The tool (in orange) is clamped upwards. The blue chuck turns counterclockwise during cutting stroke (apart from the chuck) of the violet carriage.
Red lever position determines right or left hand thread to be turned. It changes rotation direction of the yellow lead screw in relation with the rotation direction of the chuck.
Gears represent the gear train that determines the lead of the thread to be created.Device (electrical or mechanical) for reversing rotation direction of the chuck is not shown.