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CHAPTER 4 GOVERNORS AND LINKAGE
GENERAL INFORMATION
This chapter includes governor assembly and linkage illustrations to aid in governor or speed control assembly.
Tecumseh 4 cycle engines are equipped with mechanical type governors. The governor’s function is to maintain a
constant R.P.M. setting when engine loads are added or taken away. Mechanical type governors are driven off the
engine’s camshaft gear. Changes in engine R.P.M. cause the governor to move the solid link that is connected from the
governor lever to the throttle in the carburetor. The throttle is opened when the engine R.P.M. drops and closes as the
engine load is removed.
OPERATION
As the speed of the engine increases, the governor weights
(on the governor gear) move outward by centrifugal force.
The shape of the governor weights force the governor spool
to lift. The governor rod maintains contact with the governor
spool due to the governor spring tension. As the spool
rises, the governor rod rotates, causing the attached outer
governor lever to pull the solid link and close the throttle
opening. When the engine speed decreases, the lower
centrifugal force allows the governor weights to be pulled
in by the governor spring. As the spool lowers, the governor
rod rotates and the solid link pushes the throttle to a more
open position (diag. 1).
GOVERNOR SHAFT
RETAINING
RING
1
SPRING
WEIGHTS
THROTTLE
GOVERNOR GEAR
GOVERNOR
SPOOL
TROUBLESHOOTING
Engine problems where the governor is suspected to be the cause, may actually be the result of other engine system
problems. Hunting (engine R.P.M. surging up and down) indicates that the engine is incapable of maintaining a constant
R.P.M. with or without an engine load. Engine overspeeding (either with or without throttle movement) must be corrected
immediately before serious engine damage occurs. Use the following procedure to diagnose a suspected governor
problems.
SPOOL
RETAINING
RING
GEAR ASSY.
(GOV.)
WASHER
SHAFT
SPOOL
SHAFT
GEAR ASSY.
(GOV.)
WASHER
RETAINING
RING
SPOOL
WASHER
RETAINING
RING
GEAR ASSY.
(GOV.)
WASHER
SPACER
SHAFT
SHAFT
ROD
ASSY
(GOV.)
WASHER
BRACKET
GEAR
ASSY.
(GOV)
RETAINING
RING
SPOOL
SCREWS
INTERNAL COMPONENTS (VARIOUS STYLES)
TVS UPSET
HORIZONTAL
LEV
UPSET
NO RETAINING
RING
TVS STANDARD
2
3
4
6
WASHER
SHAFT
GEAR ASSY.
(GOV.)
SPOOL
5
MEDIUM FRAME