TM 5-3810-300-24&P-3
1.3.6
CRANKSHAFT VIBRATION DAMPER
Six cylinder vehicle engines require a vibration damper to
reduce the crankshaft stresses to a safe value. Three
different types of vibration dampers are available for the
six cylinder engines and their particular use depends on
the governed speed and other characteristics of the
engine.
The three types of vibration dampers are described
below.
The double (rubber) damper shown in Fig. 1, is made up
of a light damper, a heavy damper, a hub, an inner cone,
and an outer cone. The light and heavy dampers of the
assembly are in turn made up of rubber blocks bonded to
an inertia mass in the form of metal ring on one side, and
a stamped metal disc on the opposite side.
The two metal parts are, therefore, entirely separated
and free to move within certain prescribed limits by virtue
of the rubber blocks. The light and heavy dampers are
bolted and doweled together and to the driving hub. The
hub in turn is secured in place at the front end of the
Fig. 1. Crankshaft Cap and Double Vibration
crankshaft between an inner and outer cone as shown in
Damper Assembly and Mounting
Fig. 1. The two cones provide an adequate rigid
mounting when the crankshaft cap, or a pulley, is drawn
highly viscous fluid (Fig. 2). The very small clearance
up tight against the outer cone by the bolt in the end of
between the flywheel and the outer shell is filled with the
the crankshaft.
fluid which causes the flywheel to be driven upon
The single (rubber) damper is similar to the double
deceleration.
damper described above except that only the light
damper is used with the hub and cones.
During operation, the outer shell, which is firmly attached
to the crankshaft, turns at the same speed as the
Even though these vibration dampers are rigidly
crankshaft, its motion being transferred to the flywheel
constructed, and should give no trouble if given proper
through the fluid within the shell. Inasmuch as "fluid-
care; nevertheless, since rubber is used in the assembly,
drive" is more or less inefficient with frequent speed
certain precautions are necessary.
Fuel oil and
changes, considerable slippage of the flywheel will take
lubricating oil, as well as excessive heat, are destructive
place as the power impulses are transmitted through the
to rubber. The assembly, therefore, should be protected
crankshaft. In this type of operation, the slippage is
against these destructive agents. Furthermore, for the
damper to function properly and safeguard the
flywheel in the damper lessens the amplitude of the
crankshaft, it should be securely fastened to the shaft by
vibrations, thereby reducing their effects to a point where
the cones and the crankshaft cap or pulley, which also
they are not harmful to the engine.
act as a cone retainer.
The vibration damper must be removed whenever the
The viscous (fluid) type damper provides faster response
crankshaft, crankshaft front cover, or crankshaft front oil
to load and speed changes, and high temperatures have
seal is removed or replaced.
a less adverse effect than on the rubber type damper.
Remove Vibration Damper From Crankshaft
The viscous damper assembly consists of a sealed outer
shell, an internal flywheel, and a quantity of
1. Remove the crankshaft pulley or cap retaining
bolt and washer.
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