Valve actuator having a rotary bi-directional apparatus with a dual ratchet mechanism

A bi-directional valve actuator with a ratchet mechanism adapted for use in combination with a control valve which includes a rotatable stem which, when turned, adjusts the flow through the control valve, said bi-directional valve actuator comprising:

• a frame adapted for mounting with a control valve adjacent the rotatable stem thereof;
• a shaft means rotatably mounted with said frame, said shaft means mechanically coupled to the stem of the control valve for effecting rotation of the stem in response to rotation of said shaft;
• said shaft means having a first ratchet operating path and a second ratchet operating path spaced from said first operating path;
• a first pawl having a first end and a second end, said first pawl mounted for longitudinal reciprocating movement toward said first ratchet operating path on said shaft means to a coupling position during an operating stroke of said first pawl and away from said first ratchet operating path on said shaft means to an uncoupled position;
• means for coupling said first end of said first pawl to said first ratchet operating path during the operating stroke of said first pawl and for uncoupling said first end of said first pawl from said first ratchet operating path during a return stroke of said first pawl;
• a first hydraulic cylinder mounted with said frame, said first cylinder having a first piston operably coupled to said first pawl to effect engagement with said first ratchet operating path to rotate said shaft means;
• a first pair of link members mechanically coupled to said first piston for operably coupling with said first pawl for transmitting movement of said first piston to said first pawl;
• a first pair of springs each of which is mechanically coupled at one end to said frame at the other end and to one of first pair of link members;
• a second pawl having a first end and a second end, said second pawl mounted for longitudinal reciprocating movement toward said second ratchet operating path on said shaft means to a coupling position during an operating stroke of said second pawl and away from said second ratchet operating path on said shaft means to a disengaged position;
• means for coupling said first end of said second pawl to said second ratchet operating path during an operating stroke of said second pawl and for uncoupling said first end of said second pawl from said second ratchet operating path during a return stroke of said second pawl;
• a second hydraulic cylinder mounted with said frame, said second cylinder having a second piston operably coupled to said second pawl to effect engagement with said second ratchet operating path to rotate said shaft means;
• a second pair of link members mechanically coupled to said second piston for operably coupling with said second pawl for transmitting movement of said second piston to said second pawl;
• a second pair of springs each of which is mechanically coupled at one end to said frame and at the other end to one of said second pair of link members;
• said means for coupling said first pawl and said second pawl each having an urging means for reciprocably moving said first end of each of said pawls into coupling engagement with said associated ratchet operating path, said first pair of springs operating said first pawl for overcoming said urging means associated with said first pawl for reciprocably moving and normally maintaining said first pawl spaced from said first ratchet operating path, said second pair of springs operating said second pawl for overcoming said urging means associated with said second pawl for reciprocably moving and normally maintaining said second pawl spaced from said second ratchet operating path;
• said means for urging said first pawl and second pawl into coupling engagement with said shaft means are independent of said operating cylinder to avoid binding of said pawls and said operating paths upon coupling during the power stroke of each of said pawls;
• and
• said means for coupling said first pawl and said second pawl each having an associated retainer member for reciprocably moving said first end of each of said pawls from coupling engagement with said associated ratchet operating path in the absence of the operating stroke of said pawls to protect said pawls from inadvertent movement of said shaft means.