Question Air tank drains: Answers Should not be used in cold weather. Are helpful to remove water and oil from the air tanks. Are used to move air to the brakes. Clean the air in the passenger compartment. Explanation In an air brake system, air tanks have drains to remove accumulations of water and compressor oil. Allowing water and oil to accumulate in the system could cause damage to the brakes. Manually operated drains should be used daily. Take a FREE Practice Test Now This questions appears in the following tests: Connecticut Knowledge Test Class B , North Dakota Bus , Illinois Air Brakes , Massachusetts Air Brakes , Nevada Air Brakes ,