WM 777 SERIES ■\ PRODUCT DESCRIPTION DESCRIPTION Engineered for industrial or vehicle applications, the WM777A is a normally open, air pressure-actuated, electrical stoplight switch. The unit is mounted by the 14-18 NPTF male inlet port. OPERATION An internal spring holds the contacts in the normal, open position. The WM777A stoplight switch is actuated by 2-6 PSI (13,8-41,4 kPa) of air pressure. When actuated, an internal diaphragm expands, closing the contacts. APPLICATION Designed primarily for vehicular stoplight applications, the WM777A can be used in any air pressure-activated installation. A tee-fitting can be used to mount the switch to any air line. Wiring can be connected to either terminal. The WM777A stoplight switch can be used in FMVSS 121 applications. TYPICAL INSTALLATION IGNITION SWITCH TAIL LIGHTS STOPLIGHT SWITCH FROM BRAKE |;_ AIR TREADLE VALVE BRAKES FUNCTIONAL DIAGRAM H\ > WILLIAMS CONTROLS, INC. 14100 SW 72ND AVENUE, PORTLAND, OREGON 97224, TEL: (503) 684-8600, TELECOPIER: (503) 684-8610

PARTS IDENTIFICATION NUT WASHER BODY TERMINAL CONTACT SPRING DIAPHRAGM PLATE DIAPHRAGM COVER This component is classified as a nonrepayable item. TO ORDER,SPECIFY WM777A Model Number PART NUMBER 118150