There is provided a drive power transmitting mechanism that can transmit drive power losslessly and can be used in environments where silence is required. The drive power transmitting mechanism includes a rotor having a first outer circumferential surface and rotatable about a first rotational axis, a rotor having a second outer circumferential surface pressed against the first outer circumferential surface and rotatable about a second rotational axis due to a frictional force produced between the second outer circumferential surface and the first outer circumferential surface, a gear rotatable in unison with the rotor about the first rotational axis, and a gear rotatable in unison with the rotor about the second rotational axis, in which the gear and the gear are brought into mesh with each other when the second outer circumferential surface slips against the first outer circumferential surface.

A flat strain wave gearing (1) has a mechanism for preventing a flexible externally toothed gear (4) from moving in the direction of the device center axis (1a) with respect to a rigid internally toothed gears (2, 3). The mechanism has an inner-peripheral groove (11) formed on inner teeth (3a) of the internally toothed gear (3), an outer-peripheral groove (12) formed on outer teeth (4a) of the externally toothed gear (4), and a flexible ring (13) mounted between the inner-peripheral groove (11) and the outer-peripheral groove (12). The ring (13) is engageable with groove inner-peripheral surfaces (11a, 11b, 12a, 12b), from the direction of the device center axis (1a), at meshing positions of the both gears (2, 4).

A flat strain wave gearing (1) has a mechanism for preventing a flexible externally toothed gear (4) from moving in the direction of the device center axis (1a) with respect to a rigid internally toothed gears (2, 3). The mechanism has an inner-peripheral groove (11) formed on inner teeth (3a) of the internally toothed gear (3), an outer-peripheral groove (12) formed on outer teeth (4a) of the externally toothed gear (4), and a flexible ring (13) mounted between the inner-peripheral groove (11) and the outer-peripheral groove (12). The ring (13) is engageable with groove inner-peripheral surfaces (11a, 11b, 12a, 12b), from the direction of the device center axis (1a), at meshing positions of the both gears (2, 4).

Plate cylinder driving devices of a printing machine are provided with a drive shaft driving the plate cylinder, a drive helical gear fixed to the drive shaft, and an anti-backlash helical gear rotatably connected to the drive shaft and is biased by at least a spring towards a direction for preventing backlash. Both the drive helical gear and the anti-backlash helical gear are engaged with the main gear, and a plate provided with plural holes accommodating rollers is provided between the drive helical gear and the anti-backlash helical gear. Friction between the anti-backlash gear and the drive gear is reduced by a simple mechanism in the plate cylinder driving devices in a printing machine.

A seat lifter includes: a connecting member that connects a base member and a seat frame that form a seat and swings in response to external rotating force to raise or lower the seat frame; a first gear provided in the connecting member; a second gear that is provided such that an axial direction thereof is parallel to an axial direction of the first gear and meshes with the first gear; and an operating lever that applies rotating force to the second gear. The teeth of at least one of the first and second gears have such a shape that a tooth thickness of the teeth gradually decreases from one end toward the other end in the axial direction, and the first and second gears mesh with each other by approaching each other in the axial direction.

A seat lifter includes: a connecting member that connects a base member and a seat frame that form a seat and swings in response to external rotating force to raise or lower the seat frame; a first gear provided in the connecting member; a second gear that is provided such that an axial direction thereof is parallel to an axial direction of the first gear and meshes with the first gear; and an operating lever that applies rotating force to the second gear. The teeth of at least one of the first and second gears have such a shape that a tooth thickness of the teeth gradually decreases from one end toward the other end in the axial direction, and the first and second gears mesh with each other by approaching each other in the axial direction.

A camshaft unit for a vehicle includes: a cam gear shaft-coupled to one end of a camshaft; a scissors gear provided at one side of the cam gear while having the camshaft as a concentric axis and relatively rotated with respect to the cam gear; a coil spring provided between the cam gear and the scissors gear, having one end fixed to one side surface of the cam gear and the other end fixed to the other side surface of the scissors gear; and a snap ring installed in a groove formed in one side surface of the scissors gear and inhibiting separation of the scissors gear in an axial direction. In particular, the coil spring transfers a torque of the cam gear to the scissors gear while being elastically restored depending on rotation of the cam gear.

Gears, for example, for a gear train are disclosed. The gear may be divided into two axially adjacent spur gears and have a torsion spring in the form of a circular ring segment. Between two peripherally mutually opposing spring ends, a slot may be formed in which two cams engage which are each assigned to one of the two spur gears. One of the cams may be assigned to one of the two spring ends and the other cam may be assigned to the other spring end. The two cams may be arranged at least substantially overlap-free in an axial direction, wherein contact faces for the cams formed at both spring ends of the torsion spring are arranged on a radially outer end of the spring ends. The contact faces may be delimited radially inwardly by clearances on the spring ends.

Gears, for example, for a gear train are disclosed. The gear may be divided into two axially adjacent spur gears and have a torsion spring in the form of a circular ring segment. Between two peripherally mutually opposing spring ends, a slot may be formed in which two cams engage which are each assigned to one of the two spur gears. One of the cams may be assigned to one of the two spring ends and the other cam may be assigned to the other spring end. The two cams may be arranged at least substantially overlap-free in an axial direction, wherein contact faces for the cams formed at both spring ends of the torsion spring are arranged on a radially outer end of the spring ends. The contact faces may be delimited radially inwardly by clearances on the spring ends.

This anti-backlash gear includes a gear wheel and gear teeth. Each gear tooth comprises first and second flanks, a top face and a bottom face, wherein for each gear tooth each flank extends from the top face to the bottom face, wherein the gear teeth comprise a polymeric material which comprises a repeat unit of form I wherein t1, and w1 independently represent 0 or 1 and v1 represents 0, 1 or 2. For each gear tooth, at least one of said flanks comprises two or more surfaces arranged to form a single protrusion extending along the at least one said flank such that a tooth thickness of each gear tooth varies between the top face and the bottom face of said gear tooth in a direction parallel to an axis of rotation of the gearwheel in operation. In use, the single protrusion is elastically deformable so as to absorb backlash.