A transport apparatus includes: a separation roller pair which is operated when power is transmitted from a first motor; a resist roller pair which is operated when power is transmitted from a second motor; an assist roller pair which is disposed between the separation roller pair and the resist roller pair in the transport direction of the document; a first transmission mechanism portion which transmits the power from the first motor to the assist roller pair; a second transmission mechanism portion which transmits the power from the second motor to the assist roller pair; and a control portion which controls operation aspects of each roller pair.

A sheet discharge apparatus includes first and second discharge trays, a support unit, first and second discharge rollers, and first and second controlling units. The second discharge tray is disposed above the first discharge tray and is detachable from the support unit. The first and second discharge rollers discharge a sheet toward the first and second discharge trays respectively. The first controlling unit executes control such that, in a case that the second discharge tray is detached from the support unit while the first discharge roller and the second discharge roller are halted, the first discharge roller remains halted, and in a case that the second discharge tray is detached from the support unit while the first discharge roller and the second discharge roller are rotating, the first discharge roller is halted after the first discharge roller continues rotating until a sheet has been discharged toward the first discharge tray.

The apparatus includes a first clutch and a second clutch. The first clutch transmits rotation of the driving unit in a first rotation direction to the first feeding device without transmitting rotation of the driving unit in a second rotation direction that is reverse to the first rotation direction to the first feeding device. The second clutch transmits the rotation of the driving unit in the second rotation direction to the conveyance device and the double-side printing conveyance device and without transmitting the rotation of the driving unit in the first rotation direction to the conveyance device and the double-side printing conveyance device. The third transmission path is configured to transmit the rotation of the driving unit to a conveyance device. The fourth transmission path is configured to transmit the rotation of the driving unit to a double-side printing conveyance device.

A groove has a first side surface and a second side surface. The second side surface faces the first side surface and is located downstream of the first side surface in a first direction. The first side surface has a first contact surface configured to contact one side surface of a protrusion. The second side surface having a second contact surface and a guide surface. The second contact surface is smaller than the first contact surface. The second contact surface is configured to contact an other side surface of the protrusion. The guide surface is inclined away from the first contact surface in a direction from a tip-side end of the second contact surface toward a tip end of a drive shaft. The tip-side end is an end facing toward the tip end of the drive shaft. The guide surface is configured to guide the protrusion to the groove.

An image forming device includes: a conveyance unit; an image forming section; a plurality of storage units; and a sheet feeding roller, wherein provided are: one drive source; a first drive transmission system including a first one-way clutch; a second drive transmission system including: a second one-way clutch; and a first transmission interrupting unit; a third drive transmission system including: a third one-way clutch; and a second transmission interrupting unit; and a control unit, and the control unit is configured to: rotationally drive the drive source in the first direction at the time of the sending operation by the first sheet feeding roller; rotationally drive the drive source in the second direction at the time of the sending operation by the second sheet feeding roller; and rotationally drive the drive source in the second direction at the time of the sending operation by the third sheet feeding roller.

The apparatus includes a first clutch and a second clutch. The first clutch transmits rotation of the driving unit in a first rotation direction to the first feeding device without transmitting rotation of the driving unit in a second rotation direction that is reverse to the first rotation direction to the first feeding device. The second clutch transmits the rotation of the driving unit in the second rotation direction to the conveyance device and the double-side printing conveyance device and without transmitting the rotation of the driving unit in the first rotation direction to the conveyance device and the double-side printing conveyance device. The third transmission path is configured to transmit the rotation of the driving unit to a conveyance device. The fourth transmission path is configured to transmit the rotation of the driving unit to a double-side printing conveyance device.

A sheet supply device detachably attachable to an image forming apparatus includes: a main body; a sheet supply roller; an external output gear; a clutch mechanism; and first and second transmission mechanisms. The main body is provided with a sheet supply tray on which a sheet is mountable. The sheet supply roller is in contact with a sheet mounted on the sheet supply tray and configured to rotate to supply the sheet toward the image forming apparatus. The external output gear is configured to output a driving force to an outside. The clutch mechanism is configured to transmit and interrupt a driving force from the image forming apparatus. The first transmission mechanism is configured to transmit the driving force received through the clutch mechanism to the sheet supply roller. The second transmission mechanism is configured to transmit the driving force received through the clutch mechanism to the external output gear.

A sheet transport device includes a transport unit that transports a sheet to a reading position by a first transport roller, a driving unit that switches a rotating direction, a rotating unit that rotates the first transport roller in one direction, the rotating unit including a one-direction gear that directly meshes with a first planet gear when the driving unit rotates in a first direction and meshes with a second planet gear when the driving unit rotates in a second direction, a switch unit that switches between states in which rotation of the one-direction gear is or is not transmitted to the first transport roller, and a displacement-force applying part that applies a force for displacing the first planet gear to mesh with the one-direction gear when the first planet gear touches the switch unit.

A sheet transport device includes a transport unit that transports a sheet to a reading position by a first transport roller, a driving unit that switches a rotating direction, a rotating unit that rotates the first transport roller in one direction, the rotating unit including a one-direction gear that directly meshes with a first planet gear when the driving unit rotates in a first direction and meshes with a second planet gear when the driving unit rotates in a second direction, a switch unit that switches between states in which rotation of the one-direction gear is or is not transmitted to the first transport roller, and a displacement-force applying part that applies a force for displacing the first planet gear to mesh with the one-direction gear when the first planet gear touches the switch unit.

A power transmission apparatus includes a drive source, a power transmission switching section configured to switch between a transmission state in which power of the drive source is transmitted to a driven section and a non-transmission state in which power of the drive source is not transmitted to the driven section, a load switching section configured to switch between a first load state, which is a load while the driven section is driven, and a second load state, which is a load smaller than the load of the first load state, and a control section, wherein the control section switches the power transmission switching section from the non-transmission state to the transmission state while the load is in the second load state, and then uses the load switching section to switch the load from the second load state to the first load state.