the embodiments of the invention relate to actuators . while an exemplary embodiment of the invention relates to diaphragm actuators , a method to adjust a downstop in relation to a packing retainer is applicable and intended to encompass hydraulic actuators , piston actuators , and pneumatic actuators as well . the particulars shown herein are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of various embodiments of the invention . in this regard , no attempt is made to show structural details of the invention in more detail than is necessary for the fundamental understanding of the invention , the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice . valve actuators , are well known in the art . u . s . pat . nos . 7 , 028 , 986 ; 6 , 854 , 704 ; and 6 , 450 , 477 are examples of typical diaphragm type valve actuators . u . s . pat . no . 4 , 967 , 785 is an example of a hydraulic type actuator . u . s . pat . no . 4 , 783 , 046 is an example of a pneumatic type actuator . examples of the prior art related to pneumatic or piston type actuators can be found in fig1 . the following definitions and explanations are meant and intended to be controlling in any future construction unless clearly and unambiguously modified in the following examples or when application of the meaning renders any construction meaningless or essentially meaningless . in cases where the construction of the term would render it meaningless or essentially meaningless , the definition should be taken from webster &# 39 ; s dictionary 3rd edition . distal , in certain instances , can be defined as toward the top of the actuator and away from any valve on which the actuator rests . proximal , in certain instances , can be defined as toward a valve on which an actuator is mounted and away from the top of the actuator . referring now to the drawings , and more particularly to fig2 , a diaphragm actuator 10 is shown in the present invention . for the purposes of this description , the term distal may refer to a direction away from a valve and may refer to a direction toward a valve . referring to fig2 , the actuator has a top actuator housing 20 and a lower actuator housing 30 . the top actuator housing is distal to the lower actuator housing and is bolted to the distal end of the lower actuator housing via a series of actuator bolts 40 . further in fig2 , the top actuator housing 20 has an inlet port for increasing or decreasing pressure hereafter referred to as an inlet port 50 . likewise , the top actuator housing 20 has an exit port 53 , which may be fitted with a pressure release valve . the distal end of the top actuator housing 20 possesses an upper plug 70 which is welded , cast , forged or screwed into the top actuator housing . the upper plug 70 has an internal bore 73 for receiving a top shaft 80 . between the inner bore of the upper plug and the top shaft is a seal retainer 90 , preferably made of a hard substance such as stainless steel . proximal to the seal retainer 90 is at least one seal 100 . proximal to the seal retainer and seal is a top shaft seal 110 which may comprise polypack ™. proximal to the top shaft seal are wear bearings 120 which at least partially surround the top shaft 80 . the seal retainer 90 , the seal 100 and the wear bearings 120 are preferably non - metallic to eliminate close tolerance problems which may be associated with the actuator top shaft . these components may be made of hard plastic like materials such as delrin , nylon , thermoplastics , resins , polyurethanes , phenolics , acetals , polyacrylates , epoxides , polycarbonates , polyester , aramids and the like . as further illustrated in fig2 , the upper plug 70 , through which the top shaft 80 fits , is at the distal end of the top actuator housing 20 . with positional reference to the diaphragm 83 , the top shaft 80 has a proximal end pointed away from the diaphragm and a distal end pointed towards the diaphragm . while it is contemplated that the top shaft 80 may be made of any rigid material , the top shaft 80 is preferably formed from stainless steel . additionally , it is preferable , that the top shaft is large enough in diameter to prevent bucking stresses when loaded by a manual override or a hydraulic override . the proximal end of the top shaft passes through the diaphragm retainer nut 130 and interacts with the diaphragm retainer plate 190 . more particularly illustrated in fig2 , the proximal end of the top shaft 80 possesses a flange 85 . the diaphragm retainer nut 130 has external threading near its proximal end which and threads into a diaphragm retainer plate nut 134 , which is at the distal end of the partial diaphragm retainer plate bore 136 . still further , to secure the top shaft flange 85 , a retainer ring 138 is employed which rests distal to the top shaft flange 85 . the proximal side of the diaphragm retainer plate 190 has an indentation which is adapted to receive the downstop peg 191 which is at the distal end of the downstop 192 . referring further to the downstop 192 as depicted in fig2 , the downstop possesses exterior threading 193 and a downstop partial bore 194 with downstop interior threading 195 adapted to receive an operator shaft with an external threaded region 197 . surrounding the exterior of the downstop 192 is a drift adjuster 202 . a downstop assembly may comprise the downstop 192 and the drift adjuster 202 . the drift adjuster 202 has a drift adjuster internal bore 205 , which , in this particular embodiment is threaded and adapted to receive the downstop 192 via the downstop exterior threading 193 . however , it is contemplated that in some embodiments , a threaded connection is not present . further , the downstop 192 can be considered to have a distal portion abutting the diaphragm retainer plate 190 and a proximal end in the shape of a protrusion extending from the distal portion of the downstop . in this manner , the drift adjuster may associate with the protrusion area of the downstop . the drift adjuster may further comprise one or more threaded bores from the external side of the drift adjuster to the drift adjuster internal bore 205 and which are adapted to receive one or more drift adjuster screws 203 to prevent rotation of the drift adjuster with respect to the downstop once the desired adjustment has taken place . in order to adjust the drift adjuster , external access ports 196 are spaced annularly around the lower actuator housing . a tool , such as a screw driver or similar long instruments can be inserted through the external access ports to adjust the drift adjuster 202 . the benefit of having an internal adjustable downstop is the ease of measurement , the adjustment of the stroke or travel of the actuator can be adjusted externally using common tools . direct labor time and injury to components is reduced . in general , diaphragm actuators adjust the stroke using shims or spacers placed proximally to the downstop or distally to the packing retainer . however , such spacers and shims have a specific width . with the close tolerances required in valve adjustment , the ability to move a drift adjuster to any functional width is advantageous . surrounding the upper portion of the downstop 192 is the spring retainer plate 204 . the proximal side of the upper spring retainer plate abuts the distal portion of the central spring 210 . the central spring 210 surrounds the drift adjuster 202 , the downstop , 192 and the operator shaft 140 as depicted in fig2 . the proximal end of the central spring abuts the bonnet ring 220 . in other aspects of fig2 , the external circumference of the bonnet ring abuts the lower actuator housing 20 . the internal bore of the bonnet ring 220 is threaded . preferably , to secure the bonnet ring 220 to the lower actuator housing 20 , the bonnet ring 220 may have a series of threaded holes 230 of a defined circumference which are perpendicular to the operator shaft 140 . likewise , the lower actuator housing 20 may have a series of holes which are approximately the same circumference as the threaded holes 230 of the bonnet ring 220 and which are capable of aligning with the threaded holes 230 of the bonnet ring . bolts 240 may be screwed into the threaded holes from the exterior of the lower actuator housing such that the lower actuator housing abuts the bonnet ring . preferably the interface of the lower actuator housing with the bonnet ring is air tight . as further illustrated in fig2 , the bolts 240 are positioned in a horizontal or latitudinal direction relative to the top shaft 80 . by orienting the bolts in a horizontal position , the lower actuator housing does not need to be as thick to accommodate threaded bolt holes . thus , the advantage of horizontal positioning of bolts 240 is a decrease in the weight of the actuator housing , which can aid in transportation and installation . as indicated previously , the internal bore of the bonnet ring 220 is threaded . threaded into the bonnet ring is the bonnet 250 . thus the actuator housing can be screwed onto the bonnet 250 via the bonnet ring 220 . the tension on the central spring 210 can also be adjusted by rotating the actuator housing with respect to the bonnet . as illustrated in fig2 , the bonnet 250 comprises an internal bore . the distal portion of the internal bore is threaded so as to receive the packing retainer 260 . the packing retainer 260 preferably surrounds the operator shaft 140 . distal to the packing retainer 260 are two o rings . o rings are preferably viton ® o rings . the operator shaft o ring 280 surrounds the operator shaft 140 and is between the packing retainer 260 and the operator shaft 140 . the packing retainer o ring 290 surrounds the packing retainer and is in between the packing retainer and the bonnet as illustrated in fig2 . proximal to the packing retainer and within the bore of the bonnet are operator seals 300 . preferably the operator seals are polypack ™ seals . at the proximal end of the bonnet as depicted in fig2 , the operator shaft possesses an operator shaft shoulder 320 preventing upward or distal movement of the operator shaft . proximal to the operator shaft shoulder 320 is an operator shaft screw 330 . the foregoing detailed disclosure and description of the invention is illustrative and explanatory thereof , and it will be appreciated by those skilled in the art , that various changes in the size , shape and materials as well as in the details of the illustrated construction , reliability configurations , or combination of features of the various valve actuator elements of the present invention may be made without departing from the spirit of the invention .