Abstract: A viscous and rubber-type torsional damper including a boss portion, a pulley portion, and connecting members for elastically connecting the boss portion and the pulley portion. The connecting portions are spaced from each other in an axial direction of the torsional damper and define a fluid-tight closed space therebetween. At least one protrusion is formed on at least one of the boss portion and the pulley portion. The protrusion protrudes into the closed space and a gap is formed between the surfaces of the protrusion and the surfaces opposing the protrusion. The area between the surfaces is filled with a viscous fluid such as a silicone oil. Due to this structure, the viscous damping ability of the damper is increased without increasing the radial size of the damper and without increasing the number of constructing members of the damper.

Abstract: A muffler for automobiles having a drum-shaped expansion chamber of diameter D and length h, to which gas inlet and outlet pipes and an insert pipe of a Helmholtz resonator open so that the gas flow traverses the expansion chamber substantially diametrically therethrough, wherein the ratio h/D is substantially 0.25 - 0.4.

Abstract: A coupling assembly for operatively connecting an output shaft of an internal combustion engine to a member associated with the engine such as a cooling fan, in which a rotor is fixed to the output shaft and a first casing is fixed relative to the member associated with the engine and surrounds the rotor. A first reservoir is defined within the first casing and contains a coupling fluid for transferring the torque of the rotor to the casing. A second casing is fixed to the first casing and defines a second reservoir for the fluid, with the second casing having a plurality of openings formed therethrough for permitting the fluid to pass from the first reservoir to the second reservoir to reduce the amount of torque transferred from the rotor to the first casing. An inertia valve is responsive to angular acceleration of the rotor and selectively controls the amount of fluid passing through the openings and thus the amount of torque transferred.