Examples of stalling of operation of imaging devices are described herein. In an example, the imaging device includes an input roller assembly to transport a medium in the imaging device and a line feed roller assembly disengagably coupled to the input roller assembly to selectively drive the input roller assembly. To stall the operation of the imaging device, a line feed shaft of the line feed roller assembly can be automatically disengaged from the input roller assembly to discontinue advance of the medium along a print path.

A drive transmission device transmits a driving force of a drive source to conveyance rollers to convey a sheet, the conveyance rollers including: a relay conveyance roller upstream from a registration roller in a sheet conveyance direction to convey at least a sheet fed from a sheet feeding cassette toward the registration roller; and a bypass relay conveyance roller in a bypass relay path to convey a sheet fed from a bypass tray to a joining point where the sheet fed from the bypass tray joins into a conveyance path on which the sheet fed from the sheet feeding cassette is conveyed. The drive transmission device includes a drive transmission interrupter in a drive transmission path from the drive source to the relay conveyance roller to interrupt drive transmission. The driving force of the drive source is transmitted via the drive transmission interrupter to the bypass relay conveyance roller.

To enable a user, when removing a sheet of paper from a transport mechanism, to easily remove the sheet of paper from the transport mechanism even with structure in which a transport roller is provided at a position inaccessible to a user. A paper-sheet transport device, including: a drive part which drives a transport mechanism transporting a sheet of paper; a cover; a shaft that rotatable in a predetermined direction by drive generated by the drive part, the shaft including a transport roller fixed thereto for transporting the sheet of paper; a lever which is arranged at, at least, a drive part side end out of both ends of the shaft and which, through a part of the cover, receives force due to an opening/closing operation of the cover; and a ratchet via which the lever and the shaft are engaged or disengaged, and which changes from the engaged state to the disengaged state in response to the lever receiving the force due to the opening/closing operation of the cover.

A sheet feeder includes: a sheet feeding assembly including: a shaft having an insertion part; and a feed roller; and a main body including: a rotary part; and first and second bearings. The main body supports the sheet feeding assembly. The rotary part rotates upon transmission of a drive force and receives the insertion part. The bearings support the shaft. An opening of an open portion of the first bearing has a circumferential dimension greater than a diameter of the shaft. The shaft supported by the bearings is movable between a mounted position and a retracted position. The feed roller is supported by the shaft, and movable as the shaft moves between the mounted position and the retracted position. The insertion part is separated from the rotary part when the shaft is in the retracted position, and inserted into the rotary part to place the shaft in the mounted position.

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.

To enable a user, when removing a sheet of paper from a transport mechanism, to easily remove the sheet of paper from the transport mechanism even with structure in which a transport roller is provided at a position inaccessible to a user. A paper-sheet transport device, including: a drive part which drives a transport mechanism transporting a sheet of paper; a cover; a shaft that rotatable in a predetermined direction by drive generated by the drive part, the shaft including a transport roller fixed thereto for transporting the sheet of paper; a lever which is arranged at, at least, a drive part side end out of both ends of the shaft and which, through a part of the cover, receives force due to an opening/closing operation of the cover; and a ratchet via which the lever and the shaft are engaged or disengaged, and which changes from the engaged state to the disengaged state in response to the lever receiving the force due to the opening/closing operation of the cover.

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 feeder includes: a sheet feeding assembly including: a shaft having an insertion part; and a feed roller; and a main body including: a rotary part; and first and second bearings. The main body supports the sheet feeding assembly. The rotary part rotates upon transmission of a drive force and receives the insertion part. The bearings support the shaft. An opening of an open portion of the first bearing has a circumferential dimension greater than a diameter of the shaft. The shaft supported by the bearings is movable between a mounted position and a retracted position. The feed roller is supported by the shaft, and movable as the shaft moves between the mounted position and the retracted position. The insertion part is separated from the rotary part when the shaft is in the retracted position, and inserted into the rotary part to place the shaft in the mounted position.

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.