Abstract:
A cargo dolly having a suspension assembly incorporated therein, wherein the suspension assembly is adapted to maintain the dolly at a prescribed height relative to an underlying surface. Thus, as cargo is loaded onto the dolly, and subsequently unloaded from the dolly, the dolly will substantially remain at the same height, which facilitates use of the dolly with standardized loading docks, such as loading docks associated with aircraft.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority to U.S. Provisional Patent Application Ser. No. 62/097,817, entitled CART SUSPENSION SYSTEM, filed on Dec. 30, 2014, all of the teachings of which are incorporated herein by reference. 
     
    
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT 
       [0002]    Not Applicable 
       BACKGROUND 
       [0003]    The present disclosure is generally directed toward a suspension system, and more specifically to a suspension system for a cargo dolly adapted to maintain a loading deck of the cargo dolly at a prescribed height as cargo is loaded onto the dolly, and subsequently, unloaded from the dolly. 
         [0004]    The transport of perishable cargo by aircraft is well-known in the art. In this regard, such perishable cargo, which can encompass any type of product that must be maintained in a temperature-controlled environment, can only be efficiently and timely delivered by aircraft in many parts of the world. In fact, shipping via air may be the only viable option of transporting many types of perishable goods. Exemplary of such type of goods include fresh produce, seafood, meat products, blood and a variety of other temperature-sensitive medications, such as vaccines and the like. Perishable cargo will also encompass many other types of products well-known to those skilled in the art. 
         [0005]    While in some cases, the duration that perishable cargo must go without being refrigerated (or heated) is of so short duration as to not affect the cargo, in many other instances perishable cargo will go for sufficient lengths of time from when delivered in a refrigerated condition at the airport to when the cargo is actually loaded on a plane. In this latter scenario, failure to continue providing adequate environmental control will cause the cargo to start spoiling, completely spoil, or otherwise become unusable for its intended purpose. Such phenomena occur very frequently with respect to food items and other heat sensitive materials such as blood and other biological/pharmaceutical products. The frequency that such damage occurs is also substantially high in areas having extremely hot climates as occurs in major cities in the states of Arizona, Nevada, New Mexico, and Texas during the summer months. Numerous other cities throughout the world likewise experience such extreme temperatures. 
         [0006]    In practice, perishable cargo is typically containerized at refrigerated terminals and held in refrigeration until the same is transported to airlines, typically via refrigerated roller floor trucks, prior to flight time. As soon as such trucks are unloaded at the designated terminal at the airport, airline containers containing perishable cargo are first weighed and then placed into open container transport dollies for transport to the aircraft. At such point in the shipping process, however, the perishable cargo is no longer maintained in a temperature-controlled environment. As is well-known to those skilled in the art, such point in the transport of such cargo is referred to as a breaking in the “cool chain” where the perishable cargo is vulnerable to the temperatures of the external environment. During such time, the airline containers containing such perishable cargo will sit upon such open transport dollies, in some cases for up to four or more hours, and often times will be exposed to direct sunlight and extreme temperatures before ultimately being loaded into an aircraft for departure. 
         [0007]    Such interval makes the perishable cargo especially vulnerable and it is during such time that substantial damage can occur by virtue of being exposed to a non-temperature controlled environment. In this regard, from the time that the temperature-controlled cargo is delivered to the airport and ultimately loaded on a plane, where the cargo is kept out of direct sunlight and at least protected to some extent by air conditioning, presents a significant risk that often times causes irreparable damage to the cargo resulting in substantial financial losses and property destruction. 
         [0008]    These same issues also arise with respect to perishable air cargo being unloaded from aircraft. As discussed above, such interval from when the perishable cargo is unloaded from the aircraft to the time from when the same is ultimately stored in a temperature-controlled environment places such perishable cargo at substantial risk. 
         [0009]    In addition to the foregoing problems associated with the potential spoilage of perishable air cargo resulting from a break in the “cool chain” is the additional vulnerability that such cargo can be tampered with, damaged, lost or even stolen. In this regard, many complications can and often do arise with respect to the transport of cargo to and from storage facilities to aircraft that, given the open nature by which perishable/high value cargo is transported, present numerous opportunities where such unfortunate events can occur. Indeed, the risk for perishable/high value cargo to become lost, damaged or stolen is exceptionally high at major airports that are very large and encounter heavy volumes of air traffic. 
         [0010]    In fact, such vulnerability may even be deemed to pose a potential threat to safety and even national security. With respect to the former, it is well-known that the importation of numerous types of perishable cargo, and in particular agricultural products, can (or must) be inspected to insure that the same is not contaminated, whether by parasites, insects or any other type of contamination. In addition or, alternatively, the open nature by which air cargo is typically transported presents an opportunity that the same will go unchecked and thus exposes a vulnerability that the cargo can be detrimentally manipulated. 
         [0011]    In view of the foregoing, Tofco Industries, Inc., Assignee of the present application, has developed a temperature controlled cargo transport dolly for use in transporting perishable/high value cargo to and from an aircraft. Exemplary of such apparatus is disclosed in U.S. Pat. No. 7,043,932, entitled Temperature Controlled Air Cargo Container Transport Dolly, the contents of which are expressly incorporated herein by reference. The temperature controlled cargo transport dolly includes a housing having an enclosure, and a temperature control unit attached to the housing and adapted to control the temperature within the enclosure. 
         [0012]    Although the previously designed temperature controlled cargo transport dolly addressed many of the then-existing deficiencies associated with conventional transport containers or dollies by incorporating a temperature control unit into the dolly, there are certain limitations associated therewith. For instance, the dolly is generally operated at slow speeds to mitigate shock-related damage to the temperature control unit, as well as to the cargo being transported within the dolly. Along these lines, previous temperature controlled transport dollies typically do not include suspensions because a conventional suspension would result in a varying height of the dolly cargo deck, e.g., a heavier load would cause the deck to lower, while a lighter load would cause the deck to rise. In many instances, the dollies are used with loading docks that have a universal height requirement, such as around 20.5 inches in the air cargo industry. Thus, a dolly having a variable deck height would be difficult to use with a fixed, universal loading dock height. 
         [0013]    Therefore, there is a substantial need in the art for temperature controlled cargo dolly having suspension capabilities, while at the same time being capable of maintaining a prescribed height of a dolly loading deck. Various aspects of the present disclosure address this particular need, as will be discussed in more detail below. 
       BRIEF SUMMARY 
       [0014]    According to various aspects of the present disclosure, there is provided a cargo dolly having a suspension assembly incorporated therein, wherein the suspension assembly is adapted to maintain the dolly at a prescribed height relative to an underlying surface. Thus, as cargo is loaded onto the dolly, and subsequently unloaded from the dolly, the dolly will substantially remain at the same height, which facilitates use of the dolly with standardized loading docks, such as loading docks/K Loaders associated with aircraft. 
         [0015]    According to one embodiment, the dolly includes a chassis, a tow bar coupled to the chassis, and a deck coupled to the chassis and having a deck surface spaced from a ground plane by a first distance. At least two front wheels are coupled to the chassis and are rotatable about respective front wheel axes, with the at least two front wheels being adapted to roll on the ground plane. At least two rear wheels are coupled to the chassis and are rotatable about respective rear wheel axes, with the at least two rear wheels being in spaced relation to the at least two front wheels and adapted to roll on the ground plane. At least two front suspension assemblies connect respective ones of the at least two front wheels to the chassis, with each front suspension assembly being adapted to enable movement of a corresponding front wheel axis relative to the chassis. At least two rear suspension assemblies connect respective ones of the at least two rear wheels to the chassis, each rear suspension assembly being adapted to enable movement a corresponding rear wheel axis relative to the chassis. A front leveler is operatively coupled to the at least two front suspension assemblies and is adapted to individually adjust the at least two front suspension assemblies for moving the corresponding front wheel axes relative to the chassis. A rear leveler is operatively coupled to the at least two rear suspension assemblies and is adapted to individually adjust the at least two rear suspension assemblies for moving the corresponding rear wheel axes relative to the chassis. The front leveler and the rear leveler are collectively configured to adjust the respective at least two front suspension assemblies and at least two rear suspension assemblies to maintain the deck and at a prescribed distance relative to the ground plane. 
         [0016]    Each of the at least two front wheels may be capable of swiveling about respective swivel axes extending generally perpendicular to the ground plane. The front wheels may be capable of swiveling 360 degrees, and thus, may function as a caster under a respective front suspension assembly. 
         [0017]    The front leveler and the rear leveler may be collectively configured to maintain the first distance between 18 and 23 inches. The front leveler and the rear leveler may be further collectively configured to adjust the respective at least two front suspension assemblies and at least two rear suspension assemblies to maintain the deck substantially parallel to the ground plane. 
         [0018]    Each front leveler may include at least one inflatable body operatively coupled to a respective one of the at least two front suspension assemblies, with the at least one inflatable body being selectively transitional between an inflated configuration and an deflated configuration, wherein transition from the deflated configuration toward the inflated configuration enables the suspension to counteract an increased load applied on the suspension from the chassis. The air cargo transport dolly may further include a source of pressurized fluid fluidly connected to the at least one inflatable body. 
         [0019]    Each front suspension assembly may include a first/upper arm adapted to pivot relative to the chassis, with a portion of the first arm residing in a first plane. A second/lower arm may be operatively coupled to the first arm, with the second arm being adapted to pivot relative to the chassis, and a portion of the second arm may reside in a second plane. The first and second planes may remain parallel to each other as the first and second arms pivot relative to the chassis. Each front suspension assembly further includes a rod pivotally coupled to the first/upper arm and the second/lower arm. 
         [0020]    The air cargo transport dolly may further include a housing coupled to the chassis, with the housing and the deck being configured to collectively define an enclosure for storing cargo. The housing may include at least one door. A temperature control unit may be coupled to the housing and adapted to control a temperature within the enclosure. 
         [0021]    According to another embodiment, there is provided method of transporting cargo. The method includes receiving cargo on a dolly having a deck including a deck surface spaced from a ground plane, a plurality of wheels adapted to roll on the ground plane, and a suspension assembly, with the plurality of wheels being coupled to the deck via the suspension assembly. The suspension assembly is adapted to impart a variable suspension force on the deck. The method includes adjusting the suspension force imparted on the deck from the suspension assembly so as to maintain the deck surface at a prescribed distance from the ground plane. 
         [0022]    The suspension force may be increased as a weight associated with the cargo increases, and the suspension force may be decreased as the weight associated with the cargo decreases. 
         [0023]    The suspension assembly may include an inflatable body, and the adjusting step may include adjusting a fluid pressure within the inflatable body to adjust the suspension force imparted on the deck. The suspension force may be increased by adding fluid to the inflatable body to increase the fluid pressure, and the suspension force may be decreased by exhausting fluid from the inflatable body. 
         [0024]    The dolly may further include a housing coupled to the deck to define an enclosure, and the method may further include the step of monitoring a temperature within the enclosure. The method may also comprise adjusting the temperature within the enclosure to maintain the temperature within the enclosure within a prescribed temperature range. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    These and other features and advantages of the various embodiments disclosed herein will be better understood with respect to the following description and drawings, in which like numbers refer to like parts throughout, and in which: 
           [0026]      FIG. 1  is a rear upper perspective view of an air cargo dolly having a temperature control unit and an adjustable suspension assembly; 
           [0027]      FIG. 2  is an upper perspective view of the air cargo dolly shown in  FIG. 1 , with the wall panels removed therefrom to expose a structural support assembly; 
           [0028]      FIG. 3  is a partial upper perspective view of a deck including a plurality of deck rollers and retractable pegs; 
           [0029]      FIG. 4  is a partial upper perspective view of a forward portion of the dolly including a front suspension assembly and a corresponding support structure therefore; 
           [0030]      FIG. 5  is a front upper perspective view of a front suspension assembly coupled to a pair of front wheels; 
           [0031]      FIG. 6  is a rear upper perspective view of the front suspension assembly and front wheels shown in  FIG. 5 ; 
           [0032]      FIG. 7  is a side view of the front suspension assembly in a first position; 
           [0033]      FIG. 8  is a side view of the front suspension assembly in a second position; 
           [0034]      FIG. 9  is an upper perspective view of a front leveler operatively coupled to the front suspension assembly; 
           [0035]      FIG. 10  is a schematic view of a pneumatic system used to control the front and rear suspension assemblies; 
           [0036]      FIG. 11  is a lower perspective view of a rear portion of the dolly to depict a plurality of rear wheels and corresponding rear suspension assemblies; 
           [0037]      FIG. 12  is an upper perspective view of a rear suspension assembly; 
           [0038]      FIG. 13  is a side view of the rear suspension assembly in a first position; 
           [0039]      FIG. 14  is a side view of the rear suspension assembly in a second position; 
           [0040]      FIG. 15  is a side view of the front and rear suspension assemblies in their respective first positions; and 
           [0041]      FIG. 16  is a side view of the front and rear suspension assemblies in their respective second positions. 
       
    
    
     DETAILED DESCRIPTION 
       [0042]    Referring now to the drawings, wherein the showings are for purposes of illustrating a preferred embodiment of the present disclosure, and are not for purposes of limiting the same, there is depicted a dolly  10  specifically configured and adapted for transporting cargo to and from an airplane. The dolly  10  differs from conventional airport cargo dollies due to the inclusion of a suspension assembly adapted to maintain the dolly  10  at a desired loading/unloading level, while at the same time being capable of absorbing shock as the dolly  10  is transported from one location to another. 
         [0043]    The dolly  10  includes a chassis  12  including a front chassis member  14 , an intermediate chassis member  16 , and a rear chassis member  18  spaced from one another and extending in generally parallel relation to each other. A pair of side chassis members  20 ,  22  (see  FIG. 11 ) are coupled to the front, intermediate and rear chassis members  14 ,  16 ,  18  and extend in generally opposed relation to each other. Each side chassis member  20 ,  22  includes a forward section and a rearward section, with the forward section extending between the front and intermediate chassis members  14 ,  16  and the rearward section extending between the intermediate and rear chassis members  16 ,  18 . The chassis members may be formed from metal or other materials known in the art. The chassis  12  may additionally include additional chassis members to provide further structural support. 
         [0044]    A tow bar  24  is attached to the front chassis member  14  and a hitch  25  may be coupled to the rear chassis member  18 . The tow bar  24  is coupled to the front chassis member  14  a connecting bracket  26  which allows the tow bar  24  to pivot relative to the chassis  12 . In particular, the tow bar  24  may be coupled to the connecting bracket  26  via journals or bearings which allow for pivotal motion of the tow bar  24  about a pivot axis  28 . The tow bar  24  includes a distal end portion  30  adapted to be connected to a towing vehicle, such as a towing tractor, as is commonly used at airports for towing trailers and dollies. For instance, the distal end portion  30  may include an opening adapted to receive a pin which connects the tow bar  24  to the towing vehicle. 
         [0045]    A deck  32  is coupled to the chassis  12 , with the deck  32  being adapted to support cargo thereon. The deck  32  includes a deck plate  36  and a plurality of deck rollers  38  extending through the deck plate  36 . According to one embodiment, the deck plate  36  extends between the intermediate chassis member  16  and the rear chassis member  18 , with the front chassis member  14  being spaced forwardly from the deck plate  36 . Therefore, as cargo is placed on the deck  32 , the weight of the cargo will be placed between the intermediate chassis member  16  and the rear chassis member  18 , which provides room from the front suspension and enhances maneuverability of the dolly  10 , as will be described in more detail below. 
         [0046]    Each roller  38  includes a roller ball located within a roller ball housing, with the roller ball being capable of rotating within the housing. Cargo may be slid onto the deck  32  on top of the roller balls to facilitate entry and removal of cargo to and from the dolly  10 . The top of the roller balls preferably reside within a common deck plane  40  (see  FIG. 15 ), which is spaced above an underlying ground plane by a deck height H. Of course, other embodiments may not include rollers  38 , and instead, cargo may be placed directly on the deck plate  36 . In that case, the deck plate  36  resides within the deck plane  40 . In this regard, the term “deck plane” is being used broadly herein and is associated with the surface of the dolly  10  upon which cargo is placed when loaded onto the dolly  10 . 
         [0047]    The dolly  10  may optionally be outfitted with one or more pegs  44  coupled to the deck plate  36 . Each peg  44  is located within a peg opening  46  formed in the deck plate  36 , and may be selectively transitional between a retracted position and an extended position. When the peg  44  is in the retracted position, a peg surface  48  is positioned flush with the deck plate  36 , or below the deck plate  36 , and thus, the peg  44  does not extend above the deck plate  36 . When the peg  44  is in the extended position, the peg surface  48  is located above the deck plate  36 . The pegs  44  may be placed in the retracted position when loading/unloading cargo, with the pegs  44  being transitioned to the extended position when cargo is located on the deck  32  to prevent the cargo from inadvertently sliding off the deck  32 . It is contemplated that the pegs  44  transition between the retracted and extended positions by pivoting relative to the deck plate  36 . In other words, the pegs  44  may be “flipped up” when transitioning from the retracted position to the extended position, and may be “flipped down” when transitioning from the extended position to the retracted position. However, it is understood that in other embodiments the pegs  44  may be spring-loaded pegs, with the pegs  44  being lockable in retracted position, and releasable therefrom by pressing down on the pegs  44  to unlock the pegs  44  to allow the spring-biasing force to transition the pegs  44  toward the extended position. 
         [0048]    The dolly  10  further includes a housing  50  coupled to the chassis  12 . The housing  50  and the deck  32  collectively define an enclosure for receiving the cargo. According to one embodiment, the housing  50  includes a front wall  52 , a first side wall  54 , a second side wall  56  in generally opposed relation to the first side wall  54 , and a rear wall  58  in generally opposed relation to the front wall  52 . A ceiling or roof  60  may extend over the deck  32  and cover the enclosure. The walls  52 ,  54 ,  56 ,  58  and ceiling  60  are shown in  FIG. 1 , but have been removed from  FIG. 2  to illustrate the internal support structure for the walls  52 ,  54 ,  56 ,  58  and ceiling  60 . According to one embodiment, at least one of the walls, and preferably two of the walls have doors operatively coupled thereto. In the exemplary embodiment, the first side wall  54  includes a side opening which may be covered by a side door  62  and the rear wall  58  includes a rear opening which may be covered by a rear door  64 . Each door may be separately and individually transitioned between open and closed positions relative to the respective openings which the doors cover. The doors  62 ,  64  may have a latch or lock which maintains the respective door in the closed position. 
         [0049]    The walls of the housing  50  may be coupled to support members  66 , which are coupled to the chassis  12 . The support members  66  may include both vertical and horizontal support elements to provide adequate support to the housing  50 . 
         [0050]    A temperature control unit  68  may be coupled to the housing  50  and adapted to control a temperature within the enclosure. In particular, the temperature control unit  68  may include an air conditioner for cooling the temperature within the enclosure, as well as a heater for heating the temperature within the enclosure. For instance, the cargo placed within the enclosure may include temperature-sensitive products, such as food or pharmaceuticals, which may be damaged if subjected to extreme temperatures, as is often the case when the dolly  10  sits on a tarmac. Thus, the temperature control unit  68  may be set to maintain a desired temperature within an acceptable temperature range (e.g., +/−2 degrees from the desired temperature). The housing  50  and deck  32  may be filled with insulation to mitigate heat transfer with the external environment through the housing and/or the deck  32 . 
         [0051]    The dolly  10  includes a plurality of front wheels  70  and a plurality of rear wheels  72  coupled to the chassis  12  to facilitate movement of the dolly  10  and to support the weight of the cargo placed in the dolly  10 , with the front and rear wheels  70 ,  72  being adapted to roll on the ground plane  42 . In the exemplary embodiment, the dolly  10  includes two pairs of front wheels  70  and three pair of rear wheels  72 . Each pair of front wheels  70  is rotatable about a respective front wheel axis  74 , and each pair of rear wheel  72  is rotatable about a respective rear wheel axis  76  to effectuate movement of the dolly  10  in a forward and rearward direction. Each pair of front wheels  70  is additionally capable of swiveling  360  degrees about a swivel axis  78  generally perpendicular to the ground plane  42  to enable steering of the dolly  10 . In this regard, each pair of front wheels  70  may function as a caster, enabling steering of the dolly  10  about a relatively small turning radius. The rear wheels  72  are not capable of swiveling. 
         [0052]    Each pair of front wheels  70  is coupled to the chassis  12  via a respective front suspension assembly  80 , and each pair of rear wheels  72  is coupled to the chassis  12  via a respective rear suspension assembly  82 . The front and rear suspension assemblies  80 ,  82  differ from each other, as will be described in more detail below. 
         [0053]    Each front suspension assembly  80  is adapted to enable movement of a corresponding front wheel axis  74  relative to the chassis  12  along a suspension axis  84 , and also allows for swiveling of the front wheels  70  about the swivel axis  78 , which may be aligned with the suspension axis  84 . The ability of the front wheels  70  to swivel 360 degrees, while also being coupled to a front suspension arm provides a significant departure from conventional dolly wheels.  FIGS. 5 and 6  are front and rear upper perspective views of a front suspension assembly  80 , which generally includes a first arm  86 , a second arm  88 , and a suspension rod  90 . Each front suspension assembly  80  is coupled to the chassis  12  via a front support frame  94  (see  FIG. 4 ), which includes a pair of upper support members  96  and a front plate  98 . The upper support members  96  extend between the front plate  98  and the support member(s)  66  of the housing  50 . A brace  100  may extend between the upper support members  96  to provide stabilization therebetween as well as to provide shock absorber mounting. The front support frame  94  further includes a press-bracket  102 , which is positioned in generally opposed relation to a portion of the second arm  88 . 
         [0054]    The first arm  86  of the front suspension assembly  80  includes a first end portion  104  pivotally coupled to the front support frame  94 , and a second end portion  106  pivotally coupled to the suspension rod  90 . In the exemplary embodiment, the first end portion  104  includes a pair of fingers, each being pivotally coupled to the front support frame  94 , while the second end portion  106  is pivotally coupled to diametrically opposed portions of the suspension rod  90 . 
         [0055]    The second arm  88  includes a first end portion  108  pivotally coupled to the front support frame  94  and an aperture  110  through which the suspension rod  90  extends. The second arm  88  is pivotally coupled to the suspension rod  90  via a pivot bearing  112 . The second arm  88  further includes a press-plate  114  in generally opposed relation to the press-bracket  102  of the front support frame  94 . 
         [0056]    The pivotal connection of the first and second arms  86 ,  88  to the front support frame  94  allows the first and second arms  86 ,  88  to also pivot relative to the chassis  12 . Furthermore, since the first pivot arm  86  and the second pivot arm  88  are also pivotally connected to the suspension rod  90 , the first pivot arm  86  remains generally parallel to the second pivot arm  88  as the arms  86 ,  88  transition through their pivotal range of motion. Along these lines, a portion of the first arm  86  resides in a first plane, and a portion of the second arm  88  may reside in a second plane, with the first and second planes remaining substantially parallel to each other as the first and second arms  86 ,  88  pivot relative to the chassis  12 . 
         [0057]    The first and second pivot arms  86 ,  88  are adapted to pivot relative to the chassis  12  to control the height of the deck  32  relative to the ground plane  42 . Referring now specifically to  FIGS. 7 and 8 , the front suspension assembly  80  is shown in two different positions. In  FIG. 7 , the front suspension assembly  80  is shown in a first position, with the press-bracket  102  of the front support frame  94  being spaced from the press-plate  114  of the second pivot arm  88  by a first suspension distance S 1 . In  FIG. 8 , the front suspension assembly  80  is shown in a second position, with the press-bracket  102  of the front support frame  94  being spaced from the press-plate  114  of the second pivot arm  88  by a second suspension distance S 2  greater than the first suspension distance S 1 . In this respect, as the front suspension assembly  80  transitions from the first position to the second position, the front portion of the deck  32  may be raised relative to the ground plane  42 . Conversely, as the front suspension assembly  80  transitions from the second position to the first position, the front portion of the deck  32  may be lowered relative to the ground plane  42 . 
         [0058]    According to one embodiment, the position of the front suspension assembly  80  is adjusted by a front leveler  116 , which includes an inflatable body  118  and a control valve  120  for inflating/exhausting the inflatable body  118 . In this respect, the control valve  120  is fluidly coupled to a source of pressurized fluid  122  (e.g., air), as well as being fluidly coupled to the inflatable body  118 . The inflatable body  118  is selectively transitional between an inflated configuration and a deflated configuration, wherein transition from the deflated configuration toward the inflated configuration enables the front suspension assembly  80  to apply an increased suspension force on the dolly chassis  12  to counteract an increased load applied on the front suspension assembly  80  from the chassis  12 . 
         [0059]    The front leveler  116  further includes a control lever  126 , a linkage  128 , and a connector  130 . The control valve  120  is mounted to the front support frame  94 , while the connector  130  is mounted to the second pivot arm  88 . Pivotal movement of the second pivot arm  88  causes the control lever  126  to pivot relative to the control valve  120 , which in turn, opens or closes the control valve  120  to regulate the volume of the inflatable body  92 . Along these lines, the control valve  120  includes a supply port  132  which receives pressurized fluid from the pressurized fluid source  122 , a delivery port  134  which delivers pressurized fluid to the inflatable body  92  via delivery tube  135 , and an exhaust  136  which allows fluid from the inflatable body  92  to be exhausted to the ambient environment. 
         [0060]    When the control lever  126  pivots to a first position corresponding to a low deck height H, the control valve  120  is opened to allow pressurized fluid from the pressurized fluid source  122  to flow to into the control valve  120  through the supply port  132 , and then exit the control valve  120  via the delivery port  134  for delivery to the inflatable body  118 . When the inflatable body  118  is inflated to a desired position, the control lever  126  will pivot to a second position associated with an acceptable deck height H, which closes the control valve  120  to prevent further inflation of the inflatable body  118 . When the control lever  126  pivots to a third position corresponding to a high deck height H, the exhaust valve is opened to allow fluid to be exhausted from the inflatable body  118 . 
         [0061]    An exemplary control valve  120  is the Extreme Air™ height control valve from Ridewell Suspensions, although other control valves/mechanisms known in the art may also be used without departing from the spirit and scope of the present disclosure. 
         [0062]    Turning now to the rear portion of the dolly  12 , and referring specifically to  FIGS. 11-14 , each rear suspension assembly  82  is operatively coupled to a pair of rear wheels  72  and the chassis  12 , and includes a rear suspension arm  138 . The rear suspension arm  138  includes a rear suspension press-plate  142 , which is positioned in generally opposed relation to a rear chassis press-plate  144  coupled to the chassis  12 . A brake bar  140  extends under the deck  32  and is mounted to each rear suspension arm  138 . A multiple linkage assembly  145  may extend between the brake bar  140  and the rear suspension arm  138 . The brake bar  140  may be associated with a rear parking brake, which may be activated by the tow bar  24 . In particular, the brake bar  140  may be operatively coupled to the tow bar  24 , such that when the tow bar  24  is lifted upwardly from its normal towing position, a parking brake associated with the brake bar  140  may be activated. 
         [0063]    A rear leveler  146  is operatively coupled to the rear suspension assemblies  82  and is adapted to individually adjust the rear suspension assemblies  82  for adjusting the position of the rear portion of the deck  32 . This is effectively achieved by adjusting the distance between the rear wheel axes  76  and the chassis  12 . The rear leveler  146  is similar to the front leveler  116  discussed above, and generally includes a control valve  148 , control lever  150 , a linkage  152 , and a connector  154  and an inflatable body  156 . Each control valve  148  is mounted to the chassis  12  via a mounting bracket, while the connector  154  is mounted to the rear suspension arm  138 . Pivotal movement of the rear suspension arm  138  causes the control lever  150  to pivot relative to the control valve  148 , which in turn, opens or closes the control valve  120  to regulate the volume of the inflatable body  156 . Along these lines, the control valve  120  includes a supply port which receives pressurized fluid from the pressurized fluid source  122 , a delivery port which delivers pressurized fluid to the inflatable body  156  via delivery tube, and an exhaust which allows fluid from the inflatable body  156  to be exhausted to the ambient environment. 
         [0064]    When the control lever  150  pivots to a first position corresponding to a low deck height H, the control valve  148  is opened to allow pressurized fluid from the pressurized fluid source  122  to flow to into the control valve  148  through the supply port, and then exit the control valve  148  via the delivery port for delivery to the inflatable body  156 . When the inflatable body  156  is inflated to a desired position, the control lever  150  will pivot to a second position associated with an acceptable deck height H, which closes the control valve  148  to prevent further inflation of the inflatable body  156 . When the control lever  150  pivots to a third position corresponding to a high deck height H, the exhaust valve is opened to allow fluid to be exhausted from the inflatable body  156 . 
         [0065]    Please note that some structure, including the rear leveler  146 , has been removed or modified from  FIG. 14  to more clearly illustrate the position of the rear suspension arm  138  and the inflatable body  156 . 
         [0066]    The front leveler  116  and the rear leveler  146  are collectively configured to adjust the front suspension assemblies  80  and the rear suspension assemblies  82  to maintain the deck  32  at a prescribed distance relative to the ground plane  42 . In this respect, it is understood that as cargo is loaded on the deck  32 , the deck height will decrease, thereby creating an offset between the loading dock and the dolly deck  32 , which makes subsequent loading of the dolly  32  difficult or unsafe. Therefore, the levelers  116 ,  146  can adjust the deck height to maintain the deck height at the same height as the loading dock, and level with the loading dock. Thus, if cargo is loaded toward the back of the deck  32 , the rear suspension assemblies  82  may be adjusted more than the front suspension assemblies  80 . Since various implementations of the dolly  10  may be specifically configured for use in transporting cargo for loading on airplanes, it is known that many air cargo loading docks are universally set at between 18-23 inches, and more particularly 20.5 inches. Thus, the front leveler  116  and the rear leveler  146  may be collectively configured to maintain the deck height between 18-23 inches, and more specifically 20.5 inches. Furthermore, the front levelers  116  and the rear levelers  146  may be further collectively configured to adjust the respective front suspension assemblies  80  and rear suspension assemblies  82  to maintain the deck  32  substantially parallel to the ground plane  42 . Although the foregoing describes the deck height as being set to be maintained between 18-23 inches, it is understood that the dolly may be configured to set the deck height at other heights. Furthermore, the dolly may include an input device (e.g., joystick, keypad, etc.) to allow the user to set the deck height. 
         [0067]    Referring now to  FIG. 10 , there is shown an exemplary pneumatic system associated with the suspension described herein. In particular, a pressurized fluid source  122  (e.g., air tank) is fluidly coupled to the front and rear levelers  116 ,  146  via a manifold  158  and hoses  160 . A compressor  162  is coupled to the pressurized fluid source  122  to refill the pressurized fluid source  122  with fluid and maintain the pressure therein at a prescribed pressure level. The pressurized fluid source  122 , air compressor  162 , and manifold  158  may be located within the dolly enclosure and separated from the main loading area of the deck by a bar  164  so as to prevent inadvertent contact between the cargo and the pressurized fluid source  122 . 
         [0068]    With the basic structure of the dolly  10  described above, the following discussion will highlight an exemplary use of the dolly  10  for transporting cargo. The dolly  10  may be positioned next to a loading dock to receive cargo therefrom. The side door  62  and/or the rear door  64  may be used to load the cargo onto the dolly  10 . As the cargo is loaded on the dolly  10 , the cargo is received on the deck  32 . The suspension assembly (e.g., the front and rear suspension assemblies  80 ,  82 ) is adapted to impart a variable suspension force on the deck  32 . Such suspension force is adjusted so as to maintain the deck surface at a prescribed distance from the ground plane. In particular, the suspension force is increased as a weight associated with the cargo increases, as may be the case when cargo is loaded onto the dolly  10 , and the suspension force is decreased as the weight associated with the cargo decreases, as may be the case when cargo is unloaded from the dolly  10 . 
         [0069]    The suspension force is adjusted by adjusting a fluid pressure within one or more of the inflatable bodies  118 ,  156  associated with the front and rear suspension assemblies  80 ,  82  to adjust the suspension force imparted on the deck  32 . The suspension force may be selectively increased by adding fluid to the inflatable bodies  118 ,  156  to increase the fluid pressure, and the suspension force may be selectively decreased by exhausting fluid from the inflatable bodies  118 ,  156 . 
         [0070]    While the cargo is located within the dolly  10 , the temperature within the enclosure may be monitored and adjusted to maintain the temperature within the enclosure within a prescribed temperature range. 
         [0071]    The inclusion of the suspension on the dolly  10  may allow the dolly  10  to be transported between an airplane and a loading dock at a speed that is greater than conventional temperature controlled dollies. In particular, the suspension assembly absorbs shock loads/vibrations generated as the dolly travels over uneven terrain at higher speeds, which in turn protects delicate components associated with the temperature control unit  68 , as well as the cargo located within the dolly  10 . In this regard, the dolly  10  may be particularly suitable for carrying berries or other shock sensitive products, which require transport in a temperature controlled environment, and which may bruise if subject to large vibrations. 
         [0072]    Although the exemplary embodiment shows the dolly specifically configured and adapted for use in transporting cargo to and from an airplane, it is understood that other embodiments of the dolly may be configured for other uses. For instance, the dolly may be used to transport high value items, such as money/currency. The dolly may also be used as a quarantine or as a freezer to freeze bugs or undesirable cargo to destroy it if it is so needed. 
         [0073]    The above description is given by way of example, and not limitation. Given the above disclosure, one skilled in the art could devise variations that are within the scope and spirit of the disclosure disclosed herein, including various ways of implementing a suspension on a cargo dolly. Further, the various features of the embodiments disclosed herein can be used alone, or in varying combinations with each other and are not intended to be limited to the specific combination described herein. Thus, the scope of the claims is not to be limited by the illustrated embodiments.