Home › Forums › Coking › Operations › Cutting, Drilling, Unheading › Drilling › Drilling Equipment › Drill stem position limit switches This topic contains 0 replies, has 1 voice, and was last updated by Freddy Martinez 11 years, 4 months ago. Author Posts July 20, 2009 at 4:52 pm #3050 Freddy MartinezParticipant Can anyone provide feedback on type of drill stem position limit switches that are robust and reliable. The A-B position limit switches seems to be failing more often than the P+F. Thanks. Author Posts You must be logged in to reply to this topic.