Patent Publication Number: US-2010117038-A1

Title: Foot-Operated Hydraulic Lift for Trailer

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to lifting mechanism or apparatus for use with wheeled trailers for lifting a portion of the trailer. More particularly, the present invention relates to such mechanisms or apparatus for lifting a portion of the trailer associated with a hitch to facilitate coupling the hitch and trailer to another vehicle. 
     2. Summary of the Prior Art 
     Trailers, as the name implies, typically are coupled to and trail behind a towing vehicle. A ball-and-socket type trailer hitch is conventionally employed to couple the two together. The hitch is usually a forward portion of the trailer referred to as the “tongue.” Such lifts are sometimes called “tongue jacks.” 
     In many cases, the trailer is not coupled to the towing vehicle until the trailer is already loaded and quite heavy. The load exerted on the tongue and hitch portion of a trailer often is in excess of several hundred pounds. In such cases, attaching the trailer to the vehicle can be challenging because the hitch and tongue of the trailer generally must be raised above the level of the hitch on the vehicle, the two portions of the hitch aligned, and the tongue portion of the trailer lowered to fully engage the hitch. Accordingly, various lifting mechanisms have been associated with such trailers to facilitate the coupling operation. The lifting mechanism also supports the tongue and receiver (or forward) end of the trailer when it is uncoupled from the towing vehicle. 
     Improvements have been made over time to the lifting mechanisms or apparatus used in conjunction with trailers. Such improvements include the use of electric motors and hydraulics to raise and lower the tongue and hitch of the trailer. Hydraulic lifts are smoother and often safer in operation than mechanical lifts, which can be subject to backlash. U.S. Pat. No. 3,273,858 to Coburn discloses a hand-operated hydraulic elevator for a trailer tongue. U.S. Pat. No. 4,911,460 to DePaula discloses a hand-operated mechanical arrangement. U.S. Pat. No. 5,011,119 to Harrington discloses another hand-operated hydraulic jack. 
     A typical consumer use for a trailer is to haul a boat. In such applications, the trailer often is partially submerged in water when launching and trailering the boat. Use in or near water militates against the use of electrically actuated systems. Even without the presence of water, electrically operated systems require a connection to an electric power source (usually that of the towing vehicle) and present complications in use, safety and reliability concerns. Hand-pumped hydraulic or hand-cranked mechanical systems avoid these shortcomings, but require the use of at least one of the operator&#39;s hands, which leaves only one (if any) hand free to manipulate the hitch or perform other operations. Moreover, the level of the lift and trailer tongue is usually low enough to the ground to make hand operation awkward and possibly unsafe. 
     A need exists, therefore, for a lift mechanism or apparatus for a wheeled trailer that has simple, reliable construction and that is safe, easy, and convenient to use. 
     SUMMARY OF THE INVENTION 
     It is a general object of the present invention to provide an improved lift for a wheeled trailer to be towed behind a vehicle. This and other objects of the invention are attained by providing a lift comprising an inner sleeve and a foot member coupled to a lower end of the inner sleeve. An outer sleeve is concentrically and slidingly mounted over the inner sleeve. A mount is secured to an upper end of the outer sleeve opposite the foot member for securing the frame to the trailer at a location proximal to the hitch. An hydraulic pump is contained within the inner sleeve. A rod is selectively extensible from the hydraulic pump. An upper end of the rod is coupled to the upper end of the outer sleeve. A foot-pedal actuator is operatively connected to the hydraulic pump to selectively actuate the hydraulic pump, extend the rod, and move the outer sleeve relative to the inner sleeve. The pedal actuator is mounted at a lower end of the inner sleeve and configured to be engaged and operated by the foot of a human user. A positive stop member is arranged between the inner and outer sleeves, the stop member configured to stop relative axial or longitudinal movement between the sleeves and mechanically fix the lift in a selected position. 
     According to a preferred and illustrative embodiment of the invention, the foot member includes a wheel configured to roll on the ground surface. 
     According to a preferred and illustrative embodiment of the invention, a pressure-relief valve is accessible to a user to selectively relieve pressure from the hydraulic pump. 
     According to a preferred and illustrative embodiment of the invention, the mount permits the frame to pivot from an operative position in which the sleeves are generally perpendicular to the ground surface and a stowed position in which the sleeves are oriented at an acute angle to the ground surface. 
     According to a preferred and illustrative embodiment of the invention, the actuator further includes a biasing member to maintain the actuator in an operative position. 
     According to a preferred and illustrative embodiment of the invention, at least one key and keyway is disposed between the inner and outer sleeves to prevent relative rotation therebetween. 
     According to a preferred and illustrative embodiment of the invention, the pedal actuator pivots between a folded position adjacent the inner and outer sleeves, and a deployed position for actuation by the foot of a human user standing on the ground surface. 
     According to a preferred and illustrative embodiment of the invention, the key and keyway further comprises a longitudinally extending slot formed in an exterior of the inner sleeve; and a longitudinally extending key formed in an interior of the outer sleeve and registering with the slot in the inner sleeve upon assembly of the two. 
     Other objects, features, and advantages of the present invention will become apparent with reference to the drawings and detailed description, which follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevation view of a wheeled trailer including the lifting apparatus according to the present invention. 
         FIG. 2  is an enlarged elevation view of the lifting apparatus of  FIG. 1  in a deployed or near-vertical position. 
         FIG. 3  is an elevation view of the lifting apparatus of  FIGS. 1 and 2  pivoted into a stowed or near-horizontal position. 
         FIGS. 4 and 5  are an enlarged elevation view, partially in section, of the lifting apparatus of  FIGS. 1 ,  2 , and  3 . 
         FIG. 6  is an enlarged, fragmentary view, partially in section, of the attachment or mounting of a portion of lifting apparatus according to the present invention to a portion of the trailer. 
         FIG. 7  is an elevation view of a second illustrative embodiment of the lift of the present invention. 
         FIG. 8  is a fragmentary longitudinal section of a lower portion of the lift of  FIG. 7 , taken along section line  8 - 8  of  FIG. 7 . 
         FIG. 9  is a fragmentary longitudinal section of an upper portion of the lift of  FIG. 7 , the section being rotated 90 degrees from that of  FIG. 8 . 
         FIG. 10  is a cross-section view of the lift of  FIG. 7 , taken along section line  10 - 10  of  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the Figures and particularly to  FIG. 1 , the numeral  1  designates a wheeled trailer of the type with which the present invention is employed. The present invention is particularly adapted to those wheeled trailers that are adapted to haul or carry boats  3 , such as that illustrated in  FIG. 1 , because of the relatively great loaded weight of such trailers and the frequency with which they are coupled and uncoupled from a towing vehicle. As can be seen, trailer  1  has a hitch  5  at a forward portion thereof, which is secured to a tongue portion  7  of trailer  1 . Typically, hitch  5  is a socket member that registers with a corresponding hitch ball (not shown) on a towing vehicle (also not shown). 
     A lifting mechanism or apparatus (“lift”)  11  according to the present invention is secured to a tongue portion  7  of trailer proximal to or near hitch receiver  5 . As shown in  FIG. 1 , lift  11  serves as a third wheel or support to maintain trailer  1  in a generally level orientation when trailer  1  is not coupled to a towing vehicle. A lift  11  according to the present invention finds particular utility in those trailers  1  adapted to carry or haul boats because such trailers often are extremely heavy and incapable of being manipulated solely by a user, without the assistance of a mechanical advantage. 
       FIGS. 2 and 3  are enlarged elevation views of the lift  11  according to the present invention illustrating the lift in a deployed or near-vertical position ( FIG. 2 ) and a stowed or near-horizontal position ( FIG. 3 ). Lift  11  generally comprises a hydraulically extensible frame  13  that is coupled to a generally horizontally extending portion of trailer tongue  7  by a pivoting mount or bracket  15 . At its lower end, frame  13  terminates in a foot member, which is preferably a wheel but may be another type of support. Additionally, frame  13  (and lift  11 ) is provided with an actuator  19  in the form of a foot pedal. Foot pedal  19  is arranged to be no higher than a selected height h of about 18-24 inches so that it is adapted to be engaged and operated by a foot of a human user. 
       FIGS. 4 and 5  are enlarged elevation views, partially in section, of lift  11  according to the present invention.  FIG. 4  depicts lift  11  in a retracted or fully compressed stated while  FIG. 5  depicts lift  11  in an extended state in which tongue  7  of trailer  1  is being (or has been) raised by lift  11 . The hydraulically extensible frame ( 13  in  FIG. 2 ) of lift  11  comprises a conventional bottle jack, which has an hydraulic cylinder  21  and a rod  23  extending or protruding a selected and variable distance from cylinder  21 . According to the preferred embodiment of the present invention, the bottle jack is commercially available, such as the AC-Delco® Hydraulic Bottle Jack, Model 34112. 
     Rod  23  terminates at its end in a cylindrical member  25 , which preferably is a steel cylinder welded to the end of rod  23 . Rod  23  preferably has a threaded exterior and its protrusion from cylinder  21  is adjustable by rotating rod  23  relative to cylinder  21 . This provides an adjustment of the overall height of frame  13  to accommodate towing vehicles with differing bumper (and hitch) heights. A conventional bolt  27  extends through cylindrical member  25  to couple a tubular frame member  29  to rod  23 . Rod  23  is the portion of the bottle jack that extends upwardly from cylinder  21  responsive to hydraulic actuation of the bottle jack. Tubular frame member  29  thus moves up and down with rod  23  relative to cylinder  21 . Tubular frame member  29  is dimensioned to slide concentrically over and cover cylinder  21 . In the fully compressed position depicted in  FIG. 4 , cylinder  21  of the bottle jack is almost completely covered by frame member  29 . 
     Foot pedal or actuator  19  is coupled to an actuator cylinder  31  and actuator rod  33 . Actuator rod and cylinder  31 ,  33  are part of the bottle jack and operate to exert pressure on the hydraulic fluid in cylinder  21  of the bottle jack, thereby extending rod  23  from cylinder  21  and raising or extending the frame of lift  11 , in turn raising tongue  7  of trailer  1 . As noted previously, actuator pedal  19  is designed, intended, and adapted to be operated by the foot of a human user. Accordingly, it is preferably no higher than a height h of about 18 inches from the ground when lift  11  is in the deployed position. Height h should not exceed 24 inches if an average human operator is to use lift  11  without risking the loss of balance. 
     In addition to being positioned to be engaged by a foot, foot pedal or actuator  19  is biased into an upward position by a compression coil spring or biasing member  41 . Spring  41  maintains pedal  19  in the upward position at all times (except when pedal  19  is depressed by an operator) and permits the operator&#39;s foot to do actuation work only on the downward stroke of pedal  1 . Spring  41  is captured between pedal  19  and base plate  47  of the bottle jack by a tube  43 . The upper extent of spring  41  is covered with a plastic or metallic bellows  45  for aesthetic and functional purposes (to improve appearance and to keep materials from being pinched or caught in spring  41 ). 
     A stopcock  37  functions to release pressure within the bottle jack, thereby permitting rod  23  and tubular frame  29  to compress or retract relative to bottle jack cylinder  21 , in turn lowering tongue  7  of trailer  1 . 
       FIG. 6  is an elevation view, partially in section, of pivoting mount  15 , taken along the section line  6 - 6  of  FIG. 5 . Mount  15  comprises a pair of parallel, spaced-apart plates  51  that are secured to either side of the box-girder of trailer tongue  7  by four bolts  53 , two of which are shown in  FIG. 6 . A bracket  55  is mounted for rotation on one of plates  51  by a pivot or axle  57 . Bracket  55  is, in turn, welded to tubular frame member  29 . 
     A U-shaped, spring-loaded handle  59  is secured to bracket  55 . One end  59 A of handle  59  extends through an aperture in bracket  55  and into an aperture in plate  51 , thereby securing bracket  55  and tubular frame member  29  of lift  11  against rotation relative to trailer tongue  7 . By pulling outward (to the right in  FIG. 6 ) on handle  59 , end  59 A is disengaged from the aperture in plate  51 , freeing bracket  55 , frame  29  and lift  11  to pivot between the stowed and deployed positions illustrated in  FIGS. 2 and 3 . Although a horizontal stowed position is shown in  FIG. 3 , it is actually preferred that the lower end of lift  11  be angled slightly downward to permit drainage of water from the assembly. In this stowed position, lift  11  should describe an acute angle relative to tongue  7  or the ground surface of about 15-30 degrees. 
       FIG. 6  also illustrates a fixed height adjustment provided for lift  11  by holes or apertures  29 A formed in the wall of tubular frame member  29 . By removing bolt  27 , moving frame member  29  relative to cylindrical member ( 25  in  FIGS. 4 and 5 ) into alignment with one of the other apertures  29 A, and re-inserting bolt  27 , the overall height of lift  11  can be adjusted in a fixed fashion, without regard to the level of extension of rod ( 23  in  FIGS. 4 and 5 ) relative to cylinder ( 21  in  FIGS. 4 and 5 ) or tubular member  29 . 
     In operation, the first illustrative or preferred embodiment of lift  11  is coupled to tongue  7  of trailer near hitch  5  as shown in  FIGS. 1 and 6 . Frame  13  of lift  11  is pivoted to the deployed or near-vertical position as shown in  FIG. 2 . Lift then is capable of supporting the forward or front end of trailer  1 , even under load. To couple hitch to a towing vehicle, foot pedal  19  is actuated by an operator&#39;s foot, extending rod  23  from cylinder  21  and extending tubular frame  29  relative to foot member  17 , thereby raising tongue  7  relative to the ground. Tongue  7  and hitch  5  may then be aligned, with the assistance of wheeled foot member  17 , over the hitch ball. Stopcock  37  is then released to permit rod  23  to retract into cylinder  21  and frame member  29  to retract relative to foot member  17 . Tongue  7  and hitch  5  then are lowered into engagement with the hitch ball. The process is essentially reversed to disengage or uncouple trailer  1  from the towing vehicle. Additionally, by manipulating handle  59  of mount  15 , lift  11  may be pivoted between stowed and deployed positions to facilitate towing trailer  1  over uneven terrain. 
       FIGS. 7 through 10  illustrate another embodiment of a trailer lift  111  according to the present invention. This embodiment employs a purpose-built hydraulic pump assembly, as opposed to the bottle jack of the embodiments of  FIGS. 1 through 6 . This embodiment of trailer lift  111  functions virtually identically (except as noted below) and appears similar to the embodiment of  FIGS. 1 through 6 . Generally like structures are numbered similarly. 
       FIG. 7  shows trailer lift  111  in a deployed (vertical) and extended position. Lift  111  is shown coupled to the tongue  7  proximate the hitch receiver portion  5  of a trailer (shown in  FIG. 1 ). Lift  111  is coupled to trailer tongue  7  by a pivoting bracket  15 , substantially similar to that illustrated with reference to  FIGS. 1 through 6 . 
     At the lowermost end of lift  111 , a foot member or wheel  17  is arranged in a swiveling, caster fashion. A foot pedal  119  is pivotally secured by joint  119 A and folds with respect to lift  111 , as indicated by the phantom lines for storage “out of the way.” The pivoting foot pedal also functions as a handle or grip to assist a user in moving lift  111  between the deployed or vertical, and stowed positions shown in  FIGS. 2 and 3 . In the stowed position, lift  111  preferably occupies a position in which the longitudinal axis of lift  111  describes an acute angle with reference to the ground surface or the tongue  7  portion of trailer to facilitate drainage of water from the assembly. 
     An upper cylinder or sleeve  129  slides over and reciprocates or telescopes with respect to an inner cylinder or sleeve  121  in response to actuation of lift  111  by foot pedal  119 . Upper cylinder  129  is coupled by bolts and a flange ( 199  in  FIGS. 9 and 10 ) to bracket  15  to permit deployment and stowage. Actuation of pedal  119  by the foot of a user selectively extends upper cylinder  129  relative to inner cylinder  121  and foot or wheel  17 , thus effectuating lifting of trailer tongue  7  and hitch receiver  5 . Again, foot pedal should be arranged to be engaged by the foot of a user and should be no more than about 18-24 inches off the ground in its position of maximum upward travel. 
     As will be described in greater detail with reference to  FIG. 10 , outer cylinder or sleeve  129  is provided with a positive stop member  191  in the form of a spring-loaded cylinder that selectively engages a receptacle in inner cylinder  121 . Inner cylinder  121  (in the hydraulic assembly contained therein) includes a bypass valve  181 . Additionally, at least one (three are illustrated in  FIG. 10 , only one of which is shown in  FIG. 7 ) longitudinally or axially extending groove, recess, or keyway  125  is provided in inner cylinder or sleeve  121 , which maintains alignment and prevents rotation between inner and outer cylinders or sleeves  121 ,  129 . 
     Referring now to  FIG. 8 , a longitudinal section view of the lowermost extent of inner cylinder  121  is shown. Wheel  17  and associated hardware are omitted from  FIG. 8  for clarity. As illustrated, a portion of foot pedal  119 B acts as a lever through roller element  119 C upon a piston  151 , which reciprocates in a bore  153 . A coil spring biasing member  155  is provided to bias or urge piston  151  in a normally downward direction. Reciprocation of piston  151  in bore  153  pumps or pressurizes hydraulic fluid, which passes through a passage  157  through a check valve  159 , another passage  161 , and into an hydraulic chamber  163  (shown in greater detail in  FIG. 9 ). Check valve  159  prevents return of hydraulic fluid from chamber  163  into bore  153 . Thus, actuation of foot pedal  119  pumps or pressurizes hydraulic fluid and causes it to raise or extend upper cylinder  129  relative to lower cylinder or sleeve  121 , as shown in greater detail with reference to  FIG. 9 . 
       FIG. 9  is another longitudinal section view of an upper portion of trailer lift  111  according to this embodiment of the present invention. The section of  FIG. 9  is rotated 90° from the longitudinal section of  FIG. 8 . Fluid pumped into hydraulic chamber  163  acts on a piston or hydraulic rod  165  to cause rod  165  to extend upward. A cylindrical sleeve  167  surrounds hydraulic rod  165  and defines the exterior of hydraulic chamber  163 . The upper end of rod  165  is coupled by a pivoting joint  169  to a cap  171 , which is in turn secured to an upper end of outer cylinder or sleeve  129 . Thus, extension of rod  165  responsive to pumping of fluid by foot pedal  119  causes relative movement between outer cylinder or sleeve  129 , coupled to the trailer, and inner cylinder or sleeve  121 , coupled to foot or wheel  17 . Raising of the trailer by lift  111  is thereby accomplished. 
     Hydraulic chamber  163  is in fluid communication with a pressure-relief valve  181 , operated by a thumb screw, through passage  185 . When pressure-relief valve  181  is open, hydraulic fluid flows from chamber  163  through passage  185 , past ball-check  183  (which prevents reverse flow), into passage  187  and into a reservoir defined between sleeve  167  and another, larger diameter sleeve  189 . Another passage (not shown) communicates fluid from the reservoir back to bore  153  through a check valve (the second ball shown in  FIG. 8  adjacent ball  159 ). Thus, fluid circulates freely from reservoir  183 , to bore  153 , and to chamber  163 . When valve  181  is open, upper cylinder  129  and associated rod  165  are free to move (retract under weight) relative to one another. Pressure-relief valve  181  should be configured either with a check valve or in such a manner that it cannot easily be removed to prevent loss of fluid from the system. 
     When pressure-relief valve  181  is closed, fluid is prevented from exiting chamber  163  and relative movement between cylinders or sleeves  121 ,  129  is prevented, except extension in response to pumping of fluid by actuation of foot pedal  119  is permitted and maintained by pressure in chamber  163 . Thus, lift  111  may be maintained in an extended (or retracted) position by closing pressure relief valve  181 . A more positive mechanical stop  191  is also provided, as discussed in greater detail with reference to  FIG. 10 , below. 
       FIG. 10  is a cross-section view through positive stop  191 , showing various features of trailer lift  111  according to this embodiment of the invention.  FIG. 10  illustrates that outer sleeve or cylinder  129  is a close sliding fit over inner sleeve or cylinder  121 . A plurality of keys or lands (three are illustrated) on the interior surface of outer sleeve  129  engage with corresponding grooves, recesses or keyways  125  formed in exterior surface of inner cylinder  121 . This insures that both cylinders or sleeves  121 ,  129  are maintained in proper axial and rotational alignment, thus avoiding or preventing bending and torsional stresses on hydraulic components on the interior of sleeve  121 . Further, sleeves  121 ,  129  cover or shroud the components of the hydraulic system from exposure to road debris and the like both in the extended and retracted positions. A longitudinally extending flange  199  is provided on one side of sleeve  129  to permit sleeve  129  (and remaining components of lift) to be secured by bolts or rivets to bracket  15 . 
     As depicted, a positive-stop member  191 , in the form of a spring-loaded cylinder, is carried on the exterior of outer sleeve  129 . Stop member  191  has a knob and is arranged so that twisting the knob in one direction or the other moves the cylinder in and out. Thus, when the knob is twisted and the cylinder moves inwardly, it engages one of a plurality of corresponding apertures formed in inner sleeve  121  to secure inner and outer cylinders or sleeves,  121 ,  129  against movement relative to one another. An aperture may be provided in inner sleeve  121  at an upper position corresponding to an extended position of lift  111 , and a lower position, corresponding to a retracted position, and a plurality of apertures provided in between to fix upper and lower sleeves  121 ,  129  at selected extended heights that may correspond, for example, to common hitch or bumper heights. Upon alignment of stop member  191  with a selected one of the aperture, and twisting of the knob, the spring biases the cylinder into engagement with the aperture, preventing relative movement between the inner and outer sleeves or cylinders  121 ,  129 . Stop member  191  must be pulled outwardly and twisted to the retracted position by the operator to raise or lower lift  111 . Because trailer lift  111  is intended to be used in connection with a trailer in both stationary and over-the-road applications, it is important that lift be securely fastened in both extended and retracted positions so that the position of lift  111  is not dependent solely upon hydraulics. 
     In operation, pivoting bracket  15  is employed to move lift  111  between deployed and stowed positions. In the deployed position, pressure-relief valve  181  is opened and positive stop  191  is released (by pulling outwardly) to permit foot or wheel  17  to extend or lower into engagement with the ground surface. Pressure-relief valve  181  then is closed and foot pedal  119  is unfolded and actuated to extend lift  111  and raise trailer tongue  7  and hitch receiver  5  (for example to disconnect hitch  5  from a vehicle). At full extension, spring-loaded stop member  191  engages and mechanically secures lift  111  in the extended position. To lower lift (and tongue  7  and hitch receiver  5 ) positive stop member  181  is disengaged (if engaged), and pressure-relief valve  181  opened to permit lift to lower under load. Upon full retraction, stop member  191  engages, mechanically securing lift  111  in the retracted position. Lift  111  then can be rotated into the stowed position for travel over-the-road by pulling on folding foot pedal  119  to rotate bracket  15 . Foot pedal  119  then is folded into the stowed position for travel. 
     According to the preferred embodiment of the present invention, outer sleeve or cylinder  129  is about three inches in diameter. The overall length of lift  111  is about 39 inches fully extended and 10 inches shorter in fully retracted position. Thus, particularly second illustrative embodiment of the present invention provides a safe, compact, strong lift that is particularly adapted to use with boat trailers, where wet conditions can be expected. The design is also configured to be especially safe and resistant to damage while the trailer is being pulled over-the-road. The hydraulic components are all enclosed within a structure and exposure to bending and torsional forces is largely avoided. 
     The lift according to the present invention has a number of advantages. It is hydraulic, so it is smooth in operation and avoids the potentially dangerous “kickback” and backlash sometimes encountered in purely mechanical systems. It is not electrically operated, making it safe and reliable even in marine environments. It is operated by the foot and leg muscles of the operator, which are stronger than hand and arm muscles. Further, foot operation or actuation permits the operator to keep his or her head or face away from trailer and hitch components for safety in the event of failure. Foot-pedal actuation allows the user to have both hands free and to stand mostly erect in use. This allows the user to have a better field of vision while coupling an uncoupling the hitch and launching or trailer boats. The lift according to the present invention is simple in construction and operation, making manufacturing, repair, and replacement inexpensive. 
     The invention has been described with reference to preferred or illustrative embodiments thereof. It is thus not limited, but is susceptible to variation and modification without departing from the scope of the invention.