18
AIR VANE GOVERNORS.
All Tecumseh 2 cycle engines
covered in this book 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 fins on the flywheel. Changes
in the engine R.P.M. cause the air vane to move. The
throttle is opened as the engine R.P.M. drops and is
closed as the engine load is removed.
OPERATION
Engine R.P.M. changes cause an increase or decrease
in the air velocity created by the fins on the flywheel.
The air velocity exerts pressure on the air vane while
a governor spring exerts pressure against the air velocity
force. The air vane pivots on the engine flange or is
attached to the throttle shaft of the carburetor. As an
engine load is applied and the engine's R.P.M drop,
the air velocity also drops, allowing the governor spring
to pull open the throttle shaft and increase engine
speed.
LINKAGE INSTALLATION.
The best method is to record
the linkage attachment points prior to disassembly
and reinstall the same way.
Illustrations showing most governor and linkage hookups
are pictured in this section. Select the diagram that
resembles the engine you are servicing. R.P.M. settings
may be found in microfiche catalog, card number 30.
GOVERNORS AND LINKAGE
AIR VANE
SLEEVE
TABS
Rotate sleeve clockwise to increase R.P.M.;
counterclockwise to decrease R.P.M.
NOTE:
The sleeve is serrated to rotate in a clockwise
direction and must be raised using the sleeve tabs
before it can be rotated counterclockwise.
To disassemble, remove choke shutter with needle-
nose pliers; the vane assembly may then be removed
from the carburetor.
AIR VANE
ASSEMBLY
BEND TAB TO
ADJUST RPM
HORIZONTAL FIXED SPEED
PLASTIC AIR VANE GOVERNOR
Summary of Contents for AH520 -
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