Abstract:
A method and apparatus for bead seating a tubeless tire onto a rim. Air stored in a portable tank is released as a single pneumatic pulse having an extremely fast rise time. This is accomplished using a charging reservoir having a fill/quick-release port, an inlet and an outlet. A piston divides the charging reservoir into two sections, a control section containing the fill/quick-release port and an outlet section containing the inlet and the outlet. The portable tank is connected to the inlet of the outlet section. Air that is introduced into the fill/quick-release port fills the control section of the charging reservoir. Since the piston is a loose fit, air is able to slowly leak past the piston and fill the outlet section of the charging reservoir and the portable tank that is connected to the inlet. The pressure differential across the piston keeps the piston tightly against the outlet, holding the pressurized air in the outlet section and the portable tank. Once the pressurized air in the quick-release section is released, the pressure differential is reversed and the piston is propelled away from the outlet, thereby explosively releasing the air from outlet section and the connected portable tank as a single pneumatic pulse. The pneumatic pulse is directed between the rim of the wheel and the bead of the tire by a unique nozzle to seat the bead of the tire.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a method for bead seating a tubeless tire onto a rim and an apparatus for the same. 
     2. Description of the Related Art 
     While tubeless tires provide significant advantages over the tube-type, it is extremely difficult to seat the bead of the tire on the rim. This difficulty creates a special problem when trying to change a tire on the road, far from the customary equipment used to seat the tire. 
     One solution to the problem had been the introduction of ether inside the tire. The ether is the ignited and the resulting explosion often will seat the bead of the tire on the rim of the tire. Of course, determining the precise amount of ether necessary to seat the tire without potential injury to the operator is often difficult to determine. Factors such as the volume of the tire, the relative humidity in the air, ambient breeze, volume of ether are virtually impossible for the operator to calculate in order to be reasonably certain that sufficient ether is being used. However, if too much ether, again virtually impossible to consistently determine, is used, then a dangerous explosion is possible. Although extremely dangerous and despite the warning by every tire manufacturer that this procedure should not be used, this method is still being employed even though a number of deaths and serious injury result each year. 
     Another solution, which is best described as mechanical, although it may include some pneumatic elements, relies on the use of flexible straps or segmented hoops which squeeze along the circumference of the tire and thereby force the bead upward toward the bead seating surface. These mechanical devices are not conducive to being portable and require a substantial amount of time in the preparation of the equipment prior to the inflation process. 
     Still another solution is a class of pneumatic tools, which utilize a source of compressed air to impart momentum to the bead and inject air into the tire, thereby initiating a progressive bead seating process. While these tools are substantial improvement over the above-described apparatus, this type of design still presents problems and, as yet, no pneumatic tool has been universally adopted or totally eliminated the practice of using ether. 
     U.S. Pat. No. 3,866,654, issued to Duquesne on Feb. 18, 1975, discloses a portable device for inflating tubeless tires that utilizes a source of compressed air stored within a tank which directly supplies an injection nozzle through a long flexible hose. A complicated valve is used for releasing the air stored within a portable tank to control the airflow. The device is expensive to construct, especially due to its complicated valve assembly and cannot release enough air in a sufficiently short period of time so that the bead of the tire will be forced against the rim to properly seat the bead. The inadequacy of this device to meet tire bead seating requirements is primarily due to its cumbersome valve as well as the use of a relatively long flexible standard compressed air hose. 
     U.S. Pat. No. 5,042,547, issued to Van De Sype on Aug. 27, 1991, discloses a tire bead seating device having multiple air injection nozzles. Four are depicted which direct air from a portable tank. Van De Sype recognized the need for using a simple valve, a ball valve, that permits faster release of the air than was achievable with Duquesne&#39;s disclosed valve. However, Van De Sype defeated any advantage gained by the use of the ball valve by requiring multiple flexible long flexible lines having small nozzles. This arrangement substantially increases the airflow resistance downstream of the ball valve, thus correspondingly slowing the rise time of the air released against the bead of the tire and subsequently, reducing the impact on the bead of the tire. 
     U.S. Pat. No. 5,072,764, issued to Ochoa on Dec. 17, 1991, discloses, as did Van De Sype, a bead seating apparatus that utilizes a hand-operated valve, preferably a ball-type valve, to release a charge of air from a portable storage tank. However, Ochoa, while recognizing the need for a very fast discharge of air from the storage tank, failed to recognize that his nozzle is unnecessarily restricting airflow. Ochoa teaches the use of a nozzle having a discharge area that is less than the cross-sectional area of the discharge barrel. Ochoa also teaches away from the use of large diameter discharge barrels, that is, discharge barrels having an opening larger than 20.4 square centimeters. Ochoa incorrectly states that larger dimensions of discharge barrels tend to cause the discharge impulse of air to impart an undesirably large quantity of momentum to the sidewall of the tire, thereby introducing undesired components into the motion of the bead of the tire. Consequently, much of the advantage gained by the use of a short, rigid, discharge short discharge barrel is lost. Ochoa failed to recognized that the time its takes for the ball valve to be moved from the fully closed to the fully opened position retards the rise time of the pulse of air, thus reducing the effectiveness of the apparatus. 
     An improvement on the Ochoa device is a tire bead seating apparatus that was manufactured by the BEAD SEATER Corporation. This device also featured a portable tank, a ball-type valve as taught by Van De Sype, Ochoa and a short, rigid discharge barrel as disclosed by Ochoa. However, the BEAD SEATER apparatus provided a unique fan-shaped nozzle having a radius that was dimensioned to correspond to the rim of the tire and had a discharge area that was always greater than cross-sectional area of the discharge barrel. While the nozzle as well as the use of discharge barrel larger than taught by Ochoa resulted in substantially improves performance over its predecessors. However, this device was still limited by the use of the ball-type valve. 
     U.S. Pat. No. 5,456,302, issued to Demers on Oct. 10, 1995, discloses a tire bead seating apparatus that eliminates the use of discharge barrel and its corresponding valve. This results in the pulse of air having a substantially faster pressure rise time than is found with above-referenced devices. This device makes use of piston that is releasably sealed against the outlet of the portable tank such that the piston is held against the tank outlet by having an air pressure that is higher on the side away from the outlet than is found on the side adjacent to the outlet. Once the air is released on the side of the piston away from the outlet via a quick release valve, the piston moves away from the outlet of the tank, allowing the air inside the tank to be released. The air flows from the tank and is immediately discharged out the discharge nozzle. 
     This device is substantially more effective than previous attempts due to the substantial faster response time and the further reduction in airflow resistance. However, the design suffers from having a higher cost of manufacture than the Ochoa or BEAD SEATER devices. By having an integral nozzle, this device exhibits an appreciable kickback, especially if the tank is filled to a higher pressure such as 100 lbs/in 2 . Further, the device is particularly sensitive to even small leaks since the volume of air on side of the piston away from tank outlet is very small compared to the volume of air in the tank. Once a small amount of air leaks, the pressure differential across the piston can easily be lost, thus preventing the piston from releasing sufficiently quickly to produce the desired very fast pressure rise time of air that is necessary to efficiently seat the bead of the tire. 
     A device that is inexpensive to produce, relatively insensitive to leaks, substantially reduces or eliminates kickback, and still provides the extremely fast release of air from the reservoir tank is not found in the prior art. 
     SUMMARY OF THE INVENTION 
     It is an aspect of the invention to provide a tire bead seating apparatus that has the least restrictive passage-way for the air charge stored within a tank to proceed to the tire that is to be seated. 
     It is another aspect of the invention to provide a tire bead seating apparatus that can be activated without the use of a ball-type valve or gate valve and without the use of a conduit or discharge barrel. 
     It is another aspect of the invention to provide a tire bead seating apparatus that is adaptable to a wide range of truck tire sizes and manufacturers, including those having the most difficult tire beads to seat. 
     It is still another aspect of the invention to provide a tire bead seating apparatus which is portable and can be easily stowed. 
     Another aspect of the invention is to provide a tire bead seating apparatus that can be manufactured inexpensively from readily available parts. 
     Still another aspect of the invention is to provide a tire bead seating apparatus that is insensitive to leaks so that high tolerances between parts are unnecessary. 
     It is another aspect of the invention to provide a tire bead seating apparatus that substantially eliminates or reduces kickback by using a specially designed nozzle that corresponds to the air releasing assembly of the invention. 
     Finally, it is an aspect of the invention to provide a tire bead seating apparatus that can be activated by a push button so that the operator can easily activate the device with one hand. 
     The invention is an apparatus for seating the bead of a tubeless tire on rim. A charging reservoir having a predetermined cross-sectional area is provided. Said charging reservoir is also provided with a fill/quick-release port, an inlet and an outlet. An inflation tank having a predetermined volume and an inlet/outlet is provided, wherein the inlet/outlet of said inflation tank is connected to the inlet of said charging reservoir. Moveably disposed within said charging reservoir is a piston. When said charging reservoir and said inflation tank is pressurized with air via the fill/quick-release port of said charging reservoir, said piston is moveably urged against the outlet of said charging reservoir. Once in this position, the pressurized air in said charging reservoir and said inflation tank is substantially prevented from exiting the outlet of the charging reservoir. When the pressurized air within said charging reservoir is quickly released via the fill/quick-release port of said charging reservoir, said piston substantially instantaneously moves away from the outlet of said charging reservoir. Then, the pressurized air stored in said inflation tank is explosively released through the outlet of said charging reservoir. 
     A nozzle having an inlet and an outlet is provided. The inlet of said nozzle is connected to the outlet of said charging reservoir. The cross-sectional area of the outlet of said nozzle corresponds to the inlet of said nozzle as well as the outlet of charging reservoir. When the pressurized air from said inflation tank is released, the air passes into the inlet of said nozzle and exits the outlet of said nozzle so that the airflow is directed between the bead of the tire and the rim, thereby seating the tire on the rim. 
    
    
     The above and further objects and advantages of the present invention will become apparent from the description contained hereinafter in combination with the accompanying illustrative figures. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial cut-away side view of the apparatus for seating the bead of a tubeless tire in accordance with the invention. 
     FIG. 2 is a top view of the nozzle. 
     FIG. 3 is a front end view of the nozzle. 
     FIG. 4 is rear view of the charging reservoir head plate. 
     FIG. 5 is a top detailed view of the preferred embodiment of the charging reservoir head plate. 
     FIG. 6 is a side view of an alternative embodiment of the piston. 
     FIG. 7 is an end view of the charging reservoir flange. 
     FIG. 8 is a side view of an alternative embodiment for controlling the outlet. 
     FIG. 9 is a cross-sectional view of another alternative embodiment of the piston. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a partial cut-away side view of invention  10 . An inflation tank  12  is preferably a pressure vessel having a capacity of at least 1500 cubic inches and a capability of storing air at pressures of at least 125 lb/in. While ASME approved tanks should be used wherever possible, non-rated tanks which meet the specifications provided herein are also acceptable for use as inflation tank  12 . The actual size and pressure rating of inflation tank  12  will vary according to the size of the tire to be sealed and to the pressure of the air stored therein. The preferred size of tank  12  specified will enable the user to seat the beads of most standard truck tire sizes. 
     The parts and specifications cited for the preferred embodiment disclosed herein are dimensioned to accommodate typical truck tubeless tires. Substantially smaller tires could obviously be seated with the preferred size specified, however, dimensions and sizes of the parts could be reduced accordingly to meet smaller tire requirements. Substantially larger tires may also be seated with specified apparatus, however, the air pressure within the unit may have to be adjusted accordingly as long as safe limits were not exceeded. The dimensions and parts of the apparatus could be scaled upward to meet the requirements of tires substantially larger than typical truck tires if so desired. 
     Invention  10  is easily maneuvered and transported by a handle (not shown) attached to the exterior of inflation tank. Another handle  84  is attached to charging head plate  34  which is shown in detail in FIGS. 4 and 5. 
     Attached to inflation tank  12  is relief assembly  13 , including a pressure gauge  14  which is provided to display the internal air pressure of inflation tank  12 . A pressure relief valve (not shown) that is well known in the art, preferably rated 150 psi, is provided to prevent over-inflation and to release the excess pressure within inflation tank  12 . Relief assembly  14  is connected to inflation tank  12  via nipple  16 . Relief assembly  13  is shown for the sake of clarity opposite to fill/quick-release assembly  51 . However, relief assembly  14  is preferably placed on inflation tank  12  under fill/quick-release assembly  51  so that both structures may be protected from damage during use by handle  84 . 
     As shown in FIG. 1, fill/quick-release assembly  51  is attached to invention  10  by way of a threaded on end (TOE) nipple  52  which is connected to the charging head plate  34 . Nipple  52  is preferably ⅜ inch sized fitting. Attached to nipple  52  is quick release valve  50  such as manufactured by Deltrol of Bellwood, Ill., model EV 24 A2. However, any type of valve which permits the air to be very rapidly exhausted from charging reservoir  22  could be also be used. Further, the inventor has found that a ⅜ inch or larger ball-type of valve could be substituted for quick release valve  50 . However, the performance of invention  10  will be degraded somewhat due to the slower rise time found with this type of design as discussed above. 
     Exhaust port  54  is left open so that exiting air is not restricted when valve  50  is actuated. Attached to the other port of quick release valve  50  is a ⅜ inch by ¼ inch bushing  55 . Attached to bushing  55  is ¼ inch close nipple  53 . A “T”  48 , also ¼ inch, is then attached to nipple  53 . Attached to one port of“T”  48  is discharge trigger  49  such as sold by TRAMEC, part number 35000. Attached to the remaining port of“T”  48  is ¼ inch street elbow  60 . Note that elbow  60  is not shown turned at a 90 degree angle for the sake of clarity. Attached to elbow  60  is ¼ ball valve  46 . Assembly  51  is completed by attaching air coupler  44  to ball valve  46 . 
     FNPT Spud  76  is sized to accommodate nipple  18  and is welded to inflation tank  12  as shown. Inflation assembly  11  is then attached inflation tank  12  via 2 inch TOE nipple  18  which is screwed into spud  76 . The other end of nipple  18  is then welded to outlet section  87  of charging reservoir  22  via welds  20 . Nipple  18  is preferably about five inches long. 
     Inflation assembly  11  comprises charging reservoir  22 , outlet nipple  38 , and piston  36 . The wall thicknesses and materials for the parts described below are not critical provided the parts are able to withstand the pressures that will be experienced and meet government safety requirements. Also, the dimensions specified can be scaled upwardly or downwardly to correspond to the sizes of tires that are to be seated. 
     The end of outlet section  87  of charging reservoir  22  is closed off via end plate  57  which is fitted with an opening so that outlet nipple  38  is within the outlet section  87  of charging reservoir  22 . While outlet nipple  38  is shown substantially axially centered within end plate  57  and charging reservoir  22 , nipple  38  could also be offset within charging reservoir  22 . Nipple  38  is welded via welds  20  to end plate  57  and end plate  57  is, in turn, welded to one end of charging reservoir  22  to complete the closure at that end. Note that outlet nipple  38  is also positioned with the threaded end  40  outside of assembly  11  and so that end  42  of nipple  38  is about ¼ inch beyond the opening provided by nipple  18 . In this manner, when piston  36  is urged against end  42  of nipple  38 , piston  36  substantially closes off the control section  89  from the outlet section  87  of charging reservoir  22  thus positioning piston  36  away from the opening provided by nipple  18  which is connected to the outlet section  87 . 
     In order that a tight seal is provided when piston  36  is urged against end  42  of nipple  38 , end  42  is smoothed by any suitable method such as machining, sanding, etc. Both nipples  38  and  18  are preferably made of steel and about 5 inches long with a wall thickness of approximately {fraction (3/16)} inches. 
     Attached to threads  40  of nipple  38  is nozzle  66 . Referring now to FIGS. 2 and 3 as well as FIG. 1, nozzle  66  is shown in detail. The inventor has discovered that if invention  10  is discharged without nozzle  66  in position, then the apparatus exhibits substantial kickback as if the user were discharging a firearm. However, the use of nozzle  66  substantially reduces if not eliminates kickback so that the apparatus can held comfortably. 
     Nozzle  66  is preferably fabricated from sheet steel by folding and spot welding at welds  20 . A 2 inch half-coupling  64  with internal threads  40  is provided so that nozzle  66  can be screwed onto external threads  40  of nipple  38 . Nozzle  66  is designed so that discharge opening  70  has a cross-sectional area that is preferably greater than or equal to the cross-sectional area of nipple  38 . If discharge opening  70  is approximately ¾ inches wide and 6 inches long, this will meet that requirement. However, smaller sized openings for discharge opening  70  can be used as long as the decrease in performance is acceptable. However, the cross-sectional area of discharge opening  70  should always be greater than or equal to 70% of the cross-sectional area of the outlet opening  97  of charging reservoir  22 . 
     If the preferred dimensions are utilized, nozzle  66  will not present any impediment to the charge of air as it exits through opening. Nozzle  66  is completed by welding a u-shaped rim guide  68  to the top of nozzle  66  via welds  20 . Rim guide  68  serves to position discharge opening  70  between the bead of the tire and rim of the wheel so that bead of the tire can be seated. Also, since nozzle  66  is threaded onto is nipple  38 , nozzle  38  may be turned as desired by a user to facilitate seating the bead of tire when the tire is placed in different positions relative to the user. The other end of charging reservoir  22  is closed via flange  24  which is welded to that end of charging reservoir  22  via welds  20 . As shown in FIG. 7, flange  24  is provided with circumferential holes  26  which serve to bolt via bolts  28  and nuts  30 , head plate  34  onto charging reservoir  22 . Gasket  32  is placed between flange  24  and head plate  34  to seal against leaks. Eight holes  26  are shown, however, more or less could be used as long as charging reservoir  22  is reasonably sealed. 
     Note that small leaks at this juncture or any other place in the unit are not critical since pressurized air is meant to be stored in inflation tank  12  for only a short period of time, generally, minutes. As noted above, it is an aspect of the invention to be relatively insensitive to air leaks over the short time. Since the preferred embodiment of piston  36  permits air flow to leak past the piston  36  in either direction, any small amount of air which might leak from control area  89  will be replenished from outlet area  87  and storage tank  12 . In this manner, essentially the same pressure will be kept within the control area  89 , outlet area  87  and storage tank  12  so that the release performance of piston  36  will not be degraded over the short term. 
     In fact, it is preferable not to have invention  10  sealed too tightly, since the unit might be stored in a charged condition which is undesirable for safety considerations. Therefore, it is preferable to have one or more small leaks so that the unit will discharge completely within an hour or so, to prevent storage of the apparatus with a pressurized tank of air. 
     As shown in FIGS. 4 and 5, head plate  34  provides matching holes  26  so that head plate  34  may be bolted onto flange  24 . Ears  80  extend beyond head plate to serve to provide a point of attachment for handle  84 . Ears  80  are preferably fabricated as part of head plate  34  but ears  80  could also be attached separately. Flange  82  is bent upward from ears  80  which provides two holes through handle  84  may be bolted via bolts  86 . Only one bolt  86  on each side of ears  80  is fastened during shipping the apparatus so that handle  84  may be easily folded to fit within a smaller profile shipping carton. As noted above, once both bolts  86  are in place, handle  84  serves also to protect inflation assembly  11  and relief assembly  13  from being damaged during use. 
     Referring again to FIG. 1, charging reservoir  22  is preferably a piece of steel pipe about 5 ¼ inches long and 3 ¾ inches OD. This provides an ID measurement for charging reservoir  22  of about 3.510 inches. Corresponding to the dimension of charging reservoir  22 , piston  36  should be 3 ½ inches in diameter. This provides clearance  72  of approximately 10 thousandths. This clearance is sufficient to enable the pressurized air that is introduced via nipple  52  to charging reservoir  22  to fill inflation tank  12  and the outlet section  87  of charging reservoir  22  by leaking past piston  36  through clearance  72 . However, since this opening is so small compared to the two inch opening provided by nipple  18  when piston  36  moves away from end  42  of outlet nipple  38 , substantially all of the air in inflation tank  12  is released through outlet nipple  38  and only a very small amount back through clearance  72 . Of course, if piston  36  configured to permit air to flow in only one direction, no air would flow back into control section  89  once piston  36  is propelled away from end  42  of nipple  38 . 
     While charging reservoir  22 , nipple  38 , and piston  36  are shown as having a circular cross-section, this is not critical. Other shapes, such as square or rectangular, oval, etc. could be substituted. As shown in FIG. 8, the use of rectangular shape would enable the use of a control member  111  hinged on one side via hinge  112  rather than using a piston to close off the end  42  of outlet nipple  38 . Hinge  112  is preferable any of the various “piano-type” hinges, well known in the art. The use of gasket  90  and hole  94  as shown in FIG. 6 could also be used in this alternative embodiment. 
     However, a cylinder is the preferred shape since this type of structure is readily available on the market in various sizes and wall thicknesses and thus keeps the cost of manufacture minimized. 
     As shown in FIG. 6, other options exist for piston  36 . The inventor has found that a disk of DELRIN plastic approximately 3.500 inches in diameter and ¾ inches thick is preferable. The use of this material and size for piston  36  enables the apparatus to be constructed inexpensively without compromising performance. The alternative embodiment for piston  36  shown in FIG. 6 features an aluminum disk, again about ¾ inches thick so that piston  36  will not wobble or bind when piston  36  slides inside of charging reservoir  22 . 
     As noted above, air is able to leak past piston  36  in either direction using the preferred embodiment. However, piston  36  could also be configured as a one-way (check) valve by the addition of gasket  90  which is attached to piston  90  via flat washer  92  and bolt  88 . A plurality of holes  94  could also be provided in piston  36  to help facilitate airflow in direction  96  but not in the reverse path. 
     The inventor has discovered that the use of a piston cup, such as manufactured by McMaster Carr of New Brunswick, N.J. 08903, model no. 9411 K27, could be used in place of gasket  90 . A piston cup serves to make piston  36  function even more efficiently as a one-way valve in situations where such precision may be desirable. 
     The resistance of the airflow path from the inflation tank  12  into end  42  must be very small compared to the resistance through the clearance  72 . Therefore, piston  36  preferably must be permitted to slide far enough away from end  42  in control section  89  to provide a cross-sectional piston discharge area that is greater than or equal to cross-sectional area of end  42 . The inventor has discovered that stroke dimension  78  should be preferably ½ to 1 inch. The minimum stroke dimension  78  that will provide a piston discharge area greater than the cross-sectional area of end  42  of the nipple  38  is easily calculated by dividing the radius of end  42  of nipple  38  squared divided by the diameter of end  42  of nipple  38 . As before, if decreased performance is acceptable, then stroke dimension  78  can be reduced accordingly but should be sufficiently long so that the air passageway between piston  36  and end  42  is at least 70% of the cross-sectional open area of end  42 . 
     The inventor has discovered that an essential aspect for successful seating a bead of a tire using this type of apparatus is releasing the stored air as quickly as possible between the rim and the bead of the tire. Therefore, the airflow must not be subjected to unnecessary resistance which will restrict the flow along the path from the air storage tank to the tire. As shown in FIG. 6 of the inventor&#39;s U.S. Pat. No. 5,456,302, incorporated herein by reference, the faster the response curve, the more effective the apparatus will be in seating the bead of a tire. 
     As noted above, the preferable OD dimension for charging reservoir  22  is 3 ¾ inches steel cylinder having a wall thickness of approximately ⅛ inch. This provides an ID of approximately 3.510 inches. However, a smaller ID pipe for charging reservoir  22  could also be used. 
     A pipe having a two-inch diameter ID such as outlet nipple  38  has a cross-sectional area of approximately 3.14 square inches. Therefore, to prevent the air flow path from having an air flow resistance greater than that of nipple  38 , the cross-sectional area of the ID of charging reservoir  22  less the area occupied by the OD of nipple  38  is preferably greater than or equal to 3.14 square inches. Using the ID dimension of charging reservoir  22  and the OD dimension of nipple  38 , this yields a cross-sectional area of about 5.24 square inches between the inner wall of charging reservoir  22  and the outer wall of nipple  38 , that is, outlet section  87 . This is calculated by finding the cross-sectional area of the ID of charging reservoir  22 , which is 9.67 square inches and subtracting the cross-sectional area of OD of nipple  38  which is 4.43 square inches, thus yielding 5.24 square inches for outlet section  87 . 
     Clearly, the airflow through this section of the unit has a resistance that is substantially less than that provided by the opening  97  in nipple  38 . The ID of charging reservoir  22  could be reduced without detrimentally increasing the resistance of outlet section  87  of charging reservoir  22  as long as the cross-sectional area of charging reservoir  22  was not less than 7.57 square inches. This results in an ID of approximately 3 ⅛ inches for charging reservoir  22 . If reduced performance is acceptable, even smaller ID charging reservoirs could be used. However, the cross-sectional area of outlet section  87  should be at least 70% of the cross-sectional area of opening  97  of the charging reservoir  22 . 
     Also, note that the difference between the cross-sectional area of piston  36  and nipple  38  determines the force that holds piston  36  against end  42  of nipple  38 . For example, assume that invention  10  is charged with air at a pressure of 100 psi. The force against the control section  89  side of piston  36  is 100 times 9.62 square inches or approximately 960 pounds of force. The force pushing against the outlet section  89  side of piston  36  is 100 times 4.43 square inches (provided by area  75  which was shown above to be the cross-sectional area of the charging reservoir  22  less that cross-sectional area of the OD of nipple  38 ) plus 14.7 times 3.14 square inches (the cross-sectional area of the ID of outlet nipple  38  which is at atmospheric pressure) or approximately 489 pounds. Therefore, a net force (pressure differential) of approximately 470 pounds is forcing piston  36  against end  42  of nipple  38 . 
     This also explains why invention  10  provides such a fast response time. By rapidly reducing the pressure in control section  89  using quick-release valve  50 , the pressure on the outlet section  87  side still remains at approximately 489 pounds thus forcing piston  36  away from end  42 . As soon as piston  36  is just slightly away from end  42 , the force pushing piston  36  changes to 100 psi over the entire outlet section  87  side of piston  36  or approximately 960. Thus, piston  36  is propelled toward the head plate  34  of charging reservoir  22  permitting the air held within inflation tank  12  to exit explosively via outlet nipple  38  through nozzle  66  and out discharge port  70  (FIG.  3 ). 
     To use invention  10 , an air hose (not shown) is attached to air coupler  44  and ball valve  46  is opened. Air enters through nipple  52  into charging reservoir  22 . Air is entering faster in control section  89  than can leak through clearance  72 . Therefore, piston  36  is forced against end  42 . Air pressure continues to build up in charging reservoir  22  and continues to leak through clearance  72  causing outlet section  87  of charging reservoir  22  and inflation tank  12  to fill. Once pressure gauge  14  reaches the desired pressure, ball valve  46  is closed and outlet section  87 , control section  89  of charging reservoir  22 , and inflation tank  12  are substantially at the same pressure. Then, the nozzle  66  of invention  10  is positioned between the bead of a tire and the rim as shown in the referenced FIG. 5 of the &#39;302 patent. Trigger  49  is depressed which causes the air within the control section  89  of charging reservoir  22  to be released from port  54  of quick release valve  50 . Piston  36  is then violently propelled toward head plate flange  24 , explosively releasing the air in inflation tank  12  into outlet section  87  to exit through nipple  38  and, finally, through nozzle  66  to seat the bead of the tire onto the rim. 
     While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention and it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.