.
Alignment techniques have been developed to resolve some of these concerns. It is known to place a straight edge between two pulleys or to attach a mechanical arm to one pulley and extend it out to reach the other pulley to visually check for alignment. A more accurate alignment tool used is a coordinate measuring machine (CMM). This tool requires either the removal of the engine from the vehicle to place on a CMM or a significant teardown of the vehicle to create access to the pulleys for a portable CMM. The raw data from the CMM is then converted to the misalignment angle by use of custom software algorithms.
The inventors of the present invention have found certain disadvantages with these prior art devices. For example, using visual and straight edge alignment produces inaccurate results and causes unnecessary adjustments to the pulleys. These procedures fail to satisfy the customer resulting in second repairs or loss of repeat business. A mechanical arm may correctly align the two pulleys; however, multiple mechanical arms of various spans would be required to accommodate the different lengths between the pulleys in a single drive belt system. And, although using a CMM accurately aligns the pulleys, using this method of alignment is impractical for service due to the extensive time and cost spent tearing down the vehicle and collecting the data.