A propeller shaft (1) that is a power transmission shaft has a shaft member (2) as a tubular body made of iron-based metal and a balance weight (3) made of iron-based metal and welded to an outer peripheral surface of this shaft member (2). At least a part of the balance weight (3) of the propeller shaft (1) is covered with a sacrificial metal coating (4) made of sacrificial corrosion prevention material that contains metal whose ionization tendency is higher than that of metal forming the shaft member (2). With this, it is possible to suppress local progression of corrosion at a periphery of the balance weight (3) and improve durability of the propeller shaft (1) .

Embodiments are directed toward an engine. In some embodiments, the engine includes a water pump and a balancer shaft. In some embodiments, the water pump has a plain bearing. In some embodiments, plain bearing is supplied with pressurized oil. In some embodiments, the balancer shaft drives the water pump as well as cam shafts.

A crankshaft assembly for a motor vehicle drive train, including a crankshaft segment and a centrifugal pendulum secured thereon, which has a carrier secured to the crankshaft segment and at least one pendulum mass that moves relative to the carrier along a predetermined track. The crankshaft assembly has a friction unit connected to the carrier, which rests on the at least one pendulum mass such that, with a relative movement of the pendulum mass in relation to the carrier, the friction unit applies a frictional torque on the pendulum mass counteracting the relative movement, wherein the friction unit extends over a peripheral section of less than 360°.

A propeller shaft (1) that is a power transmission shaft has a shaft member (2) as a tubular body made of iron-based metal and a balance weight (3) made of iron-based metal and welded to an outer peripheral surface of this shaft member (2). At least a part of the balance weight (3) of the propeller shaft (1) is covered with a sacrificial metal coating (4) made of sacrificial corrosion prevention material that contains metal whose ionization tendency is higher than that of metal forming the shaft member (2). With this, it is possible to suppress local progression of corrosion at a periphery of the balance weight (3) and improve durability of the propeller shaft (1).

A crankshaft (1) for a crankcase scavenged two stroke piston engine (2) is disclosed. The crankshaft (1) is configured to rotate around a rotation axis (ax) during operation. The crankshaft (1) comprises a crankpin (3) configured to move in a crank plane (cp) during operation, and a first and a second counterweight (5, 7) arranged on either side (S1, S2) of the crank plane (cp). The first counterweight (5) has a first outer radius (r1) measured from the rotation axis (ax) and the second counterweight (7) has a second outer radius (r2) measured from the rotation axis (ax). The first outer radius (r1) is smaller than the second outer radius (r2). The present disclosure further relates to a power unit (10), a crankcase scavenged two stroke piston engine (2), and a hand-held power tool (20).

A crankshaft (1) for a crankcase scavenged two stroke piston engine (2) is disclosed. The crankshaft (1) is configured to rotate around a rotation axis (ax) during operation. The crankshaft (1) comprises a crankpin (3) configured to move in a crank plane (cp) during operation, and a first and a second counterweight (5, 7) arranged on either side (S1, S2) of the crank plane (cp). The first counterweight (5) has a first outer radius (r1) measured from the rotation axis (ax) and the second counterweight (7) has a second outer radius (r2) measured from the rotation axis (ax). The first outer radius (r1) is smaller than the second outer radius (r2). The present disclosure further relates to a power unit (10), a crankcase scavenged two stroke piston engine (2), and a hand-held power tool (20).

The rotary body according to the present invention is made of resin and attached to a crankshaft. The rotary body has an outside plate element and an inside plate element which are attached to an outside surface and an inside surface of an arm portion of the crankshaft, respectively, and a pair of filler elements disposed between the outside plate element and the inside plate element and on both sides of the arm portion. The outside plate element and the pair of the filler elements are coupled to each other, and the pair of the filler elements and the inside plate element are coupled to each other.

Provided is a damper device enabling to exert stable vibration damping performance over a wide range of rotational speed regardless of environmental changes. A damper device attached to a rotating shaft to suppress amplitude at resonance of the rotating shaft, includes: a damper housing formed annularly and concentrically with the rotating shaft; a plurality of mass bodies annularly arranged around the rotation shaft inside of the damper housing and configured to be movable in the diameter direction by centrifugal force; an annular elastic body, formed of a circular spring-shaped elastic body abutting on the outside of the plurality of the mass bodies, so as to bias the mass body inward; and a biasing member, being a leaf spring-shaped elastic body abutting on the outside of the annular elastic body, so as to bias the annular elastic body inward.

Provided is a damper device enabling to exert stable vibration damping performance over a wide range of rotational speed regardless of environmental changes. A damper device attached to a rotating shaft to suppress amplitude at resonance of the rotating shaft, includes: a damper housing formed annularly and concentrically with the rotating shaft; a plurality of mass bodies annularly arranged around the rotation shaft inside of the damper housing and configured to be movable in the diameter direction by centrifugal force; an annular elastic body, formed of a circular spring-shaped elastic body abutting on the outside of the plurality of the mass bodies, so as to bias the mass body inward; and a biasing member, being a leaf spring-shaped elastic body abutting on the outside of the annular elastic body, so as to bias the annular elastic body inward.

Embodiments are directed toward an engine. In some embodiments, the engine includes a water pump and a balancer shaft. In some embodiments, the water pump has a plain bearing. In some embodiments, plain bearing is supplied with pressurized oil. In some embodiments, the balancer shaft drives the water pump as well as cam shafts.