User's Manual

43
CHAPTER 7. DYNA-STATIC
®
BALANCING SYSTEM
TECUMSEH DYNA-STATIC
®
BALANCING SYSTEM.
Dyna-Static
®
Tecumseh’s Balancing system for horizontal
crankshaft 10, 12, 14, 16 and 18 H.P.
Dyna-Static
®
operates by means of a pair of
counterweighted gears driven off the crankshaft to
counteract the unbalance caused by the counterweights
on the crankshaft. The exterior distinguishing feature
of an engine equipped with a balance system is the
“deep-dished” side cover. This cover contains the
counterbalance gears and shaft.
Tecumseh Dyna-Static
®
balancing system also utilizes
a helical (angle) cut set of gears consisting of a
crankshaft gear and two counterbalance gears. There
are two sets of helical counterweight assemblies.
The difference between the two assemblies is the
counterweight mass. They cannot be distinguished
by size. Check Parts Manual or Microfiche for correct
counterweight set. The helical cut gear assemblies
may be interchanged with the regular cut gear
assemblies, but only if all three gears (crankshaft
gear and two counterweight gears) are interchanged
as a set.
On some production models the counterbalancing
gears are placed top and bottom of crankshaft.
ALIGNING THE COUNTERWEIGHTS (Side-by-Side
counterweights) This view of the side cover is from
the outside showing the pipe plugs which plug the
alignment holes during normal operation.
NOTE: Be careful when installing the cylinder cover
that the counterweight balance gears remain in
alignment.
Remove pipe plugs from flange, assemble flange
to cylinder making sure the slots stay in hole. Slots
may have to be moved either way with punch or
screwdriver to mesh gears. If you can see any part
of slots in holes after assembled, it is correctly
assembled. Reinstall pipe plugs.
The important thing is to keep the counterweight
gears perfectly aligned on the crankshaft gear. Any
misalignment of these gears can cause vibration.
Insure also that the governor rod assembly is correctly
placed.
TOP & BOTTOM COUNTERWEIGHTS
On some production models the counterweight balancing
gears are placed top and bottom of the crankshaft.
The gears mesh with the driver gear on crankshaft
when the piston is at T.D.C. and the gear weights
are down as shown.
NOTE: If a damaged gear is replaced, the mating
gear should also be replaced.
Example: If the camshaft is damaged and replaced,
the crankshaft gear should be replaced.
T.D.C.
PIPE PLUGS
T.D.C.
PIPE PLUGS