A drive shaft extends between axial ends and has at least one portion through which an outer diameter of the drive shaft changes through an infinite number of diameters, with the at least one portion extending across at least 15% of an axial distance between the axial ends of the drive shaft. A drive shaft with a generally spiral undulation at its outer periphery is also disclosed.

A drive shaft body extends between axial ends and has an outer peripheral surface with undulations extending between relatively greater and smaller outer diameters. The undulations extend along a non-zero angle relative to a circumferential direction defined relative to a drive axis of the drive shaft. The undulations extend along a spiral. The drive shaft body is formed of a fiber-reinforced composite material.

Vacuum cleaner, comprising a tube having a first diameter, a hose having a second diameter exceeding the first diameter by at least 15%, and a transition piece (T) having a first end (1) arranged for being connected to the tube, and a second end (2) arranged for being connected to the hose, wherein the transition piece (T) has a curved part that has a non- circular cross-section, the curved part having a first part (I) in which in a direction from the first end (1) to the second end (2), a first dimension (R1) of the cross-section increases to a diameter exceeding the first diameter by 15%, the first dimension (R1) being in a radial direction of the curved part, while a second dimension (R2) of the cross-section, perpendicular to the first dimension (R1), does not exceed the first diameter by more than 10%. Preferably, the transition piece (T) has a second part (II), between the first part (I) and the second end (2), the second part (II) having a non-circular cross-section where the second part (II) meets the first part (I), and a circular cross-section where the second part meets the second end (2). Advantageously, in the first part (I), in a direction from the first end (1) to the second end (2), the first dimension (R1) of the cross-section increases to a diameter exceeding the second diameter, while the second dimension (R2) stays below the second diameter.

A tube for a power transmission shaft is made of fiber-reinforced plastic, rotated to transmit power, and includes a main body in a shape of cylinder about an axis, wherein the main body has an outer diameter thereof gradually decreasing from a central portion thereof toward both ends thereof, and has a thickness thereof gradually decreasing from said both ends toward the central portion.

A drive shaft extends between axial ends and has at least one portion through which an outer diameter of the drive shaft changes through an infinite number of diameters, with the at least one portion extending across at least 15% of an axial distance between the axial ends of the drive shaft. A drive shaft with a generally spiral undulation at its outer periphery is also disclosed.

Vacuum cleaner, comprising a tube having a first diameter, a hose having a second diameter exceeding the first diameter by at least 15%, and a transition piece (T) having a first end (1) arranged for being connected to the tube, and a second end (2) arranged for being connected to the hose, wherein the transition piece (T) has a curved part that has a non-circular cross-section, the curved part having a first part (I) in which in a direction from the first end (1) to the second end (2), a first dimension (R1) of the cross-section increases to a diameter exceeding the first diameter by 15%, the first dimension (R1) being in a radial direction of the curved part, while a second dimension (R2) of the cross-section, perpendicular to the first dimension (R1), does not exceed the first diameter by more than 10%. Preferably, the transition piece (T) has a second part (II), between the first part (I) and the second end (2), the second part (II) having a non-circular cross-section where the second part (II) meets the first part (I), and a circular cross-section where the second part meets the second end (2). Advantageously, in the first part (I), in a direction from the first end (1) to the second end (2), the first dimension (R1) of the cross-section increases to a diameter exceeding the second diameter, while the second dimension (R2) stays below the second diameter.

A tube for a power transmission shaft is made of fiber-reinforced plastic, rotated to transmit power, and includes a main body in a shape of cylinder about an axis, wherein the main body has an outer diameter thereof gradually decreasing from a central portion thereof toward both ends thereof, and has a thickness thereof gradually decreasing from said both ends toward the central portion.

A hollow shaft includes a cylindrical main body part and an extremity drawn part that is integrally connected to one end of the main body part on the same axis and whose diameter is made smaller than a diameter of the main body part by drawing processing, wherein an inner peripheral face of the main body part and an inner peripheral face of a base portion, which is continuous with one end side of the main body part, of the extremity drawn part are formed as cut faces that are subjected to cutting processing before the drawing processing, and an inner peripheral face of a tip portion, which is continuous with an extremity side of the base portion, of the extremity drawn part is a non-cut face. Accordingly, the hollow shaft can be molded with high shape precision while maintaining a low drawing ratio for an extremity drawn part.

A drive shaft extends between axial ends and has at least one portion through which an outer diameter of the drive shaft changes through an infinite number of diameters, with the at least one portion extending across at least 15% of an axial distance between the axial ends of the drive shaft. A drive shaft with a generally spiral undulation at its outer periphery is also disclosed.