Actualy there were a couple of companies that made Vending machines, Westinghouse for example sold units that did not have glass doors Because thoes used slightly more electricity to stay cold, Cavalire made a unit that used a conveyr belt type system to move cylinders of bottled coke to a vending hatch, (some of thoes were retrofited with glass doors but usualy just had a coin unlockable plate) then there were the Honor system Ice chests (some of which also used a conveyor system)
http://www.ebay.com/itm/VINTAGE-1950s-CAVALIER-COCA-COLA-MACHINE-WOW-10-56-MINI-GLASS-COKE-BOTTLE/301505596053?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20131003132420%26meid%3Da478d3ccb626488f87094e81d99cc972%26pid%3D100005%26rk%3D5%26rkt%3D6%26sd%3D161577971859
Others used a "Ice chest" or simple cool box with a rotating turntable type arangment, The Ice chest type used a cooler and very cold water to keep bottles chiled
Turntable type
http://www.ebay.com/itm/Coca-Cola-Machine-Restored/271866183111?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20131003132420%26meid%3D45babedd92b14bd8944d8b96823a6462%26pid%3D100005%26rk%3D5%26rkt%3D6%26sd%3D161087628667
Ice cold water chest type
http://www.ebay.com/itm/Vintage-Coca-Cola-Coke-Machine-Vendo-spintop-159-1940s/161770370913?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20131003132420%26meid%3Db585f84f99454a85bedc28a1c89b0397%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D161087628667
there were also signs that said things like "We let you see the bottle!" back then. Apparently the company that put that sign on their machines thought that people were out to rip off people by leaving the coke machine empty and swindeling there customers a nickle at a time.
I also found it a bit amusing that the machines often had a tray for the empty coke bottles, just stick em in when your done (and given that the usual size was 6 oz back then. . .. Seriously disapointing to find out that corperations back then cared more about recycling than they do now. . .
(Just to clarify one of thoes turntables was strictly on top, the other... well it was complicated