Patent Publication Number: US-11376171-B2

Title: Powered roll-in cots

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. application Ser. No. 16/128,873 filed Sep. 12, 2018, which is a continuation application of U.S. application Ser. No. 15/335,865, filed Oct. 27, 2016, which is a divisional application of U.S. application Ser. No. 14/245,107, filed Apr. 4, 2014, now U.S. Pat. No. 9,510,982, which is a continuation-in-part of U.S. application Ser. No. 13/520,627, filed Dec. 21, 2012, now U.S. Pat. No. 9,233,033, which is a U.S. National Stage of International Application No. PCT/US2011/021069, filed Jan. 13, 2011, which claims the benefit of U.S. Provisional Application No. 61/294,658, filed Jan. 13, 2010. 
    
    
     TECHNICAL FIELD 
     The present disclosure is generally related to emergency cots, and is specifically directed to powered roll-in cots. 
     BACKGROUND 
     There is a variety of emergency cots in use today. Such emergency cots may be designed to transport and load bariatric patients into an ambulance. 
     For example, the PROFlexX® cot, by Ferno-Washington, Inc. of Wilmington, Ohio U.S.A., is a manually actuated cot that may provide stability and support for loads of about 700 pounds (about 317.5 kg). The PROFlexX® cot includes a patient support portion that is attached to a wheeled undercarriage. The wheeled under carriage includes an X-frame geometry that can be transitioned between nine selectable positions. One recognized advantage of such a cot design is that the X-frame provides minimal flex and a low center of gravity at all of the selectable positions. Another recognized advantage of such a cot design is that the selectable positions may provide better leverage for manually lifting and loading bariatric patients. 
     Another example of a cot designed for bariatric patients, is the POWERFlexx® Powered Cot, by Ferno-Washington, Inc. The POWERFlexx® Powered Cot includes a battery powered actuator that may provide sufficient power to lift loads of about 700 pounds (about 317.5 kg). One recognized advantage of such a cot design is that the cot may lift a bariatric patient up from a low position to a higher position, i.e., an operator may have reduced situations that require lifting the patient. 
     A further variety is a multipurpose roll-in emergency cot having a patient support stretcher that is removably attached to a wheeled undercarriage or transporter. The patient support stretcher when removed for separate use from the transporter may be shuttled around horizontally upon an included set of wheels. One recognized advantage of such a cot design is that the stretcher may be separately rolled into an emergency vehicle such as station wagons, vans, modular ambulances, aircrafts, or helicopters, where space and reducing weight is a premium. 
     Another advantage of such a cot design is that the separated stretcher may be more easily carried over uneven terrain and out of locations where it is impractical to use a complete cot to transfer a patient. Example of such prior art cots can be found in U.S. Pat. Nos. 4,037,871, 4,921,295, and International Publication No. WO01701611. 
     Although the foregoing multipurpose roll-in emergency cots have been generally adequate for their intended purposes, they have not been satisfactory in all aspects. For example, the foregoing emergency cots are loaded into ambulances according to loading processes that require at least one operator to support the load of the cot for a portion of the respective loading process. 
     SUMMARY 
     The embodiments described herein address are directed to a versatile multipurpose roll-in emergency cot which may provide improved management of the cot weight, improved balance, and/or easier loading at any cot height, while being rollable into various types of rescue vehicles, such as ambulances, vans, station wagons, aircrafts and helicopters. 
     According to one embodiment, In one embodiment, a roll-in cot can include a support frame, a back carriage member, a pair of back legs, a pair of front legs and a cot actuation system. The support frame can include a front end and a back end. The back carriage member can be slidingly engaged with the support frame. The pair of back legs can be rotatably coupled to the back carriage member. Each of the pair of back legs can include a wheel linkage and a back wheel coupled to the wheel linkage. Each of the pair of back legs can define a back leg span that extends from the back carriage member through the wheel linkage. The pair of front legs can be slidingly coupled to the support frame. Each of the pair of front legs can include a front wheel and an intermediate load wheel having an axis of rotation. The intermediate span can be demarcated by the axis of rotation of the intermediate load wheel and the back carriage member. The cot actuation system can include a front actuator that moves the pair of front legs and a back actuator that moves the pair of back legs. The front actuator can retract the pair of front legs such that the intermediate load wheel is supported by a loading surface. The back actuator can retract the pair of back legs such that the back wheel is supported by a lower surface. The lower surface can be lower than the loading surface. A back leg angle ⊖ can be formed between the back leg span and the intermediate span. The back leg angle ⊖ can be an acute angle. 
     According to another embodiment, a roll-in cot may include a support frame, a pair of back legs, a pair of front legs, and a cot actuation system. The support frame may include a front end, and a back end. The pair of back legs can be slidingly coupled to the support frame. The pair of front legs can be slidingly coupled to the support frame. Each of the pair of front legs can include a front wheel and an intermediate load wheel. The intermediate load wheel is offset from the front wheel by a load wheel distance. The cot actuation system can include a front actuator that moves the pair of front legs and a back actuator that moves the pair of back legs. The front actuator can raise the pair of front legs such that the front wheel and the intermediate load wheel of each of the pair of front legs are aligned along a loading level. The intermediate load wheel of each of the pair of front legs can be offset, along the loading level, from the pair of back legs by a loading span. The load wheel distance can be greater than the loading span. 
     According to yet another embodiment, a roll-in cot can include a support frame, a pair of legs slidingly and pivotally engaged with the support frame, and an actuator coupled to the pair of legs. The actuator can be operable to actuate the pair of legs such that the pair of legs slide and rotate with respect to the support frame. A method for actuating the roll-in cot can include receiving from an actuator sensor, automatically with a processor, a load signal indicative of a force acting upon or exerted by the actuator. A control signal indicative of a command to change a height of the roll-in cot can be received. The actuator can be caused to actuate the pair of legs relatively slowly. The actuator can be determined, automatically with the processor, to be unloaded based upon the load signal. The actuator can be caused, automatically with the processor, to actuate the pair of legs at a higher rate. The pair of legs can be actuated at the higher rate after the actuator is determined to be unloaded. 
     According to a further embodiment, a roll-in cot can include a support frame, a pair of front legs, a pair of back legs, a pair of back hinge members, and a cot actuation system. The support frame can include a front end, and a back end. The pair of front legs can be slidingly coupled to the support frame. The pair of back legs can be slidingly coupled to the support frame. Each of the pair of back legs can include a sinuous internal edge that faces the front end of the support frame. The sinuous internal edge can form an upper angle β. The upper angle β can be an obtuse angle. Each of the pair of back hinge members can be pivotingly coupled to the support frame at a first end and pivotingly coupled to one of the pair of back legs at a second end. The upper angle β of the sinuous internal edge can be located above the second end of one of the pair of back hinge members. The cot actuation system can include a front actuator that moves the pair of front legs and a back actuator that moves the pair of back legs. 
     According to a further embodiment, a roll-in cot can include a support frame, a pair of front legs, a pair of back legs, and a cot actuation system. The support frame can include a front end, and a back end. The front end can include a pair of front load wheels. The pair of back legs can be slidingly coupled to the support frame. The pair of front legs can be slidingly coupled to the support frame. Each of the front legs can include a front wheel and an intermediate load wheel. The cot actuation system can include a front actuator that moves the pair of front legs and a back actuator that moves the pair of back legs. When the pair of front legs is retracted towards the support frame, the roll-in cot can be configured to be load balanced forward of the intermediate load wheel. 
     These and additional features provided by the embodiments of the present disclosure will be more fully understood in view of the following detailed description, in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of specific embodiments of the present disclosures can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: 
         FIG. 1  is a perspective view depicting a cot according to one or more embodiments described herein; 
         FIG. 2  is a top view depicting a cot according to one or more embodiments described herein; 
         FIG. 3  is a perspective view depicting a cot according to one or more embodiments described herein; 
         FIG. 4  is a perspective view depicting a cot according to one or more embodiments described herein; 
         FIGS. 5A-5C  is a side view depicting a raising and/or lower sequence of a cot according to one or more embodiments described herein; 
         FIGS. 6A-6E  is a side view depicting a loading and/or unloading sequence of a cot according to one or more embodiments described herein; 
         FIG. 7A  is a perspective view depicting an actuator according to one or more embodiments described herein; 
         FIG. 7B  schematically depicts an actuator according to one or more embodiments described herein; 
         FIG. 8  perspective view depicting a cot according to one or more embodiments described herein; 
         FIG. 9  schematically depicts a timing belt and gear system according to one or more embodiments described herein; 
         FIG. 10  is a perspective view depicting a hook engagement bar according to one or more embodiments described herein; 
         FIG. 11  schematically depicts a tension member and pulley system according to one or more embodiments described herein; and 
         FIG. 12  schematically depicts the back legs of  FIG. 6A  in isolation according to one or more embodiments described herein. 
     
    
    
     The embodiments set forth in the drawings are illustrative in nature and not intended to be limiting of the embodiments described herein. Moreover, individual features of the drawings and embodiments will be more fully apparent and understood in view of the detailed description. 
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a roll-in cot  10  for transport and loading is shown. The roll-in cot  10  comprises a support frame  12  comprising a front end  17 , and a back end  19 . As used herein, the front end  17  is synonymous with the loading end, i.e., the end of the roll-in cot  10  which is loaded first onto a loading surface. Conversely, as used herein, the back end  19  is the end of the roll-in cot  10  which is loaded last onto a loading surface. Additionally it is noted, that when the roll-in cot  10  is loaded with a patient, the head of the patient may be oriented nearest to the front end  17  and the feet of the patient may be oriented nearest to the back end  19 . Thus, the phrase “head end” may be used interchangeably with the phrase “front end,” and the phrase “foot end” may be used interchangeably with the phrase “back end.” Furthermore, it is noted that the phrases “front end” and “back end” are interchangeable. Thus, while the phrases are used consistently throughout for clarity, the embodiments described herein may be reversed without departing from the scope of the present disclosure. Generally, as used herein, the term “patient” refers to any living thing or formerly living thing such as, for example, a human, an animal, a corpse and the like. 
     Referring collectively to  FIGS. 2 and 3 , the front end  17  and/or the back end  19  may be telescoping. In one embodiment, the front end  17  may be extended and/or retracted (generally indicated in  FIG. 2  by arrow  217 ). In another embodiment, the back end  19  may be extended and/or retracted (generally indicated in  FIG. 2  by arrow  219 ). Thus, the total length between the front end  17  and the back end  19  may be increased and/or decreased to accommodate various sized patients. Furthermore, as depicted in  FIG. 3 , the front end  17  may comprise telescoping lift handles  150 . The telescoping lift handles  150  may telescope away from the support frame  12  to provide lifting leverage and telescope towards the support frame  12  to be stored. In some embodiments, the telescoping lift handles  150  are pivotingly coupled to the support frame  12  and are rotatable from a vertical handle orientation to a side handle orientation, and vice versa. The telescoping lift handles  150  may lock in the vertical handle orientation and the side handle orientation. In one embodiment, when the telescoping lift handles  150  are in the side handle orientation, the telescoping lifting handles  150  provide a gripping surface adjacent to the support frame  12  and are each configured to be gripped by a hand with the palm substantially facing up and/or down. Conversely, when the telescoping lift handles  150  are in the vertical handle orientation, the telescoping lifting handles  150  may each be configured to be gripped by a hand with the thumb substantially pointing up and/or down. 
     Referring collectively to  FIGS. 1 and 2 , the support frame  12  may comprise a pair of parallel lateral side members  15  extending between the front end  17  and the back end  19 . Various structures for the lateral side members  15  are contemplated. In one embodiment, the lateral side members  15  may be a pair of spaced metal tracks. In another embodiment, the lateral side members  15  comprise an undercut portion  115  that is engageable with an accessory clamp (not depicted). Such accessory clamps may be utilized to removably couple patient care accessories such as a pole for an IV drip to the undercut portion  115 . The undercut portion  115  may be provided along the entire length of the lateral side members to allow accessories to be removably clamped to many different locations on the roll-in cot  10 . 
     Referring again to  FIG. 1 , the roll-in cot  10  also comprises a pair of retractable and extendible front legs  20  coupled to the support frame  12 , and a pair of retractable and extendible back legs  40  coupled to the support frame  12 . The roll-in cot  10  may comprise any rigid material such as, for example, metal structures or composite structures. Specifically, the support frame  12 , the front legs  20 , the back legs  40 , or combinations thereof may comprise a carbon fiber and resin structure. As is described in greater detail herein, the roll-in cot  10  may be raised to multiple heights by extending the front legs  20  and/or the back legs  40 , or the roll-in cot  10  may be lowered to multiple heights by retracting the front legs  20  and/or the back legs  40 . It is noted that terms such as “raise,” “lower,” “above,” “below,” and “height” are used herein to indicate the distance relationship between objects measured along a line parallel to gravity using a reference (e.g. a surface supporting the cot). 
     In specific embodiments, the front legs  20  and the back legs  40  may each be coupled to the lateral side members  15 . Referring to  FIG. 8 , the front legs  20  may comprise front carriage members  28  slidingly coupled to the tracks of lateral side members  15 , and the back legs  40  may also comprise back carriage members  48  slidingly coupled to the tracks of lateral side members  15 . Referring to  FIGS. 5A-6E and 10 , when the roll-in cot  10  is raised or lowered, the carriage members  28  and/or  48  slide inwardly or outwardly, respectively along the tracks of the lateral side members  15 . 
     As shown in  FIGS. 5A-6E , the front legs  20  and the back legs  40  may cross each other, when viewing the cot from a side, specifically at respective locations where the front legs  20  and the back legs  40  are coupled to the support frame  12  (e.g., the lateral side members  15  ( FIGS. 1-4 )). As shown in the embodiment of  FIG. 1 , the back legs  40  may be disposed inwardly of the front legs  20 , i.e., the front legs  20  may be spaced further apart from one another than the back legs  40  are spaced from one another such that the back legs  40  are each located between the front legs  20 . Additionally, the front legs  20  and the back legs  40  may comprise front wheels  26  and back wheels  46  which enable the roll-in cot  10  to roll. 
     In one embodiment, the front wheels  26  and back wheels  46  may be swivel caster wheels or swivel locked wheels. As is described below, as the roll-in cot  10  is raised and/or lowered, the front wheels  26  and back wheels  46  may be synchronized to ensure that the plane of the roll-in cot  10  and the plane of the wheels  26 ,  46  are substantially parallel. For example, the back wheels  46  may each be coupled to a back wheel linkage  47  and the front wheels  26  may each be coupled to a front wheel linkage  27 . As the roll-in cot  10  is raised and/or lowered, the front wheel linkages  27  and the back wheel linkages  47  may be rotated to control the plane of the wheels  26 ,  46 . 
     A locking mechanism (not depicted) may be disposed in one of the front wheel linkages  27  and the back wheel linkages  47  to allow an operator to selectively enable and/or disable wheel direction locking. In one embodiment, a locking mechanism is coupled to one of the front wheels  26  and/or one of the back wheels  46 . The locking mechanism transitions the wheels  26 ,  46  between a swiveling state and a directionally locked state. For example, in a swiveling state the wheels  26 ,  46  may be allowed to swivel freely which enables the roll-in cot  10  to be easily rotated. In the directionally locked state, the wheels  26 ,  46  may be actuated by an actuator (e.g., a solenoid actuator, a remotely operated servomechanism and the like) into a straight orientation, i.e., the front wheels  26  are oriented and locked in a straight direction and the back wheels  46  swivel freely such that an operator pushing from the back end  19  would direct the roll-in cot  10  forward. 
     Referring again to  FIG. 1 , the roll-in cot  10  may also comprise a cot actuation system comprising a front actuator  16  configured to move the front legs  20  and a back actuator  18  configured to move the back legs  40 . The cot actuation system may comprise one unit (e.g., a centralized motor and pump) configured to control both the front actuator  16  and the back actuator  18 . For example, the cot actuation system may comprise one housing with one motor capable to drive the front actuator  16 , the back actuator  18 , or both utilizing valves, control logic and the like. Alternatively as depicted in  FIG. 1 , the cot actuation system may comprise separate units configured to control the front actuator  16  and the back actuator  18  individually. In this embodiment, the front actuator  16  and the back actuator  18  may each include separate housings with individual motors to drive the actuators  16  or  18 . While the actuators are shown as hydraulic actuators or chain lift actuators in the present embodiments, various other structures are contemplated as being suitable. 
     Referring to  FIG. 1 , the front actuator  16  is coupled to the support frame  12  and configured to actuate the front legs  20  and raise and/or lower the front end  17  of the roll-in cot  10 . Additionally, the back actuator  18  is coupled to the support frame  12  and configured to actuate the back legs  40  and raise and/or lower the back end  19  of the roll-in cot  10 . The cot actuation system may be motorized, hydraulic, or combinations thereof. Furthermore, it is contemplated that the roll-in cot  10  may be powered by any suitable power source. For example, the roll-in cot  10  may comprise a battery capable of supplying a voltage of, such as, about 24 V nominal or about 32 V nominal for its power source. 
     The front actuator  16  and the back actuator  18  are operable to actuate the front legs  20  and back legs  40 , simultaneously or independently. As shown in  FIGS. 5A-6E , simultaneous and/or independent actuation allows the roll-in cot  10  to be set to various heights and angles with respect to a surface supporting the roll-in cot  10 . 
     Any actuator suitable to raise and lower the support frame  12  as well as retract the front legs  20  and back legs  40  is contemplated herein. As depicted in  FIGS. 3 and 8 , the front actuator  16  and/or the back actuator  18  may include chain lift actuators (e.g., chain lift actuators by Serapid, Inc. of Sterling Heights, Mich. U.S.A.). Alternatively, the front actuator  16  and/or the back actuator  18  may also include wheel and axle actuators, hydraulic jack actuators, hydraulic column actuators, telescopic hydraulic actuators electrical motors, pneumatic actuators, hydraulic actuators, linear actuators, screw actuators, and the like. For example, the actuators described herein may be capable of providing a dynamic force of about 350 pounds (about 158.8 kg) and a static force of about 500 pounds (about 226.8 kg). Furthermore, the front actuator  16  and the back actuator  18  may be operated by a centralized motor system or multiple independent motor systems. 
     In one embodiment, schematically depicted in  FIGS. 1-2 and 7A-7B , the front actuator  16  and the back actuator  18  comprise hydraulic actuators for actuating the roll-in cot  10 . In the embodiment depicted in  FIG. 7A , the front actuator  16  and the back actuator  18  are dual piggy back hydraulic actuators. The dual piggy back hydraulic actuator comprises four hydraulic cylinders with four extending rods that are piggy backed (i.e., mechanically coupled) to one another in pairs. Thus, the dual piggy back actuator comprises a first hydraulic cylinder with a first rod, a second hydraulic cylinder with a second rod, a third hydraulic cylinder with a third rod and a fourth hydraulic cylinder with a fourth rod. 
     In the depicted embodiment, the dual piggy back hydraulic actuator comprises a rigid support frame  180  that is substantially “H” shaped (i.e., two vertical portions connected by a cross portion). The rigid support frame  180  comprises a cross member  182  that is coupled to two vertical members  184  at about the middle of each of the two vertical members  184 . A pump motor  160  and a fluid reservoir  162  are coupled to the cross member  182  and in fluid communication. In one embodiment, the pump motor  160  and the fluid reservoir  162  are disposed on opposite sides of the cross member  182  (e.g., the fluid reservoir  162  disposed above the pump motor  160 ). Specifically, the pump motor  160  may be a brushed bi-rotational electric motor with a peak output of about 1400 watts. The rigid support frame  180  may include additional cross members or a backing plate to provide further rigidity and resist motion of the vertical members  184  with respect to the cross member  182  during actuation. 
     Each vertical member  184  comprises a pair of piggy backed hydraulic cylinders (i.e., a first hydraulic cylinder and a second hydraulic cylinder or a third hydraulic cylinder and a fourth hydraulic cylinder) wherein the first cylinder extends a rod in a first direction and the second cylinder extends a rod in a substantially opposite direction. When the cylinders are arranged in one master-slave configuration, one of the vertical members  184  comprises an upper master cylinder  168  and a lower master cylinder  268 . The other of the vertical members  184  comprises an upper slave cylinder  169  and a lower slave cylinder  269 . It is noted that, while master cylinders  168 ,  268  are piggy backed together and extend rods  165 ,  265  in substantially opposite directions, master cylinders  168 ,  268  may be located in alternate vertical members  184  and/or extend rods  165 ,  265  in substantially the same direction. 
     Referring now to  FIG. 7B , a master-slave hydraulic circuit is formed by placing two cylinders in fluidic communication. Specifically, the upper master cylinder  168  is in fluidic communication with the upper slave cylinder  169  and may communicate hydraulic fluid via the fluid connection  170 . The pump motor  160  pressurizes hydraulic fluid stored in the fluid reservoir  162 . The upper master cylinder  168  receives pressurized hydraulic fluid from the pump motor  160  in a first master volume  172  disposed on one side of the upper master piston  164 . As pressurized hydraulic fluid displaces the upper master piston  164 , the upper master rod  165 , which is coupled to the upper master piston  164 , extends out of the upper master cylinder  168  and a secondary hydraulic fluid is displaced from a second master volume  174  disposed on another side of the upper master piston  164 . The secondary hydraulic fluid is communicated through the fluid connection  170  and received in a slave volume  176  disposed on one side of upper slave piston  166 . Since the volume of secondary hydraulic fluid displaced from the upper master cylinder  168  is substantially equal to the slave volume  176 , the upper slave piston  166  and the upper master piston  164  are displaced at substantially the same speed and travel substantially the same distance. Thus, the upper slave rod  167 , which is coupled to the upper slave piston  166 , and the upper master rod  165  are displaced at substantially the same speed and travel substantially the same distance. 
     Referring back to  FIG. 7A , a similar master-slave hydraulic circuit is formed by placing the lower master cylinder  268  in fluidic communication with the lower slave cylinder  269 . Thus, the lower master rod  265  and the lower slave rod  267  are displaced at substantially the same speed and travel substantially the same distance. In another embodiment, a flow divider may be used to regulate the distribution of pressurized hydraulic fluid from pump motor  160  and substantially equally divide the flow between the upper master cylinder  168  and the lower master cylinder  268  to cause all of the rods  165 ,  167 ,  265 ,  267  to move in unison, i.e., the fluid can be divided equally to both master cylinders which causes the upper and lower rods to move at the same time. The direction of the displacement of the rods  165 ,  167 ,  265 ,  267  is controlled by pump motor  160 , i.e., the pressure of the hydraulic fluid may be set relatively high to supply fluid to the master cylinders for raising the corresponding legs and set relatively low to pull hydraulic fluid from the master cylinders for lowering the corresponding legs. 
     While the cot actuation system is typically powered, the cot actuation system may also comprise a manual release component (e.g., a button, tension member, switch, linkage or lever) configured to allow an operator to raise or lower the front and back actuators  16 ,  18  manually. In one embodiment, the manual release component disconnects the drive units of the front and back actuators  16 ,  18  to facilitate manual operation. Thus, for example, the wheels  26 , 46  may remain in contact with the ground when the drive units are disconnected and the roll-in cot  10  is manually raised. The manual release component may be disposed at various positions on the roll-in cot  10 , for example, on the back end  19  or on the side of the roll-in cot  10 . 
     To determine whether the roll-in cot  10  is level, sensors (not depicted) may be utilized to measure distance and/or angle. For example, the front actuator  16  and the back actuator  18  may each comprise encoders which determine the length of each actuator. In one embodiment, the encoders are real time encoders which are operable to detect movement of the total length of the actuator or the change in length of the actuator when the cot is powered or unpowered (i.e., manual control). While various encoders are contemplated, the encoder, in one commercial embodiment, may be the optical encoders produced by Midwest Motion Products, Inc. of Watertown, Minn. U.S.A. In other embodiments, the cot comprises angular sensors that measure actual angle or change in angle such as, for example, potentiometer rotary sensors, hall effect rotary sensors and the like. The angular sensors can be operable to detect the angles of any of the pivotingly coupled portions of the front legs  20  and/or the back legs  40 . In one embodiment, angular sensors are operably coupled to the front legs  20  and the back legs  40  to detect the difference between the angle of the front leg  20  and the angle of the back leg  40  (angle delta). A loading state angle may be set to an angle such as about 20° or any other angle that generally indicates that the roll-in cot  10  is in a loading state (indicative of loading and/or unloading). Thus, when the angle delta exceeds the loading state angle the roll-in cot  10  may detect that it is in a loading state and perform certain actions dependent upon being in the loading state. 
     It is noted that the term “sensor,” as used herein, means a device that measures a physical quantity and converts it into a signal which is correlated to the measured value of the physical quantity. Furthermore, the term “signal” means an electrical, magnetic or optical waveform, such as current, voltage, flux, DC, AC, sinusoidal-wave, triangular-wave, square-wave, and the like, capable of being transmitted from one location to another. 
     Referring now to  FIG. 3 , the front legs  20  may further comprise a front cross beam  22  extending horizontally between and moveable with the pair of front legs  20 . The front legs  20  also comprise a pair of front hinge members  24  pivotingly coupled to the support frame  12  at one end and pivotingly coupled to the front legs  20  at the opposite end. Similarly, the pair of back legs  40  comprise a back cross beam  42  extending horizontally between and moveable with the pair of back legs  40 . The back legs  40  also comprise a pair of back hinge members  44  pivotingly coupled to the support frame at one end and pivotingly coupled to one of the back legs  40  at the opposite end. In specific embodiments, the front hinge members  24  and the back hinge members  44  may be pivotingly coupled to the lateral side members  15  of the support frame  12 . As used herein, “pivotingly coupled” means that two objects coupled together to resist linear motion and to facilitate rotation or oscillation between the objects. For example, front and back hinge members  24 ,  44  do not slide with the front and back carriage members  28 ,  48 , respectively, but they rotate or pivot as the front and back legs  20 ,  40  are raised, lowered, retracted, or released. As shown in the embodiment of  FIG. 3 , the front actuator  16  may be coupled to the front cross beam  22 , and the back actuator  18  may be coupled to the back cross beam  42 . 
     Referring to  FIG. 4 , the front end  17  may also comprise a pair of front load wheels  70  configured to assist in loading the roll-in cot  10  onto a loading surface  500  (e.g., the floor of an ambulance). The roll-in cot  10  may comprise sensors operable to detect the location of the front load wheels  70  with respect to a loading surface  500  (e.g., distance above the surface or contact with the surface). In one or more embodiments, the front load wheel sensors comprise touch sensors, proximity sensors, or other suitable sensors effective to detect when the front load wheels  70  are above a loading surface  500 . In one embodiment, the front load wheel sensors are ultrasonic sensors aligned to detect directly or indirectly the distance from the front load wheels  70  to a surface beneath the load wheels. Specifically, the ultrasonic sensors, described herein, may be operable to provide an indication when a surface is within a definable range of distance from the ultrasonic sensor (e.g., when a surface is greater than a first distance but less than a second distance). Thus, the definable range may be set such that a positive indication is provided by the sensor when a portion of the roll-in cot  10  is in proximity to a loading surface  500 . 
     In a further embodiment, multiple front load wheel sensors may be in series, such that the front load wheel sensors are activated only when both front load wheels  70  are within a definable range of the loading surface  500  (i.e., distance may be set to indicate that the front load wheels  70  are in contact with a surface). As used in this context, “activated” means that the front load wheel sensors send a signal to the control box  50  that the front load wheels  70  are both above the loading surface  500 . Ensuring that both front load wheels  70  are on the loading surface  500  may be important, especially in circumstances when the roll-in cot  10  is loaded into an ambulance at an incline. 
     In the embodiments described herein, the control box  50  comprises or is operably coupled to a processor and a memory. The processor may be an integrated circuit, a microchip, a computer, or any other computing device capable of executing machine readable instructions. The electronic memory may be RAM, ROM, a flash memory, a hard drive, or any device capable of storing machine readable instructions. Additionally, it is noted that distance sensors may be coupled to any portion of the roll-in cot  10  such that the distance between a lower surface and components such as, for example, the front end  17 , the back end  19 , the front load wheels  70 , the front wheels  26 , the intermediate load wheels  30 , the back wheels  46 , the front actuator  16  or the back actuator  18  may be determined. 
     In further embodiments, the roll-in cot  10  has the capability to communicate with other devices (e.g., an ambulance, a diagnostic system, a cot accessory, or other medical equipment). For example, the control box  50  may comprise or may be operably coupled to a communication member operable to transmit and receive a communication signal. The communication signal may be a signal that complies with Controller Area Network (CAN) protocol, Bluetooth protocol, ZigBee protocol, or any other communication protocol. 
     The front end  17  may also comprise a hook engagement bar  80 , which is typically disposed between the front load wheels  70 , and is operable to swivel forward and backward. While the hook engagement bar  80  of  FIG. 3  is U-shaped, various other structures such as hooks, straight bars, arc shaped bars, etc. may also be used. As shown in  FIG. 4 , the hook engagement bar  80  is operable to engage with a loading surface hook  550  on a loading surface  500 . Loading surface hooks  550  are commonplace on the floors of ambulances. The engagement of the hook engagement bar  80  and the loading surface hook  550  may prevent the roll-in cot  10  from sliding backwards from the loading surface  500 . Moreover, the hook engagement bar  80  may comprise a sensor (not shown) which detects the engagement of the hook engagement bar  80  and the loading surface hook  550 . The sensor may be a touch sensor, a proximity sensor, or any other suitable sensor operable to detect the engagement of the loading surface hook  550 . In one embodiment, the engagement of the hook engagement bar  80  and the loading surface hook  550  may be configured to activate the front actuator  16  and thereby allow for retraction of the front legs  20  for loading onto the loading surface  500 . 
     Referring still to  FIG. 4 , the front legs  20  may comprise intermediate load wheels  30  attached to the front legs  20 . In one embodiment, the intermediate load wheels  30  may be disposed on the front legs  20  adjacent the front cross beam  22 . Like the front load wheels  70 , the intermediate load wheels  30  may comprise a sensor (not shown) which are operable to measure the distance the intermediate load wheels  30  are from a loading surface  500 . The sensor may be a touch sensor, a proximity sensor, or any other suitable sensor operable to detect when the intermediate load wheels  30  are above a loading surface  500 . As is explained in greater detail herein, the load wheel sensor may detect that the wheels are over the floor of the vehicle, thereby allowing the back legs  40  to safely retract. In some additional embodiments, the intermediate load wheel sensors may be in series, like the front load wheel sensors, such that both intermediate load wheels  30  must be above the loading surface  500  before the sensors indicate that the load wheels are above the loading surface  500  i.e., send a signal to the control box  50 . In one embodiment, when the intermediate load wheels  30  are within a set distance of the loading surface the intermediate load wheel sensor may provide a signal which causes the control box  50  to activate the back actuator  18 . Although the figures depict the intermediate load wheels  30  only on the front legs  20 , it is further contemplated that intermediate load wheels  30  may also be disposed on the back legs  40  or any other position on the roll-in cot  10  such that the intermediate load wheels  30  cooperate with the front load wheels  70  to facilitate loading and/or unloading (e.g., the support frame  12 ). 
     Additionally as shown in  FIGS. 8 and 11 , the roll-in cot  10  can comprise a tension member and pulley system  200  comprising carriage tension members  120  coupled to the front carriage members  28  and the back carriage members  48 . A carriage tension member  120  forms a loop that links each of the front carriage members  28  to one another. The carriage tension member  120  is slidingly engaged with pulleys  122  and extends through the front carriage members  28 . Similarly, a carriage tension member  120  forms a loop that links each of the back carriage members  48  to one another. The carriage tension member  120  is slidingly engaged with pulleys  122  and extends through the back carriage members  48 . The carriage tension members  120  ensure the front carriage members  28  and the back carriage members  48  move (generally denoted by arrows in  FIG. 11 ) in unison, i.e., the front legs  20  move in unison and the back legs  40  move in unison. 
     By coupling carriage tension members  120  both of the front carriage members  28  and both of the back carriage members  48 , the pulley system ensures parallel movement of the front legs  20  or back legs  40 , reduces side to side rocking of the support frame  12 , and reduces bending within the lateral side members  15 . The pulley system may have the additional benefit of providing a timing system which ensures that movements of opposite sides of the roll-in cot  10  are synchronized (e.g., each of the front legs  20 , each of the back legs  40 , and/or other components). The timing system may be achieved by arranging carriage tension members  120  and pulleys  122  in the embodiment depicted in  FIG. 11 , wherein the carriage tension member  120  is crossed to ensure that one front leg  20  cannot move separately from the other front leg  20 . As used herein, the phrase “tension member” means a substantially flexible elongate structure capable of conveying force through tension such as, for example, a cable, a cord, a belt, a linkage, a chain, and the like. 
     Referring now to  FIG. 9 , in some embodiments the roll-in cot  10  can comprise a timing belt and gear system  201 . The gear system  201  comprises a timing belt  130  that is disposed within at least a portion of a front leg  20 . The timing belt  130  is engaged with gears  132  that are pivotingly coupled to the front leg  20 . One of the gears  132  is coupled to the front hinge member  24  and one of the gears is coupled to the front wheel linkage  27  such that the front linkage can rotate around an axis of rotation  134 . The front hinge member  24 , which pivots around an axis of rotation  136  as the front leg  20  is actuated, causes the gear  132  to pivot with respect to the front leg  20 . As the gear  132  coupled to the front hinge member  24  rotates, the timing belt  130  communicates the rotation to the gear  132  coupled to the front wheel linkage  27 . In the embodiment depicted in  FIG. 9 , the gear  132  coupled to the front hinge member  24  is half the diameter of the gear  132  coupled to the front wheel linkage. Thus, a rotation Δ 1  of the front hinge member  24  will cause a rotation Δ 2  of the front wheel linkage  27  of half the magnitude of the rotation Δ 1  of the front hinge member  24 . Specifically, when the front hinge member  24  rotates 10°, the front wheel linkage  27  will only rotate 5°, due to the diameter disparity. In addition to a timing belt and gear system  201  as described herein, it is contemplated that other components, e.g., a hydraulic system or rotation sensors, could also be utilized herein. That is, the timing belt and gear system  201  may be replaced with an angle detection sensor and a servomechanism that actuates the front wheel linkage  27 . As used herein, the phrase “timing belt” means any tension member configured to frictionally engage a gear or a pulley. 
     In further embodiments, both of the front legs  20  can comprise a timing belt and gear system  201 . In such embodiments, raising or lowering the front end  17  of the support frame  12  by the front legs  20  trigger the rotation of the front wheel linkage  27 . Additionally, the back legs  40  may comprise a timing belt and gear system  201 , wherein the raising or lowering of the back end  19  of the support frame  12  by the back legs  40  triggers the rotation of the back wheel linkage  47 . Specifically, rotation of the back hinge member  44  with respect to the back leg  40  around the axis of rotation  136  can cause the back wheel linkage  47  with respect to the back leg  40  around the axis of rotation  134 . Thus in embodiments where each of the front legs  20  and the back legs  40  comprise a timing belt and gear system  201 , the front wheels  26  and back wheels  46  can be rotated to ensure that the front wheels  26  and back wheels  46  can roll across surfaces at various cot heights. Thus, the roll-in cot  10  may be rolled side to side at any height when the support frame  12  is substantially parallel to the ground, i.e., the front legs  20  and the back legs  40  are actuated to substantially the same length. 
     Referring again to  FIG. 3 , the roll-in cot  10  may comprise a front actuator sensor  62  and a back actuator sensor  64  configured to detect whether a force is applied to or exerted by the front and back actuators  16 ,  18 , respectively. In some embodiments, the front actuator sensor  62  and the back actuator sensor  64  can be configured to detect whether the front and back actuators  16 ,  18  are under tension or compression. As used herein, the term “tension” means that a pulling force is being detected by the sensor. Such a pulling force is commonly associated with the load being removed from the legs coupled to the actuator, i.e., the leg and or wheels are being suspended from the support frame  12  without making contact with a surface beneath the support frame  12 . Furthermore, as used herein the term “compression” means that a pushing force is being detected by the sensor. Such a pushing force is commonly associated with a load being applied to the legs coupled to the actuator, i.e., the leg and or wheels are in contact with a surface beneath the support frame  12  and transfer a compressive strain on the coupled actuator. In one embodiment, the front actuator sensor  62  and the back actuator sensor  64  are coupled to the support frame  12 ; however, other locations or configurations are contemplated herein. The sensors may be proximity sensors, strain gauges, load cells, hall-effect sensors, or any other suitable sensor operable to detect when the front actuator  16  and/or back actuator  18  are under tension or compression. In further embodiments, the front actuator sensor  62  and the back actuator sensor  64  may be operable to detect the weight of a patient disposed on the roll-in cot  10  (e.g., when strain gauges are utilized). 
     Referring to  FIGS. 1-4 , the movement of the roll-in cot  10  may be controlled via the operator controls. Referring again to the embodiment of  FIG. 1 , the back end  19  may comprise operator controls for the roll-in cot  10 . As used herein, the operator controls are the components used by the operator in the loading and unloading of the roll-in cot  10  by controlling the movement of the front legs  20 , the back legs  40 , and the support frame  12 . Referring to  FIG. 2 , the operator controls may comprise one or more hand controls  57  (for example, buttons on telescoping handles) disposed on the back end  19  of the roll-in cot  10 . Moreover, the operator controls may include a control box  50  disposed on the back end  19  of the roll-in cot  10 , which is used by the cot to switch from the default independent mode and the synchronized or “sync” mode. The control box  50  may comprise one or more buttons  54 ,  56  which place in the cot in sync mode, such that both the front legs  20  and back legs  40  can be raised and lowered simultaneously. In a specific embodiment, the sync mode may only be temporary and cot operation will return to the default mode after a period of time, for example, about 30 seconds. In a further embodiment, the sync mode may be utilized in loading and/or unloading the roll-in cot  10 . While various positions are contemplated, the control box may be disposed between the handles on the back end  19 . 
     As an alternative to the hand control embodiment, the control box  50  may also include a component which may be used to raise and lower the roll-in cot  10 . In one embodiment, the component is a toggle switch  52 , which is able to raise (+) or lower (−) the cot. Other buttons, switches, or knobs are also suitable. Due to the integration of the sensors in the roll-in cot  10 , as is explained in greater detail herein, the toggle switch  52  may be used to control the front legs  20  or back legs  40  which are operable to be raised, lowered, retracted or released depending on the position of the roll-in cot  10 . In one embodiment the toggle switch is analog (i.e., the pressure and/or displacement of the analog switch is proportional to the speed of actuation). The operator controls may comprise a visual display component  58  configured to inform an operator whether the front and back actuators  16 ,  18  are activated or deactivated, and thereby may be raised, lowered, retracted or released. While the operator controls are disposed at the back end  19  of the roll-in cot  10  in the present embodiments, it is further contemplated that the operator controls be positioned at alternative positions on the support frame  12 , for example, on the front end  17  or the sides of the support frame  12 . In still further embodiments, the operator controls may be located in a removably attachable wireless remote control that may control the roll-in cot  10  without physical attachment to the roll-in cot  10 . 
     In other embodiments as shown in  FIG. 4 , the roll-in cot  10  may further comprise a light strip  140  configured to illuminate the roll-in cot  10  in poor lighting or poor visibility environments. The light strip  140  may comprise LED&#39;s, light bulbs, phosphorescent materials, or combinations thereof. The light strip  140  may be triggered by a sensor which detects poor lighting or poor visibility environments. Additionally, the cot may also comprise an on/off button or switch for the light strip  140 . While the light strip  140  is positioned along the side of the support frame  12  in the embodiment of  FIG. 4 , it is contemplated that the light strip  140  could be disposed on the front and/or back legs  20 ,  40 , and various other locations on the roll-in cot  10 . Furthermore it is noted that the light strip  140  may be utilized as an emergency beacon analogous to ambulance emergency lights. Such an emergency beacon is configured to sequence the warning lights in a manner that draws attention to the emergency beacon and that mitigates hazards such as, for example photosensitive epilepsy, glare and phototaxis. 
     Turning now to embodiments of the roll-in cot  10  being simultaneously actuated, the cot of  FIG. 4  is depicted as extended, thus front actuator sensor  62  and back actuator sensor  64  detect that the front actuator  16  and the back actuator  18  are under compression, i.e., the front legs  20  and the back legs  40  are in contact with a lower surface and are loaded. The front and back actuators  16  and  18  are both active when the front and back actuator sensors  62 ,  64  detect both the front and back actuators  16 ,  18 , respectively, are under compression and can be raised or lowered by the operator using the operator controls as shown in  FIG. 2  (e.g., “−” to lower and “+” to raise). 
     Referring collectively to  FIGS. 5A-5C , an embodiment of the roll-in cot  10  being raised ( FIGS. 5A-5C ) or lowered ( FIGS. 5C-5A ) via simultaneous actuation is schematically depicted (note that for clarity the front actuator  16  and the back actuator  18  are not depicted in  FIGS. 5A-5C ). In the depicted embodiment, the roll-in cot  10  comprises a support frame  12  slidingly engaged with a pair of front legs  20  and a pair of back legs  40 . Each of the front legs  20  are rotatably coupled to a front hinge member  24  that is rotatably coupled to the support frame  12  (e.g., via carriage members  28 ,  48  ( FIG. 8 )). Each of the back legs  40  are rotatably coupled to a back hinge member  44  that is rotatably coupled to the support frame  12 . In the depicted embodiment, the front hinge members  24  are rotatably coupled towards the front end  17  of the support frame  12  and the back hinge members  44  that are rotatably coupled to the support frame  12  towards the back end  19 . 
       FIG. 5A  depicts the roll-in cot  10  in a lowest transport position (e.g., the back wheels  46  and the front wheels  26  are in contact with a surface, the front leg  20  is slidingly engaged with the support frame  12  such that the front leg  20  contacts a portion of the support frame  12  towards the back end  19  and the back leg  40  is slidingly engaged with the support frame  12  such that the back leg  40  contacts a portion of the support frame  12  towards the front end  17 ).  FIG. 5B  depicts the roll-in cot  10  in an intermediate transport position, i.e., the front legs  20  and the back legs  40  are in intermediate transport positions along the support frame  12 .  FIG. 5C  depicts the roll-in cot  10  in a highest transport position, i.e., the front legs  20  and the back legs  40  positioned along the support frame  12  such that the front load wheels  70  are at a maximum desired height which can be set to height sufficient to load the cot, as is described in greater detail herein. 
     The embodiments described herein may be utilized to lift a patient from a position below a vehicle in preparation for loading a patient into the vehicle (e.g., from the ground to above a loading surface of an ambulance). Specifically, the roll-in cot  10  may be raised from the lowest transport position ( FIG. 5A ) to an intermediate transport position ( FIG. 5B ) or the highest transport position ( FIG. 5C ) by simultaneously actuating the front legs  20  and back legs  40  and causing them to slide along the support frame  12 . When being raised, the actuation causes the front legs to slide towards the front end  17  and to rotate about the front hinge members  24 , and the back legs  40  to slide towards the back end  19  and to rotate about the back hinge members  44 . Specifically, a user may interact with a control box  50  ( FIG. 2 ) and provide input indicative of a desire to raise the roll-in cot  10  (e.g., by pressing “+” on toggle switch  52 ). The roll-in cot  10  is raised from its current position (e.g., lowest transport position or an intermediate transport position) until it reaches the highest transport position. Upon reaching the highest transport position, the actuation may cease automatically, i.e., to raise the roll-in cot  10  higher additional input is required. Input may be provided to the roll-in cot  10  and/or control box  50  in any manner such as electronically, audibly or manually. 
     The roll-in cot  10  may be lowered from an intermediate transport position ( FIG. 5B ) or the highest transport position ( FIG. 5C ) to the lowest transport position ( FIG. 5A ) by simultaneously actuating the front legs  20  and back legs  40  and causing them to slide along the support frame  12 . Specifically, when being lowered, the actuation causes the front legs to slide towards the back end  19  and to rotate about the front hinge members  24 , and the back legs  40  to slide towards the front end  17  and to rotate about the back hinge members  44 . For example, a user may provide input indicative of a desire to lower the roll-in cot  10  (e.g., by pressing a “−” on toggle switch  52 ). Upon receiving the input, the roll-in cot  10  lowers from its current position (e.g., highest transport position or an intermediate transport position) until it reaches the lowest transport position. Once the roll-in cot  10  reaches its lowest height (e.g., the lowest transport position) the actuation may cease automatically. In some embodiments, the control box  50  ( FIG. 1 ) provides a visual indication that the front legs  20  and back legs  40  are active during movement. 
     In one embodiment, when the roll-in cot  10  is in the highest transport position ( FIG. 5C ), the front legs  20  are in contact with the support frame  12  at a front-loading index  221  and the back legs  40  are in contact with the support frame  12  a back-loading index  241 . While the front-loading index  221  and the back-loading index  241  are depicted in  FIG. 5C  as being located near the middle of the support frame  12 , additional embodiments are contemplated with the front-loading index  221  and the back-loading index  241  located at any position along the support frame  12 . For example, the highest transport position may be set by actuating the roll-in cot  10  to the desired height and providing input indicative of a desire to set the highest transport position (e.g., pressing and holding the “+” and “−” on toggle switch  52  simultaneously for 10 seconds). 
     In another embodiment, any time the roll-in cot  10  is raised over the highest transport position for a set period of time (e.g., 30 seconds), the control box  50  provides an indication that the roll-in cot  10  has exceeded the highest transport position and the roll-in cot  10  needs to be lowered. The indication may be visual, audible, electronic or combinations thereof. 
     When the roll-in cot  10  is in the lowest transport position ( FIG. 5A ), the front legs  20  may be in contact with the support frame  12  at a front-flat index  220  located near the back end  19  of the support frame  12  and the back legs  40  may be in contact with the support frame  12  a back-flat index  240  located near the front end  17  of the support frame  12 . Furthermore, it is noted that the term “index,” as used herein means a position along the support frame  12  that corresponds to a mechanical stop or an electrical stop such as, for example, an obstruction in a channel formed in a lateral side member  15 , a locking mechanism, or a stop controlled by a servomechanism. 
     The front actuator  16  is operable to raise or lower a front end  17  of the support frame  12  independently of the back actuator  18 . The back actuator  18  is operable to raise or lower a back end  19  of the support frame  12  independently of the front actuator  16 . By raising the front end  17  or back end  19  independently, the roll-in cot  10  is able to maintain the support frame  12  level or substantially level when the roll-in cot  10  is moved over uneven surfaces, for example, a staircase or hill. Specifically, if one of the front legs  20  or the back legs  40  is in tension, the set of legs not in contact with a surface (i.e., the set of legs that is in tension) is activated by the roll-in cot  10  (e.g., moving the roll-in cot  10  off of a curb). Further embodiments of the roll-in cot  10  are operable to be automatically leveled. For example, if back end  19  is lower than the front end  17 , pressing the “+” on toggle switch  52  raises the back end  19  to level prior to raising the roll-in cot  10 , and pressing the “−” on toggle switch  52  lowers the front end  17  to level prior to lowering the roll-in cot  10 . 
     In one embodiment, depicted in  FIG. 2 , the roll-in cot  10  receives a first load signal from the front actuator sensor  62  indicative of a first force acting upon the front actuator  16  and a second load signal from the back actuator sensor  64  indicative of a second force acting upon a back actuator  18 . The first load signal and second load signal may be processed by logic executed by the control box  50  to determine the response of the roll-in cot  10  to input received by the roll-in cot  10 . Specifically, user input may be entered into the control box  50 . The user input is received as control signal indicative of a command to change a height of the roll-in cot  10  by the control box  50 . Generally, when the first load signal is indicative of tension and the second load signal is indicative of compression, the front actuator actuates the front legs  20  and the back actuator  18  remains substantially static (e.g., is not actuated). Therefore, when only the first load signal indicates a tensile state, the front legs  20  may be raised by pressing the “−” on toggle switch  52  and/or lowered by pressing the “+” on toggle switch  52 . Generally, when the second load signal is indicative of tension and the first load signal is indicative of compression, the back actuator  18  actuates the back legs  40  and the front actuator  16  remains substantially static (e.g., is not actuated). Therefore, when only the second load signal indicates a tensile state, the back legs  40  may be raised by pressing the “−” on toggle switch  52  and/or lowered by pressing the “+” on toggle switch  52 . In some embodiments, the actuators may actuate relatively slowly upon initial movement (i.e., slow start) to mitigate rapid jostling of the support frame  12  prior to actuating relatively quickly. 
     Referring collectively to  FIGS. 5C-6E , independent actuation may be utilized by the embodiments described herein for loading a patient into a vehicle (note that for clarity the front actuator  16  and the back actuator  18  are not depicted in  FIGS. 5C-6E ). Specifically, the roll-in cot  10  can be loaded onto a loading surface  500  according the process described below. First, the roll-in cot  10  may be placed into the highest transport position ( FIG. 5C ) or any position where the front load wheels  70  are located at a height greater than the loading surface  500 . When the roll-in cot  10  is loaded onto a loading surface  500 , the roll-in cot  10  may be raised via front and back actuators  16  and  18  to ensure the front load wheels  70  are disposed over a loading surface  500 . In one embodiment, depicted in  FIG. 10 , as the roll-in cot  10  continues being loaded, the hook engagement bar  80  may be swiveled over the loading surface hook  550  of a loading surface  500  (e.g., an ambulance platform). Then, the roll-in cot  10  may be lowered until front load wheels  70  contact the loading surface  500  ( FIG. 6A ). 
     As is depicted in  FIG. 6A , the front load wheels  70  are over the loading surface  500 . In one embodiment, after the load wheels contact the loading surface  500  the front pair of legs  20  can be actuated with the front actuator  16  because the front end  17  is above the loading surface  500 . As depicted in  FIGS. 6A and 6B , the middle portion of the roll-in cot  10  is away from the loading surface  500  (i.e., a large enough portion of the roll-in cot  10  has not been loaded beyond the loading edge  502  such that most of the weight of the roll-in cot  10  can be cantilevered and supported by the wheels  70 ,  26 , and/or  30 ). When the front load wheels are sufficiently loaded, the roll-in cot  10  may be held level with a reduced amount of force. 
     Additionally, in such a position, the front actuator  16  is in tension and the back actuator  18  is in compression. Thus, for example, if the “−” on toggle switch  52  is activated, the front legs  20  are raised ( FIG. 6B ). In one embodiment, after the front legs  20  have been raised enough to trigger a loading state, the operation of the front actuator  16  and the back actuator  18  is dependent upon the location of the roll-in cot. In some embodiments, upon the front legs  20  raising, a visual indication is provided on the visual display component  58  of the control box  50  ( FIG. 2 ). The visual indication may be color-coded (e.g., activated legs in green and non-activated legs in red). This front actuator  16  may automatically cease to operate when the front legs  20  have been fully retracted. Furthermore, it is noted that during the retraction of the front legs  20 , the front actuator sensor  62  may detect tension, at which point, front actuator  16  may raise the front legs  20  at a higher rate, for example, fully retract within about 2 seconds. 
     After the front legs  20  have been retracted, the roll-in cot  10  may be urged forward until the intermediate load wheels  30  have been loaded onto the loading surface  500  ( FIG. 6C ). As depicted in  FIG. 6C , the front end  17  and the middle portion of the roll-in cot  10  are above the loading surface  500 . As a result, the pair of back legs  40  can be retracted with the back actuator  18 . Specifically, an ultrasonic sensor may be positioned to detect when the middle portion is above the loading surface  500 . When the middle portion is above the loading surface  500  during a loading state (e.g., the front legs  20  and back legs  40  have an angle delta greater than the loading state angle), the back actuator may be actuated. In one embodiment, an indication may be provided by the control box  50  ( FIG. 2 ) when the intermediate load wheels  30  are sufficiently beyond the loading edge  502  to allow for back leg  40  actuation (e.g., an audible beep may be provided). 
     It is noted that, the middle portion of the roll-in cot  10  is above the loading surface  500  when any portion of the roll-in cot  10  that may act as a fulcrum is sufficiently beyond the loading edge  502  such that the back legs  40  may be retracted a reduced amount of force is required to lift the back end  19  (e.g., less than half of the weight of the roll-in cot  10 , which may be loaded, needs to be supported at the back end  19 ). Furthermore, it is noted that the detection of the location of the roll-in cot  10  may be accomplished by sensors located on the roll-in cot  10  and/or sensors on or adjacent to the loading surface  500 . For example, an ambulance may have sensors that detect the positioning of the roll-in cot  10  with respect to the loading surface  500  and/or loading edge  502  and communications means to transmit the information to the roll-in cot  10 . 
     Referring to  FIG. 6D , after the back legs  40  are retracted and the roll-in cot  10  may be urged forward. In one embodiment, during the back leg retraction, the back actuator sensor  64  may detect that the back legs  40  are unloaded, at which point, the back actuator  18  may raise the back legs  40  at higher speed. Upon the back legs  40  being fully retracted, the back actuator  18  may automatically cease to operate. In one embodiment, an indication may be provided by the control box  50  ( FIG. 2 ) when the roll-in cot  10  is sufficiently beyond the loading edge  502  (e.g., fully loaded or loaded such that the back actuator is beyond the loading edge  502 ). 
     Once the cot is loaded onto the loading surface ( FIG. 6E ), the front and back actuators  16 ,  18  may be deactivated by being lockingly coupled to an ambulance. The ambulance and the roll-in cot  10  may each be fitted with components suitable for coupling, for example, male-female connectors. Additionally, the roll-in cot  10  may comprise a sensor which registers when the roll-in cot  10  is fully disposed in the ambulance, and sends a signal which results in the locking of the actuators  16 ,  18 . In yet another embodiment, the roll-in cot  10  may be connected to a cot fastener, which locks the actuators  16 ,  18 , and is further coupled to the ambulance&#39;s power system, which charges the roll-in cot  10 . A commercial example of such ambulance charging systems is the Integrated Charging System (ICS) produced by Ferno-Washington, Inc. 
     Referring collectively to  FIGS. 6A-6E , independent actuation, as is described above, may be utilized by the embodiments described herein for unloading the roll-in cot  10  from a loading surface  500 . Specifically, the roll-in cot  10  may be unlocked from the fastener and urged towards the loading edge  502  ( FIG. 6E  to  FIG. 6D ). As the back wheels  46  are released from the loading surface  500  ( FIG. 6D ), the back actuator sensor  64  detects that the back legs  40  are unloaded and allows the back legs  40  to be lowered. In some embodiments, the back legs  40  may be prevented from lowering, for example if sensors detect that the cot is not in the correct location (e.g., the back wheels  46  are above the loading surface  500  or the intermediate load wheels  30  are away from the loading edge  502 ). In one embodiment, an indication may be provided by the control box  50  ( FIG. 2 ) when the back actuator  18  is activated (e.g., the intermediate load wheels  30  are near the loading edge  502  and/or the back actuator sensor  64  detects tension). 
     When the roll-in cot  10  is properly positioned with respect to the loading edge  502 , the back legs  40  can be extended ( FIG. 6C ). For example, the back legs  40  may be extended by pressing the “+” on toggle switch  52 . In one embodiment, upon the back legs  40  lowering, a visual indication is provided on the visual display component  58  of the control box  50  ( FIG. 2 ). For example, a visual indication may be provided when the roll-in cot  10  is in a loading state and the back legs  40  and/or front legs  20  are actuated. Such a visual indication may signal that the roll-in cot should not be moved (e.g., pulled, pushed, or rolled) during the actuation. When the back legs  40  contact the floor ( FIG. 6C ), the back legs  40  become loaded and the back actuator sensor  64  deactivates the back actuator  18 . 
     When a sensor detects that the front legs  20  are clear of the loading surface  500  ( FIG. 6B ), the front actuator  16  is activated. In one embodiment, when the intermediate load wheels  30  are at the loading edge  502  an indication may be provided by the control box  50  ( FIG. 2 ). The front legs  20  are extended until the front legs  20  contact the floor ( FIG. 6A ). For example, the front legs  20  may be extended by pressing the “+” on toggle switch  52 . In one embodiment, upon the front legs  20  lowering, a visual indication is provided on the visual display component  58  of the control box  50  ( FIG. 2 ). 
     Referring back to  FIGS. 4 and 10 , in embodiments where the hook engagement bar  80  is operable to engage with a loading surface hook  550  on a loading surface  500 , the hook engagement bar  80  is disengaged prior to unloading the roll-in cot  10 . For example, hook engagement bar  80  may be rotated to avoid the loading surface hook  550 . Alternatively, the roll-in cot  10  may be raised from the position depicted in  FIG. 4  such that the hook engagement bar  80  avoids the loading surface hook  550 . 
     Referring collectively to  FIGS. 6A to 6E , embodiments of the roll-in cot  10  can be configured to facilitate loading and unloading. Specifically, the front legs  20  and the back legs  40  can include geometric features that can reduce the amount of force needed to hold the roll-in cot  10  level. Accordingly, the middle portion of the roll-in cot  10  can operate as a fulcrum that facilitates loading and unloading, i.e., the geometric features of the front legs  20  and the back legs  40  can enhance the balance of the roll-in cot  10  during loading and unloading. For example, the arrangement of the intermediate load wheel  30  along the front leg  20  can enhance the balance of a roll-in cot  10  when supporting a patient during loading and unloading. 
     Referring now to  FIG. 6A , the front leg  20  can define a front leg span  32  that extends along the front leg  20  from the front carriage member  28  through the front wheel linkage  27 . A distance  33  of the front leg span  32  can be measured between the carriage member  28  and the axis of rotation  134 . The front wheel  26  can be offset from the support frame  12  by the distance  33  of the front leg span  32 . A hinge member distance  34  can be defined along the front leg span  32  between the axis of rotation  136  and the axis of rotation  134 . Thus, the intersection between the front hinge member  24  and the front leg  20  can be offset from the front wheels by the hinge member distance. Additionally, a load wheel distance  36  can be defined along the front leg span  32  between the axis of rotation  136  and the intermediate load wheel  30 . Accordingly, the intermediate load wheel  30  can be offset from the front wheel  26  by the load wheel distance  36 . The applicants have discovered that the relationships between the distance  33  of the front leg span  32  and each of the hinge member distance  34  and the load wheel distance  36  can be configured to enhance the balance of the roll-in cot  10  during loading and unloading. In some embodiments, the load wheel distance  36  can be less than about 50% of the distance  33  of the front leg span  32  such as, for example, less than about 45% in one embodiment. In further embodiments, the load wheel distance  36  can be between about 50% and 20% of the distance  33  of the front leg span  32  such as, for example, between about 45% and 35% of the distance  33  of the front leg span  32  in one embodiment, or between about 40% and 30% of the distance  33  of the front leg span  32  in another embodiment. Alternatively or additionally, the hinge member distance  34  can be greater than about 50% of the distance  33  of the front leg span  32  such as, for example, greater than about 60% in one embodiment, or greater than about 70% in another embodiment. In further embodiments, the hinge member distance  34  can be between about 55% and 90% of the distance  33  of the front leg span  32  such as, for example, between about 65% and 85% of the distance  33  of the front leg span  32  in one embodiment, or between about 70% and 80% of the distance  33  of the front leg span  32  in another embodiment. Accordingly, the hinge member distance  34  can be greater than the load wheel distance  36 . 
     Referring now to  FIG. 6C , the arrangement of back leg  40  with respect to the front leg  20  can enhance the balance of the roll-in cot  10  during loading and unloading. For example, the arrangement of back leg  40  during loading and unloading from the loading surface  500  can improve the fulcrum effect of the middle portion of the roll-in cot  10 . In some embodiments, the back leg  40  can be configured to form a loading angle α with respect to a loading level  504  during loading and unloading. Specifically, the back leg  40  can define a back leg span  38  that extends along the back leg  40  from the back carriage member  48  through the back wheel linkage  47  and that forms the loading angle α with respect to a loading level  504  during loading and unloading. A distance  39  of the back leg span  38  can be measured between the back carriage member  48  and the axis of rotation  134  of the back wheel linkage  47 . Accordingly, the back wheel  46  can be offset from the support frame  12  by the distance  39  of the back leg span  38 . In some embodiments, the distance  39  of the back leg span  38  can be substantially equal to the distance  33  of the front leg span  32  ( FIG. 6A ). 
     As is described in greater detail above, during loading or unloading, the intermediate load wheel  30 , the front wheel  26  and the front load wheel  70  can be in contact with the loading surface  500 . Accordingly, the outer diameters of the intermediate load wheel  30 , the front wheel  26  and the front load wheel  70  can be substantially aligned. The loading level  504  can be defined by the alignment of the outer diameters of the intermediate load wheel  30 , the front wheel  26 , the front load wheel  70 , the loading surface  500 , or any combination thereof. The back leg span  38  of the back leg  40  can be configured to form a loading angle α with respect to the loading level  504 . In embodiments where the loading level  504  is substantially parallel to the support frame  12  of the roll-in cot  10 , the back leg span  38  of the back leg  40  can be configured to form the loading angle α with respect to the support frame  12  of the roll-in cot  10 . In some embodiments, the loading angle α can be substantially acute such as, for example, less than about 85° (about 1.48 radians) in one embodiment, between about 75° (about 1.31 radians) and about 40° (about 0.70 radians) in another embodiment, or between about 60° (about 1.05 radians) and about 45° (about 0.79 radians) in a further embodiment. 
     As is noted above, the arrangement of back leg  40  with respect to the front leg  20  can enhance the balance of the roll-in cot  10  during loading and unloading. For example, when the intermediate load wheel  30 , the front wheel  26  and the front load wheel  70  are aligned along the loading level  504 , the intermediate load wheel  30  can be offset from the back leg  40  by a loading span  506 . The loading span  506  can be measured along the loading level  504  between an axis of rotation  31  of the intermediate load wheel  30  (e.g., a wheel axle) and the back leg  40 . 
     Referring collectively to  FIGS. 6A and 6C , the loading span  506  can be less than the load wheel distance  36  such as, for example, the loading span  506  can be less than about 95% of the load wheel distance  36  in one embodiment, or the loading span  506  can be between about 50% and about 95% of the load wheel distance  36  in another embodiment. In further embodiments, the loading span  506  can be between about 4 inches (about 15.2 cm) and about 24 inches (about 61 cm) such as, for example, between about 5 inches (about 25.4 cm) and about 12 inches (about 45.7 cm) in another embodiment. 
     Referring again to  FIG. 6C , the back leg span  38  of the back leg  40  can be configured to form a back leg angle ⊖ with respect to an intermediate span  142  during loading and unloading. The intermediate span  142  can be demarcated by the axis of rotation  31  of the intermediate load wheel  30  (e.g., a wheel axle) and the back carriage member  48 . In some embodiments, the back leg angle ⊖ can be configured to enhance the balance of the roll-in cot  10  during loading and unloading. Specifically, when loading or unloading the roll-in cot  10 , the back leg  40  can be supported by a surface that is lower than the loading surface  500  and the intermediate load wheel  30  can be supported by the loading surface  500 . For example, the back wheel  46  can be supported by the ground or a floor, while the intermediate load wheel  30  is supported by a floor of an ambulance. According to the embodiments described herein, the back leg angle ⊖ can be substantially acute, when the back leg  40  is supported by a surface that is lower than the loading surface  500  and the intermediate load wheel  30  is supported by the loading surface  500  such as, for example, less than about 85° (about 1.48 radians) in one embodiment, between about 60° (about 1.05 radians) and about 80° (about 1.40 radians) in another embodiment. 
     According to the embodiments described herein, the roll-in cot  10  can be configured to be load balanced towards the front end  17  of the roll-in cot  10 . As used herein, the phrase “configured to be load balanced” refers to a center of gravity of a cot-patient combination. As used herein the phrase “cot-patient combination” can mean the resultant combination of the roll-in cot  10  and an anthropomorphic test device  508  such that the top of the head of the anthropomorphic test device  508  is in line with the center of the front load wheel  70 . Additionally, it is noted that the phrase “anthropomorphic test device” refers to a 95 th  Percentile Adult Male Hybrid III Dummy as defined by the National Highway Traffic Safety Administration. The anthropomorphic test device  508  can be supported directly by the support frame  12  or indirectly via patient supporting structure, which is in turn supported by the support frame  12 . In some embodiments, the roll-in cot  10  can be configured to be load balanced forward (i.e., towards the front end  17  of the roll-in cot  10 ) with respect to the intermediate load wheel  30 , when the front leg  20  of the roll-in cot  10  is retracted towards the support frame  12 . Examples of the front leg  20  being retracted towards the support frame are depicted in  FIGS. 5A, and 6B-6E . Thus, in some embodiments, when the back leg  40  is supported by a surface that is lower than the loading surface  500  and the intermediate load wheel  30  is supported by the loading surface  500 , the cot-patient combination can have a center of gravity that is forward of the intermediate load wheel  30 . 
     Referring now to  FIG. 12 , the back leg  40  can comprise a sinuous internal edge  144  configured to assist with unloading the roll-in cot  10 . The sinuous internal edge  144  can be formed along the portion of the back leg  40  that is facing the front end  17  of the roll-in cot  10 . In some embodiments, the sinuous internal edge  144  can be formed from one or more facets, one or more polynomial shaped contours, or combinations thereof. For example, the sinuous internal edge  144  can comprise a first edge segment  146 , a second edge segment  147 , and a third edge segment  148 . As used herein, the phrase “edge segment” can mean a partition of an edge. Thus an edge segment can be a partition of a substantially curved line, a substantially straight line, or combinations thereof. The first edge segment  146  can be located towards the top of the sinuous internal edge  144 , i.e., towards the intersection of the back leg  40  and the support frame  12 . The third edge segment  148  can be located towards the bottom of the sinuous internal edge  144 , i.e., towards the back wheel  46 . The second edge segment  147  can be located between the first edge segment  146  and the third edge segment  148 . 
     In some embodiments, the sinuous internal edge  144  of the back leg  40  can comprise an upper angle β formed between the first edge segment  146  and the second edge segment  147 . The upper angle β can be configured such that extension of the back leg  40  imparts an unloading force  510  upon the roll-in cot  10 . Specifically, as the back leg  40  extends, the sinuous internal edge  144  of the back leg  40  can contact (depicted in  FIG. 12  as a dashed line object) the loading surface  500 , the loading edge  502 , or both. When such contact is made, extension of the back leg  40  can generate the unloading force  510  and urge the roll-in cot  10  along the direction of the unloading force  510 . In some embodiments, the upper angle β can be formed to enhance contact between the second edge segment  147  of the sinuous internal edge  144  and the loading surface  500 , the loading edge  502 , or both. Specifically, the upper angle β can be substantially obtuse such as, for example, between about 140° (about 2.44 radians) and about 175° (about 3.05 radians) in one embodiment, or between about 155° (about 2.71 radians) and about 175° (about 3.05 radians) in another embodiment, or between about 160° (about 2.79 radians) and about 170° (about 2.97 radians) in a further embodiment. 
     Alternatively or additionally, the sinuous internal edge  144  of the back leg  40  can comprise a lower angle φ formed between the second edge segment  147  and the third edge segment  148 . The lower angle φ can be configured to provide clearance between the back leg  40  and the loading edge  502 , when the back leg  40  is fully extended. The lower angle φ can be a reflex angle such as, for example, between about 185° (about 3.23 radians) and about 240° (about 4.19 radians) in one embodiment, or between about 195° (about 3.40 radians) and about 230° (about 4.01 radians) in another embodiment, or between about 205° (about 3.58 radians) and about 220° (about 3.84 radians) in a further embodiment. 
     In embodiments where the sinuous internal edge  144  comprises both the upper angle β and the lower angle φ, the upper angle β and the lower angle φ can be defined in combination such that the intersection between the back hinge member  44  and the back leg  40  is disposed substantially in line with the back leg span  38 . In some embodiments, the upper angle β can be located above the axis of rotation  136  of the back hinge member  44 . For example, the upper angle β can be closer to the support frame  12  than the axis of rotation  136  of the back hinge member  44  as measured along the back leg span  38 . Alternatively or additionally, and the lower angle φ can be located below the axis of rotation  136  of the back hinge member  44 . For example, the lower angle φ can be further from the support frame  12  than the axis of rotation  136  of the back hinge member  44  as measured along the back leg span  38 . Accordingly, the upper angle β of the sinuous internal edge  144  can be located above the lower angle φ of the sinuous internal edge  144 . 
     It should now be understood that the embodiments described herein may be utilized to transport patients of various sizes by coupling a support surface such as a patient support surface to the support frame. For example, a lift-off stretcher or an incubator may be removably coupled to the support frame. Therefore, the embodiments described herein may be utilized to load and transport patients ranging from infants to bariatric patients. Furthermore the embodiments described herein, may be loaded onto and/or unloaded from an ambulance by an operator holding a single button to actuate the independently articulating legs (e.g., pressing the “−” on the toggle switch to load the cot onto an ambulance or pressing the “+” on the toggle switch to unload the cot from an ambulance). Specifically, the roll-in cot  10  may receive an input signal such as from the operator controls. The input signal may be indicative of a first direction or a second direction (i.e., lower or raise). The pair of front legs and the pair of back legs may be lowered independently when the signal is indicative of the first direction or may be raised independently when the signal is indicative of the second direction. 
     It is further noted that terms like “preferably,” “generally,” “commonly,” and “typically” are not utilized herein to limit the scope of the claimed embodiments or to imply that certain features are critical, essential, or even important to the structure or function of the claimed embodiments. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present disclosure. 
     For the purposes of describing and defining the present disclosure it is additionally noted that the term “substantially” is utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The term “substantially” is also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. 
     Having provided reference to specific embodiments, it will be apparent that modifications and variations are possible without departing from the scope of the present disclosure defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these preferred aspects of any specific embodiment.