Have You Considered Air-Over-Oil Circuits?

The article focuses on the Air-Over-Oil systems, Topics include offer a cost-effective alternative for many closed-loop speed control applications by combining the convenience of readily available compressed air for power with hydraulics to control motion; mentions that having an air valve connected to the air-over-oil tanks forces oil from the tanks into the cylinder and also mentions the low-pressure hydraulic cylinders with air-over oil tanks is a common way to create an air-over-oil system.