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 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 rotation device capable of improving safety includes a plurality of screw holes that each extend along the radial direction of a rotation member and each has an opening on a surface of the rotation member; and a stopper for preventing a screw disposed inside the screw hole from protruding to the outside of the opening, without interfering with insertion of a tool, for turning the screw, into the screw hole.

An oscillating power tool with an electric motor is provided, including an armature shaft with an armature and a fan wheel, including an eccentric arranged on the armature shaft at one end thereof, a first balancing mass for balancing an unbalance of the eccentric and possibly an eccentric bearing, being arranged in the proximity of the eccentric or the eccentric bearing, respectively, however, at an axial distance, further including a second balancing mass for balancing a couple unbalance caused by the axial distance between the eccentric and the eccentric bearing, respectively, and the first balancing weight, wherein the second balancing mass is arranged on the armature shaft at the side facing away from the eccentric or the eccentric bearing. Also a method for balancing such an electric motor is provided.

A shaft vibration absorber for absorbing vibrations of a shaft includes an elastomer body that is reached through by a central longitudinal centre axis. In embodiments, the elastomer body includes holding geometries that protrude in the radial direction and extend in the longitudinal direction for pressing the shaft vibration absorber to the shaft. The holding geometries may be arranged in each case in two first angle windows that lie opposite one another with regard to the longitudinal centre axis with a width of in each case at most 90°. With embodiments, the shaft vibration absorber can configure a radial pressing force of the shaft along a first tuning axis that runs in the radial direction, and the radial pressing force may be greater than a pressing force in a spatial direction that differs therefrom and runs in the radial direction.

To provide an electric motor enabling easy and high-precision balance correction, and a machine toll including this electric motor. An electric motor (1) includes: a cylindrical stator (2); a rotor (3) having a rotary shaft part (31) inserted inside of the stator (2); a housing (4) installed to both ends in an axial direction of the stator (2); an opening (51a) provided in at least one outer peripheral lateral face of the housing (4), and disposed to be separated from an internal space (S) of the stator and a ventilation passage (9) formed in the stator (2); and a balance correction component (6, 61) that is installed to the rotary shaft part (31), and corrects balance of the rotor (3), in which the balance correction component (61) is exposed to outside from the opening (51a); and a machine tool (10) includes this electric motor (1).

A balance device for an internal combustion engine includes a crankshaft and a balance shaft. The crankshaft includes a CS eccentric weight. The balance shaft includes a BS eccentric weight. A CS connected point deviated from the CS main shaft, and a BS connected point deviated from the BS axial shaft are connected with a connection rod. A CS connection mechanism that enables relative rotation of the crankshaft and the connection rod is provided at the CS connected point. A BS connection mechanism that enables relative rotation of the balance shaft and the connection rod is provided at the BS connected point. A guide section guides a motion of the connection rod so that the balance shaft rotates in an opposite direction to the crankshaft.

Disclosed is a device for attaching corrective weights to a cylindrical outer surface of a rotor by means of electric resistance pressure welding, including an electrode (1) having a contact surface (20) for application against the rotor and comprising a supporting body (2) and a swinging body (6) having oppositely facing, congruent, spherical bearing surfaces (5, 8) suitable for abutting engagement with each other. The swinging body (6) is movably secured to the supporting body (2) such as to be able to perform limited swinging movements to all sides. A spring (14) arranged between the supporting body (2) and the swinging body (6) enables a gap to be produced between the spherical bearing surfaces (5, 8), whereby the contact surface (20) is in a position to align itself relative to the opposite surface of the rotor prior to pressure application by the welding force.

A turbomachinery rotor apparatus includes: a rotatable disk having an array of slots spaced around its periphery; an array of blades installed in the slots, wherein the blades have variable weights; and a plurality of connection components installed in the disk, each connection component forming a portion of a mechanical joint between one of the blades and its respective slot, wherein the connection components have variable weights.

A machine for balancing vehicle wheels includes: a base frame; a balancing shaft on which a vehicle wheel to be balanced can be fixed; a rotoidal resting unit, fitted on the base frame and supporting the balancing shaft in a revolving way around its own axis; and motor elements for placing in rotation the balancing shaft around its own axis; wherein the balancing shaft includes at least a measuring section which is magnetized and subject to a stress condition due to the unbalance of the wheel revolving on the balancing shaft, in proximity of the measuring section being arranged magnetic field sensor elements which are suitable for detecting by magnetostrictive effect the stress condition of the measuring section and are operatively associated with at least one processing and control unit suitable for determining the unbalance of the wheel starting from the stress condition of the measuring section.