MB 280S '76: What's the air pump do?

Ive had this car for just over a month. The air pump has always had a slight squeak once in a while. I just thought it was the bearings. I may have added to the problem by adding too much tension when I replaced all the belts. After about 3 weeks, it began squealing more. I took off the belt to see if it was the source of the noise. It was indeed the culprit. I took it out and drove it some without the belt. Everything appeared to be the same. Is the air pump similar to a supercharger when it is forcing air into the engine? Would it hurt the car running with out the belt on? Due to the age, do you think that there is any benefit of the air pump until I replace it or rebuild it? Thanks

J.Wigton