Abstract:
A suspension system that restricts side-to-side airflow between air springs on opposite sides of a vehicle or trailer. In one embodiment, active airflow discs in suspension ports of a valve operate in two modes; restrictive and non-restrictive. A disc attains a non-restrictive mode when air is exhausted from an air spring. A disc attains a restrictive mode when air is injected into the suspension port from the valve toward an air spring. Airflow discs in opposing suspension ports both attain a non-restrictive state to rapidly dump air from the springs and lower vehicle ride height. In another embodiment, a pneumatic circuit includes one-way check valves, in fluid communication with opposing air springs, aligned to restrict airflow between the opposing springs under uneven loading conditions. A pair of electronic solenoids acts in concert with the check valves to selectively inflate or deflate the air springs.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a leveling system for a vehicle, and more particularly to a valve body for distributing air to suspension elements. 
     Conventional leveling systems are installed in a wide variety of vehicles ranging from passenger cars to semi-trucks and semi-trailers. The larger leveling systems typically include pneumatic suspension elements, such as shocks or air springs, that can be inflated or deflated to control the height of the frame with respect to the axle. For example, on semi-trailers, heavy loads can cause a suspension to sag, thereby decreasing the distance between the frame and the axle. Accordingly, the ride height of the trailer, that is, the distance between the trailer bed and the ground, may be reduced. In conventional leveling systems, the ride height of the trailer may be adjusted by inflating or deflating the pneumatic suspension to compensate for the load. Specifically, when the ride height of a trailer has been affected by a heavy or light load, the suspension elements can be inflated or deflated to return the trailer to the desired ride height. 
     In leveling systems of the prior art, the height of the suspension is controlled by mechanical height control valves including a valve assembly and a valve body. The valve assembly senses the fluctuations in the ride height due to loading and controls the inflation/deflation of the suspension elements through the valve body. Typically, the valve body is located within the leveling circuit between a source of compressed air and the suspension elements. During operation, the valve body typically is in a neutral or “closed” mode. Accordingly, air cannot enter or leave the leveling circuit. However, due to fluid communication between suspension elements on opposite sides of the vehicle via the valve body, air may flow from a left side element to a right side element when the left side element is excessively loaded-this is called “side-to-side” air transfer. Obviously, air may flow from right to left when the right side is excessively loaded as well. 
     Illustrated in FIG. 1 is an uneven loading situation resulting in side-to-side air transfer. A vehicle  110  traversing a corner has a tendency to tilt or roll outward away from the “center” of the corner, due to centrifical force. During this tilting action, the right side elements  104  are excessively compressed by the load being shifted outward. Due to the fluid communication between the left  102  and right  104  side suspension elements, air is forced from right side suspension elements  104 , travels through the valve body  108 , and into the left side suspension elements  102 . As a consequence, the left side suspension elements  102  extend and exacerbate the tilt or roll of the vehicle. Further, given the advent of larger airflow lines used in conventional leveling circuits to promote quicker inflation/deflation of air suspension elements, side-to-side air transfer is substantially increased. 
     Illustrated in FIG. 2 is a valve body  115  of the prior art that attempts to correct side-to-side transfer of air by placing a passive restrictive element  112  within the valve body  115 . Although the use of the restrictive element does limit the side-to-side transfer of air A during cornering, it creates a variety of problems. First, the restrictive element restricts (a) dumping of air from the suspension elements, through the dump port  122  during deflation, and (b) injection of air into the valve body  115  via the supply port  126 , and consequently into the suspension elements, during inflation. Second, dirt or debris accidentally entering the interior portion of the valve body, may become lodged between the restrictive element and the valve body to substantially impede airflow through the valve body. Moreover, to remove the debris, the valve body must be detached from the valve assembly. 
     SUMMARY OF THE INVENTION 
     The aforementioned problems are overcome by the present invention wherein the valve body of a height control leveling system is provided with devices to actively restrict side-to-side transfer of air between suspension elements. 
     In one embodiment, a restrictive airflow disc is positioned in each of the two suspension ports of a valve body to actively restrict side-to-side air transfer. The airflow disc is a thin, flat circular plate with an orifice through its center, and bypass orifices disposed around the disc&#39;s circumference. A coil spring is attached to a first side of the disc, and a sealing element is disposed around the central orifice on a second side of the disc. In each of the suspension ports, the coil spring abuts an internal seat of the valve body and forces the sealing element in sealing engagement with a suspension fitting associated with the air supply line coupled to the suspension port. 
     The disc has two modes; restrictive and non-restrictive. The disc attains a non-restrictive mode when air, forcibly exhausted from an air spring, presses against the disc and compresses the coil spring. The compression of the spring causes the disc to move away from the suspension fitting, and disengages the sealing element from the suspension fitting, thereby allowing air to exhaust into the valve body through the bypass orifices as well as the central orifice. The disc attains a restrictive mode when air is injected into the suspension port from the valve body. The sealing engagement of the sealing element against the suspension fitting is reinforced so that air enters the suspension lines through the central orifice alone. Thus, when air is forced from a compressed suspension element during cornering to the valve body through a suspension port, the airflow disc associated with the suspension port connected to the compressed element attains a non-restrictive state; and air flows freely into the valve body. Conversely, when air passes through the valve body into the suspension port associated with the suspension element on the opposing, unloaded side of the vehicle, the airflow causes the airflow disc in that suspension port to substantially obstruct the suspension port, so that air cannot pass freely to the unloaded suspension port. Thus, at least for short periods of time, tilting or rolling is not exacerbated by side-to-side air transfer. 
     In another aspect of the invention, both airflow discs attain a nonrestrictive state to promote rapid dumping of air simultaneously from the suspension elements to lower the ride height of the vehicle. 
     In a third aspect of the present invention, the airflow discs are easily installed and maintained in conventional valve bodies. The airflow discs are disposed within the suspension ports between an internal seat of the valve body and an external fitting associated with an air supply line leading to the suspension elements. 
     In a second embodiment of the invention, a system or pneumatic circuit of solenoids and one-way valves actively restrict side-to-side air transfer. Suspension elements on opposite sides of a vehicle, a supply port and dump port are plumbed into a system including solenoids and multiple check valves. A first solenoid may be selectively actuated (a) to allow air into the suspension elements through the supply port or (b) to prevent air from escaping the system through the supply port. A second solenoid may be selectively actuated (a) to dump air from the suspension elements through the exhaust port or (b) to prevent air from escaping the system through the exhaust port. 
     In this second embodiment, the check valves are oriented in the system so that when suspension elements on one side of the vehicle exhaust air therefrom, such as during cornering, that air is restricted by the check valves and will not rapidly transfer through the system to the suspension elements on the other side. The solenoids act in concert with the check valves to restrict side-to-side transfer, and prevent air from being lost or input into the system during side-to-side transfer and under even-load conditions. 
     The check valves also act in concert with the solenoids to supply air to or dump air from the suspension elements. For example, when dumping air from the suspension elements, some of the check valves attain a non-restricting state and act in concert with the exhaust solenoid to allow air to dump from the system. Similarly, when supplying air to the suspension elements, different check valves attain a non-restricting state and act in concert with the supply solenoid to allow air to enter the system and fill the suspension elements. 
     These and other objects, advantages, and features of the invention will be readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a vehicle suspension system during cornering; 
     FIG. 2 is a sectional view of the prior art valve body with a restrictive body therein; 
     FIG. 3 is a plan view of the leveling system of the present invention; 
     FIG. 4 is a perspective view of the valve body; 
     FIG. 5 is a top plan view of an airflow disc of one embodiment; 
     FIG. 6 is a sectional view of the airflow disc taken along lines  6 — 6  of FIG. 5; 
     FIG. 7 is a sectional view of a valve body with airflow discs when suspension elements are in equilibrium; 
     FIG. 8 is a sectional view of the valve body with airflow discs when the suspension elements are unevenly loaded; 
     FIG. 9 is a sectional view of the valve body with airflow discs while inflating the suspension elements; 
     FIG. 10 is a sectional view of the valve body with airflow discs while dumping the suspension elements; 
     FIG. 11 is a top plan view of an alternative embodiment of the airflow disc; 
     FIG. 12 is a side of view of an alternative embodiment of the airflow disc; 
     FIG. 13 is a schematic view of a second alternative embodiment of the leveling system incorporating a system of one-way valves and solenoids; 
     FIG. 14 is a schematic view of a third alternative embodiment of the leveling system incorporating a system of one-way valves and solenoids; 
     FIG. 15 is a schematic view of a fourth alternative embodiment of the leveling system incorporating a system of one-way valves and solenoids; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A valve body according to a first embodiment of the present invention is illustrated in FIGS. 3,  4  and  7 - 10  and generally designated  10 . For purposes of disclosure, the valve body  10  is described in connection with a conventional leveling system where the valve mechanism  30  couples to valve body  10  where the valve mechanism functions to control the flow of air into and out of the suspension elements  42 ,  44  through valve body  10  (see FIG.  3 ). The valve body is well suited for use in a variety of other leveling systems besides suspension, such as conventional truck cab leveling systems designed to level the truck cab with respect to the truck frame. 
     The leveling system of the present invention generally includes valve body  10  coupled to a valve mechanism  30  including an actuator yoke  33 . The valve mechanism  30  is mounted to the vehicle frame  40  in a conventional manner and connected to the axle  46  or any other part suspension via actuator yoke  33 . The actuator yoke  33  may be mounted to virtually any element that moves with the axle or to any portion of a suspension. Also, the valve mechanism  30  may be installed in reverse with a valve body secured to the axle (or other suspension-related element). In other applications, such as a truck cab leveling system, the height control valve mechanism is mounted between the two components for which relative movement is to be controlled. 
     With reference to FIGS. 4 and 7, part of the valve mechanism  30  (not shown) extends into the internal bore  12  of valve body  10 . As will be appreciated by those skilled in the art, the valve mechanism controls the supply of air through the supply port  24  into the suspension ports  16  and  18  as well as exhaust and dumping of air from the suspension ports  16  and  18  through dumping port  20  and exhaust port  22 . For the sake of simplicity, the valve mechanism within the internal bore  12  responsible for controlling the supply, dumping and exhaust of air through the valve body  10  has been omitted in FIGS. 7-10. To indicate open and closed valves associated with the supply port and exhaust port, “Valve Open” and “Valve Closed” is indicated in FIGS. 7-10. As will be appreciated by those skilled in the art, the actual opening and closing of valves associated with these ports is controlled by the omitted valve mechanism. 
     As depicted in FIGS. 3 and 7, the valve body  10  includes suspension ports  16  and  18  which are connected to the suspension elements  42  and  44  via air lines  32  and  34 . Conventional suspension fittings or air line fittings  17  and  19  are used suspension ports  16  and  18 . As will be appreciated by those skilled in the art, fittings may include threaded fittings, snap-fit fittings, permanently connected fittings, and other types of fittings. The fittings  17  and  19  are further connected to the air line  32  and  34 , respectively, as depicted in FIG.  3 . Accordingly, suspension elements  44  and  42  are in fluid communication with one another through the valve body  10 . Screens  26  and  27  may optionally be positioned in each of the suspension ports to prevent debris from entering the internal bore  12  of the valve body. These screens may be of any type or material as will be appreciated by those skilled in the art. Each of the suspension ports  16  and  18  include internal seats  14  and  15 . As depicted in FIGS. 7-10, the internal seats are generally reductions in the diameter of the bore of each suspension port  16  and  18 ; however, “internal seat” also includes any type of protrusion into the bore of the suspension port. The valve body  10  is made out of plastic so that it is resistant to corrosion. The valve body also may be made of metal or alloys as desired. The valve body of the present invention may be used in conjunction with multiple suspension elements associated with multiple axles of a vehicle as will be appreciated by those skilled in the art. The spring elements  60 ,  80  of the airflow disc,  50 ,  70  seat against the internal seats  14  and  15  of the valve body  10 . On the opposite faces of the disc plates  51 ,  71 , sealing elements  54 ,  74  seal the airflow discs  50 ,  70  against the fittings  19  and  17 . 
     As depicted in FIGS. 5 and 6, a first embodiment of the airflow disc includes disc plate  51  and an orifice  52  defined by the approximate center of the disc plate  51 . The orifice is any hole of any size or shape, depending on the desired air flow defined by the plate  51 . Disposed concentrically around the orifice  52  is sealing element  54 . A “sealing element” includes washers, o-rings, gaskets, integrated seals, or any other seals, made from rubber, plastic, silicone, cork, or any other suitable material. Around the periphery of the disc plate  51  are bypass orifices  56 . These orifices may be of any number or size or configuration depending on the desired flow of air that is bypassed. On the side of the disc plate  51  opposite the sealing element  54  and contained by the spring guide flange  58  is spring element  60 . The spring element may be a helical coil as depicted in FIG. 6, or any other configuration, including that depicted in FIGS. 11 and 12 of a second embodiment for an airflow disc where the spring elements are leaf prongs  160  disposed around the outer circumference of the airflow disc plate  151 . Depending on the desired airflow, the spring element  60  of the preferred embodiment may be of a predetermined elasticity. The airflow disc  50  and all components thereof are preferably manufactured using corrosion resistant materials such as engineered polymers or elastomers. 
     Operation 
     The operation of the valve body of the present invention to prevent side-to-side air transfer while still providing rapid deflation of the suspension elements will now be described. 
     FIG. 7 illustrates the valve body of the preferred embodiment when the suspension elements are evenly loaded and thus in equilibrium. The airflow discs  50  and  70  are disposed in each of the suspension ports  18  and  16  so that the sealing elements  54 ,  74  abut against the fittings  19  and  17  within the suspension ports. The sealing elements  54 ,  74  abut the fittings  19  and  17  to provide sealing engagement between the fittings  19  and  17  and the airflow disc plates  51  and  71  respectively. The spring elements  60 ,  80  bias the disc plates  51  and  71  to reinforce sealing engagement of the sealing elements  54 ,  74  between the disc plates  51  and  71  and fittings  19  and  17 . Because valves associated with the supply port  24  and exhaust port  22  are closed, the system is in equilibrium. Accordingly, air is not transferred through the suspension ports  16  and/or  18  into or out from the internal bore  12 , the airflow discs  50  and  70  remain abutting fittings  19  and  17 . 
     FIG. 8 illustrates the airflow discs actively restricting side-to-side air transfer. As discussed above, and illustrated in FIG. 1, when a vehicle traverses a corner, the vehicle will tilt and, accordingly, unevenly load suspension elements on opposite sides of the vehicle. For example, the suspension element on the outside of a corner will be compressed thus exhausting the air from that suspension element through the suspension port the valve body. When air, depicted in FIG. 8 as A, flows through the fitting  19 , it forcefully pushes against the disc plate  51 . The spring element  60  thus is compressed and the disc plate  51  is forced away from the fitting  19  whereby air A flows through the central orifice  52 , as well as around the bypass orifices  56  into the internal bore  12 . Accordingly, the flow of air from the suspension port is increased over that which it would be if air flowed through the central orifice alone. 
     Because the dump port  20 , supply port  24  and exhaust port  22  are closed, air cannot escape the internal bore  12  via the exhaust port  22  or the supply port  24 . Thus, the internal pressure of the internal bore  12  raises and forces the airflow toward the opposing suspension port  16 . As the air contacts the airflow disc in the left side suspension port  16 , the air forces the airflow disc  71  against the fitting  17  in the suspension port  16 . Accordingly, the sealing element  74  is pushed in further sealing engagement against the fitting  17 . Consequently, the air within the internal bore  12  may only pass through central orifice  72  of the disc plate  71 ; no air flows around bypass orifices  76 . Notably, after extended periods of time, air passes through the central orifice and the suspension element on the “unloaded” side of the vehicle eventually fills with air. 
     The valve body of the present invention also provides for inflation of suspension elements on opposing sides of the vehicle to raise the ride height of the vehicle. As depicted in FIG. 9, air A from an air supply (not shown), is forced under pressure into supply port  24 , as will be appreciated by those skilled in the art. The air enters the internal bore  12  of the valve body  10 . Because the valve (not shown) associated with exhaust port  22  is closed, air is prevented from escaping internal bore  12  therethrough. Once air enters into the internal bore  12 , it is dispensed into the suspension ports  16  and  18 . Because of the increased internal pressure, the air pushes the airflow discs  50  and  70  into sealing engagement with the fittings  17  and  19 . Accordingly, air enters the fittings  17 ,  19 , that are in fluid communication with the suspension elements on opposing sides of the vehicle (not shown) through internal orifices  52  and  72 . 
     The valve body of the present invention also provides for rapid dumping of air from opposing suspension elements of a vehicle to lower the ride height of the vehicle. FIG. 10 depicts the valve body and associated airflow discs  50  and  70  while simultaneously dumping air from suspension elements on opposing sides of a vehicle. To initiate dumping, the dump port  20  is pressurized by actuation of the valve mechanism within the internal bore  12 , as will be appreciated by those skilled in the art. The supply port  24  and dump port  20  remain closed during dumping. Once the valve (not shown) is opened, air exits the suspension elements through the suspension ports  16  and  18 . Air exiting through the fittings  17  and  19  forcibly pushes against the disc plates  51  and  71 . Accordingly, the airflow discs  50  and  70  are pushed inward, thus compressing spring elements  60  and  80  simultaneously. With the spring elements compressed, the air from the suspension ports  16  and  18  may flow through bypass orifices  56  and  76  freely into the internal bore  12  and out through the exhaust port  22 . In this manner, the air flow is substantially unrestricted so that the air may be dumped from the suspension elements rapidly. 
     Alternative Embodiments 
     The airflow discs of the present invention may be used in conjunction with a dual suspension port valve body and alternatively with a single suspension port valve body. In the single suspension port application, a modification of the preferred embodiment is required. A T-type connector is attached to the single suspension port to provide fluid communication between that suspension port and suspension elements on opposite sides of the vehicle. For example, one part of the T connects to the single suspension port of the valve body, one part of the T connects to the left side suspension elements, and the third and last part of the T connects to the right side suspension ports. Like the preferred embodiment, airflow discs are disposed opposedly within the T-connector ports associated with the suspension elements in a fashion similar to that in the first embodiment side-to-side air transfer is restricted in the same manner as in the first embodiment. 
     In a second, third and fourth embodiments of the present invention, a system or pneumatic circuit of one-way valves and solenoids restrict side-to-side transfer of air between opposing suspension elements and additionally allows adequate supply and dumping of air from those elements. Generally, in these three embodiments, depicted in FIGS. 13-15, right side suspension element  242  and left side element  244  are in fluid communication with conventional air supply reservoir  200  and conventional dump port  222  via: valve system  210  in the first alternative embodiment depicted in FIG. 13; valve system  310  of the second alternative embodiment depicted in FIG. 14; and valve system  410  of the third alternative embodiment depicted in FIG.  15 . Although only two suspension elements are depicted, any number of suspension elements on opposite sides of a vehicle or trailer may be plumbed into the system. The air reservoir  200  may be plumbed into any air supply device, such as a compressor. The dump port may be any commercially available air outlet, which may or may not be restricted. 
     More particularly, with reference to the second alternative embodiment of FIG. 13, suspension elements  242  and  244  are in fluid communication with valve system  210  via suspension lines  232  and  234 . Suspension line  232  provides fluid communication between suspension element  242 , preferably a right side suspension element or elements, and intermediate dump line  236  and intermediate supply line  238 . 
     Intermediate right dump line  236  includes one-way valve  224 , which preferably is a check valve, but may be any one-way valve that restricts or prevents flow in one direction and allows free flow in an opposite direction. As used herein “prevent,” when used with reference to a one-way valve preventing fluid or air flow, means to stop air from passing by the one-way valve to the extent it is feasible with conventional valves. In some cases, such as with a ball-bearing check valve, a minute amount of air may flow between the bearing and the internal surface of the valve, even when the bearing is in its restricting state. In this case, the valve is still considered prevented by the valve. One-way valve  224  is oriented to allow air to flow unrestricted from intermediate right dump line  236  to dump solenoid line  223 , but restrict or prevent air from flowing from the dump solenoid line  223  back into intermediate right dump line  236 . Preferably, the one-way valves used herein restrict airflow sufficiently so that no air passes through those valves. 
     Intermediate right supply line  238  includes one-way valve  254 , which preferably is a check valve, but may be any one-way valve that restricts or prevents flow in one direction and allows relatively free flow in an opposite direction. One-way valve  254  is oriented to allow air to flow unrestricted from solenoid line  233  to intermediate right supply line  238  but restrict or prevent air from flowing from the intermediate right supply line back into right solenoid supply line  238 . 
     As can be seen in FIG. 13, suspension line  234  provides fluid communication between suspension element  244 , preferably a left side suspension element or elements, and intermediate left dump line  246  and intermediate left supply line  248 . Intermediate left dump line  246  includes one-way valve  225 , which preferably is a check valve, but may be any one-way valve that restricts or prevents flow in one direction and allows relatively free flow in an opposite direction. One-way valve  225  is oriented to allow air to flow unrestricted from intermediate left dump line  246  to dump solenoid line  223 , but restricts or prevents air from flowing from the dump solenoid line  223  back into intermediate left dump line  246 . 
     Dump solenoid line  223  is in fluid communication with intermediate left and right dump lines  236  and  246 , and dump solenoid  220 . The dump solenoid is preferably an electronic solenoid that may be actuated by an operator, such as a computer or human operator, to selectively allow air to pass freely from solenoid dump line  223  to dump line  221  and out dump port  222 . Air flowing from the suspension elements through the valve system out the dump port, is referred to as “dumping” or “deflating.” As will be appreciated, any type of electronic or selectively actuatable valves may be substituted for the solenoids of the present invention. 
     Intermediate left supply line  248  includes one-way valve  255 , which preferably is a check valve, but may be any one-way valve that restricts or prevents flow in one direction and allows relatively free flow in an opposite direction. One-way valve  255  is oriented to allow air to flow unrestricted from supply solenoid line  233  to intermediate right supply line  248  but restrict or prevent air from flowing from the intermediate right supply line  248  into solenoid supply line  233 . 
     Supply solenoid line  233  is in fluid communication with intermediate left and right supply lines  238  and  248 , and supply solenoid  230 . The supply solenoid is preferably an electronic solenoid that may be actuated by an operator, such as a computer or human operator, to selectively allow air to pass freely from air supply line  231  through the solenoid  230 , through the solenoid supply line  233  and into right and left intermediate supply lines  238  and  248  respectively. Air flowing into the suspension elements through the valve system is referred to as “filling” or “inflating.” 
     With reference to FIG. 13, the left  244  and right  242  suspension elements are preferably in restricted fluid communication via a relief system, several options of which are shown in dotted lines. This relief system allows air to exhaust air from one side of suspension elements to the other should the suspension elements of one side become excessively loaded. The use of one of this relief systems prevents damage, and in some cases rupture of excessively loaded suspension elements by transferring air from those elements to others. Preferably, the relief system includes a line including an orifice of a pre-selected diameter therein to selectively restrict flow of air through the line. Any type of restricting device may be used. Optionally, the lines may themselves be of a pre-selected diameter to restrict flow. 
     In a first option, an orifice line  240  provides fluid communication between suspension lines  232  and  234 . In a second option, bypass dump-side orifice lines  245  and  247  bypass one-way valves  224  and  225  to allow restricted fluid communication between intermediate right  236  and left  246  dump lines, and consequently restricted fluid communication between suspension lines  232  and  234 . In a third option, bypass supply-side orifice lines  241  and  243  bypass one-way valves  254  and  255  to allow restricted fluid communication between intermediate right  238  and left  248  supply lines, and consequently restricted fluid communication between suspension lines  232  and  234 . Preferably, the orifices of the orifice lines of the present invention include internal diameters that are about 0.001 to about 0.25 inches, more preferably about 0.01 to about 0.09 inches, and most preferably about 0.030 inches. Optionally, the orifices may be of any dimension or shape with an area of 0.00001 square inches to 0.25 square inches. 
     In operation, the second alternative embodiment: (1) prevents completely unrestricted side-to-side air transfer in suspension elements of a vehicle or trailer; for example, from element  242  to element  244  or vice versa; (2) rapidly fills the suspension elements to increase ride height; and (3) rapidly dumps air from the suspension elements to lower ride height. Under normal conditions, when the suspension elements and are under equal loads, the system is static, that is, fluid is neither being input into the system or exiting from the system. 
     During cornering, one side of the vehicle is under a greater load due to tilt of the vehicle. Accordingly, one set of suspension elements is loaded more and naturally attempts to expel air therefrom. For example, during a hard left turn, right suspension element  242  is subjected to a loading force, and compensates by expelling air therefrom. With reference to FIG. 13, if suspension element  242  expels air into suspension line  232 , that air travels unrestricted into two other lines; intermediate right dump line  236  and intermediate right supply line  238 . Preferably, dump solenoid  220  and supply solenoid  230  are not actuated and thus closed during operation of the vehicle to prevent air from being dumped or input into the valve system. With the configuration of the one-way valves in these two lines, air cannot be transferred directly, that is, unrestricted, through the intermediate right dump line  236  to the intermediate right supply line  238  or any other line associated with the left side suspension elements. Thus, side-to-side air transfer is restricted. Similar restriction of side-to-side transfer occurs when the vehicle corners to the right and air attempts to rapidly expel from the left suspension elements  244 . 
     Notably, a small amount of air is transferred in restricted flow from the right suspension line  232  to the left suspension line via orifice line  240 , bypass dump-side orifice lines  245  and  247 , and/or bypass supply-side orifice lines  241  and  243 , depending on which of these options is implemented in the valve system  210 . Because these orifice lines are so restricting, a substantial amount of air cannot rapidly pass from the right suspension elements to the left suspension elements and exacerbate tilt or roll of the vehicle. 
     To inflate the suspension elements with air, for example to increase the ride height of the vehicle, supply solenoid  230  is activated, and consequently air passes from reservoir  200 , through supply line  231  and into solenoid supply line  233 . Because one-way valves  254  and  255  do not restrict or prevent flow in a direction from the supply solenoid  230  to the intermediate right and left supply lines  238  and  248  respectively, air freely flows into these lines, and consequently inflates suspension elements  242  and  244 . During this supply of air into the suspension elements, the dump solenoid remains closed. Therefore, air does not flow out of the system through exhaust line  221 . 
     To dump air from the suspension elements, dump solenoid  220  is activated, and consequently air passes through the dump solenoid line  223 , the dump solenoid  220 , dump line  221  and out dump port  222 . Because one-way valves  224  and  225  do not restrict flow in a direction from the intermediate left and right dump lines  236  and  246  to the solenoid dump line  223 , air freely flows out through the dump port  222 . During this dumping of air from the suspension elements, the supply solenoid  230  remains closed. Therefore, air does not flow into or out of the system through supply line  231 . 
     In the third alternative embodiment of the present invention, a valve system similar to the second embodiment is implemented. With reference to FIG. 14, the valve system  310  of the third embodiment has substantially all of the same elements as the second embodiment of FIG. 13, except the set of one-way valves associated with the intermediate left and right dump lines  236  and  246  is replaced by a shuttle valve as depicted. As will be appreciated, any valve may be substituted for the shuttle valve that prevents or restricts fluid communication between right intermediate dump line  236  and left intermediate dump line  246 . Preferably, some sort of relief system such as orifice line  240  or supply-side orifice bypass lines  241  and  243  are implemented in this embodiment. As will be appreciated, the restriction of side-to-side transfer of air to/from suspension elements, the filling of suspension elements, and the dumping of suspension elements all operate in a manner similar to the operation described in reference to the second alternative embodiment and explained with reference to FIG.  13 . 
     In the fourth alternative embodiment of the present invention, a valve system somewhat similar to the second embodiment is implemented. With reference to FIG. 15, the valve system  410  of the fourth alternative embodiment includes dump solenoid  220 , related dump line  221  and supply solenoid  230 , with related supply line  231 , as in the valve system  210  of the second embodiment. But unlike the second embodiment, dump solenoid line  423  is in fluid communication with supply solenoid line  433 . These lines are further in fluid communication with right suspension line  232  and left suspension line  234 . Additionally, right suspension line  232  includes one-way valve  454 , which preferably is a check valve, but may be any one-way valve that restricts or prevents flow in one direction and allows relatively free flow in an opposite direction. One-way valve  454  is oriented to allow air to flow unrestricted from right suspension line  232  to supply solenoid line  433  but restrict or prevent air from flowing from the solenoid supply line  433  into right suspension line  232 . Similarly, left suspension line  234  includes one-way valve  455 , which preferably is a check valve, but may be any one-way valve that restricts or prevents flow in one direction and allows relatively free flow in an opposite direction. One-way valve  455  is oriented to allow air to flow unrestricted from left suspension line  234  into supply solenoid line  433  but restrict or prevent air from flowing from solenoid supply line  433  into the left suspension line  234 . 
     Right and left suspension lines preferably also include orifice bypass lines  441  and  443  to allow restricted fluid communication between intermediate right  232  and left  234  supply lines, and consequently fluid communication between suspension lines  232  and  234 . However, these bypass orifice lines are somewhat larger than the orifice lines used in the second and third embodiments described above. Preferably, the orifice bypass lines have internal diameters of about 0.005 to about 0.4 inches, more preferably about 0.02 to about 0.1 inches, and most preferably about 0.050 inches. These bypass orifice lines are larger than the orifice lines of the previous embodiments because they are used also to fill the suspension elements with air and increase the ride height of the vehicle. 
     In operation, the fourth embodiment: (1) prevents completely unrestricted side-to-side air transfer in suspension elements of a vehicle, for example, from element  242  to element  244  or vice versa; (2) fills the suspension elements at a rate somewhat less than the rate of the previously described embodiments to increase ride height; and (3) rapidly dumps air from the suspension elements to lower ride height. Under normal conditions, when the suspension elements and are under equal loads, the system is static. 
     During cornering, for example, taking a hard left turn, right suspension element  242  would be subjected to a tremendous force, and would try to compensate by expelling air therefrom. With reference to FIG. 15, if suspension element  242  expels air into suspension line  232 , that air travels unrestricted through one-way valve  454 . Thereafter, the air cannot go through one-way valve  455  and enter left side suspension line  234 , because that valve is forced closed to prevent air flow therethrough. The air does not flow through supply solenoid line  433  or dump solenoid line  423  because the solenoids  220  and  230  are not activated, and therefore prevent air from passing through them. However, air may optionally pass to the left side suspension element in a restricted flow through bypass orifice line  443 . 
     Although bypass orifice line  443  substantially restricts flow, during extended periods when the right side suspension elements are excessively loaded relative to the left side elements, the air from those right side elements will slowly flow into the left side elements. But, for periods of brief, excessive, uneven loading, such as during cornering, typically encountered under normal driving conditions, this fourth embodiment adequately restricts side-to-side air transfer. Of course, the system would react in a similar manner under right cornering situations when the left side elements are excessively loaded. 
     To fill the suspension elements with air, supply solenoid  230  is activated, and consequently air passes from reservoir  200  and through supply line  433 . From there, the air passes, in a restricted flow, through bypass orifice lines  441  and  443  into suspension lines  232  and  234  to ultimately fill right  232  and left  244  suspension elements. During this supply of air into the suspension elements, the dump solenoid remains closed. Therefore, air does not flow out of the system through exhaust line  221 . 
     To dump air from the suspension elements, dump solenoid  220  is activated, and consequently air passes through the dump solenoid line  423 , the dump solenoid  220 , dump line  221  and out dump port  222 . Because one-way valves  454  and  455  do not restrict flow in a direction from the suspension lines  232  and  234  respectively, air freely flows out through the dump port  222 . During this dumping of air from the suspension elements, the supply solenoid  230  remains closed. Therefore, air does not flow into or out of the system through supply line  231 . 
     The above descriptions are those of the preferred embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. Any references to claim elements in the singular, for example, using the articles “a,” “an,” “the,” or “said,” is not to be construed as limiting the element to the singular.