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A well choke has a quick closure device quickly moving the choke element to a closed position. The closure device mounts between an actuator and a choke. The actuator has a stepper motor and gear train for incrementally moving an actuator rod and a choke element linearly. The quick closure has a hyd

A well choke has a quick closure device quickly moving the choke element to a closed position. The closure device mounts between an actuator and a choke. The actuator has a stepper motor and gear train for incrementally moving an actuator rod and a choke element linearly. The quick closure has a hydraulic cylinder that will move the entire actuator, including the actuator rod, toward the choke, when actuated.

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We claim: 1. A well choke apparatus, comprising: a choke housing having a flow passage; a choke element carried in the choke housing for linear movement in forward and rearward directions relative to the choke housing to vary a flow area through the flow passage; an actuator housing located rearwar

We claim: 1. A well choke apparatus, comprising: a choke housing having a flow passage; a choke element carried in the choke housing for linear movement in forward and rearward directions relative to the choke housing to vary a flow area through the flow passage; an actuator housing located rearward of the choke housing; an actuator rod extending forward from the actuator housing to the choke element for linearly moving the choke element; a drive mechanism having a motor and a drive train in the actuator housing for selectively extending and retracting the rod; and a quick closure assembly having a rearward side mounted to a forward side of the actuator housing and a forward side mounted to a rearward side of the choke housing for moving the actuator housing, the entire drive mechanism and the rod in unison with each other in a closing direction relative to the choke housing to cause the choke element to close the flow passage. 2. The apparatus according to claim 1, wherein the quick closure assembly comprises: a hydraulic chamber and a piston carried within for causing the movement of the actuator housing, the entire drive mechanism and the rod in the closing direction, the hydraulic chamber being stationarily fixed to one of the forward side of the actuator housing and the rearward side of the choke housing, and the piston being stationarily fixed to the other of the forward side of the actuator housing and the rearward side of the choke housing. 3. The apparatus according to claim 1, wherein the quick closure assembly comprises: a spring for biasing the actuator housing in an opening direction relative to the choke housing, the spring having one end in engagement with the forward side of the actuator housing and the other end in engagement with the rearward side of the choke housing, the spring being compressed between the housings for urging the actuator housing away from the choke housing. 4. The apparatus according to claim 1, wherein the quick closure assembly comprises: a hydraulic chamber and a piston carried within the hydraulic chamber, the hydraulic chamber being fixed to one of the forward side of the actuator housing and the rearward side of the choke housing, and the piston being fixed to the other of the forward side of the actuator housing and the rearward side of the choke housing, so that the application of hydraulic fluid pressure to one side of the piston causes movement of the actuator housing in a forward direction toward the choke housing; and a spring having a rearward end in engagement with the forward side of the actuator housing and a forward end in engagement with the rearward side of the choke housing for urging the actuator housing a rearward direction apart from the choke housing. 5. The apparatus according to claim 1, wherein the quick closure assembly comprises: an actuator plate stationarily mounted to the forward side of the actuator housing; a choke plate stationarily mounted to the rearward side of the choke housing; a cylinder stationarily mounted to one of the plates and extending toward the other of the plates; a piston stationarily mounted to the other of the plates and extending into the cylinder, so that the application of hydraulic fluid pressure causes the actuator plate to move forward toward the choke plate. 6. The apparatus according to claim 1, wherein the quick closure assembly comprises: an actuator plate stationarily mounted to the forward side of the actuator housing; a choke plate stationarily mounted to the rearward side of the choke housing; a cylinder stationarily mounted to one of the plates and extending toward the other of the plates; a piston stationarily mounted to the other of the plates and extending into the cylinder; the rod extending concentrically through the piston and the cylinder; a spring compressed between the plates; wherein the application of hydraulic fluid pressure to the piston causes the actuator plate to move toward the choke plate; and removing hydraulic fluid pressure causes the spring to push the actuator plate away from the choke plate. 7. The apparatus according to claim 1, further comprising: a guide receptacle stationarily mounted to one of the housings; and a guide member stationarily mounted to the other of the housings and in sliding engagement with the guide receptacle when the actuator housing moves in the closing direction, the guide member and the guide receptacle having a common longitudinal axis offset from and parallel to an axis of the actuator rod to prevent rotation of the housings relative to each other. 8. The apparatus according to claim 1, wherein the quick closure assembly comprises: an outer sleeve assembly that is contractible from an extended to a contracted position, the outer sleeve assembly having a forward end stationarily fixed to the rearward side of the choke housing and a rearward end stationarily fixed to the forward side of the actuator housing; an inner sleeve assembly located concentrically within the outer sleeve assembly, the inner sleeve assembly being contractible from an extended to a contracted position, the inner sleeve assembly having a forward end stationarily fixed to the rearward side of the choke housing and a rearward end stationarily fixed to the forward side of the actuator housing, the rod extending concentrically within the inner sleeve assembly; a piston and hydraulic fluid chamber incorporated within one of the sleeve assemblies to cause the inner and outer sleeve assemblies to move to the contracted position when supplied with hydraulic fluid pressure; and a spring located in an annular space between the inner and outer sleeve assemblies for urging the inner and outer sleeve assemblies to the extended positions. 9. A well choke apparatus for causing quick closure of a choke assembly having a choke housing, a choke element, an actuator housing, and an actuator rod extending in a forward direction from the actuator housing to the choke element for linearly moving the choke element, the apparatus comprising: an actuator plate for mounting to a forward side of the actuator housing; a choke plate for mounting to a rearward side of the choke housing; a cylinder stationarily mounted to one of the plates and extending toward the other of the plates; and a piston stationarily mounted to the other of the plates and extending into the cylinder, so that the application of hydraulic fluid pressure to the cylinder causes the actuator plate to move linearly toward to the choke plate for moving the actuator housing and the rod in unison with each other in a closing direction relative to the choke housing to cause the choke element to close the flow passage. 10. The apparatus according to claim 9, further comprising: a spring mounted between the plates for urging the plates apart from each other. 11. The apparatus according to claim 9, wherein the cylinder and piston are centered on the plates. 12. The apparatus according to claim 9, further comprising: an outer sleeve having a first portion mounted to the actuator plate and a second portion mounted to the choke plate, the first and second portions sealingly engaging each other and being retractable when the actuator plate moves in the closing direction, the outer sleeve concentrically encircling the cylinder and piston; and a spring mounted between the plates in an annular space between the outer sleeve and the cylinder for urging the plates in an opening direction. 13. The apparatus according to claim 9, further comprising: a guide receptacle stationarily mounted to one of the plates; and a guide member stationarily mounted to the other of the plates and in sliding engagement with the guide receptacle when the actuator plate moves in the closing direction, the guide member and the guide receptacle having a common longitudinal axis offset from a central axis of the plates to prevent rotation of the plates relative to each other. 14. The apparatus according to claim 9, further comprising: an outer sleeve having a first portion mounted to the actuator plate and a second portion mounted to the choke plate, the first and second portions sealingly engaging each other and being retractable when the actuator plate moves in the closing direction, the outer sleeve concentrically encircling the cylinder and piston; a spring mounted between the plates in an annular space between the outer sleeve and the cylinder for urging the plates in an opening direction; a guide receptacle stationarily mounted to one of the plates radially outward from the outer sleeve, relative to a central axis of the plates; and a guide member stationarily mounted to the other of the plates and in sliding engagement with the guide receptacle when the actuator plate moves in the closing direction to prevent rotation of the plates relative to each other. 15. A method of quickly closing a well choke having a choke housing, a choke element carried in the choke housing for linear movement relative to the choke housing, an actuator housing, an actuator rod extending from the actuator housing to the choke element for linearly moving the choke element in forward and rearward directions, and a drive mechanism including a motor and gear train in the actuator housing for selectively extending and retracting the rod, the method comprising: (a) mounting a rearward side of a quick closure assembly to a forward side of the actuator housing forward of the motor and gear train and mounting a forward side of the quick closure assembly to a rearward side of the choke housing; and (b) actuating the quick closure assembly, to cause it to move the actuator housing, the entire drive mechanism and the rod in unison with each other in a closing direction relative to the choke housing to cause the choke element to move to a closed position. 16. The method according to claim 15, wherein step (b) comprises applying hydraulic fluid pressure to the quick closure assembly. 17. The method according to claim 15, wherein: step (a) comprises placing a rearward end of a spring in engagement with a forward side of the actuator housing and a forward end of the spring in engagement with the rearward side of the choke housing, the spring being compressed so that it urges the actuator housing to move away from the choke housing; step (b) comprises applying hydraulic fluid pressure to the quick closure assembly to move the actuator housing toward the choke housing; and wherein the method further comprises: releasing the hydraulic fluid pressure from the quick closure assembly and with the spring moving the actuator housing away from the choke housing. 18. The method according to claim 15, further comprising preventing rotation of the actuator housing relative to the choke housing while performing step (b).