TC/TM SERIES 2-Cycle Engines - Small Engine Suppliers

CHAPTER 4 GOVERNORS AND LINKAGEGENERAL INFORMATIONTC/TM series engines are equipped with pneumatic (air vane) governors. The governor's function is to maintain a R.P.M.setting when engine loads are added or taken away. Air vane governors are controlled by the air velocity created by finson the flywheel. Changes in the engine R.P.M. cause the air vane to move. This movement opens the throttle shaft eitherby a link between the air vane and the throttle plate, or the air vane is mounted directly onto the throttle shaft. The throttleis opened as the engine R.P.M. drops and is closed as the engine load is removed.This chapter includes governor assembly linkage and speed control illustrations to aid in assembly.OPERATIONEngine R.P.M. changes cause an increase or decrease inthe air velocity created by the fins on the flywheel. The airvelocity exerts pressure on the air vane while a governorspring exerts pressure against the air velocity force. Theair vane pivots on the engine blower housing base or isattached to the throttle shaft of the carburetor. As an engineload is applied and the engine's R.P.M. drop, the air velocityalso drops, allowing the governor spring to pull open thethrottle shaft and increase engine speed (diag. 4-1).If the engine uses a remote speed control, the bowdenwire will move the speed control plunger or the throttleshaft. Moving the speed control plunger results inchanging the governor spring tension which increases ordecreases the engine's governed speed.COMPONENTSTC TYPE IAir VaneTC TYPE II/TMAir Vane1. AIR VANE2. BACKLASH SPRING3. GOVERNOR LINK4. GOVERNOR SPRING5. MOUNTING SCREW6. SPEED ADJUSTMENT SCREW7. SPEED CONTROL BODY8. SPEED CONTROL LEVER9. SPEED CONTROL PLUNGER4-11.TC TYPE II/TMTC TYPE I andEARLY TYPE II1.5.Spring HookedIn Notch8.9.4.2.4.Insert Throttle Link7.3.6.4-225