Abstract:
A hoist with a cradle for coupling with a pressurized tank. A linear actuator assembly raises the cradle above the floor surface. A base with casters allows a raised tank to be safely lifted and transported by a single operator. The cradle can be rotated and locked in a vertical or horizontal position for cylinder insertion and removal in EMS vehicles with either a vertical or a horizontal stowage compartment. When handling a horizontal cylinder stowage situation, an embodiment of the cradle features a retractable foot to allow the cylinder to be slid from the cradle into the compartment bottom first. Another embodiment has a fixed foot and allows the cylinder to be slid from the cradle into the compartment top first. Safety interlocks are provided to prevent rotation of the cradle if the foot is in the wrong position with respect to the horizontal orientation of the cradle.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   This application is a continuation-in-part of prior application Ser. No. 11/424,184, filed Jun. 14, 2006. 

   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not Applicable 
   THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
   Not Applicable 
   INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
   Not Applicable 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to an apparatus for lifting and moving pressurized tanks and more particularly relates to a compact apparatus for lifting and moving heavy pressurized oxygen tanks to assist in their installation in and removal from EMS response vehicles. 
   2. Description of Related Art 
   Pressurized oxygen cylinders are standard equipment onboard most ambulances and other EMS response vehicles. Most pressurized cylinders are constructed from aluminum or steel. Though lightest in weight, an empty aluminum pressurized oxygen cylinder can still weigh over one hundred pounds. 
   The Occupational Safety and Health Administration (OSHA) has no standard which sets limits on how much an employee may lift or carry. However, a sister agency, the National Institute for Occupational Safety and Health (NIOSH), has developed a mathematical model which helps predict the risk of injury based on the weight being lifted and accounts for many confounding factors. The model is based on previous medical research into the compressive forces needed to cause damage to bones and ligaments of the back. 
   NIOSH has shown through research that a lifting index greater than 3.0 can clearly be linked to an increased risk of back and other injuries. In applying the NIOSH equation for calculating a lifting index, an EMS worker or maintenance individual lifting a one hundred pound pressurized oxygen tank from the floor and stowing it in a compartment of an ambulance would likely encounter a lifting index of 3.9 or higher. A heavier (steel) tank would yield an even higher lifting index. Because of this, a single EMS worker attempting to lift and move such a cylinder faces a significant risk of back injury. 
   Cylinder storage compartments onboard EMS vehicles tend to be quite small, some barely larger than the cylinders themselves. These cramped spaces further compound the dangers faced by an EMS worker when changing out a cylinder. Because the spaces are small, only one worker can realistically fit within the compartment to manipulate the cylinder. 
   Some EMS vehicles feature horizontal storage compartments that require the cylinder to be installed either top or bottom first. Traditionally, the EMS worker must physically lift the cylinder from vertical storage and rotate it to a horizontal position without dropping it. This can be extremely difficult given the cylinder&#39;s weight, round shape, and lack of hand grips. Once horizontal, the cylinder must then be carefully slid into the compartment where it sits upon stowage rails or guides. 
   Potential back injury is not the only possible hazard associated with pressurized tanks. The cylindrical shape makes them difficult to grasp and awkward to handle by a single person. However, due to the cramped compartment in which they are stored, only one person can realistically be expected to handle the cylinders. Thus, a real danger exists that a pressurized cylinder being handled could fall from a vehicle unexpectedly. If the cylinder were to strike an object with the exposed valve, the cylinder might rupture. A ruptured cylinder can explode with tremendous force or even become a missile that can cause significant damage to anything it impacts. 
   Horizontally mounted cylinders also pose hazards to the worker&#39;s hands. Typically, the compartment on the ambulance will have rails with rollers or slides upon which the cylinder rests. To remove the cylinder, the EMS worker must grasp the cylinder near the supporting rollers and apply upward pressure to maintain sufficient friction to drag the bottle from the compartment. Often, injuries occur in this process due to the tank shifting and fingers becoming pinched between the tank and the rollers/slides. 
   Therefore, a need exists for a device that allows a vertically stored cylinder to be securely lifted, transported, and/or rotated horizontally such that it can be safely inserted into a horizontal storage compartment onboard an EMS vehicle. Further, a need exists for a safe and secure device that allows the cylinder to be inserted into and removed from the compartment either top first (valve end) or bottom first (foot end). Further, a need exists for such a device that positively supports and locks the cylinder in the horizontal position. Finally, a need exists for a device that allows a horizontally stored cylinder to be safely and easily gripped to allow an individual to move the cylinder. These needs and others are satisfied by the disclosed invention. 
   BRIEF SUMMARY OF THE INVENTION 
   In light of the difficulties faced with lifting and moving pressurized tanks, it is one object of the present invention to provide an apparatus that can safely and efficiently lift, support, and control a pressurized tank during transport. 
   It is yet another objective of the present invention to provide an apparatus that allows a mounted cylinder to be rotated to or from a horizontal position for removal from or insertion into an EMS stowage compartment. 
   It is yet another objective of the present invention to provide an apparatus that allows the cylinder to be inserted either top first or bottom first into an EMS stowage compartment. 
   It is yet another objective of the present invention to provide an apparatus that can be easily maneuvered by a single operator under all load conditions. 
   It is yet another objective of the present invention to provide an apparatus that is simple to operate. 
   It is yet another objective of the present invention to provide an apparatus that is compact in size to allow easy manipulation of tanks within the confines of ambulance stowage compartments. 
   It is yet another object of the present invention to provide an apparatus that allows an EMS worker to safely and securely grasp a horizontal cylinder for removal from or insertion to an EMS vehicle&#39;s stowage compartment. 
   In accordance with a preferred embodiment of the present invention, a battery-powered electric hoist is provided that incorporates a tank cradle for firmly and safely restraining a pressurized tank for transport. The hoist incorporates an electric linear actuator that can raise the tank to the desired height of an ambulance stowage compartment. The tank cradle features a locking mechanism that allows the cradle and cylinder to be rotated between the vertical and horizontal positions. Large swivel casters are also provided to allow for easy movement of the hoist and attached tank by a single operator. In addition, the tank cradle and base are compact in size to allow for easy maneuverability. This affords greater ease in inserting and removing a pressurized tank from the cramped stowage compartments of an ambulance. 
   An additional embodiment features a novel foot retraction mechanism that allows a cylinder, when mounted in the cradle in the horizontal position, to be slid horizontally from the cradle bottom first into an ambulance stowage compartment. A novel positive integrated locking mechanism is incorporated such that when the foot is retracted the tank cradle cannot be moved from the horizontal position. Other embodiments of the invention feature a fixed foot mechanism so that the cylinder can only be slid horizontally from the cradle top first into an ambulance stowage compartment. 
   The invention accordingly comprises the features described more fully below, and the scope of the invention will be indicated in the claims. Further objects of the present invention will become apparent in the following detailed description read in light of the drawings. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
     The present invention will be more fully understood by reference to the following detailed description of the preferred embodiments of the present invention when read in conjunction with the accompanying drawings, in which like reference numerals refer to like parts throughout the views, wherein: 
       FIG. 1  is a perspective view of an embodiment of the present invention with a fixed foot and the tank cradle with cylinder raised and locked in the horizontal position for a top first insertion; 
       FIG. 2  is a perspective view of an embodiment of the present invention with a retractable foot mechanism and the cylinder raised and locked in the horizontal position for a bottom first insertion; 
       FIG. 3  is a close-up view of the retractable foot mechanism actuating handle in the extended position with the tank cradle locked in the vertical position; 
       FIG. 4  is a close-up view of the retractable foot mechanism and tank cradle cylinder support surface; 
       FIG. 5  is a close-up view of the retractable foot mechanism handle and linkage with the foot in the extended position on a tank cradle unlocked while in the horizontal position; 
       FIG. 6  is a close-up view of the retractable foot mechanism handle and linkage with the foot in the retracted position on a tank cradle positively locked in the horizontal position; 
       FIG. 7  is a perspective view of an embodiment of the present invention as it is used to insert a cylinder or remove it from a vertical stowage compartment onboard an EMS vehicle; 
       FIG. 8  is a perspective view of an embodiment of the present invention as used in a foot first stowage situation in an EMS vehicle with a horizontal compartment; 
       FIG. 9  is a perspective view of an embodiment of the present invention as used in a top first stowage situation in an EMS vehicle with a horizontal compartment; 
       FIG. 10  is a detailed view of an embodiment of the tank gripping device for safely gripping and positioning a horizontal tank; 
       FIG. 11  is a drawing of the tank gripping mechanism as it is attached to a cylinder; and 
       FIG. 12  is a drawing depicting the proper use of the tank gripping device to position a horizontal cylinder. 
   

   Where used in the various figures of the drawing, the same reference numbers designate the same or similar parts. Furthermore, when the terms “top,” “bottom,” “first,” “second,” “upper,” “lower,” “height,” “width,” “length,” “end,” “side,” “horizontal,” “vertical,” and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawing and are utilized only to facilitate describing the invention. 
   All figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the figures with respect to number, position, relationship, and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following teachings of the present invention have been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following teachings of the present invention have been read and understood. 
   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  illustrates a hoist  100  according to one embodiment of the present invention with a cylinder  108  mounted in the tank cradle  102  and raised for transport. The cradle  102  features a fixed foot  104  and only allows the hoist  100  to be used in either a vertical or top first cylinder installation/removal situation. When the cylinder  108  is positioned for transport, an operator can grasp the handle  118  and easily move the hoist  100  into position. The rugged support base  116  features large casters for ease of movement of the hoist  100  with cylinder  108  over standard surfaces by a single operator. 
   Outside of an EMS vehicle, the cylinder  108  is typically stored standing vertically. An EMS worker or other individual seeking to replace a cylinder will position the hoist  100  such that the vertical tank cradle  102  is touching the cylinder  108 . A ratchet strap or similar retention mechanism is then utilized to positively retain the cylinder  108  to the tank cradle  102  during transport. Once strapped into the tank cradle  102 , the controller and power source  114  allows the linear actuator  112  to raise the tank cradle  102  to the desired height. Once raised, the tank cradle  102  can be rotated and locked in the horizontal position with the pivot mechanism  110 . 
   The pivot mechanism  110  features stops that prevent the tank cradle  102  from rotating more than approximately 90 degrees from the vertical position such that the cylinder remains on top of the tank cradle  102  in the horizontal position. In another embodiment the tank cradle  102  is allowed to rotate slightly more than 90 degrees from the vertical position to allow gravity to assist the operator in removing the cylinder  108  from the tank cradle  102 . 
     FIG. 2  illustrates a hoist  200  according to another embodiment of the present invention. In this embodiment, the tank cradle  102  features a retractable foot mechanism  202  and actuating handle  204 . The actuating handle  204  is tied to the foot mechanism  202  via linkage that interacts with the pivot mechanism  110 . In this embodiment, the handle  204  is rotated counterclockwise (when viewed from the handle  204  to the foot  202 ) to extend the foot  202 . To retract the foot  202  requires approximately a quarter turn of the handle  204  in the clockwise direction. One skilled in the art will appreciate that the direction and amount that the handle  202  turns can vary without straying from the inventive concept. 
     FIG. 3  shows a close-up view of the linkage  302  as it interacts with the pivot mechanism  110 . When the tank cradle  102  is in the vertical position, the linkage  302  does not allow the actuating handle  204  to be moved from the “foot mechanism extended” position. Thus, the foot  202  remains extended while the cradle  102  is vertical. If the foot  202  were retracted in this vertical position, the cylinder would likely slip from the tank cradle  102  and cause damage.  FIG. 4  illustrates the foot mechanism  202  in the extended position. 
     FIG. 3 ,  FIG. 5 , and  FIG. 6  each illustrate the pivot mechanism  110  in greater detail. The mechanism  110  has two brackets. One bracket is affixed to the linear actuator  112  and the other is affixed to the tank cradle  102 . A central support shaft connects the two brackets and allows the cradle side to rotate on bearings independently of the actuator side. In another embodiment the central support shaft utilizes bushings in place of bearings. 
     FIG. 5  and  FIG. 6  depict the linkage  302  and its interaction with the pivot mechanism  110 .  FIG. 6  shows the mechanism with the tank cradle  102  in the horizontal position and the foot  202  retracted. The linkage  302  engages a hole in the pivot mechanism  110  to positively lock the cradle  102  in the horizontal position. When the foot  202  is extended as in  FIG. 5 , the linkage  302  disengages the hole in the pivot mechanism  110  and the cradle  102  is allowed to rotate to vertical. When the cradle  102  is vertical, as shown in  FIG. 3 , the linkage  302  is blocked from movement by the spring loaded locking pin. This creates a positive means for locking the foot retraction mechanism handle  204  in the extended position and thus prevents a mounted cylinder from slipping off of the bottom of the tank cradle  102 . 
   The pivot mechanism  110  further comprises perforations through which the linkage  302  can pass to physically lock the two sides of the mechanism  110 . The spring-loaded locking pin with handle utilizes its own perforations. This spring-loaded locking pin allows the operator to lock the cradle in either the horizontal or vertical position. 
   The major structural components of the hoist ( 100  and  200 ) are constructed from steel. Steel is preferable because is inexpensive, easy to fabricate, structurally stable, and readily available. However, a person having ordinary skill in the art of fabrication would realize that other metals such as aluminum or even materials such as polymer composites may be used depending upon the structural load requirements. Lighter materials may make the hoist ( 100  and  200 ) easier to maneuver due to the lighter weight. However, the tradeoff may be in increased cost and reduced stability of a fully-loaded device. Steel provides a good balance of manufacturability, cost, stability, and maneuverability. 
   With reference to  FIG. 1  and  FIG. 2 , the hoist ( 100  and  200 ) features a support base  116  with swivel casters for maneuverability. The base  116  is fabricated such that there is a center opening between two outer rails. The center opening is just wide enough to allow for a pressurized cylinder to fit between the rails for attachment to the tank cradle  102 . 
   With reference to  FIG. 1  and  FIG. 2 , the hoist ( 100  and  200 ) features a tank cradle  102  that is shaped to wrap partially around a pressurized tank for support. The radius of the curve of the cradle  102  approximates the radius of the body section of the pressurized tank. The cradle  102  also extends vertically to the approximate height of the body portion of a full-sized pressurized tank. Thus, because its height is suitable for the tallest tank, the cradle  102  can support essentially any sized pressurized tank. One skilled in the art will recognize that the length of the tank cradle can be tailored to the desired application without straying from the inventive concept. 
   With reference to  FIG. 4 , the cradle  102  features support rails  402  for the cylinder. The supports  402  in one embodiment comprise polymer strips (such as polytetrafluoroethylene which is sold under the trademark TEFLON). The polymer strips reduce the coefficient of friction between the cradle  102  and cylinder  108  and allow the cylinder  108  to be easily slid to or from an EMS vehicle&#39;s storage compartment on the cradle  102 . Other surface materials, such as natural fibers or metal, can be utilized as well so long as they serve to reduce friction and aid in cylinder  108  movement. Other embodiments may utilize metal or plastic rollers to reduce friction and aid in cylinder  108  movement. 
     FIG. 7  depicts an ambulance with a vertical stowage compartment. In this illustration, the present invention is being used to either install a cylinder to or remove a cylinder from the vertical compartment. If removing the cylinder, the hoist is positioned next to the compartment and the tank cradle is raised to the proper height. The cradle can then be inserted into the compartment and the cylinder strapped to the cradle. By slightly raising the cradle further, the cylinder, which rests upon the foot of the cradle, is raised clear of the compartment floor. The hoist can then be pulled from the compartment and the cylinder extracted for replacement. To insert a cylinder into the stowage compartment merely requires reversal of the steps for removal. 
     FIG. 8  depicts an ambulance with a horizontal stowage compartment requiring a bottom first insertion. Once the cylinder is resting on the cradle foot and is strapped to the vertical tank cradle, it can be raised clear of the floor. The cradle can then be rotated approximately 90 degrees from vertical and the cylinder height positioned such that it aligns with the horizontal compartment. Once the hoist is positioned next to the compartment, the cradle foot can be retracted. Once retracted, the foot retraction mechanism linkage positively locks the cradle in this horizontal position. With the foot retracted, the cylinder retention strap can be removed and the cylinder can then be slid from the cradle bottom first into the compartment. Removal of a horizontally mounted tank merely requires reversal of the steps for insertion. 
     FIG. 9  depicts an ambulance with a horizontal stowage compartment requiring a top first insertion. As with the previous steps, once the cylinder is resting on the cradle foot and is strapped to the vertical tank cradle, it can be raised clear of the floor. The cradle can then be rotated approximately 90 degrees from vertical and the cylinder height positioned such that it aligns with the horizontal compartment. Once the hoist is positioned next to the compartment, the cylinder retention strap can be removed and the cylinder can then be slid from the cradle top first into the compartment. Removal of a horizontally mounted tank merely requires reversal of the steps for insertion. 
     FIG. 10  illustrates a tank gripping device  1000  that facilitates safe movement of a horizontal cylinder. This device  1000  comprises flexible material  1006 , a locking adjustable buckle  1002 , and an integral handle  1004 . The flexible material in the present embodiment is nylon strap that is of sufficient size and strength to support a substantial portion of the weight of a full cylinder. Other materials such as polypropylene, polyester, leather or canvas strap may also be used for the strap  1006 . 
   Another embodiment of the device  1000  comprises a rubberized coating  1008  on the inner surface of the device material. This rubberized coating improves the devices grip strength on a cylinder. This prevents the strap from slipping on the cylinder&#39;s outer surface as force is applied to move the cylinder. 
   The device  1000  also features a buckle  1002  that is self locking with a single pull adjustment. However, the same effect can be achieved through the use of a cam buckle, rectangular ring, circular ring, slider, glide, or ladderloc buckle. In addition, the buckle  1002  can be either metal or plastic so long as it too is sufficiently strong to withstand a substantial portion of the weight of a full cylinder. 
   The device  1000  features an integral handle  1004  that provides a means for the EMS worker to safely and confidently grip and move a cylinder. This handle  1004  is typically made from the same material as the strap  1006 . However, the handle can be different. For instances, the handle  1004  could be made from nylon strap encased with glove leather for a more comfortable grip. 
   The handle  1004  comprises a length of material that is attached to the outer surface of the device  1000 . The means of attachment is dictated by the materials chosen. For example, the present embodiment is made from nylon strap, which allows the handle  1004  to be sewn directly to the device&#39;s outer surface. Other materials, such as natural or synthetic leather, may be sewn or attached using buckles. The attachment means used should be capable of withstanding a substantial portion of the weight of a full cylinder. 
     FIG. 11  depicts a tank gripping device  1000  as it is attached to a cylinder. The adjustment on the device  1000  is loosened and the device is wrapped around the perimeter of the cylinder. Once buckled, the device is tightened. This provides an EMS worker with a handle for securely gripping a cylinder for positioning. 
     FIG. 12  depicts a cylinder  108  as it appears in a horizontal stowage compartment. The cylinder  108  rests on rails or rollers within the compartment. An EMS worker seeking to move the cylinder  108  opens the device&#39;s buckle  1002  and wraps it around the perimeter of an accessible portion of the cylinder  108 . This may require lifting the cylinder  108  slightly upward in order to get the strap  1006  between the cylinder and the rails upon which it rests. Once the device  1000  is in place, the buckle  1002  can be closed and the strap tightened to securely grip the cylinder  108 . The EMS worker can then grasp the handle  1004  and safely pull the cylinder  108  from the compartment without concern for pinched fingers. 
   In view of the foregoing, the hoist serves special needs required by the EMS community. In particular, the hoist allows a single operator to safely and efficiently lift and transport a pressurized tank without the risk of back injury. The compact features of the hoist lend to the device&#39;s maneuverability and ease of operation. Thus, a single operator can effectively remove a pressurized tank from an ambulance compartment and install a new one without assistance. 
   Although the invention hereof has been described by way of a preferred embodiment, it will be evident that other adaptations and modifications can be employed without departing from the spirit and scope thereof. The terms and expressions employed herein have been used as terms of description and not of limitation; and thus, there is no intent of excluding equivalents, but on the contrary it is intended to cover any and all equivalents that may be employed without departing from the spirit and scope of the invention.