VEHICLE -ACTUATED TILTING HOIST
TECHNICAL FIELD
The invention pertains to hoists or lifts in general, and more specifically to a garage hoist that is raised by moving a vehicle back and forth on a pair of tilting ramps having opposed fiilcrums, thereby elevating the hoist into a convenient position for access to the vehicle's undercarriage.
BACKGROUND ART
Previously, many types of vehicle elevating hoists or lifts have been used to provide an effective means for raising a vehicle to allow access underneath to provide maintenance, repair and storage. In most cases, the power to lift the vehicle is provided by hydraulic or mechanical systems, however some inventions utilize the weight of the vehicle itself to level the vehicle when driven up a ramp. A search of the prior art did not disclose any patents that possess the novelty of the instant invention; however the following U.S. patents are considered related: Patent Number Inventor Issue Date 4,486,006 Fawdry Dec. 4, 1984 5,015,146 Barnes et al. May 14, 1991 5,141,371 Pish Aug. 25, 1992 5,236,065 Isogal Aug. 17, 1993 5,641,150 Rober Jun. 24, 1997 6,619,620 Carter Sep. 16, 2003 Fawdry, of the United Kingdom, in U.S. patent 4,486,006 teaches a self-leveling vehicle support ramp having a pair of side-by-side tracks. The tracks pivot on a stand from an inclined position to a horizontal position under the weight of the vehicle moving fully onto the tracks. Telescoping dampers, in the form of cylinders, are located adjacent to the ends of the tracks to retard the arcuate movement of the tracks. Patent No. 5,015,146 issued to Barnes et al. is for a vehicle display lift having a vertical mast containing a hoist mechanism for raising and lowering a movable carriage. A cantilever support member on the carriage extends outward and has a vehicle support frame on the outer end for vehicle support. A ramp allows a vehicle to be driven on the support frame at ground level. The vehicle support frame pivots forward when elevated and is secured by a spring-loaded safety latch when the carriage is at the top of the mast. Pish in U.S. patent 5,141,371 discloses an inclined lifting apparatus for storing aircraft in a stacked or tiered position to increase utilization of available hanger space. The apparatus utilizes hydraulics to lift the aircraft. Isogal in U.S. patent 5,236,065 teaches a movable one-post lift for maintenance of a vehicle, which includes a base with transport wheels and an upright support post attached to the rear end. A driving mechanism is disposed in the post with a cantilever beam for supporting the body of a vehicle. Patent No. 5,641,150 issued to Rober is for a tilting lift apparatus providing access to the undercarriage of a vehicle. A base pivotally mounts at least two longitudinally extending ramps which move from an angle position to a level position when a vehicle is moved onto the ramps. A movement attenuating assembly is connected to the ramps for slowing their movement. A tilter leg is pivotally connected to the ramp and swings down to a level position. Carter's patent No. 6,619,620 is directed to a hoist that includes a lower and an upper platform capable of moving between a position from under a vehicle to a raised position, thus permitting access to the vehicle undercarriage. The upper platform is raised with a hydraulic cylinder and locking arms arrest the telescopic movement. For background purposes and as indicative of the art to which the invention is related, reference may be made to the remaining cited patent issued to Yeo et al. in U.S. patent 6,244,390.
DISCLOSURE OF THE INVENTION
In the early days of automotive transportation, in order to obtain access to a vehicle's undercarriage, pits were dug between spaced-apart tracks, thus permitting the vehicle to drive over the pit. An individual working on the vehicle was then required to climb down steps or a ladder to obtain the required accessibility. Later, typical garage hoists were developed that actually lifted the vehicle from the ground to provide a space underneath the vehicle high enough for a person to work. While these garage hoists are completely functional they are also rather complicated and costly, as they function using hydraulic pressure or mechanical action to lift a vehicle. Conventional hydraulically actuated hoists, in common usage today, almost all require the hydraulic cylinder to be located in the ground beneath the hoist, which is expensive to install and requires an electrically operated hydraulic pump with the attached piping and necessary ancillary equipment. Above ground systems are also in use, with a structure either on the four corners of the vehicle, or a pair of beams located in the vehicle's center. With the above ground equipment either a hydraulic or a mechanical force is required. Therefore, the primary object of the invention is to simplify the concept of a hoist to the point that no external force is necessary to lift a vehicle by using the weight of the vehicle oscillating back and forth on a pivoting platform in a seesaw manner. The actual lifting process is accomplished by reversing the pivot point between two fulcrums. The fulcrums function independently, when the center of gravity of the vehicle is shifted from one fulcrum to the other by the movement of the vehicle itself when simply driving back and forth. To be in command of the vehicles rearward movement, the ramp is normally level when backing up. Lifting a vehicle to the height of a man may be accomplished in a few passes back and forth according to the geometry of the hoist relative to the length of the platform. An important object is that the invention is adaptable to vehicles of any size and weight, from golf carts to tanks, as the only limiting factor is the structural integrity of the platform and the fulcrums. It is easily seen that the structure size and strength is adapted to the actual vehicle use and is accomplished in a simple straightforward ratio. Another object of the invention permits easy adjustment between the ramps of the platform to accommodate different wheel widths. Since the tracks may or may not be fixed stationary to the floor, or attached to a physical structure, sliding the tracks apart or together is easily accomplished. Even when the tracks are bolted to the floor, one set may have multiple holes permitting simple unbolting the specific set and sliding the longitudinal pair in the desired direction. Still another object of the invention is that the garage hoist is completely above ground and does not require any modification of a building. The hoist only requires a flat rigid surface, preferably a concrete slab or solid floor, and sufficient height in the structure to permit a motor vehicle to be lifted high enough for a person to work underneath. Yet another object of the invention is that the hoist is environmentally friendly since there are no contaminants used, or pumps, high pressure hoses and fittings that have the propensity for leaking liquid. Instead, the invention uses only low pressure fluid that is produced, not by positive pump pressure, but by suction of a set of cylinders when the ramp is elevated by the vehicle pivoting on the opposite fulcrum. Safety features are also included in the invention that lock the height of the platform in place at any level or progression in the elevating process. The ramp incorporates a no slip surface which tenaciously grips the vehicle's tires to prevent slipping when the ramp tracks tilt in one direction or the other. The ramp may also include a vehicle safety stop at each end of the ramp and a ladder may be utilized for a person to come down from the elevated ramp. A further object of the invention is directed to the ease of installation, as the hoist is preferably shipped in parts for assembly in the field. The assembly procedures are limited to simple mechanical attachment using conventional threaded fasteners well known in the art and therefore no special skills or tools are necessary. Because the hoist is shipped unassembled, and due to the simplicity of design, the entire apparatus is unusually cost effective particularly relative to conventional hydraulic systems. Yet another object is that no electrical power is required from the mains, as the hoist is completely self contained. There are only two solenoid valves that require electrical power, which is provided by standard batteries, and a switch panel is requisite for the operator to select front or rear rigid fulcrum position with a conventional cable connecting them together. In an optional embodiment, remote switches and receivers energize the valves with a battery located adjacent to each valve. A final object of the invention is that the telescoping cylinders, acting as fulcrums, also retard the pivotal movement of the track platform. Since the action of the cylinders is controlled in the rigid and movable position, when the vehicle is driven over the center of the rigid cylinder, the opposed movable cylinder is drawn upward, thus creating a negative pressure on the inlet and drawing hydraulic fluid into the opposed cylinders. As there are restrictions in the connection caused by the physical size of the lines and orifices, the cylinders act as dampers to slow down the pivotal travel of the platform, instead of a jarring effect when the platform pivots under the pressure of the vehicle. Further, when the platform is in its fully raised position and then lowered, all four cylinders force the hydraulic fluid back into the reservoirs, and the cylinders perform as dampers to slow the decent in an even and manner. These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a partial isometric view of the preferred embodiment in a lowered position. FIGURE 2 is a partial isometric view of the preferred embodiment in a fully elevated position. FIGURE 3 is a side elevation view of a vehicle driven upon the hoist in the preferred embodiment illustrating the first step of lifting the vehicle with the vehicle center of gravity forward and the platform pivoting on the front fulcrum. Arrows illustrate the direction of vehicle travel and the ultimate effect upon the platforms movement. FIGURE 4 is a side elevation view of a vehicle driven on the hoist in the preferred embodiment illustrating the second step of lifting the vehicle with the vehicle center of gravity rearward and the platform pivoting on the rear fulcrum. Arrows illustrate the direction of vehicle travel and the ultimate effect upon the platforms movement. FIGURE 5 is a side elevation view of a vehicle driven on the hoist in the preferred embodiment illustrating the third step of lifting the vehicle with the vehicle center of gravity forward and the platform pivoting on the front fulcrum. Arrows illustrate the direction of vehicle travel and the ultimate effect upon the platforms movement. FIGURE 6 is a side elevation view of a vehicle driven on the hoist in the preferred embodiment illustrating the fourth step of lifting the vehicle with the vehicle center of gravity rearward and the platform pivoting on the rear fulcrum. Arrows illustrate the direction of vehicle travel and the ultimate effect upon the platforms movement. FIGURE 7 is a side elevation view of a vehicle driven on the hoist in the preferred embodiment illustrating the fifth step of lifting the vehicle with the vehicle center of gravity forward and the platform pivoting on the front fulcrum. Arrows illustrate the direction of vehicle travel and the ultimate effect upon the platforms movement. FIGURE 8 is a side elevation view of a vehicle driven on the hoist in the preferred embodiment illustrating the final step which consists of centering the vehicle on the platform. The arrow illustrates the direction that the vehicle traveled to be positioned in the middle of the platform ready for a person to lock the safety structure and gain access the vehicle's undercarriage. FIGURE 9 is a partial isometric view of the right ramp track in the preferred embodiment shown removed from the invention for clarity. FIGURE 10 is a partial isometric view of the left ramp track in the preferred embodiment shown removed from the invention for clarity. FIGURE 11 is a cross-sectional view taken along lines 11-11 of FIGURE 9. FIGURE 12 is a cross-sectional view taken along lines 12-12 of FIGURE 9. FIGURE 13 is a cross-sectional view taken along lines 13-13 of FIGURE 9. FIGURE 14 is a cross-sectional view taken along lines 14-14 of FIGURE 9. FIGURE 15 is a cross-sectional view taken along lines 15-15 of FIGURE 9. FIGURE 16 is a cross-sectional view taken along lines 16-16 of FIGURE 10. FIGURE 17 is a cross-sectional view taken along lines 17-17 of FIGURE 10. FIGURE 18 is a cross-sectional view taken along lines 18-18 of FIGURE 10. FIGURE 19 is an exploded view of the right ramp track shown removed from the invention for clarity. FIGURE 20 is a partial isometric view of the safety leg in preferred embodiment shown removed from the invention for clarity. FIGURE 21 is a partial isometric view of one of the ring grip quick release pins in preferred embodiment shown removed from the invention for clarity. FIGURE 22 is a partial isometric view of one of the telescoping hydraulic cylinders in preferred embodiment shown removed from the invention for clarity. FIGURE 23 is a partial isometric view of the one of the threaded nuts and bolts in preferred embodiment shown removed from the invention for clarity. FIGURE 24 is a partial isometric view of the stationary base for the front fulcrum telescoping hydraulic cylinder in preferred embodiment shown removed from the invention for clarity. FIGURE 25 is a partial isometric view of the pivotal base for the rear fulcrum telescoping hydraulic cylinder in preferred embodiment shown removed from the invention for clarity. FIGURE 26 is a pictorial schematic of the fulcrum controls to raise and lower the platform.
BEST MODE FOR CARRYING OUT THE INVENTION
The best mode for carrying out the invention is presented in terms of a preferred embodiment for a vehicle-actuated tilting hoist 20. As shown in FIGURES 1 through 26, the hoist 20 is comprised of a pair of side-by-side ramp tracks 22, with each having a front end 24 and a rear end 26. The ramp tracks 22 are preferably made of a pair of spaced-apart steel rectangular tubes 22', as shown in FIGURES 9-19. On top of the ramp tracks 22 is a perforated metal top 28, as shown in the cross-section of FIGURE 15, preferably with the perforations formed having an upstanding Hp with a sufficient protrusion to create a non-slip surface for gripping vehicle tires. To complete the ramp tracks 22, a longitudinal side rail 30 is attached on an inner edge of the track for guidance of a vehicle 32 when driven on the tracks 22. The side rail 30 assures that the vehicle's tires are completely within the confines of the tracks 22. A front tire stop rail 34 is also attached to each ramp track on the front end 24, thus providing a barrier to preclude the vehicle 32 from driving off of the rails. The side rails 30 and front tire stop rails 34 are illustrated in FIGURES 1-19 of the drawings and consist preferably of rectangular tubing 22' attached together with inserts 22" and connecting plates 22'", however structural shapes such as angles are also an acceptable substitute. A tapered ramp approach 36 is attached to each ramp track rear end 26 with a hinge 38, thereby providing a gradual slope for vehicle entry onto the tracks 22. The ramp front 36 is constructed of the same materials as the ramp tracks 22, including the metal top 28 and side rail 30. On the tapered distal end of each ramp front 36, a pair of rollers 40 are provided to permit the ramp front 36 to slide on the floor 42 as the tracks 22 are elevated. Any type of roller 40 may be used as long as it has the structural integrity to accommodate the weight of the vehicle 32. An adjustable truss 44 is pivotally positioned between the side-by-side ramp tracks 22 and the tapered ramp approach 36. The truss 44 is utilized for locking the angular displacement of each ramp front 36 in place to each track 22 when the desired height of the combined tracks 22 has been achieved. The adjustable truss 44 is illustrated best in FIGURES 1-10 and 19, consists of either a square or round tube telescoped inside of a mating tube with provisions for pivotal attachment on each end. A tension lock toggle pin 46 equipped with a chain lanyard 48 penetrates matching holes 50 through both tubes of the truss 44 for manual attachment when the desired angle of each ramp front 36 to each track 22 is achieved. The tracks 22 are adjustably connected together, thus forming a rectangular platform 52 having the width adjusted between the tracks 22 congruent with the footprint of the vehicle 32 wheel. The adjustable feature is accomplished by utilizing a pair of connecting arms 54 that are attached between the side-by-side ramp tracks 22 adjacent to the tracks front ends 24 and rear ends 26, as illustrated best in FIGURES 1, 2 and 19. The connecting arms 54 are formed of a pair of interconnecting either square or round tubes nested together and attached securely to the tracks 22, as shown in FIGURE 11. Holes 50' in each telescoping pair of arms 54 are aligned and a tension lock toggle pin 46', equipped with a chain lanyard 48', penetrates the matching holes 50' to form a secure and rigid interface. A regulateable height front fulcrum 56 is pivotally attached to a forward portion of each ramp 22, thereby providing a pivot point when the vehicle 32 is driven on the ramp platform 52 when the center of gravity of the vehicle 32 is forward of the front fulcrum 56. The front fulcrum 56 consists of a telescoping hydraulic cylinder 58 with a clevis 60 on the distal ends. The clevis 60 is attached to each track 22 in a pivotal manner preferably, as shown in FIGURES 12. A round spindle 62 is preferably disposed through the tubes of the ramp tracks 22, and spacers 64 in the form of hollow sleeves are positioned over the spindle 62 on each side of the clevis 60, as shown in FIGURE 12. The spindle 62 has hex nuts 62' threadably attached in each end for retention to the track structure. The front fulcrum 56 is in a fixed position relative to the floor 42 to assure stability of the platform 52. However, a slight arcuate condition exists between the platform 52 and the fulcrum 56 as the pivot point changes, which may be easily compensated for using a smaller diameter of spindle 56 than the clevis 60. Thus, permitting a minor forward and aft movement of the spindle 56 by slightly slotting the openings through the track structural members receiving the spindle 56. A stationary base pedestal 66, as depicted in FIGURE 24, is attached to the front fulcrum 56 and consists of a flat base platform 68 with a plurality of mounting holes 68" and a gusseted sleeve 70 providing a rigid foundation for the hydraulic cylinder 58 to rest on the horizontal floor surface. The pedestal 66 is configured to permit the hydraulic cylinder 58 to slip inside the gusseted sleeve 70 with a nut and bolt 72, shown in FIGURE 23, attaching the cylinder clevis 60 to the sleeve 70. The pedestal 66 may be attached to the floor or deck through the holes 68"with, so called, concrete moly nuts and bolts. A regulateable height rear fulcrum 74 is pivotally attached to a rearward portion of each ramp 22, providing a pivot point when the vehicle 32 is driven on the platform 52 with the vehicle's center of gravity rearward of the rear fulcrum 74. The rear fulcrum 74 consists of a telescoping hydraulic cylinder 58' having a clevis 60' on each distal end. The top clevis 60' is attached to the track in the same pivotal manner as the front fulcrum 56, and the bottom clevis 60" is attached to a pivotal base 76, as illustrated in FIGURE 25, to provide a pivot point near the horizontal floor surface. The pivotal base 76 includes a flat base platform 68' with a plurality of mounting holes 68" and a pair of vertical supports 78 parallel to the bottom end clevis 60" thereby providing an arcuate foundation for the hydraulic cylinder 58'to swivel upon while the platform 68' rests on the horizontal floor surface 42. The bottom clevis 60" is attached to the supports 78 either with a nut and bolt 72, as shown in FIGURE 23, or fastener such as a shoulder bolt or a pin with the necessary spacers 64. The pedestal 76 may be attached to the floor or deck through the holes 68"with, so called, concrete moly nuts and bolts. Fulcrum controls for height regulation of the front and rear fulcrum 56 and 74 are provided, as illustrated in FIGURE 26, for generating a rigid fulcrum position and a movable fulcrum position in the hydraulic cylinders 58 and 58'. The controls consist of a front hydraulic system interconnecting both front fulcrums 56 together, and a rear hydraulic system interconnecting both rear fulcrums 74 together, such that each pair of fulcrums 56 and 74 act together in concert. The hydraulic system includes a front reservoir 80 which contains hydraulic fluid 84, a fill opening with cap 80', an air vent 80" and a drain valve 80'". A front solenoid valve 86 is in fluid communication with the front reservoir 80, and both front fulcrums 56 are jointly in fluid communication with the front valves 86. The rear hydraulic system comprises a rear reservoir 82 which contains hydraulic fluid 84, a fill opening with cap 82', an air vent 82" and a drain valve 82'". A rear solenoid valve 88 is in fluid communication with the rear reservoir 82, and both rear fulcrums 74 jointly in fluid communication with the rear valve 88. Other configurations of hydraulic systems may also be used with equal ease. An electrical control system is provided to permit an operator to actuate the front hydraulic system and the rear hydraulic system independently or together. The electrical control system consists of a front valve control switch 90, a rear valve control switch 92, a battery 94, and interconnecting wiring therebetween. The control switches 90 and 92 are preferably housed in a switch box 95 along with the battery 94, as shown in FIGURE 26. The electrical control system permits an operator to select actuation of the appropriate front solenoid valve 86 or rear solenoid valve 88 to raise the platform 52 when the vehicle 32 is moving back and forth on the ramp tracks 22, also for lowering the platform 52 when both the front switch 90 and rear switch 92 are simultaneously actuated. Optionally, in place of the switch box 95 with its battery 94 and interconnecting wiring, a remote transmitter 96 having integral switches, similar to a garage door opener, may be employed. A remote receiver 98 and battery 94 may be located adjacent to the appropriate solenoid valve, as shown in phantom in FIGURE 26. A safety leg 100 having adjustable height increments is pivotally attached adjacent to the front end 24 of each ramp track 22 on top, and rests on the horizontal floor 42 on the bottom. The safety leg 100 consists of a set of telescoping legs 102, as shown in FIGURE 20, that are attached on the bottom to a gusseted base 104 which includes a plurality of mounting holes 68" for the purpose of mounting to the floor using the same method as employed with, the front fulcrum 56 and the rear fulcrum 74 as previously discussed. The legs 102 are adjusted in height with a plurality of tension lock toggle pins and lanyards similar to the toggle pins 45 and lanyards 48 described above. hi the function of the invention, movement of the motor vehicle 32 on the tracks 22 causes the platform 52 to pivot on the particular fulcrum that has been selected to be in the rigid fulcrum position. Subsequent vehicle movement forward and backward elevates the hoist 20 in stepped increments when the vehicle's center of gravity is outboard of the selected rigid fulcrum position. This action provides sufficient height for a person in a standing position to gain access to the vehicles undercarriage using only vehicle weight for the propulsion required for lifting. To describe the function in its method of operation, a motor vehicle 32 is driven onto the pair of side-by-side ramp tracks 22 over the attached hinged, tapered ramp approach 36 where the regulateable height front fulcrum 56 is pivotally attached to a forward portion of each ramp 22. Further, the regulateable height rear fulcrum 74 is attached to a rearward portion of each ramp track 22. The front fulcrum 56 and rear fulcrum 74 are regulated by front and rear valve control switches 90 and 92 respectively into a rigid fulcrum position or a movable fulcrum position. When the motor vehicle 32 is driven back and forth on the tracks 22, the platform 52 pivots on the fulcrum selected as the rigid fulcrum position, which elevates the hoist 20 in stepped increments each time the vehicle's center of gravity is outboard of the selected rigid fulcrum position. It has been found that it is easier for the driver to back the vehicle in the rearward movement, when the ramp is level. When the desired height is reached, the safety leg 100 is locked in place with the toggle pin 46" and the adjustable truss 44 is similarly is secured by the toggle pin 46. When the platform 52 is to be lowered, the pins 46 and 46" are removed and the front valve control switch 90 and rear valve control switch 92 are manually energized simultaneously and held until the platform 52 is in the lowered position. While the invention has been described in complete detail and pictorially shown in the accompanying drawings, it is not to be limited to such details, since many changes and modifications may be made to the invention without departing from the spirit and scope thereof. Hence, it is described to cover any and all modifications and forms which may come within the language and scope of the appended claims.
