Abstract:
A method of installing a piston position sensor proximate to a closed end of a hydraulic cylinder is provided. The sensor is attached to the face of a piston and that piston/sensor combination is inserted into the cylinder tube to position the sensor in the desired location. When properly located within the cylinder tube, the sensor is affixed to the cylinder tube by means of beveled holes in the sensor that receive bolts threadedly inserted through the cylinder tube to further properly align the sensor within the cylinder tube. When so affixed, the sensor is then detached from the piston so that the piston can thereafter move independently of the sensor. A fixture is also used that allows the assembler to accurately align the angular orientation of the sensor prior to being inserted into the cylinder tube.

Description:
CROSS REFERENCES  
       [0001]     This application is a divisional of application Ser. No. 10/098,933, filed on Mar. 15, 2002, entitled “METHOD OF ASSEMBLING AN ACTUATOR WITH AN INTERNAL SENSOR” which is related to U.S. Pat. No. 6,234,061 entitled “Precision Sensor for a Hydraulic Cylinder,” and co-pending U.S. patent application Ser. No. 09/793,218 filed Feb. 26, 2001 entitled “Precision Sensor for a Hydraulic Cylinder,” U.S. Ser. No. 09/785,097 filed Feb. 16, 2001 entitled “Multi-Turn, Non-contacting Rotary Shaft Position Sensor,” U.S. Provisional Patent Application Ser. No. 60/351,007 filed Jan. 23, 2002 entitled “An Improved Lead Guide for Cable Extension Type Position Sensors,” and U.S. Provisional Patent Application Ser. No. 60/364,711 filed Mar. 15, 2002 entitled “Method and Apparatus for Connecting Cables” filed concurrently, having the same inventor and assignee as the present application. Each of the above referenced applications is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention generally relates to actuators having an internal moving member and an internal sensor for sensing the position of the moving member relative to a fixed reference.  
       BACKGROUND  
       [0003]     Actuators are in wide spread use to actuate other implements or devices. The applications of actuators are virtually limitless and the size, shape, etc. of the actuator as well as the device actuated is relatively unconstrained. Hydraulic cylinders are one commonly used form of actuators. Such actuators include a cylinder and an internal piston which actuates an external device. In many actuator applications, there is a need for greater control of the movement of the device imparted by the actuator. One example of this need is in the equipment arena where hydraulic cylinders are used as actuators to control the movement of a mechanical device, such as the bucket or claw on construction equipment.  
         [0004]     There are, in use today, various types of piston position sensors that are used to accurately sense the position of a piston within a hydraulic cylinder. The operation of such hydraulic cylinders, therefore, depends upon a position sensor to automatically and accurately determine the location of a piston with the hydraulic cylinder, and correspondingly, the position of the particular implement that is being controlled by that hydraulic cylinder. One of such sensors and its use and construction is shown and described in U.S. Pat. No. 6,234,061 entitled “Precision Sensor for a Hydraulic Cylinder,” and the disclosures of which is hereby incorporated by reference. That particular sensor is, therefore, one that is positioned within the interior of the hydraulic cylinder proximate the closed end of the cylinder, that is, the end opposite the working end where the piston rod extends to be affixed to the equipment to be moved.  
         [0005]     In the construction and assembly of hydraulic cylinders, the manufacture of such hydraulic cylinders is an established, well-defined process. It is desirable not to disrupt that process by adding some additional complexity to the manufacturing techniques, that is, the less changes that are required in the current manufacturing practices, the better the acceptance of the sensor.  
         [0006]     In the normal manufacturing practices of assembling a hydraulic cylinder, the final assembly consists of bringing together two major subassemblies, the “tube assembly” and the “piston rod” assembly. The tube assembly consists mainly of the cylinder tube with the back cap attached thereto and the other end is open to receive the piston rod assembly. The piston rod assembly, on the other hand, consists of the piston rod, the head and the piston. As such, in the final assembly, the piston rod assembly is inserted into the tube assembly similar to loading a cannon such that the piston is inserted into the open end of the cylinder tube and is pushed all the way back to the closed end of the cylinder tube. When so inserted the head is positioned at the open end of the cylinder tube and secured thereto, either by means of a threaded connection by threads formed internal of the cylinder tube and threads formed external to the head, or by means of bolts that are threaded into a mating flange welded to the open end of the cylinder tube. In either case, once the head has been secured to the open end of the cylinder tube, the cylinder assembly is complete.  
         [0007]     Accordingly, it would be advantageous to provide a system or procedural steps in the manufacture of a hydraulic cylinder to be able to install a sensor in the closed end of a cylinder tube, and secure the sensor at that location while minimizing disruptions and changes to current manufacturing practices for the construction and assembly of such hydraulic cylinders.  
       SUMMARY OF THE INVENTION  
       [0008]     Broadly, the present invention relates to a method of assembling an actuator having an internal moving member wherein a sensor is positioned internally with the actuator during actuator assembly. An exemplary actuator of this type is a hydraulic cylinder and piston.  
         [0009]     In one aspect of the invention, the actuator is a cylinder and piston assembly and the sensor is of the type where a first portion, such as a flexible connector, connects to the piston, the sensor is positioned in the closed end of the cylinder. Prior to insertion, the first portion of the sensor is attached to the piston and the piston and sensor are inserted in the cylinder to the desired position. The sensor housing, or second portion, is secured to the cylinder via a second portion of the sensor. Advantageously, this assembly may be performed during the final stages of the actuator assembly without disrupting or altering the piston and cylinder manufacturing operations. That is, the initial stages of the construction of the cylinder is carried out in the conventional manner and the present invention comes into play during final assembly, when the piston rod assembly is interfitted into the cylinder tube assembly. At that point in the assembly procedure, the piston position sensor is attached to a portion of the piston, such as the distal piston face, and the sensor and piston are inserted into the cylinder during that final assembly.  
         [0010]     In another aspect of the invention, a flexible mounting collar affixed to the top of the piston position sensor features a hexagonal, or other configured pocket, formed in the mounting collar. The flexible connector exits the top of the sensor in the center of the hexagonal pocket and the cable connector resembles a modified bolt, having a hexagonal head that is loosely fitted into and engaged by the hexagonal pocket formed in the top of the mounting collar. The hexagonal pocket feature makes the attachment of the sensor to a portion of the piston, e.g., the distal piston face, easier and more efficient as the threaded end of the attachment bolt can be engaged with the threaded receiving hole on the piston. Since the hexagonal head of the attachment bolt is secured to the hexagonal pocket on the mounting collar, the engagement of the attachment bolt with the threaded hole in the piston is accomplished by rotating the entire sensor. When the attachment bolt is substantially screwed in, the sensor can be withdrawn from the piston for a short distance to provide access to the attachment bolt, and final tightening can be accomplished.  
         [0011]     In another aspect of the invention, the mounting collar can be attached to the distal face of the piston such that the piston position sensor is releasably affixed or attached to the distal face, that is, the face that initially enters the cylinder tube. The mounting collar is located on the outer surface of the sensor i.e. the surface that faces outwardly when in the inserted position. An internally shaped pocket is also formed on the distal face of the piston such that the mounting collar is adapted to releasably fit to the pocket in a manner that allows the fit to be later disengaged. One exemplary fit is a snap fit, but other releasable engagements can be used.  
         [0012]     In another aspect, the mounting collar is formed as a substantially conical projection from the top of the sensor and is preferably formed of an elastomeric material and can be an integral feature of the sensor external packaging. The flexible property of the mounting collar allows the mounting collar to snap fit or otherwise engage into the cylindrical mounting pocket formed in the distal face of the piston. The mounting pocket in the distal face of the piston has annular groove around the periphery of its inner face and the mounting collar is provided with an annular ridge protruding from the outer periphery of the mounting collar and which engage with each other to releasably affix or attach the sensor to the piston.  
         [0013]     Accordingly, after the connection of the flexible connector to the distal face of the piston has been completed, the mounting of the sensor onto the distal face of the piston is accomplished by pressing the mounting collar into the mounting pocket formed in the piston and twisting slightly until the collar snaps into the mounting pocket. The attachment is sufficient to hold the sensor to the piston during assembly of the hydraulic cylinder and is detachable after the final cylinder assembly is completed so that the piston can thereafter move independently of that portion of the sensor.  
         [0014]     In another aspect of the invention, which is desirable for a sensor intended to have a particular angular orientation within an hydraulic cylinder, in the actual insertion of the piston rod assembly into the cylinder tube assembly, the angular alignment of the sensor is checked since certain asymmetrical features of the sensor, such as its mounting holes, should be in approximate alignment when the sensor reaches the closed end of the cylinder tube. The angular alignment relates to the angular orientation of the sensor features around the axis of the cylinder tube and that alignment is easily adjusted. The sensor collar forms a rotatable connection with the piston face and a fixture is provided to assure that the proper angular orientation is achieved before the sensor is inserted into the cylinder tube. One means of ensuring proper angular alignment of the sensor to the cylinder tube is to fix an optical beam on an assembly bench and fix the optical beam along a flat area of the sensor. Alternative methods could, of course, be used such as utilizing a gate having a flat surface that mates with a flat surface of the sensor to arrive at the correct angular orientation of the sensor with respect to the cylinder tube.  
         [0015]     In yet another aspect, the piston rod assembly is pushed into the cylinder tube assembly by means of a push rod such the piston is pushed all the way back into the cylinder tube, thereby positioning the sensor in the desired position at the back, closed end of the cylinder tube. The sensor can be affixed in that location by means of two opposing installation bolts that are threaded from the outside of the cylinder tube through threaded holes in the cylinder tube, extending through the pressure wall and beveled engaging holes provided on each side of the sensor. The bolts are oriented perpendicular to the axis of travel of the piston and at the closed end of the cylinder tube in the sensor&#39;s operating location proximate that closed end. The engaging holes provided in the sensor are substantially opposite one another, and located to correspond with the threaded holes provided in the cylinder tube. The engaging holes provide a bevel around their open end so as to compensate for alignment errors during installation. Thus, by the beveled holes, as the bolts are secured to the holes, the bevel will steer the sensor into proper alignment and that alignment also applies to deviations in front-to-back placement of the sensor. More or less than two bolts can be used, or engagement mechanisms other than threaded engagement can be use without departing from the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]     A more complete understanding of the invention may be obtained from consideration of the following description in conjunction with the drawings in which:  
         [0017]      FIG. 1A  is a perspective view of an exemplary sensor according to the principles of the invention;  
         [0018]      FIG. 1 B  shows a front view of the sensor of  FIG. 1A ;  
         [0019]      FIG. 2  shows an exploded view of an exemplary cylinder according to the principles of the invention;  
         [0020]      FIG. 3  shows an exploded view of an exemplary cylinder and sensor according to the principles of the invention;  
         [0021]      FIG. 4  shows a perspective of an exemplary sensor and connecting means according to the principles of the invention;  
         [0022]      FIG. 5  shows a cutaway perspective of an exemplary sensor pre-installation according to the principles of the invention;  
         [0023]      FIG. 6  shows an exploded perspective of an exemplary cylinder and sensor according to the principles of the invention;  
         [0024]      FIG. 7A  shows a cutaway perspective of an exemplary cylinder and sensor according to the principles of the invention;  
         [0025]      FIG. 7B  shows a perspective of an exemplary cylinder and sensor mounting hardware according to the principles of the invention;  
         [0026]      FIG. 8  shows a perspective of an exemplary assembly system, according to the principles of the invention;  
         [0027]      FIG. 9  shows a detail perspective of an exemplary assembly system, according to the principles of the invention;  
         [0028]      FIG. 10  shows another detail perspective of an exemplary assembly system, according to the principles of the invention;  
         [0029]      FIG. 11  shows a detail perspective of an another assembly system according to the principles of the invention;  
         [0030]      FIG. 12  shows another perspective of an exemplary assembly system, according to the principles of the invention; and  
         [0031]      FIG. 13  shows a view of another assembly system, according to the principles of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0032]      FIGS. 1A and 1B  respectively show a perspective view and a front view of a sensor  100  and a securing device, such as a threaded connector  140 , constructed in accordance with the present invention. As can be seen, the sensor includes mounting collar  110  that facilitates attachment to a cylinder piston  320  ( FIG. 3 ). A threaded connector  140  extends outwardly from the center of the sensor  100  is provided for attachment of the flexible connector cable to the piston. The threaded connector  140  sits within a suitably shaped pocket formed in the mounting collar  110  that conforms to the shape of the head  142  of the threaded connector  140 . For example, if the head  142  of the threaded connector  140  is a hexagonal head, there is a hexagonal shaped pocket formed in the mounting collar  110  such that the threaded connector  140  can loosely fit within that pocket.  
         [0033]     The are also two beveled holes  130  (only one of which is shown in  FIG. 1A ) that provide a means for affixing the sensor  100  after installation and insertion into a cylinder as will be explained. A multi-pin electrical connection  120  provides signal connections. As can be seen more clearly in  FIG. 1B , the mounting collar  110  has a flattened conical shape. The mounting collar  110  is preferably formed from an elastomeric material and is capable of bending or flattening. The mounting collar  110  also comprises a ridge  112  around its periphery. The ridge  112  acts as a barb to provide a snap-fit during sensor installation. Other fits can be used as well as other engagement means. What is important is that the sensor body attach to the piston and detach from the piston.  
         [0034]     Turning now to  FIG. 2 , there is shown an exploded view of a hydraulic cylinder prior to final assembly. It may be seen that there are two major sub-assemblies. The cylinder tube assembly  200  consists of the back clevis  340 , an end cap  360 , and a cylinder tube  350  that has an open end  352  and a closed end  354 . The piston rod assembly  210  consists of a piston  320 , a piston rod  310 , a head  330 , and a rod clevis  370 . A method of assembly is to secure the cylinder tube assembly  200  on a workbench, and insert the piston rod assembly  210  into the open end  352  of the cylinder tube  350 . The head  330  is then attached to the cylinder tube  350  by threading or bolting, in some cases by the employment of an intermediate flange. In some instances, the head  330  is held stationary while the cylinder tube assembly  200  is rotated about its axis, thus screwing the cylinder tube  350  and the head  330  together.  
         [0035]     Turning now to  FIG. 3 , there is shown an exploded view of a hydraulic cylinder with the various components positioned just prior to assembly. In this view the sensor  100  of the present invention is shown in a position to be installed onto the distal face  325  of the piston  320 . As can be seen, the sensor  100  is in position to be mounted to the distal face  325  of the piston  320  and the mounting collar  110  faces that distal face  325  and the threaded connector  140  extends outwardly from the mounting collar  110  toward the distal face  325  of the piston  320 .  
         [0036]     Turning now to  FIG. 4 , there is shown a perspective view of the piston  320  with the sensor  100  in position to be affixed thereto in an intermediate step of installation onto the piston  320 . The threaded connector  140  is threaded into a hole in the distal face  325  of the piston  320 . As explained, the threaded connector  140  can be initially started into the threaded hole in the distal face  325  of the piston  320  by rotating the entire sensor  100  since the head  142  of the threaded connector  140  is loosely fitted within the pocket formed in the mounting collar  110 . Once the threading has been started, however, the sensor  100  can be withdrawn and the remaining threading can be accomplished with a wrench, as in the  FIG. 4  position. Affixed to the threaded connector  140  is a flexible connector  410  that extends into the sensor  100  in the use of the sensor  100  to determine the position of the piston  320  within the cylinder tube  350  ( FIG. 3 ) in the manner described in the aforementioned patent and co-pending patent applications.  
         [0037]     In one aspect, the attachment bolt can be hollow, and the flexible connector can be connected to the attachment bolt by means of a ball. This will permit the bolt to rotate about the connector without twisting the connector. Such an arrangement is disclosed in a provisional U.S. Provisional Patent Application Ser. No. 60/364,711 entitled “Method and Apparatus for Connecting Cables”, which is hereby incorporated by reference.  
         [0038]     A receiving pocket  420  is formed in the distal face  325  of the piston  320 . After tightening the threaded connector  140  into the distal face  325  of the piston  320 , the mounting collar  110  can be snapped into the receiving pocket  420  so that the sensor  100  is secured to the distal face  325  of the piston  320 . In this way the sensor  100  is attached to the piston rod assembly  210 , prior to the final assembly of the hydraulic cylinder in a connection that can later be disconnected in the further steps in carrying out the present invention.  
         [0039]     In  FIG. 5 , there can be seen a cutaway view showing the actual connection between the sensor  100  and the piston  320 . As can be seen, the mounting collar  110  is shown interfitting into the receiving pocket  420  such that the sensor  100  is removably affixed to the piston  320  in a manner that can later be disconnected. Due to the flexibility of the mounting collar  110  the affixation of the mounting collar  110  to the distal face  325  of the piston  320  is sufficient to insert the sensor  110  into the cylinder tube  350  ( FIG. 3 ) but, as will be seen, that junction can be disconnected in accordance with the further steps of the present invention.  
         [0040]     Turning now to  FIG. 6 , there is shown an exploded view showing the piston rod assembly  210 , with the sensor  100  installed, with the piston rod assembly  210  in position to be inserted into the open end  352  of the cylinder tube assembly  200 . This is the position of the major sub assemblies just prior to final assembly of the complete hydraulic cylinder with a sensor  100 . At this point a pusher is used to push the piston rod assembly  210  and sensor  100  is inserted into the cylinder tube assembly  200 .  
         [0041]     Next, in  FIG. 7A , there is shown a perspective view, partially cutaway, of the complete hydraulic cylinder assembly  700  with sensor  100 . The sensor  100  is located at the closed end  354  of the end cap  360  proximate to the closed end  354  of the cylinder tube assembly  200  having been pushed fully into the cylinder tube assembly  200  and is generally located in its operative position but is still attached to distal face  325  of the piston  320 . The piston  320  is driven all the way to the back of the cylinder tube assembly  200 , thus inserting the sensor  100  into the space provided in the end cap  360 .  
         [0042]     In  FIG. 7B , there is shown a perspective view of assembled hydraulic cylinder  700  and showing the attaching bolts  720  and the high-pressure connector bushing  710  that are used in completing the hydraulic cylinder assembly with sensor  100  ( FIG. 7A ). The attaching bolts  720  thread into opposing beveled holes  130  ( FIG. 4 ) in the end cap  360 . The ends of the attaching bolts  720  engage the beveled holes  130  ( FIG. 4 ) on opposing sides of the sensor  100 . In this manner, the sensor  100  is secured into the end cap  360  proximate the closed end  354  of the cylinder tube  350 . As explained, the beveled holes  130  are beveled so that as the attaching bolts are screwed into the threaded holes  132  in the end cap  360 , the sensor  100  is aligned by the tightening of those attaching bolts  720  and they move the sensor  100  to the proper, desired aligned location with the cylinder tube  350 . The high-pressure connector bushing  710 , along with a high-pressure electrical connector, is threaded into a standard port  730  in the end cap  360 . The high-pressure connector bushing  710  retains a high-pressure electrical connector that serves to take signals into and out of the high-pressure environment in the hydraulic cylinder. As noted, the high pressure connector bushing  710  utilizes a standard port  730  that is present in conventional hydraulic cylinders and therefore the potential expense of forming a special port for the high pressure connector bushing  710  is saved.  
         [0043]     Once the sensor  100  has been fully secured within the closed end  354  of the cylinder tube  350 , the piston  320  can be moved away from the sensor  100  to detach itself from the sensor  100  so that thereafter the piston  320  can move freely and independent of the sensor  100  that is now in a secured position in its operative location so that the hydraulic cylinder can operate in its normal manner.  
         [0044]     Turning now to  FIG. 8 , there is shown an assembly system or fixture  900  for the assembly of a hydraulic cylinder in accordance with the present invention. A base  810  provides supports  820  for the cylinder tube  350  to maintain the cylinder tube  350  in a fixed position as the hydraulic cylinder is assembled. A clevis pin  860  is located at one end of the base  810  and passes through the back clevis  340  to secure the cylinder tube assembly  200  to the base  810 . The piston rod assembly  210  is supported by straps  850  that are attached to a lift assist. A moveable clevis pin  840  fitted into the rod clevis  370  is used to push the piston rod assembly  210  into the cylinder tube assembly  200 . As can be seen, the sensor  100  is attached to the piston  320  such that the insertion of the piston rod assembly  210  results in the installation of the sensor  100  as described in previous figures.  
         [0045]     It is also desirable that the sensor  100  be properly aligned for insertion into the cylinder tube  350  in order to locate various physical features or components, including mounting and signal connection features of the sensor  100  in the proper aligned orientation when inserted into its operative position within the cylinder tube  350 , including the alignment of the beveled holes  130  ( FIG. 7 ). Accordingly, the geometry of the sensor  100  itself is such that the exterior peripheral surface is generally cylindrical, thereby having a generally circular cross section, but there is also formed a flat face  920  formed on that outer peripheral surface. That flat face  920  is thereby used to carry out the angular alignment of the sensor  100  and as preferred, however, it will be seen that other special shaped or characteristics of the sensor  100  can be used to achieve the proper angular alignment. Accordingly, in  FIG. 8 , there is shown one sensing means used to detect the angular location of that flat face  920  and the sensing means comprises a light emitter  830  and a light detector  835 .  
         [0046]     Thus, the light beam from the light emitter  830  will be blocked by the circular outer peripheral surface of the sensor  100 , however as the sensor  100  is rotated with respect to piston  320 , there will be a point in its angular orientation where the light beam from the light emitter  830  passes along the flat face  920  where the outer peripheral surface is inset as opposed to the normal circular periphery and the light beam from the light emitter  830  will reach the light detector  835 . As such, when the light detector  835  senses the light beam, the system recognizes that the sensor  100  is in the proper orientation for insertion into the cylinder tube assembly  200  and a pusher can, at that time push the piston rod assembly  210  into the cylinder tube assembly  200 . The use of the light emitter  830  and detector  835  can easily be employed to provide a visual or audible signal to the effect that the sensor  100  is in the proper angular orientation.  
         [0047]     Turning now to  FIGS. 9 and 10 , there can be seen upper and lower perspective views of the use of the light emitter  830  and light detector  835  as described with respect to  FIG. 8 . Thus, as can be seen in  FIGS. 9 and 10 , the light emitter  830  provides a beam of light  834  directed at the light detector  835  such that the beam of light  834  passes by the flat face  920  of sensor  100 . Since the proper alignment of the flat face  920  is the only position of the sensor  100  that will cause the light beam to actually reach the light detector  835 , when the light is detected by the light detector  835  and a corresponding signal generated, the sensor  100  is in the proper angular orientation.  
         [0048]     Turning to  FIG. 11 , there is shown an alternative sensing means to assure the proper angular alignment of the sensor  100  for insertion into the cylinder tube assembly  200 . In  FIG. 11  there is used a mechanical guide  870  that is used and which has a flat upper surface  875  that must be in alignment and basically abut the flat face  920  of the sensor  100  in order for the sensor  100  to be advanced toward the cylinder tube assembly  200 . Thus, the mechanical guide  870  will only allow the advancement of the sensor  100  if the flat face  920  is properly aligned so that the sensor  100  is in the proper angular orientation to be inserted into the cylinder tube  350 . The mechanical guide  870  is pivotally affixed to the base  810  by means of a hinge  885  so that the mechanical guide  870  can be flipped down so as to be out of the way as the piston rod assembly  210  is inserted into the cylinder tube  350 .  
         [0049]     In addition or in combination with the above, the flat surface can be used to simply orient the sensor to a reference. For example, during pushing, the flat surface can be used as a sight reference to maintain the sensor substantially in some orientation, such as maintaining the surface substantially horizontal. In this manner, the sensor is inserted such that it is approximately aligned for securing.  
         [0050]     In  FIG. 12  there is shown the completed assembly with the piston rod assembly  210  ( FIG. 2 ) having been inserted all the way into the cylinder tube assembly  200 . The head  330  is fastened to the open end  352  of the cylinder tube  350  by means of a threaded engagement or by means of bolts (not shown) that pass through the head  330  and threaded into holes provided in the cylinder tube  350  or a flange affixed to the cylinder tube  350 . The complete hydraulic cylinder assembly with a piston position sensor is therefore ready for the installation of sensor mounting hardware as described in  FIG. 7B .  
         [0051]     Turning to  FIG. 13 , there is shown a side view of an alternate means of assembly in which the piston rod assembly  210  and the cylinder tube assembly  200  are both clamped in a vertical position rather than in a horizontal position as shown in  FIGS. 11 and 12 . In this alternate embodiment, when the final assembly is ready, the cylinder tube assembly  200  is lowered onto the piston rod assembly  210  vertically downwardly. The sensor alignment is accomplished as in previous figures.  
         [0052]     It is to be understood that the invention is not limited to the illustrated and described forms of the invention contained herein. It will be apparent to those skilled it the art that various changes may be made without departing for the scope of the invention and the invention is not considered limited to what is shown in the drawings and described in the specification.  
         [0053]     First, for example, while the present invention has been disclosed with respect to a cylinder and included piston, the present invention is applicable to other actuators having a movable member disposed with a fixed member and wherein a portion of the sensor is attached to the movable member and which tracks movement of this member so that the sensor provides an indication of the position of the movable member relative to the fixed member.  
         [0054]     Second, the shape of the fixed and movable members need not be circular as in the disclosed cylinder and piston, but each of these members may have virtually any shape. Second while the disclosed cylinder and piston is oftentimes an hydraulic cylinder, the term “hydraulics” referring to any of a number of fluids, i.e., one or more liquids, one or more gases or a combination of the two, the mechanism for applying force to the movable member is virtually unconstrained. Furthermore, it is recognized that a spring for example can be used to apply force to the movable member. Accordingly, for purposes of this disclosure, the term actuator shall include hydraulic cylinders and other devices having internally moving members which are moved by a variety of force imparting mechanisms, including fluids and or other arrangements.  
         [0055]     Third, while threaded engagements are shown for attaching the flexible connector to the piston and the sensor to the cylinder, other engagements can be used without departing from the invention.  
         [0056]     Fourth, while the exemplary embodiments demonstrate insertion of a sensor into a cylinder, other objects can also be inserted without departing from the method of the invention.