Patent Publication Number: US-4545596-A

Title: Trailer coupler

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to couplers for coupling motor vehicles and trailers to be towed by such motor vehicles. The invention is a coupler which closes and locks when a hitch ball is forced within the ball receiving cavity of the coupler. 
     2. Description of Prior Art 
     Couplers for coupling vehicles with trailers to be towed are as uncomplicated as hook and pintle connectors. The ball and receiving member on the familiar boat or camper trailer are examples of ball and ball coupler hitches. 
     Locking mechanisms which lock the trailer ball within the coupling upon insertion of the trailer ball are shown in prior art. 
     Pierce in U.S. Pat. No. 4,133,553 shows a hinged jaw coupling device with an internal trigger. Isham in U.S. Pat. No. 3,013,517 also shows a coupling device with an internal trigger operating to lock the device when a trailer ball is inserted. 
     Petitioner&#39;s device is designed to hold and lock a trailer connector ball and to eliminate trigger mechanisms mounted within the ball receiving area. These trigger mechanisms become inoperative when filled with debris or when used on a heavy duty operation. They also require numerous moving parts which are subject to fatigue, rusting and wear. 
     Locking is provided in the petitioner&#39;s device by relative movement of massive coupling arms around pivot points mounted within a protective housing. 
     It is an object of the invention to produce a locking trailer coupler that does not require a separately operated trigger mechanism. 
     It is an object of the invention to produce a coupler that is of minimum size and with as few moving parts as is possible. 
     it is an object of the invention to use the relative motion of pivoting coupling arms without a seperate trigger mechanism to effect automatic closure without the necessity of providing a triggering mechanism located in the ball receiving area. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a drawing of a typical application of the invention showing a truck and trailer coupled by a means of the coupling device of the invention. 
     FIG. 2 is a frontal perspective view of the invention in a unlocked or open ball receiving position. 
     FIG. 3 is a frontal perspective view of the invention in a closed and locked position. 
     FIG. 4 is a frontal view of the invention with the operating mechanism shown in shadow. 
     FIG. 5 is a section taken on line 5--5 of FIG. 4 showing closed position in solid lines, open position in dashed lines showing relative displacement of deadbolt receiving notches as jaws are pivoted from an open to closed position about a trailer ball. 
     FIG. 6 is a side view of the coupling showing the locking mechanism open. 
     FIG. 7 is an elevational view of the coupling taken on line 7--7 of FIG. 4, with the coupling in a closed, locked position. 
     FIG. 8 is a plan view of the coupling in a neutral or safety position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The self closing trailer coupler shown in drawing FIGS. 1 through 8 comprises these numbered parts: 
     10 trailer reach generally see FIG. 2 
     12 vehicle-mounted coupler device 
     14 14&#39; coupling elements 
     15 15&#39; cups 
     16 16&#39; guide plates 
     18 trailer-reach ball 
     20 mounting plate 
     21 guide plate bolts 
     22 22&#39; strikers 
     23 23&#39; recesses for strikers 22 22&#39; 
     24 24&#39; pivot pins 
     26 26&#39; back faces of cups 15 15&#39; 
     28 face of mounting plate 20 
     30 30&#39; half-square notches 
     32 deadbolt 
     33 33&#39; deadbolt receiving apertures in guide plates 16, 16&#39; 
     34 34&#39; flat portions of coupling elements 14 14&#39; being the whole top face of such plates 
     35 deadbolt chamfer 
     36 36&#39; tension springs 
     37 deadbolt stem 
     38 cable 
     40 40&#39; bosses of cupping elements 14 14&#39; 
     42 42&#39; anchoring eyes 
     44 44&#39; round portions of coupling elements 14 14&#39; 
     45 45&#39; grooves 
     46 coupling element limiting slot 
     48 48&#39; faces of flat portions 34 34&#39; 
     50 50&#39; end faces of slot 46 designed to limit opening of coupling 
     52 52&#39; reliefs in cups 15 15&#39; 
     54 54&#39; spacers 
     55 55&#39; bolts 
     56 control lever generally 
     58 portion of control lever 56 which slides in slot 60 
     60 slot in mounting plate 20 
     62 saddle portion of slot 60 
     64 ball on control lever 56 
     66 short section of ell-shaped groove 68 
     68 ell-shaped groove 
     70 safety ridge in slot 60 
     74 deadbolt clearance 
     76 straight portion of slot 60 
     78 upper face of guide plate 16 
     80 handle on control lever 
     82 bottom edge of deadbolt 32 
     84 clevis 
     86 pivot pin in clevis 
     88 fastening thread for clevis 
     90 spring retaining flange 
     92 deadbolt spring 
     94 deadbolt spring retaining bracket 
     96 96&#39; deadbolt spring retaining bracket bolts 
     98 load-bearing portion of deadbolt 32 
     100 safety pin 
     102 102&#39; holes in lugs 104 104&#39; 
     104 104&#39; lugs 
     106 crook portion of control lever 56 
     108 chain 
     110 eyebolt 
     112 safety bar 
     114 weatherproof housing 
     115 holes in mounting plate 20 
     118 vehicle frame 
     120 cutout in vehicle frame 
     122 mounting plate bolts 
     Drawing FIG. 1 shows a vehicle with a towed trailer. Trailer reach or tongue 10 with its connector, trailer reach ball 18, connects the trailer with the towing vehicle by engagement with vehicle mounted coupler 12. The coupler 12 is mounted to the towing vehicle by mounting plate 20. Mounting plate 20 is part of an overall weatherproof housing 114. 
     The coupler comprises in essence a coupling element ball retained in a lubricated ball receiving socket. 
     Opposed mirror image coupling elements 14 and 14&#39; are pivotally mounted within an upper guide plate 16 and lower guide plate 16&#39;. The guide plates 16 and 16&#39; are secured to the mounting plate 20 by bolts 21. 
     The coupling elements 14 and 14&#39; are shown in Drawing FIG. 2 in open position and in Drawing FIG. 3 in a closed position. The guide plates 16 and 16&#39; can best be seen in the sectional views of Drawing FIGS. 6 and 7. 
     The forward ends of coupling elements 14 and 14&#39; are formed into cups 15 and 15&#39;. These cups close upon ball 18 of trailer reach member 10 to effect a secure coupling while allowing movement of the ball 18 in a vertical and horizontal plane, such two dimensional plane being generally parallel to the mounting plate 20. 
     Coupling is effected when ball 18 of trailer reach member 10 is forced against closure strikers 22 and 22&#39; of cups 15 and 15&#39;. The relative movement of strikers 22 and 22&#39; as the coupling is closed can be seen in FIG. 2 and FIG. 5. The force exerted against the strikers urges coupling elements 14 and 14&#39; pivotally about their pivot pins 24 and 24&#39; thereby closing cups 15 and 15&#39; around ball 18. FIG. 5 best shows this movement. 
     STRIKERS 
     The coupling device will close automatically around a ball inserted within the cups and forced directly back even if no strikers are provided. Such insertion gives rise to a force and moment around the pivot pins which urges the cups closed. However, the insertion into cups with no strikers also gives rise to a wedging force which rapidly wears the rear faces of the cups and makes the device difficult to use. 
     By mounting strikers on the inside ball contact faces the wedging force is minimized and closng easier. The optimum device would have a minimal distance between the ends of the strikers and further overlap of strikers is preferable. 
     With out an extended striker and some overlap however inserting the ball can result in the ball being captured by one of the cups and the device not closing. 
     Provision must be made for nesting the strikers so as to be able to close the cups around the ball. 
     Extending the strikers as an extension of the curvilinear surface of the inside of the cups and providing a recess in the opposed cup for such strikers allows overlap of the strikers. The overlap eliminates the trapping of the ball by a cup because the striker of the opposite cup extends into the ball receiving area. The extension eliminates as well the wedging force that exists when the strikers do not overlap. The force then, on the jaws results in a smooth turning or pivoting movement about the pivot points of the coupling arms. 
     The cups are opened wide enough to accept a trailer ball. The cups are kept from opening beyond a certain width spread by the meeting of the rear inner faces of the two coupling elements. Further limits are placed on opening by the width of the slot 60 in the mounting plate. This limited movement can be seen in Drawing FIG. 8. 
     If the strikers are eliminated operation of the coupler is still possible but with substantially more effort and with rapid wear to the rear perimeters of the cups. 
     Cups 15 and 15&#39; are displaced backwards towards the mounting plate 20 as the coupling elements 14 and 14&#39; pivot into a closed ball retaining position. 
     As can be seen in FIG. 6 back support faces 26 and 26&#39; are formed on the backs of cups 15 and 15&#39;. These support faces are one of the methods used to limit backward movement of the locked cups 15 and 15&#39;. These faces further limit and resist the bending moment exerted on coupling elements 14 and 14&#39; as the towed trailer pitches in travel. Such moment would flex the horizontal flat portions 34 and 34&#39; of coupling elements 14 and 14&#39;. 
     Coupling elements 14 and 14&#39; have rectangular deadbolt receiving notches 30 and 30&#39; formed therein. The purpose and function of the notches is best shown in FIG. 5. Pivoting of the coupling elements 14 and 14&#39; brings the two notches together where they form an aperture directly below a spring biased deadbolt 32 which is forced through the aperture locking the coupling device closed around the ball. FIG. 7 is a side view of the locking mechanism. 
     At locking, the back faces of the cups bear against Face 28 of mounting plate 20, the coupling elements are edge to edge and the deadbolt has been pushed into the deadbolt receiving aperture formed by the mating of the mirror image rectangular slots. 
     When the coupling is not engaged, coupling elements 14 and 14&#39; and their associated cups 15 and 15&#39; are spring biased to an open cup separated position by tension springs 36 and 36&#39; connected to cable 38. This spring biasing means can be seen in FIG. 5. Springs 36 and 36&#39; are anchored to bosses 40 and 40&#39; on coupling elements 14 and 14&#39; by means of anchoring edges 42 and 42&#39;. As can be seen in FIG. 5 and 8 they are linked by cable 38. Forward movement of the coupling elements is limited by engagement of the sides of the coupling elements and the width of the opening slot in the housing. 
     Trained about rounded portions 44 and 44&#39; of coupling elements 14 and 14&#39; spring loaded cable 38 acts to rotate coupling elements 14 and 14&#39; about pivot pins 24 and 24&#39;. Grooves 45 and 45&#39; in rounded portions 44 and 44&#39; of coupling elements 14 and 14&#39; hold cable 38 in central alignment. FIG. 7 shows the groove retainer as does FIG. 6. 
     The coupling elements pivot about axis displaced back from the face of the device. Pivoting about the displaced points keeps the deadbolt receiving apertures within the housing when the cups are open. This prevents debris from entering the aperatures and interferring with the operation of the deadbolt. 
     The coupling elements pivot in counter rotating directions towards and away from a common point such point being located along a line passing through the centers of rotation of the pivot points, such point being equidistant from the pivot points. These points are best seen in Drawing FIG. 5; such point of rotation is within the deadbolt receiving aperture when the cups are closed. Location of the common point of rotation within the deadbolt receiving aperture allows manufacture without the need for critical dimensioning of the two coupling elements in the area of the point of common rotation. 
     Limiting the width of opening of cups 15 and 15&#39; is slot 46 in mounting plate 20. FIGS. 2 and 3 show the limited room provided for opening of the cups. Faces 48 and 48&#39; of flat portions 34 and 34&#39; of the coupling elements 14 and 14&#39; abut the end faces 50 and 50&#39; of slot 46. If the cups were allowed to open to far the strikers would not overlap and the wedging effect of the ball would cause rapid wear. 
     Control lever 56 is pivotally mounted in clevis 84 by means of pivot pin 86. Clevis 84 is rotably engaged with stem 37 of deadbolt 32 by screw threads 88. When the handle is moved up and down, pivoting is about pin 86, rotation is about threads 88. 
     DEADBOLT LOCKING MEANS 
     The deadbolt mechanism is shown in Drawing FIGS. 6 and 7. 
     Deadbolt 32 retains deadbolt spring 92 by flange 90. The deadbolt is chamfered 35, to ease entry into locking notches 30 and 30&#39;. Spring 92 is retained at its upper end by bracket 94 mounted to mounting plate 20 by spring retaining bracket bolts 96 and 96&#39;. 
     OPERATION 
     In neutral or safety position as shown in Drawing FIGS. 6 and 8, neck 58 of control lever 56 is inserted in saddle 62 of slot 60 against spring force; the lower ball end 64 of control lever 56 is at the same time retained in the short section 66 of ell-shaped groove 68 formed in the upper face 78 of guide plate 16. 
     Placing the control lever in this position is accomplished by raising neck portion 58 of control lever 56 up and over the safety ridge 70 of slot 60 against the resistance of deadbolt pressure spring 92. In neutral position the coupling does not rattle or pound as the vehicle is driven. Deadbolt 32 is held clear of coupling elements 14 and 14&#39; by small clearance 74, cups 15 and 15&#39; are in open position and the control leverd 56 is locked against any possibility of disengagement. 
     In coupling-ready position shown in FIG. 2 and in shadow in FIG. 6, control lever 56 is raised to move neck 58 up and over Safety ridge 70 of slot 60 into the straight portion 76 of slot 60. In this position control lever 56 swings freely, deadbolt 32 is lowered by the control lever movement and is forced by spring 92 against the flat portions 34 and 34&#39; of coupling elements 14 and 14&#39;. 
     Cups 15 and 15&#39; in the front shown as reliefs 52 and 52&#39; to allow a greater degree of rotation of the ball through an arc whose axis is normal to the face 28 of the coupler. This allows the towing vehicle to turn in a tighter radius without the shaft to which is attached the ball, engaging the sides of the cup. 
     Recesses 23 and 23&#39; are formed to nest strikers 22 and 22&#39; of cups 15 and 15&#39; upon closure of the cups. FIG. 3 shows a front view of the recesses. FIG. 7 shows a view of the nested strikers in section. 
     Guide plates 16 and 16&#39; are spaced apart to provide operating clearances for coupling elements 14 and 14&#39; by spacers 54 and 54&#39; together with bolts 55 and 55&#39;. FIG. 6 as well as FIG. 7 shown the spacers 54 and 54&#39; by means of a sectional view through the coupler. The guide plates resist the flexing of the coupling elements and provide lubricating surfaces for the coupling elements to operate within. 
     FIGS. 6 and 7 show the deadbolt locking mechanism in open and closed positions respectively. 
     Deadbolt 32 can be placed in any one of three positions by control lever 56, the neck portion 58 of the control lever operated within inverted &#34;J&#34; configured slot 60 in mounting plate 20. Front views of the operating lever and the &#34;J&#34; slot can be seen in FIGS. 2 and 3. 
     OPERATING HANDLE 
     A handle 80 is attached to control lever 56. At the opposite end of control lever 56 is adjustment ball 64. The ball 64 is screwed into threads at the end of the lever. The ball can be screwed in or out to adjust clearance 74 between the bottom edge 82 of deadbolt 32 and the flat portions of 34 and 34&#39;. It also provides for adjustment for wear on ball 64. 
     As coupling occurs when the trailer reach ball is forced into coupling elements 14 and 14&#39; the elements 14 and 14&#39; pivot around their pivot pins, as the elements 14 and 14&#39; pivot, the square load bearing portion 98 of deadbolt 32 registers with half square notches 30 30&#39; and at the point the notches meet deadbolt 32 is forced through the aperture so formed to become a double shear linchpin simultaneously with the closing of cups 15 and 15&#39; upon ball 18 of trailer reach 10 as shown in FIG. 7. 
     When coupled, a safety pin through holes 102 and 102&#39; of lugs 104 and 104&#39; across a crook portion of control lever 56 prevents accidentally disengaging the deadbolt. The safety pin 100 is secured to mounting plate 20 by chain 108 and eyebolt 110. 
     A safety bar 112 fastened to the underside of lower guide plate 16&#39; and underlies deadbolt 32 to prevent loss of deadbolt and the towed vehicle in case of the deadbolts breaking. 
     The mechanism is weather proofed by means of a housing 114. 
     Not shown are grease fittings to grease the cups and the sliding faces of coupling elements 14 and 14&#39;. 
     Mounting holes 116 are provided in mounting plate 20 for attaching to a vehicle frame 118 as in FIGS. 6 and 7. Mounting is accomplished by making cutout 120 in vehicle frame 118 which is also drilled to match holes 116 of mounting plate 20. Mounting plate 20 is bolted to vehicle frame 118 by bolts 122.