To alternately raise and lower the drillstring, casing string or liner in the wellbore. Reciprocation is usually limited to 30 to 60 ft (9 to 18 m) of vertical travel in the derrick. The purpose of reciprocating the drillstring is usually to clean cuttings and other debris from the wellbore. Reciprocating the strings can improve the chances of a good cement job in casing or liners.