Patent Application
20080185086
The present invention relates to an improved rotary assembly for use in a central tire inflation system for automatically maintaining the inflation pressure of the pneumatic tires on moving vehicles such as tractor trailers and, more particularly, to an improvement in the rotary union assembly that is the subject of U.S. Pat. Nos. 6,105,645 and 6,585,019.
The central tire's inflation systems employed on typical tractor trailers utilize the air compressor on the tractor as a source of pressurized air to fill a leaking tire while the trailer is in motion. The compressor directs air to the reserve air brake tank on the trailer and is set to maintain the air pressure within the tank within a range of about 100 to 125 psi, which generally corresponds to the range of typical inflation pressures in the tires used on large tractor trailers. Air from the reserve air brake tank is first directed to the braking system to maintain the air pressure in the braking system at the normal brake system level of about 70 psi. Excess air is directed from the tank through a pressure protection valve to a control box for the tire inflation system. The pressure protection valve only opens to direct the air to the control unit when the air pressure in the tank exceeds 70 psi, thereby preventing air from being directed to the air inflation system which is needed for the trailer braking system. The control box contains a pressure regulator which is set to the cold tire pressure of the particular tires on the trailer so as to supply air to the tires at the desired pressure level in the event of a leak. Air is directed from the control box to the leaking tire through one of the trailer axles, which either carries an air line from the control box, or is sealed and functions as an air conduit. The pressurized air carried by the axles communicates with each pair of trailer tires mounted thereon through a rotary union assembly by which air flow is directed from a stationary air line to the valve stems on the rotating tires. Pressure responsive valves are employed between each rotary union assembly and its associated tires so that upon the occurrence of a leak in one of the tires, the resulting pressure loss will cause one of the valves to open and allow air flow from the rotary union assembly to pass there through to the leaking tire.
While these central tire inflation systems are well known and in widespread use, they suffer from several shortcomings. The rotary union assemblies employed in these systems have a relatively limited useful life span before the rotary seals begin to leak. The rotary seals, or rotary unions as they are frequently called, which are employed in these assemblies are generally located within the wheel lubrication compartments adjacent the ends of the axles. Accordingly, any air leakage in the rotary union seals causes an air pressure build up within the lubrication compartment which can damage the oil seals therein, and create an oil leak. If the wheel bearings loose their lubrication, they will seize up and can cause a fire. In addition to creating the potential for a dangerous fire, the positioning of the rotary union within the lubrication compartment of the wheel makes accessibility to the elements comprising the rotary union both difficult and awkward. As a result, the costs of repair and replacement are significantly increased.
The present invention provides a rotary union assembly for automatic central tire inflation systems which exhibits a substantially longer life than the rotary union assemblies heretofore in use. In addition, the assembly is configured so as to position the rotary union outside of the lubrication compartment for the vehicle wheels and thus avoids pressure build ups within the compartment in the unlikely event of a leak in the rotary union seal. The assembly also contains pressure relief valves which will avoid pressurizing the bearings within the assembly housing in the event of a leak in the rotary union seal, will prevent a pressure build-up within the lubrication compartment in the hub in the event of an air leak upstream of the rotary union seal, and will prevent outside water from entering into the hub. The assembly of the present invention additionally provides ready access to the rotary union components thereof without having to enter the lubrication compartment to facilitate part replacement. As a result, the present invention provides a substantial improvement in air pressure maintenance systems for tractor trailer tires.
Other problems facing central tire inflation systems include a lack of uniformity in tractor trailer wheel hub cap configurations and off center mountings. The former situation results in variations in the axial distance between the ends of the axle spindles and end walls of the hub caps. This distance generally determines the spacing between the air inlet, of the assembly and the rotary seal therein. It would be highly desirable to provide a rotary union assembly which could readily accommodate such dimensional variations and thereby obviate the need to provide differently sized assemblies or replacement components for different hub cap configurations. The rotary union assembly should also accommodate off center alignments of the axle spindle and hub caps without incurring additional wear on the air seals in the assembly which further shortens the life of the assembly. The rotary union assembly of the present invention achieves these objectives as well.
Briefly, the present invention is directed to a rotary union assembly for use in automatic tire inflation systems for vehicle tires and, particularly, for use in automatic inflation systems employed on tractor trailers having either pressurized or non-pressurized stationary axles. The rotary union assembly of the present invention communicates the valve stems on a pair of adjacent tires with either the pressurized axle interior or directly with the source of pressurized air through the use of a stationary tubular conduit, at least a downstream portion of which is flexible. In pressurized axle applications, the upstream end of the tubular conduit extends through a stationary annular seal mounted in a plug assembly in the axle spindle and communicates with the axle interior. The downstream portion of the conduit communicates with a rotary union housing containing the rotary union seal. In non-pressurized axle applications, the upstream end of the tubular conduit preferably communicates directly with the pressurized air supply by means of a flexible air hose that communicates with the tubular conduit through the plug assembly and extends therefrom to the pressurized air supply through the axle interior.
In both pressurized and non-pressurized axle applications, the rotary union housing is sealably secured against the exterior surface of the end wall of the hubcap so as to be rotatable with the hubcap and tire. The annular seal in the plug assembly forms an airtight seal about an upstream position of the tubular conduit which is preferably rigid to prevent distortion of the conduit over time. In addition, the annular seal allows for the length of the rigid portion of the tubular conduit projecting from the annular seal toward the rotary union housing to be readily varied by the simple insertion or retraction of the conduit from the plug assembly during installation, thereby accommodating wide variations and hubcap configurations without the need for part replacement and without adversely affecting the integrity of the seal. As both the tubular conduit and the annular seal through which it extends are stationary and the portion of the tubular conduit which the annular seal engages is rigid, wear it is virtually eliminated at this juncture of the assembly.
In a preferred embodiment of the invention, a portion of the tubular conduit between the plug assembly and rotary union housing is flexible. Thus, inadvertent off center mountings of the rotary housing relative to the threaded fitment on the axle spindle is readily accommodated without significantly affecting either the integrity or the life of the air seals in the assembly. Positioning the rotary housing against the exterior end surface of the hub cap locates the rotary seal formed therein outside of the lubrication compartment of the wheel and thereby prevents pressure build ups within the lubrication compartment in the event of air leakage in the rotary seal.
The rotary seal of the present invention includes a stationary shaft having an air passageway extending axially therethrough that communicates with the downstream end of the air conduit. The shaft projects through and is carried by one or more bearing members disposed in an extended portion of the rotary union housing. The extended portion of the housing projects axially through the hub cap end wall such that the shaft communicates the pressurized air passing through the tractor trailer axle with the interior of the rotary housing via the tubular conduit while providing a rotatable mounting of the rotary housing on the stationary shaft. A spring biased graphite element having a centrally disposed axial passageway is mounted in a fixed disposition within the housing so as to be rotatable therewith. The element is pressed against the downstream end of the elongated shaft in a flush disposition therewith to form with the shaft a rotary union by which air flow passes from the stationary tubular conduit into the rotating housing.
In the rotary housing mounted on the end wall of the hub cap, air is directed from the rotary union through two opposed channels into separate air lines which communicate with the valve stems on the pair of adjacent tires or, in the case of wide-based tires, through a single channel and air line to the valve stem on the single tire. Pressure responsive valves are provided in each of the lines to allow air flow through the appropriate line in response to a downstream pressure drop as would occur in the event of a leak in one of the tires. A normally open pressure responsive valve is also provided in each line which closes in the event of a drop in pressure upstream of the rotary union as would occur when the compressor is shut down to prevent the trailer tires from deflating. A warning light is also provided in the system for indicating to the driver the activation of the central tire inflation system.
A pressure relief valve system comprising at least one calibrated poppet valve is provided in the rotary union housing for venting both the rotary union and the lubrication compartment to atmosphere to avoid pressurizing the bearings within the housing in the event of a leak in the rotary union seal and to prevent a pressure build up within the lubrication compartment in the event of an air leak in the tire inflation system upstream of the rotary union seal. The valve system is configured to prevent outside water from entering into the hub in the event the rotary union housing is submerged in water or is subjected to high pressure washing and to resist oil from the lubrication compartment within the hub cap from passing therethrough and onto the vehicle wheels while discharging air therethrough.
Referring now in detail to the drawings, the rotary union assembly 10 of the present invention, while useable on a wide variety of movable vehicles employing stationary axles for automatically maintaining the inflation pressure of the pneumatic tires thereon, is particularly adapted for use on tractor trailers. Accordingly, the assembly 10 will be described in conjunction with a pair of adjacent vehicle tires 12 and 14 mounted on a stationary tractor trailer, axle 16. While identical rotary union assemblies 10 are provided at the end of each axle on the trailer to maintain the inflation pressure of the tires carried thereby, reference will be made to only one such assembly and the pair of tires it services.
The trailer axle 16 which carries tires 12 and 14 can be sealed and functions as an air conduit to communicate the spindles 18 welded to the extended ends of a trailer axle 16 with an air supply line 20. Such an arrangement is referred to herein as a sealed or pressurized axle application and is illustrated in
In pressurized axle applications (
Briefly, the spindle plug assembly 310 (as seen in
In a preferred embodiment of the invention, the tubular conduit 40 is comprised of a rigid stainless steel portion 41 and a relatively short flexible portion 42 secured to the downstream end of rigid portion 41 by a crimped ferrule 43a. Alternatively, the rigid and flexible portions of conduit 40 could be integrally formed in a molding process to obviate the need for ferrule 43a or some other suitable fitting. The rigid portion 41 of conduit 40 is preferably provided with a tapered upstream end 41′″ and projects into the interior of the axle spindle through the o-ring seal 328 in the spindle plug assembly 310 as seen in
To prevent axial separation and relative rotation between the rigid and flexible portions of tubular conduit 40, tapered axial ribs 41′ are provided on the downstream end of the rigid conduit portion 41 adjacent annular hose barbs 41″. Hose barbs 41″ extend into the upstream end portion of flexible tubing portion 42 of conduit 40 which is secured therein by the crimped ferrule 43. The upstream portion of the rotary union shaft 45 defines a threaded tubular extension 45′ that threadably engages the compression fitting 47. It is to be understood that other suitable attachment fittings could be employed to sealably engage the flexible portion 42 of the tubular conduit 40 with the rigid portion 41 and with the rotary union shaft 45.
The rotary union shaft 45 projects into a rotary housing 50 which is mounted exteriorly adjacent end wall 52 of hub cap 54. Rotary union housing 50 includes a central channel 58 extending axially therethrough for receiving shaft 45 and the other components of the rotary union 70, also referred to as a rotary union seal. A pair of high quality self-lubricating bearings 56 are mounted within housing 50 about a portion of channel 58 which receive in a press fitment a downstream portion 59 of the shaft 45 so as to provide a freely rotational mounting of the rotary housing 50 on shaft 45. Bearings marketed by NTN Bearing Corporation of America of Mt. Prospect, Ill. under the model designation W688AZZ/1K have been found to be well suited for this application. The bearings 56 are secured in place within housing 50 by a pair of clips 61a and 61b (see
An upstream portion 64 of the rotary housing 50 is of a reduced diameter and projects through a centrally disposed aperture 65 in the end wall of hub cap 54 such that the rotary housing can be sealably secured against the exterior end wall 52 of hub cap 54 in axial alignment with the hub cap, rotary union shaft 45 and tubular conduit 40. This securement can be provided by an annular resilient seal 66 carried in an annular channel 85′ formed in the upstream end 85 of the rotary union housing and mating threads 53′ formed on the exterior of the reduced diameter portion 64 of rotary housing 50 and threads 53″ formed in hub cap end wall 52 about central aperture 65 therein. Upon threadably securing the rotary union housing onto the hub cap end wall, seal 66 abuts and sealably engages an annular portion of the wall about the central opening or aperture 65 therein. Unless the hub cap is particularly designed for use with the rotary union assembly of the present invention, such as hub cap 54 shown in the drawings, the above-described securement of housing 50 generally requires the drilling and tapping of aperture 65 in the end wall of the hub cap. It should be noted, however, that the end walls of some hub caps are too thin to support the rotary union housing 50 as described. For such installations, the aperture 65 is drilled but not tapped and a suitably sized threaded fastening member in the form of a large nut (not shown) threadably engages the reduced diameter portion 64 of the housing within the hub cap and is tightened against the interior surface of the hub cap end wall about the aperture therein, securing the housing to the hub cap end wall.
It also should be noted that many hub caps of the type with which rotary union assemblies are employed have a “sight glass” 57 mounted in the end wall 52 thereof for viewing the oil level within the hub cap, as is shown in
The rotary union or seal 70 in rotary housing 50 is defined by the stationary elongated shaft 45, an axially aligned graphite element 72 having an open ended channel 74 extending axially therethrough, a steel washer 78, an o-ring 79 disposed between washer 78 and the downstream end of the graphite element 72, and a coil spring 80 disposed within a reduced diameter downstream portion 58′ of housing channel 58. The graphite element defines a hexagonal upstream portion 72′, the corners of which fit within a plurality of equiangularly spaced axial relief areas 75 formed in the side wall of the reduced diameter portion 58′ of the flow through channel 58 in rotary housing 50 such that rotational movement of housing 50 with hub cap 54 is imparted to graphite element 72. Alternatively, the channel walls about reduced diameter portion 58′ could be hexagonally or otherwise configured to provide an interference fit with the graphite element 72. The coil spring 80 in the rotary union when compressed to 0.25 inches, produces spring force of about 5.5 to 6.0 pounds and bears against the end of the reduced diameter bore 58′ and washer 78 so as to urge the upstream planar end face 73 of graphite element 72 against the flush downstream adjacent planar end face 63 of the stationary shaft 45.
A pair of oppositely aligned radial channels 90 and 92 are provided in the rotary housing 50 which communicate with the central channel 58 therein proximate spring member 80 as seen in
The opposed channels 90 and 92 in rotary housing 50 are provided with internal threads for the threaded engagement therein of fittings 100 and 102 containing Schraeder valves 100′ and 102′ respectively or other suitable check valves. (See
Through the aforesaid configuration, air under a pressure corresponding to that of the cold pressure of the vehicle tires 12 and 14 is provided from axle 16 through the rotary union assembly 10 and the open Schraeder valves 100′ and 102′ carried by the rotary housing 50. Because the air passing through valves 100′ and 102′ to valves 105 is at the same pressure as the air within tires 12 and 14, valves 105 are balanced and remain closed, preventing air flow through the rotary union assembly 10. In the event of a leak in one of the tires, the resulting pressure drop downstream in air hose 96 or 98 will create a pressure imbalance across the valve 105 mounted therein. As soon as this imbalance reaches 3 psi, the valve 105 will open, allowing air to pass therethrough to the leaking tire to maintain the desired inflation pressure within the tire. When the automatic air inflation system is shut down, the pressure within the axle remains at the tire inflation pressure. Accordingly, valves 105 remain balanced and closed so that the tires will not deflate. If the axle were to leak so that the pressure were to drop on the upstream side of valves 105, they would remain closed so that the tires would not release air to the depressurized chamber within the axle. If one were to remove one of hoses 96 or 98 from housing 50, as would occur if the hoses were damaged, valve 100′ or 102′ would close so that the system would not continually blow air to the atmosphere.
A pressure relief system is provided in the rotary union assembly 10 of the present invention which will: (1) avoid pressurizing the bearings 56 in the rotary union housing 50 in the event of an air leak in the rotary union 70 between the stationary end face 63 on the rotary union shaft 45 and the rotating planar end face 73 on the graphite element 72; and (2) prevent a pressure buildup within the lubrication compartment which could result in the event of air leak upstream of the rotary union. This pressure relief system comprises a pair of open ended channels 120 and 122 extending axially through the rotary union housing 50 parallel to and on opposite sides of the central housing channel 58. At least one of the channels (e.g. 120) communicates with the central housing channel 58 via a weep hole 86. The weep hole 86 is located such that it communicates with channel 58 adjacent a shoulder 58″ defining the interface of the reduced diameter portion 58′ of channel 58 with the larger diameter upstream portion and thus communicates with channel 58 adjacent the rotary union surfaces 73 and 63.
An elongated poppet valve member 124 is disposed in each of the pressure relief channels 120 and 122. Each valve member defines a hollow tubular body portion 126 and an enlarged radial head portion 128 having a flat outer surface 130. A pair of opposed air outlet apertures 131 extend transversely through the body portions of the valves proximate the head portions as seen in
To provide an air flow path for the pressurized air within the hub cap to the upstream ends of the pressure relief channels 120 and 122 with minimal restriction, opposed lateral portions of the threaded reduced diameter portion 64 of the rotary union housing 50 are cut away so as to define air passageways 64′ that allow the pressurized air to pass relatively unrestricted through the threaded engagement of the rotary union housing to the hub cap. Cut-out areas are also provided in the upstream end 85 of the housing 50 about the upstream ends of the relief channels, defining air collection areas 85′ adjacent the channels. The relief channels 120 and 122, valve members 124 and the outlet apertures 131 in the valve members are sized so as to be capable of passing a sufficient volume of air therethrough that in the event of a catastrophic failure, a pressure buildup within the lubrication compartment of no more than 5 psi will result given a pressurized air source of about 100-125 psi. This result was obtained with the present invention, by configuring the pressure relief system such that it could evacuate air from the hub cap at the same volumetric flow rate as a 0.250 inch diameter aperture in the hub cap wall open to atmosphere. To obtain that result, the relief channels 120 and 122 each defined a transverse dimension of 0.253±0.003 inches. The internal diameters of the poppet valve members was 0.125 in. The diameters of each of the outlet apertures 131 in each valve member was 0.063 in. and the inner diameter of the rigid portion 41 of conduit 40 was 0.086 inches.
Accordingly, in the unlikely event of an air leak through the rotary union 70 sufficient to create a pressure buildup within channel 120 of as little a 0.5 psi, the poppet valve member 124 disposed in relief channel 120 will snap to the open position allowing the air in the chamber to discharge to atmosphere through the aperture 131 in the valve member. In the event of an air leak upstream of a rotary union which would otherwise cause a pressure buildup within the oil lubrication compartment, air will flow directly from the lubrication compartment along the air passageways 64′ between the threadably engaged rotary union housing and hub cap and into the pressure relief channels 120 and 122. When this pressure build-up exceeds 0.5 psi, the force of the coil springs 134 holding the poppet valve members 124 in their closed positions will again be overcome and the valve members will snap to their open positions, relieving the pressure within the lubrication compartment. Thus, the pressure relief poppet valves will prevent any deleterious pressure buildup within either the rotary union housing or the lubrication compartment within the hub cap. In addition, in the event the rotary union housing were submerged in water or subjected to high pressure water cleaning, the spring leaked poppet relief valves would prevent any water from entering the rotary union housing or the wheel lubrication compartment.
While the preferred embodiment of the present invention employs two symmetrically positioned pressure relief valves, only one of which needs to be communicated with the central housing channel via a weep hole 86, the rotary union housing could be constructed so as to include only a single relief channel and poppet valve member, provided the housing was configured such that the relief channel would be large enough to discharge the necessary volumetric flow of air to prevent a pressure buildup in the lubrication compartment of over 5 psi. The preferred configuration of the rotary union housing employs two poppet relief valves to allow for such a discharge without having to increase the size of the housing.
Because pressure relief channels 120 and 122 communicate with the interior of the hub cap as previously described, oil in the lubrication compartment within the hub cap can, under pressure, pass into the pressure relief channels. As a result, when the interior pressure within the hub cap exceeds 0.5 psi above atmospheric and the poppet valves open to relieve the pressure, oil from the hub cap will flow through and about the valve members 124 with the escaping air and onto the vehicle wheels. To prevent such a messy and unsightly occurrence, an oil shield 500 is disposed about the upstream end portion of the rotary union shaft 45 adjacent compression fitting 47. Shield 500 is thus positioned directly in the path of any oil being expelled from the hub cap under pressure toward the upstream ends of air passageways 64′ to relief channels 120 and 122. The shield 500 is in the form of a washer preferably made of a fluoropolymer resin material such as that marketed by DuPont under its registered trademark Teflon, and is preferably provided with radial slots 501 about its central opening 500′ so that the shield can be more readily pressed into place about the upstream end portion of shaft 45.
In the preferred embodiment of the invention, the end wall of the hub cap is further modified (see
As a result of the above-described pressure relief assembly, any oil passing under pressure toward the cut-out air passageways 64′ in the threaded portion 64 of the rotary union housing will abut shield 500 and be deflected or drip into the annular oil collection area 507 and is thus prevented from passing directly through the air passageways to the pressure relief channels 120 and 122. Because the hub cap is rapidly spinning as the vehicle travels along the road, centrifugal force will cause the oil in area 507 to be driven outwardly against annular wall 508, through the inclined apertures 512 therein and back into the interior of the hub cap. As a result, the passage of oil through the rotary union housing and onto the exterior of the vehicle wheel is substantially diminished during an air leak. The apertures 512 in the annular wall 508 are inclined at about a 45° angle as above described so as to enable the apertures to communicate with the interior of the hub cap inwardly of the sight glass 57 in the end wall of the hub cap and to direct the returning oil outwardly within the hub cap, away from the rotary union shaft. When the hub caps with the preferred embodiment of the rotary union assembly of the present invention are being used do not have a sight glass, it is not necessary to incline the oil return apertures 512 as above described. However, by still inclining the apertures, the centrifugal force acting on the collected oil will drive the oil rearwardly as well as outwardly within the hub cap interior and thus further from air passageways 64′.
To facilitate the use of the preferred embodiment of the rotary union assembly of the present invention with a wide variety of hub caps, both with and without sight glasses, a two-piece ring assembly 600 has been developed. As shown in
For hub caps that do not have a sight glass in the end wall, the end ring 602 of assembly 600 is not needed. In such applications, it is only necessary to form a centrally disposed threaded aperture defining a diameter of 1.625 inches in the hub cap end wall. In hub caps having sight glasses, the same enlarged threaded opening 605 is provided in the end ring 602 which simply replaces the end ring on the original hub cap provided by the manufacturer (see
The center hub 604 comprises a base portion 610, an annular outer flange 611 at the downstream end thereof and a projecting portion 612. A recess is provided in base portion 610 adjacent flange 611 for an o-ring 617. The base portion 610 is provided with external threads 613 thereon that adapted to engage the internal threads 605 about the central aperture 615 in the end ring 602. In hub caps without sight glasses, the base portion of center hub 604 would threadably engage the internal threads formed about the 1.625 inch diameter aperture formed in the hub cap end wall. The projecting portion 612 of hub 604 is integrally formed with the base portion 610 and is inwardly spaced from the perimeter of the base portion so as to define an annular recess therebetween for an o-ring 614. The projecting portion 612 also defines a threaded central bore 616 extending axially therethrough and a radially offset interior annular wall 618 having a plurality of inclined oil return apertures 620 formed therein. Apertures 620 are virtually identical in configuration and orientation to apertures 512 discussed above. The threaded central bore 616 is also virtually identical to the above-described threaded aperture 65 and is thus adapted to receive and threadably engage rotary union housing portion 64. The radially offset wall 618 defines an annular oil collection area 622 substantially identical to the above-described collection area 507 and the return apertures 620 in center hub 604 are identical to the inclined apertures 512 in the previously described annular wall 508. Thus, ring assembly 600 allows one to easily retrofit an existing hub cap to provide the same end wall configuration as if the hub cap were specifically manufactured for the present invention.
Finally, a warning light (not shown) is preferably provided so as to alert the driver in the event of the activation of the automatic tire inflation system, which would be indicative of a tire leak. In addition, if one were to disconnect one of air hoses 96 or 98 from its respective tire stem, the warning light would also illuminate so that the automatic tire inflation system would not continuously pump air through the system without the knowledge of the driver. Such a warning system could comprise a microswitch in electrical communication with the wiring harness on the trailer which closes upon the activation of the control unit in the automatic tire inflation system and triggers a transmitter which would send a signal to a receiving unit mounted on the front left corner of the trailer. The receiving unit would activate a light source such as a plurality of LED's which would be clearly visible to the driver through the side mirror of the attached tractor.
Various other changes and modifications may be made in carrying out the present invention without departing from the spirit and scope thereof. Insofar as these changes and modifications are within the purview of the appended claims, they are to be considered as part of the present invention.
This is a continuation of pending application Ser. No. 11/051,314 filed Feb. 4, 2005, entitled Rotary Union Assembly For Use In Air Pressure Inflation Systems For Tractor Trailer Tires, which is a continuation-in-part of application Ser. No. 10/851,441 filed May 21, 2004, now U.S. Pat. No. 6,968,882 issued Nov. 29, 2005, which is a continuation of application Ser. No. 09/993,019 filed Nov. 13, 2001 (now abandoned), which is a continuation of application Ser. No. 09/522,623 filed Mar. 10, 2000, now U.S. Pat. No. 6,585,019 issued Jul. 1, 2003, which is a continuation of application Ser. No. 09/079,571 filed May 14, 1998, now U.S. Pat. No. 6,105,645 issued Aug. 22, 2000. This is also a continuation-in-part of application Ser. No. 10/941,774 filed Sep. 15, 2004, now U.S. Pat. No. 7,117,909 issued Oct. 10, 2006, entitled Expandable Spindle Plug Assembly For use With Automatic Tire Inflation Systems, which is a continuation-in-part of application Ser. No. 10/457,793 filed on Jun. 9, 2003, now U.S. Pat. No. 6,938,658 issued Sep. 6, 2005.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11051314 | Feb 2005 | US |
| Child | 11963612 | US | |
| Parent | 09993019 | Nov 2001 | US |
| Child | 10851441 | US | |
| Parent | 09522623 | Mar 2000 | US |
| Child | 09993019 | US | |
| Parent | 09079571 | May 1998 | US |
| Child | 09522623 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10851441 | May 2004 | US |
| Child | 11051314 | US | |
| Parent | 10941774 | Sep 2004 | US |
| Child | 09079571 | US | |
| Parent | 10457793 | Jun 2003 | US |
| Child | 10941774 | US |
