Fluid Power Through the Years (.PDF Download)

It goes without saying that much has changed since February 1948. The transistor was successfully demonstrated at Bell Laboratories only two months earlier. Until then, electronic controls consisted of vacuum tubes, mechanical switches, and similar devices that were large, often delicate, and often unsuitable for industrial applications.

Although larger and heavier, hydraulic logic controls were more rugged and reliable (if fluid was kept clean), so many machines—especially machine tools—relied heavily on hydraulics not only for power, but for control. Both methods, however, required skillful technicians for troubleshooting and repair, both lengthy processes that often resulted in substantial machine downtime.