OTC Tools OTC 4020 Air / Hydraulic Pump. With shop air as the energy source, this pump has the power and oil capacity (80 cu. in. usable oil) to drive even the large 55-ton rams. It is an ideal all-around power source for dozens of body, frame, and alignment applications. It can be used with a variety of rams, presses, and hydraulic pullers operating at up to 10,000 PSI. An internal relief valve protects the hydraulic components regardless of hydraulic pressure. In addition, a two-stage release mechanism gives fast or metered ram return while reducing hydraulic shock. These pumps require 9 c.f.m. at 100 PSI air pressure at the pump. Develops 10,000 PSI at 100 PSI air pressure. 3/8" NPTF oil port. 98 cu. in. usable oil capacity in plastic reservoir.