Question The two markings on a front brake limiting valve usually read: Answers "Normal" and "slippery." "Low" and "high." "Left" and "right." Explanation Some vehicles with air brake systems manufactured before 1975 have a front brake limiting valve with "normal" and "slippery" settings. Take a FREE Practice Test Now This questions appears in the following tests: Iowa Knowledge Test Class A , North Carolina Knowledge Test Class A , Tennessee Knowledge Test Class A , Alabama Knowledge Test Class B , Alaska Knowledge Test Class B , Maine Knowledge Test Class B , Minnesota Knowledge Test Class B , Oregon Knowledge Test Class B ,