Patent Document

CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is a continuation of co-pending application Ser. No. 11/424,184, filed Jun. 14, 2006, which is incorporated by reference herein in its entirety. 
    
    
     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 of the pressurized cylinders used are made from either aluminum or steel. Though a lightweight material, an empty aluminum pressurized oxygen cylinder can weigh over one hundred pounds. Steel cylinders are heavier yet. 
     The Occupational Safety and Health Administration (OSHA) does not have a standard which sets limits on how much a person 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 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 tank would increase this number even more. 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 faced with the task of changing out cylinders. Because the spaces are so small, only one worker can realistically fit within the compartment to manipulate the cylinders. 
     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. 
     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 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. 
     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. 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. 
     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; 
         FIG. 2  is a perspective view of an embodiment of the present invention with a pressurized tank attached to the cradle for transport; and 
         FIG. 3  is a side-facing illustration of an embodiment of the present invention with a pressurized tank in position for transport. 
     
    
    
     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. 
     REFERENCE NUMERALS 
     
         
           100  hoist 
           102  cradle 
           104  safety ring 
           106  strap 
           108  lip 
           110  linear actuator assembly 
           112  height switch 
           114  battery charger 
           116  battery 
           118  handle 
           120  base 
           122  swivel caster 
           124  fixed caster 
       
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  and  FIG. 2  illustrate a hoist  100  according to one embodiment of the present invention.  FIG. 1  shows the hoist  100  without a pressurized tank attached to its cradle  102 .  FIG. 2  shows the hoist  100  with a pressurized tank attached to its cradle  102  and lifted for transport. The hoist  100  features a tank cradle  102  for securely attaching a pressurized cylindrical tank and supporting it during transport. The cradle  102  is attached to a linear actuator assembly  110  that provides vertical lifting motion to the cradle  102 . The electrical power for the linear actuator comes from a 24V battery  116  that features its own trickle battery charger  114 . The linear actuator assembly  110  is attached to a narrow base  120  that features heavy duty casters on its four corners. The front of the base  120  features fixed casters  124  while the rear features swivel casters  122  to allow for easy steering and maneuverability. 
     The major structural components of the hoist  100  are constructed from steel. Steel was chosen because it 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  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 cost, stability, and maneuverability. 
     With reference to  FIG. 1  and  FIG. 2 , the hoist  100  according to the present embodiment features a narrow base  120  with swivel casters  122  for increased maneuverability. The base  120  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 . The base  120  also features an attached handle  118 . The handle  118  allows an operator to maintain a comfortable grip on the hoist  100  while maintaining proper control under a full load. The forward edge of the outer rails of the base  120  feature fixed casters  124  while the rearward edge of the rails feature swivel casters  122 . The swivel casters  122  are located essentially beneath the operator&#39;s handle  118  to allow the hoist  100  to be easily steered into position even with a load attached. In addition, the swivel casters  122  also feature locking mechanisms to allow a fully-loaded hoist  100  to be safely parked. 
     While the current embodiment provides four casters for maximum stability, other configurations are possible and are within the scope of the present invention. For example, in another embodiment all four of the casters could swivel. In yet another embodiment, the base  120  could utilize only three casters; two on the forward ends of the outer rails of the base  120  nearest the tank opening and one swivel caster on the opposite end of the base  120 , located in the center approximately beneath the linear actuator  110 . Utilizing only three casters would improve the maneuverability of the hoist  100  but at the same time would sacrifice some of the vertical stability. 
     With reference to  FIG. 1  and  FIG. 2 , the hoist  100  according to the present embodiment 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. 
     With reference to  FIG. 1  and  FIG. 2 , the cradle  102  features a lip  108  near the bottom that engages the base of a pressurized tank that is to be attached to the cradle  102 . To attach a tank, the lip  108  is brought into contact with the base of the tank. The tank is then tipped slightly away from the lip  108  so that the lip  108  can slide beneath the tank. Once the tank rests on the lip  108 , the primary and backup attachment means can be utilized to restrain the tank within the confines of the cradle  102 . 
     With reference to  FIG. 1  and  FIG. 2 , the primary attachment means provided in the present embodiment is a strap  106  with an adjustable side release buckle. The strap  106  is wrapped around the body of the tank and the side release buckle is engaged and adjusted to put tension on the strap  106  to restrain the tank within the cradle  102 . While the present embodiment utilizes a strap  106  for the primary attachment means, other embodiments could utilize chain, rope, or cable. Also, a strap with a ratchet tightening mechanism, a belt-type buckle, or a hook and loop fastener could be used in place of the adjustable side release buckle for maintaining proper tension on the strap  106 . 
     With reference to  FIG. 1  and  FIG. 2 , the backup attachment means provided in the present embodiment is a safety ring  104 . The safety ring  104  is designed to provide backup retention of the tank in the cradle  102  should the strap  106  inadvertently release. In the present embodiment, the safety ring  104  is constructed of plastic coated steel cable. The steel cable provides tensile strength while the plastic coating prevents the cable from scratching or marring the finish of a tank. While the present embodiment utilizes plastic coated steel cable for the safety ring  104 , other embodiments could utilize uncoated steel cable, chain, rope, or even strap. 
     The safety ring  104  is threaded through a piece of tubular steel that fits within the center piece of slightly larger diameter tubular steel that makes up the framework of the cradle  102 . Thus, the safety ring  104  can be lifted by raising the attached piece of tubular steel to a height that allows the safety ring  104  to slip easily over the tank&#39;s valve portion. When released, the tubular steel attached to the safety ring  104  slips down within the larger center piece of tubular steel that makes up the framework of the cradle  102 . This allows the safety ring  104  to be rapidly installed and removed. 
     The hoist  100  according to the present embodiment features a linear actuator assembly  110  that is attached to both the cradle  102  and base  120 . The linear actuator  110  uses electrical power from the 24V battery  116  to operate. The height switch  112  allows the linear actuator to extend and raise the tank cradle  102  with attached tank up to 27 inches above the floor surface. This height is sufficient for insertion of a tank into typical ambulance stowage compartments. A second position of the height switch  112  allows the linear actuator  110  to retract and thus return the cradle  102  to the floor level. 
     Power for the linear actuator  110  comes from a rechargeable 24V battery  116 . The hoist  100  also features a built-in trickle charger  114  to allow the hoist  100  to be plugged into a standard wall socket and recharged when not in use. Battery power is utilized to prevent the need for an electrical cord to provide power to operate the hoist  100 . This increases the devices portability and maneuverability. While the present embodiment utilizes a 24V power source, other voltages may be substituted as determined by the voltage requirements of the linear actuator  110  mechanism. 
       FIG. 3  shows a hoist  100  being used by an operator  300  to transport a pressurized tank  302 . The operator  300  maneuvers the hoist  100  by utilizing the handle  118 . Once in position, the hoist  100  can be parked by locking the swivel casters  122 . The cradle  102  can then be raised or lowered by operation of the height switch  112 . 
     In view of the foregoing, the hoist  100  serves special needs required by the EMS community. In particular, the hoist  100  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  100  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.

Technology Category: 7