The Type E-15 tachometer covered by this specification is designed to indicate the speed of the turbosupercharger and at the same time to light a warning lamp when the rated speed of the turbosupercharger is reached. To operator properly there must be a 20 to one reduction between the turbosupercharger and the tachometer generator. This may be achieved by the use of a proper adapter which further reduces the oil pump shaft (tachometer drive) speed to 1/20 of the turbosupercharger speed. Adapters designed for use with turbosuperchargers are covered by Specification MIL-A-6516. To connect the generator to the tachometer drive a short Type A-2 flexible shaft in accordance with Specification MIL-F-7184 is required.