Sheet conveyor and image forming apparatus

An image forming apparatus comprising:

• an image forming unit configured to form an image onto a sheet;
• and
• a sheet conveyor including
• a separation roller,
• a retard roller forming a nip with the separation roller,
• a load application device configured to apply a load to the retard roller, the load application device including
• a motor,
• a first drive train including
• a plurality of gears for transmitting a driving force from the motor to the retard roller,
• a first torque limiter configured to communicate with one of the plurality of gears to generate a first load,
• a clutch disposed between the motor and the first torque limiter, the clutch being connected to the motor via a drive train including a plurality of gears,
• a second torque limiter isolated from the first drive train and configured to communicate with the retard roller to apply a second load to the retard roller, and
• a controller configured to, during conveyance of a sheet, control the clutch to allow transmission of the driving force from the motor for a predetermined time period and to interrupt transmission of the driving force from the motor after expiration of the predetermined time period, and
• a one-way clutch disposed between the retard roller and the second torque limiter isolated from the first drive train, the one-way clutch being configured to allow the retard roller to rotate,
• wherein, while the clutch allows the transmission of the driving force, the first torque limiter of the first drive train applies the first load to the retard roller, and the second torque limiter isolated from the first drive train applies the second load to the retard roller, and
• wherein, while the clutch interrupts transmission of the driving force, the retard roller becomes free from the first load and only the second load is applied to the retard roller.