Valve position transmitter

A valve position transmitter which is comprised of an indicator assembly having a base with an aperture located thereon, an adjusting ring placed on the base about the aperture, an indicator member capable of identifying the operational position of a remote valve said indicator member being positioned on the adjusting ring, and a transparent cover placed about said indicator and secured to the base of the indicator assembly. Said valve position transmitter also comprising a shaft assembly extending from the point where it may be coupled to a valve through the aperture in the base of the indicator assembly to a point where it engages with the indicator member such that any rotation of the shaft assembly is sensed by said indicator member and some display with respect to such rotation is made. The valve position transmitter may also be comprised of a switch box assembly comprising a housing wherein are located switches for detecting rotation in the shaft member, said switches being electrically connected to a terminal strip and in turn said terminal strip being connected to remote peripheral devices. Said valve position transmitter may also be comprised of a split shaft assembly wherein upper and lower shaft members are provided for such that a peripheral device may be permanently coupled to said upper shaft member and it may be removed along with the upper shaft member to allow for easy field servicing of the remainder of the device.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to valve position transmitters in general and more 
particularly to a valve position transmitter designed to preclude the 
misalignment of the transmitter during reassembly in the field--thereby 
precluding the improper designation of valve position, designed to 
facilitate the use of peripheral devices with the transmitter, and 
designed to minimize the damage to the transmitter resulting from the 
conditions in which it is used. 
2. Description of the Prior Art 
Valve position transmitters are known and are used to identify the relative 
operational position of a valve located in a separate valve assembly. 
Quite often valve position transmitters are utilized in hazardous 
environments to allow for the identification of a valve's position from a 
safe and remote distance. Furthermore, valve position transmitters are 
often used when the valve assembly itself is remotely situated and 
difficult to reach. 
Existing valve position transmitters, however, are susceptible to misuse 
and damage. For example, it often becomes necessary during the course of 
regular maintenance to disassemble and reassemble a valve position 
transmitter in the field. Unless the valve position itself is checked at 
the time of reassembly and the system recalibrated, the valve position 
transmitter may be misaligned such that it identifies the wrong valve 
position. Such an error could have devastating effects. For example, the 
valve position transmitter disclosed in U.S. Pat. No. 4,494,566 provides 
for an indicator cover which may be placed upon the device in any of a 
number of different orientations. Accordingly, if during disassembly and 
reassembly of this device said cover is rotated ninety degrees without a 
corresponding change in the valve position, the result is a transmitter 
identifying a valve position opposite from that which actually exists. 
Furthermore, as previously noted, valve position transmitters are often 
used in environmentally hazardous conditions wherein the corrosive effect 
on the device is substantial. In addition, repeated disassembly and 
reassembly of the device itself can result in wear and tear on the various 
elements of the device. Over the course of time this corrosion and this 
wear and tear can result in inaccuracies, or a total breakdown, in the 
device's ability to correctly identify a valve position. Again, this could 
cause problems in situations where an accurate reading is critical. 
On occasion a valve position transmitter may be utilized with a peripheral 
device that is permanently coupled to the shaft portion of the 
transmitter. For example, one such device is a positioner. However, the 
permanent coupling of such a device to the transmitter shaft often times 
impedes the ability to conduct field work on the transmitter or its 
various components. 
Finally, valve position transmitters often include a switch box assembly 
containing switches connected to other peripheral devices. Such switches 
may be used to signal the valve position to these peripheral devices. 
Again, the conditions under which valve position transmitter are used can 
cause deterioration of the switch box assembly. Furthermore, the 
relatively small size of the switch box assemblies may cause difficulties 
with respect to the field work required to be performed on the switches 
and their associated connections. 
SUMMARY OF THE INVENTION 
It is therefore an object of the present invention to overcome the 
aforementioned disadvantages of prior art systems and provide a valve 
position transmitter wherein the possibility of misidentification of the 
valve position by the transmitter upon reassembly is eliminated. 
It is a further object of the present invention to provide a valve position 
transmitter wherein corrosion resulting from the hazardous environment in 
which said valve position transmitters are often utilized, and wear and 
tear resulting from the repeated handling of these devices, is minimized. 
It is a further object of the present invention to provide a valve position 
transmitter having a peripheral device permanently coupled to its shaft 
assembly wherein the presence of said peripheral device does not hinder 
field work on the transmitter. 
It is a further object of the present invention to provide a valve position 
transmitter with respect to which field work on the switches and 
associated wiring located in switch box assemblies is made easier and 
safer to conduct. 
These and other objects of the present invention are achieved in a valve 
position transmitter which is comprised of an indicator assembly having a 
base with an aperture located thereon, an adjusting ring placed on the 
base about the aperture, an indicator member capable of identifying the 
operational position of a remote valve said indicator member being 
positioned on the adjusting ring, and a transparent cover placed about 
said indicator and secured to the base of the indicator assembly. Said 
valve position transmitter also comprising a shaft assembly extending from 
the point where it may be coupled to a valve through the aperture in the 
base of the indicator assembly to a point where it engages with the 
indicator member such that any rotation of the shaft assembly is sensed by 
said indicator member and some display with respect to such rotation is 
made. The valve position transmitter may also be comprised of a switch box 
assembly comprising a housing wherein are located switches for detecting 
rotation in the shaft member, said switches being electrically connected 
to a terminal strip and in turn said terminal strip being connected to 
remote peripheral devices. Said valve position transmitter may also be 
comprised of a split shaft assembly wherein upper and lower shaft members 
are provided for such that a peripheral device may be permanently coupled 
to said upper shaft member and it may be removed along with the upper 
shaft member to allow for easy field servicing of the remainder of the 
device. 
These and other novel features and advantages of the invention will be 
described in greater detail in the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings, and in particular to FIG. 1, there is shown 
a valve position transmitter, generally identified by reference numeral 
10, which eliminates the possibility of misidentification of the valve 
position during in-field reassembly of the device, which minimizes the 
corrosive and wear and tear effect resulting from the day to day use of 
the device especially in hazardous environments, and which is designed so 
as not to hinder field work on its various elements. 
The valve position transmitter 10 is generally designed for use in 
conjunction with a valve assembly or, alternatively and most likely, in 
conjunction with the combination of an actuator assembly and valve 
assembly. The valve position transmitter 10 transmits the operational 
position of a valve located in the valve assembly. The valve position 
transmitter 10 determines the position of the valve by means of a shaft 
assembly 12 coupled through one of its elements to the shaft assembly of 
the valve assembly or of the actuator assembly. It should be noted that 
neither the actuator assembly nor the valve assembly is an element of the 
present invention and are therefore not displayed in the accompanying 
drawings. 
The valve position transmitter 10 must be held rigidly in place relative to 
its position with respect to the valve assembly or actuator assembly to 
which it is coupled through an element of shaft assembly 12. This is 
necessary so that the rotation of the element of shaft assembly 12 does 
not impart rotational movement to the entire valve position transmitter 
10. This may be accomplished by means of brackets, mounting lugs or other 
similar devices secured to any stationary item, including for that matter, 
the valve assembly or the actuator assembly. 
The valve position transmitter 10 is comprised of an indicator assembly 14. 
The indicator assembly 14 is comprised of an indicator base 16. Situated 
upon the indicator base 16 is an upper shaft aperture 18. In the preferred 
embodiment of the present invention, situated about and above said upper 
shaft aperture 18 is an upper shaft sleeve 20 which is an integral part of 
the indicator base 16. 
The indicator assembly 14 is additionally comprised of an adjustment ring 
22 which is secured in place on top of the indicator base 16 and 
concentrically about said upper shaft aperture 18. Said adjustment ring 22 
is secured to the indicator base 16 in such a manner that the adjustment 
ring 22 may be rotatably moved through an arc of at least 90.degree.. In 
the preferred embodiment of the present invention said adjustment ring 22 
may be rotated a full 360.degree.. This may be accomplished by securing 
said adjustment ring 22 in place by means of one or more adjusting screws 
24 which may be loosened or removed to allow rotation of the adjustment 
ring 22. Furthermore, situated upon the top of said adjustment ring 22 is 
one or more protrusions 26 that operate as orientation pins. 
The indicator assembly 14 is additionally comprised of an indicator member 
28 which presents a visual display indicative of the operating position of 
the valve of the valve assembly. The indicator member 28 is positioned 
upon the top of the adjustment ring 22. The bottom of said indicator 
member 28 includes one or more orientation indents 30. The number and 
relative location of said orientation indents 30 coincide with the number 
and relative location of the protrusions 26 on said adjustment ring 22 and 
are positioned in such a manner that the indicator member 28 can only be 
situated upon the adjustment ring 22 in at most two orientations, each of 
said two orientations being 180.degree. rotationally disposed from the 
other. The interaction of the protrusions 26 and the orientation indents 
30 secure the indicator member 28 upon the adjustment ring 22. In the 
preferred embodiment of the present invention there are at least two 
protrusions 26 and corresponding orientation indents 30. This allows the 
stresses resulting from the operation of the present invention to be 
better distributed and absorbed throughout the entire indicator assembly 
14. 
The indicator assembly 14 is also comprised of a transparent cover 32 which 
is placed about said indicator member 28 and secured to the indicator base 
16. Many prior art devices fail to provide a clearly observable indication 
of valve status. Often times this is due to the utilization of indication 
means not observable from all directions. For example, in some prior art 
devices the view of the entire surface of the indication means may be 
blocked by some other element of the device. The prior art device 
disclosed in U.S. Pat. No. 4,494,566 utilizes a cover wherein a portion of 
its surface is opaque. While this is an integral feature of this device, 
it nevertheless reduces the overall surface area of the device capable of 
indicating the valve status. In the present invention, the use of a 
transparent cover 32 allows for the viewing of 100% of the surface of the 
indication means, thereby greatly increasing the usefulness of the device. 
In the preferred embodiment of the present invention an O-ring 34 is 
provided to act as a compression seal between said transparent cover 32 
and said indicator base 16. This seal protects against corrosion to the 
elements of the indicator assembly 14 resulting from the environmentally 
hazardous conditions in which the present invention is often utilized. 
Furthermore, the use of a seal helps protect against dirt and/or 
condensation from collecting on the interior surface of said transparent 
cover 32, thereby protecting against obstructed viewing of the indicator 
member 28. Said O-ring 34 is situated in an O-ring indent 36 situated upon 
said indicator base 16 concentrically about said upper shaft aperture 18 
and said adjustment ring 22. In the preferred embodiment of the present 
invention said indicator base 16 is also comprised of a seating ridge 38 
which is an integral part of said indicator base 16. Said seating ridge 38 
protrudes from the top of said indicator base 16 about said upper shaft 
aperture 18 and conforms in shape to, and is slightly larger in size than, 
the bottom edge of said transparent cover 32. The O-ring 34 and O-ring 
indent 36 are enclosed by said seating ridge 38 thereby facilitating the 
positioning of said transparent cover 32 upon said indicator base 16. 
Furthermore, the seating ridge 38 may be used to facilitate removably 
securing said transparent cover to said indicator base 16. For example, a 
moveable detent 40 positioned in the seating ridge 38 and capable of being 
moved against said transparent cover 32 may be utilized to lock the 
transparent cover 32 in place upon said indicator base 16. Alternatively, 
the inner surface of the seating ridge 28 may be configured to cooperate 
with base ridges situated on said transparent cover 32 so that said 
transparent cover 32 may be snapped in and out of said seating ridge 38 
thereby eliminating the need for auxiliary fasteners. 
As previously noted, the valve position transmitter 10 is comprised of a 
shaft assembly 12. Said shaft assembly 12 is comprised of a rotatable 
shaft member 44. The lower end of said shaft member 44 is coupled by 
conventional means to an upper end of a valve assembly shaft or, 
alternatively, to the upper end of an actuator assembly shaft which in 
turn is coupled to the valve assembly shaft. As a result of this, a change 
in valve position will result in the rotation of the various shafts 
including the shaft member 44. 
The combination of the shaft assembly 12 and the indicator assembly 14 
allows for the operation of the present valve position transmitter 10. In 
particular, the shaft member 44 passed through the upper shaft aperture 18 
situated in the indicator base 16 so as to engage said indicator member 28 
in such a way that a rotation in said shaft member 44 is detected by said 
indicator member 28. If this occurs, the rotation of the shaft member 44 
will be reflected by a change in the visual display of indicator member 28 
indicative of the change in the valve's operational position. The change 
in the visual display may be observed through the transparent cover 32. 
The engagement between said shaft member 44 and said indicator member 28 is 
accomplished by the insertion of the tip 46 of the shaft member 44 into a 
slot 48 situated within said indicator member 28. Furthermore, the tip 46 
and slot 48 are each configured so that said indicator member 28 can only 
be placed on said shaft member 44 in no more than two orientations, each 
of said two orientations being 180.degree. rotationally disposed from the 
other. 
In order to properly operate the valve position transmitter 10, there must 
be an initial calibration of the indicator member 28 with the position of 
the valve in the valve assembly. The shaft assembly 44, as previously 
noted, is coupled by conventional means to the valve shaft assembly or, 
alternatively to the actuator shaft assembly which in turn is 
conventionally coupled to the valve shaft assembly A change in the valve 
position from fully open to fully closed or, alternatively, from fully 
closed to fully open results in a ninety degree rotation of the coupled 
shaft assemblies and, therefore, the shaft member 44. In order to 
calibrate the device the position of the valve at the time of calibration 
must be a known variable. While no specific valve position is required, to 
ensure the most accurate calibration of the device the valve should be 
either fully closed or fully open. 
The valve position transmitter 10 is calibrated after the shaft member 44 
is initially coupled to said valve assembly and engaged with the indicator 
member 28 which in turn is positioned on said adjustment ring 22. In all 
probability the valve position displayed by the indicator member 28 at 
this time does not match the actual valve position. Accordingly, a change 
in the valve position displayed by the indicator member 28 must be made. 
Such a change occurs when the indicator member 28 detects a rotation of 
the shaft member 44. The shaft member 44 cannot be rotated, however, 
because to do so would change the valve position. Accordingly, the 
indicator member 28 must be rotated relative to said shaft member 44. 
Therefore, keeping the shaft member 44 stable, the indicator member 28 and 
adjustment ring 22 are rotated about said shaft member 44 until the 
indicator member 28 displays the existing condition of the valve, i.e. 
open, closed. The indicator member 28 needs to be turned no more than a 
quarter turn since it will have detected a 90.degree. rotation of the 
shaft member 44 after a quarter turn and will have displayed the full 
range of valve positions. 
It is necessary to rotate the adjustment ring 22 along with the indicator 
member 28 because the protrusions 26 on said adjustment ring 22 and the 
orientation indents 30 on said indicator member 28 only allow these two 
elements to be secured together in no more than two orientations that are 
180.degree. rotationally disposed from the other. The rotation of these 
two elements is accomplished by the loosening of the adjusting screw 24. 
Once the existing condition of the valve is displayed by the indicator 
member 28, the adjusting screw 24 is again tightened so that the 
adjustment ring 22 is securely fastened to said indicator base 16. 
Once the calibration has been made, the indicator member 28 can be removed 
from the shaft member 44 as often as desired without risking the 
misalignment of the indicator member 28 upon its reinsertion. The reasons 
for this is as follows: If a change in valve position occurs while the 
indicator member has been removed, there will have been a corresponding 
rotation of the shaft member 44. When the indicator member 28 is 
reinserted the configuration of the tip 46 and slot 48 will limit its 
placement on the shaft member 44 so that it will have to be rotated to fit 
thereon. Upon its placement on the shaft member 44, however, the valve 
position display will not match the existing valve position. Furthermore, 
the indicator member 28 cannot then be secured to the adjustment ring 22 
since the protrusions 26 and the orientation indents 30 no longer are 
aligned. When, however, the indicator member 28 is then rotated to align 
said protrusions 26 and said orientation indents 30 it will detect a 
rotation relative to the shaft member 44 which remains stationary due to 
other forces, such as frictional forces of the shaft assemblies to which 
said shaft member 44 is coupled. As this rotation is detected the valve 
position display will change and at the point said protrusions 26 and said 
orientation indents 30 are aligned, the existing valve position will then 
be displayed. 
Finally, it should be noted that regardless of which of the two 
orientations--each of which is 180.degree. rotationally disposed from the 
other--for the insertion of the tip 46 and slot 48 occurs, and regardless 
of which of the two orientations--again each of which is 180.degree. 
rotationally disposed from the other--for the placement of said indicator 
member 28 on said adjustment ring 22 occurs; the result will be the same. 
This is true because a rotation of the shaft member 44 through 180.degree. 
represents an initial valve position and a final valve position that are 
exactly the same. 
The preferred embodiment of the present invention also includes a variety 
of additional elements. For example, the indicator assembly 14 may also 
comprise a tubular first shaft bearing 50. Said first bearing 50 is 
secured within said upper shaft sleeve 20 and is configured so as to 
minimize the horizontal movement of said shaft member 44 as it passes 
therethrough thereby eliminating stresses thereon. In the preferred 
embodiment of the present invention said first shaft bearing is made from 
an aluminum --nickel alloy. This feature provides for superior wear and 
run characteristics. Furthermore, this alloy occupies the same position in 
the electrochemical series as the indicator base 16 thereby preventing 
galvanic corrosion. 
Furthermore, in the preferred embodiment of the present invention the shaft 
assembly 12 also comprises a first O-ring shaft indent 52 and a first 
shaft O-ring 54 situated in said first shaft indent 52. Upon placement of 
said shaft assembly 12 through said indicator assembly 14 said first 
O-ring 54 acts as a seal between said shaft assembly 12 and said upper 
shaft sleeve 20. 
As noted above, the indicator member 28 displays changes in valve position 
upon detecting a rotation in said shaft member 44. As illustrated in FIGS. 
2 through 4, the indicator member 28 in the preferred embodiment of the 
present invention is comprised of a ring shaped base plate 56. Situated 
upon said base plate 56 are one or more grooves 58 wherein a corresponding 
number of vane gears 60 are rotatable within said grooves 58 and the outer 
edge of each vane gear 60 is comprised of gear teeth. Secured to the top 
of each vane gear 60 is a display vane 62 which in turn is rotatably 
secured to an indicator cap 64. 
Each display vane 62 has on one of its sides words, colors, characters 
and/or some other display indicating an open valve. On the opposite side 
of each display vane 62 are other words, colors, characters and/or some 
other display indicating a closed valve. The display vanes 62 are situated 
so that the side of each display vane 62 reflecting a particular valve 
position has the same orientation as all others, i.e. all facing out, in, 
etc. Furthermore, the top of each vane gear 60 has a color or other 
display on each semicircle that reflects the valve position indicated by 
the side of the display vane 62 facing said semicircle. Since the 
indicator cap 64 blocks the view from above the device of the inner half 
of each vane gear 60, the displays on the tops of the vane gear 60 allows 
a determination regarding valve position to be made by viewing the device 
from above. What is observed is the display on each vane gear 60 
associated with the outwardly facing side of the display vane 62. 
The indicator member 28 is also comprised of a driver 66. The driver 66 is 
a generally cone-shaped, hollow element. The driver 66 is rotatably 
secured to the indicator cap 64 by means of an indicator nut 68. About the 
exterior of the base of said driver 66 are situated a multiplicity of gear 
teeth. When the driver 66 is secured to said indicator cap 64, the gear 
teeth about its exterior base engage with the gear teeth of each vane gear 
60. Finally, the slot 48 referred to above is situated within the interior 
of said driver 66. 
The manner in which this indicator member 28 works is as follows: When a 
shaft member 44, which is in engagement with said slot 48, begins to 
rotate, the driver 66 will also begin to rotate. As this occurs the 
engagement of the driver's 66 gear teeth and those of each vane gear 60 
causes each vane gear 60 to rotate When this happens the same change in 
orientation of each display vane 62 situated on the vane gears 60 
simultaneously occurs. This causes a change in the display observable by 
an individual. Furthermore, the gear ratio between the driver 66 and the 
vane gears 60 is chosen to be two to one. Therefore, a rotation of 
90.degree. by the driver 66 (reflecting a change in a valve from open to 
closed) results in a 180.degree. rotation by a vane gear 60 which results 
in a turn in the display vane 62 from one side to the other. 
A more versatile valve position transmitter 10 exists when it comprises, in 
addition to said shaft assembly, a switch box assembly 70. By 
incorporating switches 72 into the present invention, the operational 
position of the valve can be transmitted to remote peripheral devices. 
Referring now to FIG. 1, the switch box assembly 70 is comprised of one or 
more switches 72 enclosed within a housing consisting of an upper housing 
member 76 secured to a lower housing member 78. The upper housing member 
76 has a first housing shaft aperture 80 situated thereon and said lower 
housing member 78 has a second housing shaft aperture 82 situated thereon. 
In the preferred embodiment of the present invention the upper housing 
member 76 includes a first housing shaft sleeve 84 that protrudes and is 
concentric with said first housing shaft aperture 80. Said first housing 
shaft sleeve 84 is an integral part of said upper housing member 76. 
Similarly, in the preferred embodiment of the present invention said lower 
housing member 78 includes a lower housing shaft sleeve 86 situated about 
and protruding above and concentric with said lower housing aperture 82. 
Said lower housing shaft sleeve 86 is an integral part of said lower 
housing shaft member 78. Furthermore, in the preferred embodiment of the 
present invention and as illustrated in FIG. 1, the same element may act 
as the upper housing member 76 and the indicator base 16. Similarly, in 
such a situation, the same elements perform as the preferred components of 
the indicator base 16 as well as the preferred components of the upper 
housing member 76. 
Furthermore, in the preferred embodiment of the present invention a seal 88 
is situated between said upper housing member 76 and said lower housing 
member 78. Said seal 88 provides waterproofing and protection from the 
hazardous environment in which the valve position transmitter 10 is 
utilized. Furthermore, in the preferred embodiment of the present 
invention the upper housing member 76 and the lower housing member 78 are 
secured together by means of one or more securing screws 90. Said securing 
screws 90 are non-removable from said housing, thereby preventing 
accidental loss during field servicing. Furthermore, said securing screws 
90 are surrounded by hooded barriers which are an integral part of said 
lower housing member 78. This aspect protects said sealing screws 90 from 
mechanical damage. Finally, as illustrated in FIG. 1, said securing screws 
90 have a conical shape just below the screwheads. This feature seals off 
the internal threads from corrosion and facilitates factory perfect 
alignment upon reassembly in the field. This last feature reduces stress 
on other components of the present device which would result if the two 
housing components were not perfectly aligned. Finally, in the preferred 
embodiment of the present invention said sealing screws 90 are made of 
stainless steel. 
The switches 72 in the switch box assembly 70 can be any of a number of 
different types of switches. For example, without limitation, said 
switches can include mechanical limit switches and magnetic reed switches. 
The switches 72 are utilized to detect the rotation of the shaft member 44 
and to transmit a signal to a peripheral device. Such peripheral devices 
are not elements of the present invention. 
This signal is generally transmitted through the wiring associated with the 
switches 72, said wiring being fastened to a terminal strip 94 situated 
within said housing. In turn said signal is then transmitted through the 
terminal strip 94 through wiring leading through one or more signal 
apertures 96 located on the face of said housing. 
In the preferred embodiment of the present invention each switch 72 is 
enclosed within a switch housing 98. This feature protects against the 
accidental grounding of the switch wires of a live switch wire during 
field servicing. Furthermore, in the preferred embodiment of the present 
invention the terminal strip 94 is situated upon a terminal strip base 100 
which in turn is situated upon a terminal barrier mount 102 that is an 
integral part of said lower housing member 78. Said terminal barrier mount 
102 provides a barrier for and insulates the wiring and any work that has 
to be done thereon from the shaft area within the housing. Furthermore, 
the terminal strip base 100 is made fairly large in order to allow 
redundant labeling thereon. Such a feature facilitates field servicing 
with respect to terminating switch wires on said terminal strip 94. Such 
redundant marking can include terminal numbers, component names, and 
industry standard wiring color codes. Furthermore, said terminal strip 
base 100 is angled or oriented so as to make the terminal strip 94 more 
accessible to field servicing. 
As previously noted, the switches 72 are used to detect rotation of the 
shaft member 44. The detection of the rotation of said shaft member 44 is 
accomplished by means of cams 104 positioned on said shaft member 44. Said 
cams 104 are mounted on sliding splines 106. Closely coupled sliding 
splines 106 are used to allow additional cams for purposes of minimizing 
the necessary enclosure height. The sliding splines 106 utilize a spring 
pin 108 for purposes of holding the cams 104 in place. The type of switch 
72 illustrated in FIG. 1 is a reed switch actuated by an external magnetic 
driver. The reed switch magnets 110 are embedded in the cams 104 to 
prevent dislodging and disabling of the system. 
As with the indicator member 28, the switches must be calibrated at the 
time the valve position transmitter 10 is first coupled to the valve or 
the valve assembly. As shown in FIG. 1, said shaft member 44 extends 
through the lower housing shaft aperture 82 through the housing interior 
and through the upper housing shaft aperture 80. As just noted, within the 
interior of said housing secured to shaft member 44 are the sliding spline 
106/cam 104 assemblies as noted in FIG. 1. There may also be utilized a 
spring 112 which facilitates the positioning of said splines 106 on said 
shaft member 44. 
The preferred embodiment of the present invention also includes a variety 
of additional elements. For example, the switch box assembly 70 may also 
comprise a tubular second shaft bearing 114. Said second bearing 114 is 
secured within said lower housing shaft sleeve 86 and is configured so as 
to minimize the horizontal movement of said shaft member 44 as it passes 
therethrough, thereby eliminating stresses thereon. As with first bearing 
50 said second bearing 114 may be made from an aluminum-nickel alloy. 
Furthermore, in the preferred embodiment of the present invention the 
shaft assembly 12 also comprises a second O-ring shaft indent 116 and a 
second shaft O-ring 118 situated in said second shaft indent 116. Upon 
placement of said shaft assembly 12 through said switch box assembly 70, 
said second O-ring 118 acts as a seal between said shaft assembly 12 and 
said lower housing shaft sleeve 86. In the event said upper housing member 
76 and said indicator base 16 are in fact two separate elements within a 
particular valve position transmitter 10, then another combination of the 
shaft O-ring and accompanying indent may be utilized in cooperation with 
said upper housing shaft sleeve 84. 
Finally, since it will not be necessary to remove the shaft assembly 44 
from the lower housing member 78 after the device is assembled, an 
additional element that may be included in the embodiment of the present 
invention is an internal stainless steel locking ring 120. Such a locking 
ring 120 is illustrated in FIG. 6. Generally said locking ring 120 is 
placed about a first locking groove 122 situated on said shaft member 44. 
It has been determined that by providing a gap in said locking ring 120 of 
approximately 36.degree. the maximum protection is obtained from said 
locking ring 120 without risking deforming said locking ring 120 upon 
insertion about said first locking groove 122. A second locking groove 124 
is situated on the interior face of said tubular second shaft bearing 114. 
Accordingly, as it is positioned within said valve position transmitter 10 
said shaft member 44 is effectively locked in place when said locking ring 
120 becomes secured within said first locking groove 122 and said second 
locking groove 124. This feature provides protection for the entire device 
from external environmental conditions and more importantly provides 
enhanced strength to the shaft assembly by reducing vertical motion to the 
difference between the tolerance between the locking grooves 122, 124 and 
locking ring 120. In the preferred embodiment of this invention, such a 
feature reduces the vertical motion to less than 0.001 inches. 
On occasion, peripheral devices may be attached to the shaft member 44 of 
the shaft assembly 12. Said peripheral devices are generally used in 
conjunction with the valve position transmitter 10 but are not an element 
of the present invention. One such peripheral device, for example, is a 
positioner. On occasion, the coupling of said peripheral device to said 
shaft member 44 is permanent or, if not, proves to be quite difficult to 
undo. Accordingly, it then becomes necessary to conduct field servicing 
without the benefit of removing such peripheral devices. Needless to say, 
this can cause substantial difficulties in correctly performing the 
necessary field services. This problem has been addressed by the 
utilization of a split shaft assembly 126 as illustrated in FIG. 5. The 
split shaft assembly 126 is generally comprised of an upper shaft member 
128 and a lower shaft member 130. In addition, a coupler 132 is utilized 
for purposes of removably securing said upper shaft member 128 to said 
lower shaft member 130. By using a split shaft assembly 126 such a 
peripheral device may be permanently coupled to said upper shaft member 
128 and may be removed away from the switch box assembly when field 
service must be provided by means of separating said upper shaft member 
128 away from the coupler 132. 
Due to limitations pertaining to said peripheral devices it may on occasion 
be necessary to insure that upon reassembly the upper shaft member 128 be 
placed in the same alignment with said lower shaft member 130 as existed 
at the time the upper shaft member 128 was removed. To insure proper 
alignment, protrusions 134 are situated upon the upper shaft member 128 
which conform in size and location with recesses 136 in said coupler 132. 
The number and location of protrusions 134 and recesses 136 are selected 
so as to insure that only one possible alignment can be made. Finally, 
when a split shaft assembly 126 is utilized, a second locking ring 138 may 
be situated at the upper end of said shaft assembly 12 such that in 
cooperation with a third locking groove 140 situated on said shaft member 
44 and a fourth locking groove 142 situated on the interior of said first 
shaft bearing 50 to lock said upper shaft member 28 within said first 
shaft bearing 50. 
In the foregoing specification, the invention has been described with 
reference to a specific exemplary embodiment thereof. It will, however, be 
evident that various modifications and changes may be made thereunto 
without departing from the broader spirit and scope of the invention as 
set forth in the appended claims: The specifications and drawings are, 
accordingly, to be regarded in an illustrative rather than in a 
restrictive sense.