A loading station for a substrate processing system includes first and second vertically-stacked loading stations. The first loading station includes a first airlock volume and first and second valves arranged at respective ends of the first loading station. The first and second valves are configured to selectively provide access to the first airlock volume and include first and second actuators, respectively, configured to open and close the first and second valves, and the first and second actuators extend downward from the first loading station. The second loading station includes a second airlock volume and third and fourth valves arranged at respective ends of the second loading station. The third and fourth valves are configured to selectively provide access to the second airlock volume and include third and fourth actuators, respectively, configured to open and close the third and fourth valves.