A drive transmission device includes a first gear, a cam configured to rotate in interrelation with rotation of the first gear and capable of changing a state of two members between a pressed state and a pressure-released state, a pressing member configured to press the cam, and a second gear configured to transmit drive to the first gear in engagement with the first gear. At least one of the first and second gears includes first teeth provided at positions corresponding to an engaging region in which the first gear is engaged with the second gear when the state of the two members is changed from the pressure-released state to the pressed state and includes second teeth provided at positions corresponding to a region other than the engaging region. Tooth thicknesses of the first teeth are thicker than tooth thicknesses of the second teeth.

A drive transmission device includes a first gear, a cam configured to rotate in interrelation with rotation of the first gear and capable of changing a state of two members between a pressed state and a pressure-released state, a pressing member configured to press the cam, and a second gear configured to transmit drive to the first gear in engagement with the first gear. At least one of the first and second gears includes first teeth provided at positions corresponding to an engaging region in which the first gear is engaged with the second gear when the state of the two members is changed from the pressure-released state to the pressed state and includes second teeth provided at positions corresponding to a region other than the engaging region. Tooth thicknesses of the first teeth are thicker than tooth thicknesses of the second teeth.

A drive gear assembly rotatably drives a driven gear of an engine component. The drive gear assembly comprises a drive shaft extending longitudinally along an axis. A main drive gear is operatively coupled to the drive shaft and a scissor gear is aligned coaxially with the main drive gear. A scissor spring is disposed and operatively coupled between the main drive gear and the scissor gear and biased therebetween wherein the main drive gear and the scissor gear rotate about the axis relative to each other. An isolation mechanism is operatively coupled between the main drive gear and the drive shaft for absorbing impulse loads generated by the driven gear when engaged with the main drive gear.

A drive gear assembly rotatably drives a driven gear of an engine component. The drive gear assembly comprises a drive shaft extending longitudinally along an axis. A main drive gear is operatively coupled to the drive shaft and a scissor gear is aligned coaxially with the main drive gear. A scissor spring is disposed and operatively coupled between the main drive gear and the scissor gear and biased therebetween wherein the main drive gear and the scissor gear rotate about the axis relative to each other. An isolation mechanism is operatively coupled between the main drive gear and the drive shaft for absorbing impulse loads generated by the driven gear when engaged with the main drive gear.

A balance shaft structure includes a balance shaft including a balance weight, a driven gear to rotate the balance shaft by being engaged with a drive gear, a scissors mechanism, whose position in an axial direction is regulated, including a scissors gear to reduce backlash between the drive gear and the driven gear and an axially urging member to urge the scissors gear toward the driven gear in the axial direction, a first regulating portion to regulate an axially inner position of the scissors mechanism, and a second regulating portion fixed to the balance shaft on a side close to the shaft end part of the balance shaft beyond the first regulating portion and configured to regulate an axially outer position of the scissors mechanism.

As viewed from a side, an output shaft is disposed rearward of a crankshaft, and an odd-numbered stage shaft and an even-numbered stage shaft are disposed rearward of the crankshaft. Moreover, the odd-numbered stage shaft is provided on a side opposite to the even-numbered stage shaft relative to a line connecting the crankshaft and the output shaft, and a shift drum is disposed on a side opposite to the output shaft relative to a line connecting the odd-numbered stage shaft and the even-numbered stage shaft. This structure reduces dimensions of the power unit for the saddled vehicle.

A pinion gear meshes with a drive gear. The drive gear is connected to a handle shaft of a fishing reel that winds a fishing line onto a spool supported by a reel body by rotational operation of the handle shaft rotatably supported to the reel body to transmit the rotation of the handle shaft. The pinion gear includes a gear portion and a shaft. The gear portion meshes with the drive gear. The shaft portion, to which the gear portion is non-rotatably fitted, is integrally rotatable with the gear portion. The gear portion and the shaft portion are formed from different materials, and the specific gravity of the shaft portion is smaller than the specific gravity of the gear portion.

A pinion gear meshes with a drive gear. The drive gear is connected to a handle shaft of a fishing reel that winds a fishing line onto a spool supported by a reel body by rotational operation of the handle shaft rotatably supported to the reel body to transmit the rotation of the handle shaft. The pinion gear includes a gear portion and a shaft. The gear portion meshes with the drive gear. The shaft portion, to which the gear portion is non-rotatably fitted, is integrally rotatable with the gear portion. The gear portion and the shaft portion are formed from different materials, and the specific gravity of the shaft portion is smaller than the specific gravity of the gear portion.

A gear includes a first gear rim, a second gear rim, and an axial groove. The first gear rim has a first gear rim rotational stiffness and includes a plurality of first gear teeth. The second gear rim has a second gear rim rotational stiffness. The second gear rim includes a plurality of second gear teeth complementing the plurality of first gear teeth defining a plurality of complementary first gear teeth and a plurality of complementary second gear teeth. The axial groove extends between the first gear rim and the second gear rim. The axial groove has an axial groove rotational stiffness that less than at least one of the first gear rim rotational stiffness and the second gear rim rotational stiffness.

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.