Universally mountable brake assembly for a hand truck
FIELD OF THE INVENTION 
     The present invention relates to a brake assembly for use on hand trucks, and more particularly, to a brake assembly that is universally mountable to any one of several different types and sizes of hand trucks. 
     PRIOR ART 
     Prior art patents include the following: 
     
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No.  U.S. Pat. No.                                                        
                 Issue Date    Name                                       
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1.   2,546,876   March 27, 1951                                           
                               J. H. Sutherland                           
2.   2,800,336   July 23, 1957 S. L. Major, et al.                        
3.   2,980,200   April 18, 1961                                           
                               W. A. Kibby                                
4.   3,035,727   May 22, 1962  F. R. Turner                               
5.   3,276,550   October 4, 1966                                          
                               A. A. Honeyman                             
6.   3,422,930   January 21, 1969                                         
                               W. S. Barron                               
7.   3,950,005   April 13, 1976                                           
                               W. C. Patterson                            
8.   3,968,974   July 13, 1976 N. Wetzel                                  
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     Others: 
     Belgium Patent No. 646,882, 22 Avril, 1964, Mr. August Manss 
     U.K. Patent (The Patent Office, London) No. 593,830, Accepted Oct. 27, 1947, Jack Turner. 
     So far as presently known to this inventor the prior art has provided a hand-operated brake for a hand truck only as an integral part of the hand truck itself. 
     SUMMARY OF THE INVENTION 
     According to the present invention a brake assembly is provided that is universally mountable to any one of several different types and sizes of hand trucks. The complete brake assembly includes a brake control handle that is removably attached to the upper frame of the hand truck; a brake bar assembly having a base removably attached to the axle of the hand truck and a brake bar with associated brake pads adapted to engage the wheels; a cam mechanism for depressing the brake bar; and a cable coupling the brake control handle to the cam mechanism. 
    
    
     DRAWING SUMMARY 
     FIG. 1 is a perspective view of a typical aluminum hand truck on which my novel retrofit brake assembly has been mounted; 
     FIG. 2 is a perspective view of a typical steel hand truck on which my novel retrofit brake assembly has been mounted; 
     FIG. 3 is an exploded fragmentary perspective view showing how the extendable brake pads of my invention are applied to the wheels of a hand truck; 
     FIG. 4 is an exploded fragmentary perspective view showing the base of my novel brake assembly attached to the axle of a hand truck, and its adjustability for wheel size; 
     FIG. 5 is an elevation view of the upper end portion of a hand truck showing the location of the brake control handle of my novel retrofit brake assembly; 
     FIG. 6 is a fragmentary perspective view of various adapters that may be used for different size axles; 
     FIG. 7 is an elevation view of my floating brake bar, with a schematic showing of a spring assembly that provides the floating action; 
     FIG. 8 is an elevation view of the brake bar, plunger assembly, and control knob, illustrating adjustability of the control knob to adjust the clearance of the brake pads from the wheels of the hand truck; 
     FIG. 9 is an elevation view, partially in a schematic form, showing how the braking action initiated by the control handle is applied through the cable to the cam mechanism, brake bar, brake pads, and wheels; 
     FIG. 10 is an elevation view, partially in schematic form and partially in cross-section, showing the cam mechanism for actuating the brake bar; and 
     FIG. 11 is a view like FIG. 10, but showing the position of the cam mechanism after the plunger has been depressed. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     (FIGS. 1-11) 
     The presently preferred embodiment of the invention includes a hand operated braking system that can be removably mounted upon almost any type of delivery hand truck that is conventionally used with commercial truck/trailer rigs. 
     Referring now to the drawings, FIGS. 1 and 2 show conventional hand trucks of the type that includes a vertically extending frame having a lower end supported by an axle on a pair of wheels, and a hand grippable upper frame portion. FIG. 1 shows a steel hand truck from the front side. In FIG. 1 the hand truck is identified by letter T, its frame by letter F, the axle by letter A, and the wheels by letter W. In FIG. 2 the same designations are used, except that the hand truck is an aluminum truck shown from the back side. The hand truck, being of a different design, is identified as T&#39;. In each figure the brake assembly B provided in accordance with the present invention is removably attached as an accessory to the hand truck. 
     The brake assembly B itself includes a base 10, best shown in FIG. 6, which is attached to the axle A, and a square tube 20 horizontally positioned above the base and in parallel relation to it. Tube 20 is best seen in cross-section in FIGS. 10 and 11. Two vertically extending posts 30, 32, see FIG. 4, are connected between the base 10 and the square tube 20 so as to support the square tube at a fixed elevation above the axle A. 
     Also included in the brake assembly B is a means for inhibiting rotatable movement of the base, the square tube, and the posts relative to the axle A. In FIG. 1 the inhibiting means includes U bolts 40, FIG. 4, FIG. 6. In FIG. 2 the square tube 20 is also attached directly to a central frame member F2. 
     A brake bar 50 is horizontally disposed between the base 10 and square tube 20 in generally parallel relationship thereto. Curved brake pads 52, 54, are hingedly supported from respective extensible ends 56, 58, of the brake bar 50. As best seen in FIGS. 7 through 11, a guide rod 60 has its lower end secured to the brake bar 50 and extends vertically upward in vertically movable relation to the square tube 20, the vertical movement being best illustrated by arrows in FIGS. 9, 10, and 11. 
     As best seen in FIGS. 10 and 11, the square tube 20 has an upper plate 22 whose lower surface acts as a cam plate. A cam mechanism 70 is associated with the under side of the cam plate and is coupled to the guide rod 60 for depressing the brake bar. A brake control handle 80 is removably attached to the hand grippable upper frame portion of the hand truck, as shown in FIG. 9, and a cable 90 couples the brake control handle 80 to the cam mechanism 70. When the cable is pulled upward, the cam mechanism forces the guide rod 60 and brake bar 50 in a downward direction, thus engaging brake shoes 52, 54, with the wheels W. 
     As best seen in FIGS. 10 and 11, the lower end of cable 90 is attached to a rigid member 92, whose lower end is pivotally coupled to a cam lever 72. Cam lever 72 extends in a horizontal direction, and its other end has a roller 74 on its upper edge, while its lower edge corner is pivotally coupled at 76 to a plunger lever 77. The mid-portion of plunger lever 77 is pivotally coupled to a plunger 62, which is a threaded collar secured to guide rod 60. 
     The apparatus of the present invention will provide the operator with increased safety and confidence while handling heavily loaded hand trucks going down declines such as truck and trailer ramps, stairs, or driveway slopes, whether moving at a safe controlled speed or coming to a complete stop. This braking ability offers the operator less physical strain and fatigue, fewer back injuries, less lost work time, and helps prevent hand truck runaway which can result in product damage and personal injury. 
     The unique design features enable the device to easily retrofit to typical &#34;top loop&#34; handle design hand trucks used for product delivery in the food service, beverage and general merchandise industry operating down truck and trailer ramps. The varied mounting design capability also provides for long service life in allowing the braking device to be transferred from one hand truck to another. 
     Pulling up the control handle 80 with either or both hands raises the control cable 90 which is linked to the cam/plunger assembly 62, 70. Raising the cam pushes the spring loaded plunger 62 downward applying downward pressure to the brake bar 50/brake pad 52, 54, assembly which makes braking contact with the hand truck tires. Depending on the amount of lifting pressure applied to the control handle, varying braking pressure is applied to control the handtruck speed or to achieve a complete stop. Fully releasing the control handle releases all braking contact with the handtruck tires, because of the return spring 94. Return spring 94 rests on top of square tube 20 and applies upward pressure to the under surface of a knob 64 on the upper end of guide rod 60. 
     The many special features of the invention include the following: 
     Extendible brake pad design allows fitting the device to handtrucks with wheelbase widths from 141/2 to 21 inches as well as others. See drawing FIG. 3. 
     Varied axle mounting bracket hole locations allow the device to fit handtruck wheel diameters of 8 and 10 inches. Fitting to other wheel diameters can be made. See drawing FIG. 4. 
     Extendible brake control handle bracket allows the brake control handle to fit handtruck frame widths from 101/2 to 14 inches as well as others. See drawing FIG. 5. 
     Axle adapter design allows bolting the device to handtruck axles of 5/8 and 3/4 inch diameter. Other axle diameters can be fitted. See drawing FIG. 6. 
     A spring loaded brake bar allows braking equalization to both wheels simultaneously, preventing unequal braking pressure causing the handtruck to dangerously pull to one side or the other. See spring 66 in drawing FIG. 6. 
     A single control knob 64 provides for the proper brake pad to tire contact clearance as well as providing adjustment for tire wear. See drawing FIG. 8. 
     A brake activation hand control allows the use of one or both hands at the top loop of the handtruck for unrestricted operator braking control. See the upper part of drawing FIG. 9. This upper brake handle positioning provides an easy brake activation control which allows the operator convenient use of one or both hands but without restricting support of the handtruck load. 
     A cam activated plunger provides compounded brake pressure when the brake control handle is operated. This varied pressure is applied to the brake bar forcing the brake pads down to make braking contact with the tires. Degrees of releasing the control handle reduces or releases all braking contact with the tires. See drawing FIG. 10. 
     Curved and hinged brake pads are contoured to make maximum braking area contact to 8 and 10 inch diameter wheels, or other sizes as desired. See drawing FIG. 3. 
     Another feature of my invention is the step plate 100 that is attached above the base 10 and secured to posts 20, 30. By using one foot on this step plate the operator is able to more precisely control the action of the hand truck, when tilting back to lift the load. 
     The presently preferred form of the invention has been disclosed in considerable detail in order to comply with the requirements of the patent laws. The breadth and scope of the invention, however, are to be judged only in accordance with the appended claims.