A shock attenuating coupling device is provided for a rotary impact tool
for drivingly connecting a hammer mechanism to a drive anvil. The shock
attenuating coupling device includes a first coupling member, a second
coupling member, a drum, a shoe, and a body of resilient material. The
first coupling member has a first drive portion. The second coupling
member has a second drive portion. The drum is provided proximate the
first drive portion and the second drive portion and has a radially inner
engagement surface. The shoe is provided within the drum and between the
first drive portion and the second drive portion. The shoe has a radially
outer surface capable of being expanded in a radially outer direction.
The body of resilient material is interposed between the drum and the
shoe. The first drive portion and the second drive portion are configured
to expand the shoe responsive to torsional displacement between the first
coupling member and the second coupling member in order to compress the
body of resilient material in engagement with the inner engagement
surface of the drum.