Drive unit, sheet conveyor, and image forming apparatus

A drive unit comprising:

• a drive source;
• and
• a driving force transmitter configured to transmit a driving force of the drive source to an object to be driven;
• the driving force transmitter including:
• a plurality of rotators;
• an endless belt stretched by the plurality of rotators;
• a pressing member configured to press the endless belt to apply tension to the endless belt;
• a first support shaft;
• a first link member rotatable around the first support shaft and holding the pressing member;
• a second support shaft;
• a second link member rotatable around the second support shaft and pressing the first link member;
• and
• a biasing member configured to bias the second link member to press the endless belt by the pressing member,
• a relation of L1 to L2 satisfying
• L1>L2, where
• L1 denotes a distance between the second support shaft and a biasing position at which the biasing member biases the second link member, and
• L2 denotes a distance between the second support shaft and a first pressing position at which the second link member presses the first link member,
• a relation of L3 to L4 satisfying
• L3>L4, where
• L3 denotes a distance between the first support shaft and the pressing position at which the second link member presses the first link member, and
• L4 denotes a distance between the first support shaft and a second pressing position at which the pressing member presses the endless belt.