Speed reducer

A speed reducer comprising:

• an input shaft
• that is provided extending along a front-rear direction and
• that is driven by a drive unit to rotate;
• a first barrel cam
• that is connected to the input shaft and
• that rotates as the input shaft rotates;
• a first output table
• that includes a plurality of first cam followers that engage with the first barrel cam, and
• that rotates due to rotation of the first barrel cam;
• an intermediate shaft
• that is connected to the first output table,
• that rotates as the first output table rotates, and
• that is provided extending along a left-right direction;
• a second cam
• that is connected to the intermediate shaft, and
• that rotates as the intermediate shaft rotates;
• and
• a second output table
• that includes a plurality of second cam followers that engage with the second cam,
• that rotates as the second cam rotates, and
• that has a rotation axis that extends in an up-down direction,
• in the first output table, the plurality of first cam followers being provided concentrically around a rotation center position of the intermediate shaft,
• concerning a certain first cam follower among the plurality of first cam followers,
• when a center position of the certain first cam follower when the certain first cam follower has been moved to a farthest end on one side in the up-down direction is defined as a reference position,
• a center position of the first barrel cam being shifted to another side in the up-down direction with respect to the reference position,
• an engagement center position in the front-rear direction between an engagement start position and an engagement end position being shifted either of forward and rearward with respect to the reference position, wherein, in the up-down direction, the engagement center position of the first barrel cam is located upward with respect to the rotation center position of the intermediate shaft,
• the engagement start position being a position where the first barrel cam and the first cam followers start engaging,
• the engagement end position being a position where the first barrel cam and the first cam followers stop engaging.