An improved actuator for oil well pumps particularly adapted for operation by well head gas comprising:
- a. an elongated, cylindrical pumping cylinder having a central axis,
- b. a power piston movably positioned in said pumping cylinder dividing said pumping cylinder into a pumping cylinder top and a pumping cylinder bottom,
- c. an elongated, cylindrical counter balance cylinder secured in prolongation of said pumping cylinder and having a common central axis with said pumping cylinder,
- d. a counter balance piston movably mounted in said counter balance cylinder dividing said counter balance cylinder into a counter balance cylinder top and a counter balance cylinder bottom,
- e. an axial piston rod interconnecting said power piston and said counter balance piston,
- f. a floating piston five-way valve having a cylinder top port, a cylinder bottom port, a gas inlet port, a gas exhaust top port, and a gas exhaust bottom port,
- g. a bottom snifter valve operably secured to said pumping cylinder bottom,
- h. a power cylinder bottom line interconnecting the said cylinder bottom port and said bottom snifter valve, said power cylinder bottom line adapted to flow gases to and from said bottom snifter valve into said power cylinder bottom,
- i. a power cylinder top line interconnecting said cylinder top port of said five-way valve and the power cylinder top permitting the flow of gas to and from said power cylinder top,
- j. a top snifter valve operably mounted in said top of said counter balance cylinder,
- k. a top control line operably interconnecting said top snifter valve and a first end of said floating piston five-way valve,
- l. a bottom control line operably interconnecting said bottom snifter valve and a second end of said floating piston five-way valve,
- m. said top snifter valve and said bottom snifter valve in conjunction with said top and said bottom control lines and said floating piston five-way valve controlling the flow of gas to and from said power cylinder top and said power cylinder bottom,
- n. a counter balance volume tank containing gas under pressure,
- o. a counter balance pressure line interconnecting said counter balance volume tank and said bottom of said counter balance cylinder.
- p. a well head gas power line adapted to receive gas under pressure from a well head connected to the said inlet port of said floating piston five-way valve,
- q. an exhaust manifold connected to said gas exhaust top port and said gas exhaust bottom port,
- r. an exhaust line leading from said exhaust manifold to,
- s. a gas delivery line,
- t. a well head gas flow line adapted to receive well head gas under pressure from a well head leading from said well head gas power line, and
- u. a well head gas delivery pressure regulator positioned between said well head gas flow line and said gas delivery line adapted to maintain a differential pressure between the said flow line and the said delivery line.