FIFTH WHEEL COUPLING

Abstract: A fifth wheel assembly (l) for coupling tractor and trailer units includes a trunnion bracket (2) comprising a pair of forged bearing caps (3) having an inverted, U-shaped configuration, with bearing sleeves (4) fixedly mountd therein. In sliding fifth wheel embodiments, the bearing caps are mounted on rectangular channels (5) fabricated from two L-shaped channel members (6, 7) with a flat plate (8) attached to the upper edges of the L-shaped channels. Plungers (9) are provided for adjustably connecting the trunnioned fifth wheel assembly with a base plate on which slotted racks (ll) have been mounted, each plunger comprising a forged, two-prong (56, 57) construction with internal guides which minimizes structural disruption in the channels to provide greater strength. Adjustable stops (l2) are mounted on the exterior sides of the racks (ll) to accurately maintain the plungers in a locked position. A manual lock release (l3) comprises an over-centred lever arm arrangement (95, 97), which securely retains the plungers in the unlocked position for adjustment.

Description: The present invention relates to fifth wheel couplings. It is divided out of European Patent Application 83300890.7 (EP-A-087903) which is directed to a fifth wheel coupling having a trunnion with a forged bearing cap of U-shaped configuration. Fifth wheel couplers for connecting a tractor unit to a trailer unit are known in the art, as exemplified by US-A-2,985,463. Sliding fifth wheel couplers, incorporating a fixed base attached to the tractor and a slidably mounted trunnion bracket and locking mechanism, are used to adjustably anchor the fifth wheel to permit variation in weight distribution and length. Heretofore, sliding fifth wheel couplers have used three-pronged locking plungers to connect the trunnion bracket with the slotted racks on the base plate. The three-pronged plunger design is somewhat wide, and therefore requires similarly wide windows in the sides of the trunnion bracket. Also, in prior fifth wheel assemblies, the plungers are slidingly received in inverted U-shaped channels or guides, which further increased the width of the plunger windows. As is apparent to those skilled in the art, it is advantageous to minimize the size of the plunger windows, so as to alleviate disruption of the load carrying portions of the trunnion bracket, and thereby achieve greater strength. In US Patent 2,985,463 mentioned above, the adjustment stops for the lock plungers are mounted on the inside wall of the trunnion bracket, and abut the interior ends of the plungers. Since the trunnion bracket can move slightly on the base plate in a lateral direction, this type of stop adjustment does not positively position the plungers with respect to the racks. Improper plunger adjustment subjects the plungers to extraordinary forces, and can cause wear. Further, the location of the adjustment stops on the interior sidewalls of the trunnion bracket makes it rather inconvenient to adjust the plungers. Heretofore, manual release embodiments of the sliding fifth wheel arrangement include a pair of handles connected with the exterior ends of the plungers. This type of manual plunger operation requires that the left and right-hand plungers be independently manipulated from the opposite sides of the trunnion bracket, such that adjustment is a two man operation. US-A-3893710 discloses a further fifth wheel coupling. A severe disadvantage with the arrangement shown is that load applied to the support plate in an aft direction is transmitted to the rack through only the forward prongs of the locking plunger, whereas forces applied in the forward direction are transmitted to the rack through only the forward set of prongs. Thus, the load is in each case applied to only one prong of each locking plunger, this prong having to bear the entire load. DE-A-2927422 discloses a fifth wheel coupling as set out in the precharacterising clause of Claim 1. The coupling shown in this document has locking plungers which have side surfaces which are arranged to mate in surface contact with corresponding teeth of the respective rack, the side surfaces being angled with respect to a vertical plane passing perpendicularly to the longitudinal extent of the racks. This provides full force transmission both in the forward and in the rearward directions. There may be a tendency, however, for the teeth to slip slightly relative to the rack if force is momentarily applied in a vertical direction, for example due to jolting of the coupling, or the action of a pulling or pushing force on the prongs which is not exactly parallel to the racks. According to the present invention there is provided a fifth wheel coupling characterised by the features set out in the characterising portion of Claim 1. The angled side surfaces of the locking plungers of the present invention abut similarly angled teeth of the respective rack, so that all four prongs transmit forces to the rack when the load is applied in either a forward or an aft direction. Thus, each prong has to bear only half of the load applied to a corresponding prong of the device in US-A-3893710. Furthermore, the similarly angled teeth of the respective rack ensure that there is full surface contact between the teeth and the prongs. This ensures that the load is spread over a large surface area. One advantage of the present invention is an improved locking plunger, having a forged, two-prong configuration which has a more precise shape, and minimized window width or "span" to improve the strength and rigidity of the trunnion bracket by providing a smoother cross-sectional modulus. The greater precision of the two-prong construction increases trunnion bracket strength without substantially reducing the shear strength of the plungers. A preferable feature of the invention is internally mounted plunger guides to further reduce window span. Another preferable feature of the invention is adjustable stops mounted on the exterior ends of the plungers. The stops are positioned to abut the exterior sidewalls of the associated slotted racks, and positively locate the plungers in the locked position. The exterior stop arrangement not only achieves greater accuracy in plunger adjustment, but is also easier and more convenient to manipulate. Yet another preferable feature of the invention is a manual plunger release, which comprises an over-centred lever arm arrangement that securely retains the plungers in the unlocked position during adjustment. The lever arms are interconnected in a fashion that does not require attachment to the base plate, such that the trunnion bracket can be bodily removed from the base plate without disassembling the plunger release mechanism. One principle object of the present invention is to provide a fifth wheel assembly which is very strong, efficient in use, economical to manufacture, capable of a long operating life, and particularly well adapted for the proposed use. The invention may be carried into practice in various ways but three fifth wheel couplings embodying the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure l is a top plan view of the first fifth wheel coupling assembly; Figure 2 is a perspective view of a trunnion bracket portion of the fifth wheel assembly; Figure 3 is a top plan view of the trunnion bracket; Figure 4 is a side elevational view of the trunnion bracket; Figure 5 is an end elevational view of the trunnion bracket; Figure 6 is a side elevational view of the trunnion bracket, with the plungers removed; Figure 7 is a fragmentary, bottom plan view of the trunnion brackets, particularly showing an integral plunger guide; Figure 8 is a top plan view of a lock plunger; Figure 9 is a cross-sectional view of the lock plunger, taken along the line IX-IX of Figure 8; Figure l0 is a fragmentary, vertical cross-sectional view of the trunnion bracket, with the plunger shown in a locked position within a channel portion of the trunnion bracket; Figure ll is a fragmentary, front elevational view of the assembly shown in Figure l0, with a portion thereof broken away; Figure l2 is a side elevational view of a second and low profile trunnion bracket; Figure l3 is a top plan view of the low profile trunnion bracket shown in Figure l2; Figure l4 is a top plan view of a third and manual release trunnion bracket, shown in a locked position; Figure l5 is an end elevational view of the manual release trunnion bracket shown in Figure l4; and Figure l6 is a top plan view of the manual release trunnion bracket, shown in an unlocked position. Figure l shows a fifth wheel assembly l for coupling tractor and trailer units. The assembly includes a trunnion bracket 2, comprising a pair of forged bearing caps 3 having an inverted, U-shaped configuration, with bearing sleeves 4 fixedly mounted therein. In the sliding fifth wheel arrangement, the bearing caps 3 are mounted on rectangular channels 5 fabricated from two L-shaped channel members 6 and 7 with a flat plate 8 attached along the upper edges thereof. A plunger 9 adjustably connects the fifth wheel assembly l with a base plate l0, having slotted racks ll attached thereto. Plungers 9 comprise a forged, two-prong construction which minimizes structural disruption in channels 5 to achieve greater strength. Adjustable stops l2 are mounted on the exterior ends of the plungers 9, and abut the exterior sides of the racks ll to accurately maintain selected engagement between the plungers 9 and the racks ll in the locked position. A manual lock rele ase l3 is illustrated in Figures l4-l6, and comprises an over-centred lever arm arrangement which securely retains plungers 9 in the unlocked position during adjustment of the trunnion bracket 2 on the base plate l0. With reference to Figure l, the base plate l0 is adapted for connection with the frame portion of a tractor (not shown). In this example, base plate l0 includes tie straps 20 at each corner of base plate l0, with fasteners 2l anchoring the same to the tractor frame. The sides of base plate l0 include upwardly and inwardly rolled edges 22, which form channels or ways in which trunnion bracket 2 is slidingly received. A fifth wheel support or plate 23 is pivotally connected with base plate l0 by trunnion bracket 2, and includes a generally flat centre area 24, inclined forks 25, and a V-shaped guide slot 26 which extends to the centre of plate area 24, and is adapted to receive and guide the kingpin (not shown) of the trailer unit into a hitch 27. With reference to Figures 2-5, bearing caps 3 have an inverted U-shaped configuration, and are forged steel to provide a one-piece, integral construction which facilitates manufacture and assembly. The forging process produces a more accurately shaped part that is easier to assemble, and alleviates the scrap and waste experienced in welded bearing designs. Bearing caps 3 have an arcuately-shaped top 30, an open bottom 3l, and a pair of parallel legs or sidewalls 32, the free ends of which are adapted for connection with fifth wheel assembly l. Preferably, bearing caps 3 have triangular gussets or reinforcing webs 33. Gussets 33 include vertical legs 34 connected with the exterior sidewalls 32 of bearing cap 3, and horizonal legs 35 adapted for connection with an associated portion of trunnion bracket 2. In this example, each bearing cap 3 includes two reinforcing gussets 33 on each sidewall 32. The opposite end edges 36 of the bearing caps 3 are bevelled, and the bearing sleeves 4 are positioned within the interior of the bearing caps 3 in an aligned relationship. Bearing sleeves 4 preferably have a generally cylindrical shape, with an outside diameter sized for close reception within the interior of the arcuate top portion 30 of bearing cap 3, and are fixedly mounted therein by suitable means such as welds 37 or the like. Pins 38 (Figure l) extend through bearing sleeves 4, and are attached to opposite sides of fifth wheel plate 24 to pivotally mount the same on trunnion bracket 2. The channels 5 of trunnion bracket 2 have a generally rectangular shape with substantially flat upper surfaces 4l, and open bottoms which form apertures or slots 42 that define open ended guides which are received over and mate with racks ll for sliding movement along racks ll. As best illustrated in Figures 10 and ll, L-shaped channel members 6 and 7 have oppositely oriented horizontal legs 44, and parallel vertical legs 45 which are spaced apart a distance sufficient to receive the corresponding rack ll therebetween. The horizontal leg 44 of exterior channel 7 is received under the upturned edge 22 of base plate l0, and slidingly guides trunnion bracket 2 over base plate 8. The horizontal legs 44 of the two interior channel members 6 are interconnected by a pair of transverse cross braces 46 at the forward and rearward sides of trunnion bracket 2. In the example illustrated in Figure 2, bearing caps 3 are fixedly attached to the upper surface 4l of channel plate 8 by welds 48, or other suitable means, and are laterally aligned and oriented generally perpendicular with the longitudinal axis of channels 5. In the embodiments illustrated in Figures l to ll and l4 to l6, bearing caps 3 are positioned directly above, and on centre with plungers 9. In these embodiments, sliding trunnion bracket 2 combines forging and fabrication and is accurately shaped and very strong. Locking plungers 9 (Figures 8-ll) have a forged, two-prong construction that provides a more precise shape for improv ed mating with racks ll, and reduced width for greater trunnion bracket strength. Plungers 9 are substantially identical in shape, and have a rectangular outline in plan view, comprising a stem 54 and a head 55 in which a pair of prongs or ribs 56 and 57 are formed. Each of the prongs 56 and 57 has opposite sidewalls 58 and 59, the facing sidewalls of the two prongs diverging toward the interior side or end 60 of the plunger 9, so as to engage similarly shaped teeth 53 in racks ll with a wedge locking action. Prong sidewalls 58 and 59 also taper toward the bottom surface 6l of plunger 9 to facilitate construction by forging. The outer side faces 50 of plunger heads 55 are flat and mutually parallel. The upper faces 5l of the plunger heads 55 include a pair of upstanding ribs 52 positioned along the sides of upper faces 5l. The upper surfaces of ribs 52 are disposed adjacent to the lower surface of channel plate 8 for sliding contact therebetween. The exterior end wall 62 of each plunger head 55 extends downwardly to the bottom surface 6l of prongs 56 and 57, and includes a threaded aperture 63 extending through the centre, bottom portion of end wall 62 into the gap or space 64 formed between the prongs 56 and 57. In the illustrated example, as best shown in Figure l0, stops l2 comprise threaded fasteners mounted in the end wall apertures 63 of plungers 9, and include an outwardly extending head 65, and a lock nut 66 mounted on the shank of the fastener. The interior end 67 of fastener l2 abuts the exterior surface 68 of the associated rack ll to positively position prongs 56 and 57 with respect to the mating teeth 53 of rack ll. Typically, it is preferred that the plunger prongs 56 and 57 just mate with the teeth 53 of rack ll, without any longitudinal stress between them to avoid forcing plungers 9 upwardly against plate 8. After proper adjustment has been achieved, lock nut 66 is tightened against the plunger end wall 62, so as to maintain the selected position. In the illustrated structure, the plunger heads 55 have a width of approximately 63.25 mm, which is approximately 44.7 mm less than the prior three-prong plungers discussed above. By reducing the width of the plunger heads 55, the prongs 56 and 57 can be forged more accurately. This results in a better mesh with the teeth 53 of racks ll to maximize contact area therebetween, minimize mismatch between the teeth, and alleviate stress concentrations. With reference to Figures 6 and l0, plungers 9 are slidably mounted in aligned apertures or windows 75 that extend through the vertical legs 34 of trunnion bracket channel members 6 and 7. Windows 75 have a substantially rectangular front elevational shape, and include a horizontal bottom edge 76, and a pair of parallel side edges 77 which extend from bottom edge 76 through the upper edges of the channel members 6 and 7, so that the bottom surface of the plate 8 forms the upper edges 78 of the windows 75. The two-prong construction of plungers 9 permits reducing the width of the window 75, so as to minimize the disruption of the cross-sectional modulus of channels 6 and 7. Forged gussets 79 (Figures 6 and 7) are fixedly mounted between channel members 6 and 7 at the side edges 77 of plunger windows 75 to reinforce channels 5, and to also form guides in which plungers 9 reciprocate. Gussets 79 have flat end faces 80 which extend laterally between the inside surfaces of channel members 6 and 7, and are aligned with the corresponding side edges 77 of plunger windows 75. The lower edges of gusset end faces 80 are positioned slightly above the upper surfaces of rack teeth 53. Gussets 79 taper inwardly at their exterior ends, and have wedge-shaped apertures therethrough defined by edges 8l. Gussets 79 are welded in the interior of channels 5 along the sides, front and rear of the gussets. Curved edges 8l provide additional weld area to the bottom surface of channel plate 8. Gussets 79 form integral, interior guides for plungers 9, and replace the inverted U-shaped channel guides used in prior fifth wheel assemblies. The interior guide construction of the present invention permits reducing the span of the windows 75 to a dimension just slightly greater than the width of plunger 9. For example, the width of prior windows is approximately l27 mm, whereas the width of the present window is just slightly greater than 63.25 mm. The combination of the two-prong plunger design and the internal guide construction results in a reduction of the required window span by over fifty percent (50%). With reference to Figure 2, plungers 9 are normally biased into the locked position by coil springs 83. The stem portions 54 of plungers 9 extend through the centres of the coil springs 83, and retainer brackets 84 are mounted on the exterior sides of springs 83 to provide a stationary surface. Another pair of retainer brackets 85 are attached to the interior ends of plunger stems 54, and include outwardly extending wings 86 which engage the coil springs 83. The coil springs 83 are pretensed so that the plunger stops l2 normally retain the plungers 9 in the preselected locked position in the racks ll. In the embodiment illustrated in Figures 2, 3 and 5, plungers 9 are diverged into the unlocked position by a pneumatic cylinder 90 which is connected between the ends of the plunger stems 54. Extension of the pneumatic cylinder 90 overcomes the biasing force of the coil springs 83 and diverges or laterally moves the plungers 9 outwardly through the windows 75, so that the plunger prongs 56 and 57 disengage the teeth 53 in the racks ll. In the unlocked position, the trunnion bracket 2 may be moved longitudinally along the base plate l0 to adjust vehicle weight distribution. When the pneumatic pressure in cylinder 90 is released, the coil springs 83 return plungers 9 to the locked position, thereby securely connecting the trunnion bracket 2 with the base plate l0. In the embodiment illustrated in Figures l4-l6, a manual plunger release mechanism is provided, and comprises a first lever arm 95 having one end 96 pivotally connected with an adjacent one of the plunger stems 54. A second lever arm 97 has one end 98 pivotally connected with the other plunger stem 54, and its opposite end 99 pivotally connected with a medial portion of the first lever arm 95 at a pivot joint l00. Selective rotation of the lever arm 95 in a counterclockwise direction (as viewed in Figures l4 and l6) compresses the coil springs 83, and diverges the plungers 9 into the unlocked position. A stop l0l is mounted on the upper surface of lever arm 95 and abuts the second lever arm 97 in a slightly over-centred position, as shown in Figure l6, to retain the plungers 9 in the unlocked position to facilitate adjustment of the trunnion bracket 2 on base plate l0. In the illustrated example, the lever arm 95 is bent at an obtuse angle to provide a somewhat L-shaped plan configuration to facilitate applying force to the outer end l02 of arm lever 95. The second lever arm 97 is generally straight, and positioned on top of the L-shaped lever arm 95, so that the lever arms move in a scissors fashion. Pivot joint l00 is located on the interior leg l03 of L-shaped lever arm 95 at a location adjacent to bend l04, so that lever arms 95 and 97 will assume an over-centred relationship when plunger 9 is in the unlocked position. Since the manual plunger release l3 is free floating, in that it is not physically attached to any portion of the fifth wheel assembly other than the interior ends of the plunger stems 54, the unit can be quickly disassembled, and trunnion bracket 2 can be bodily removed from base plate l0 without disassembling the plunger release mechanism. Manual plunger release l3 simultaneously locks and unlocks both plungers, and is easy to reach and manipulate from a central location at the rearward side of the trunnion bracket 2. This enables fifth wheel assembly l to be conveniently adjusted by a single operator. In the low profile embodiment il lustrated in Figures l2 and l3, the height of channel members 6 and 7 is minimized to lower the central axis of the trunnion bearing sleeves 4. In this embodiment, bearing caps 3 are attached directly to the upper surfaces of channel plate 8, and plunger windows 75 are formed through the vertical legs 34 of bracket channels 6 and 7 at a location spaced longitudinally from bearing caps 3. Specially formed plates or caps l05 are positioned over window openings 75, and form a part of the windows, so that plungers 9 can be used interchangeably in all embodiments. Caps l05 have a raised central area, with a downwardly opening, rectangular aperture that forms side edges which extend transversely across the width of channels 5. These cap side edges define the sides of the plunger guides, such that gussets 79 are not required in the low profile embodiment illustrated in Figures l2-l3. The fifth wheel assembly l provides an improved trunnion bracket construction which is easier and more economical to manufacture, without sacrificing strength or reliability. The forged bearing cap design reduces scrap and waste, and provides a more accurately shaped part, which is very strong and easy to assemble. The forged two-prong plunger construction and internal guide design increases the strength of the trunnion bracket 2 by minimizing the structural disruption caused by the plunger windows 75. The more precise shape of the plunger prongs 57 and 57 provides a better fit with the teeth 53 of racks ll so that the overall shear strength of the plunger lock is not substantially reduced. The adjustment stops l2 not only positively position the plungers 9 with respect to the racks ll, but are also located on the exterior sides of the trunnion bracket 2 to provide greater convenience in adjustment. The manual plunger release l3 provides an uncomplicated mechanism which is operable by one person at a central location to release both plungers 9 at the same time.

Claims: A fifth wheel coupling for selectively interconnecting tractor and trailer units, including a base plate (10) adapted for connection with a tractor unit, and having a pair of slotted, parallel racks (11) mounted thereon in a laterally spaced apart relationship; a trunnioned fifth wheel assembly having a pair of channels (5) received over the racks for sliding movement therealong; a pair of locking plungers (9) slidably mounted in aligned windows (75) disposed in opposite sides of the channels, the windows (75) being shaped for close, sliding reception of the plungers therein; means (83, 13, 90) for selectively engaging the locking plungers with the racks to adjustably anchor the fifth wheel assembly on the base plate; the locking plungers (9) having a two-prong configuration (56, 57) with each prong being tapered longitudinally thereof and having side surfaces arranged to mate in surface contact with corresponding teeth of the respective rack (11), the side surfaces being angled with respect to a vertical plane passing perpendicularly to the longitudinal extent of the racks (11); characterised in that the locking plungers are forged and in that the side surfaces thereof are further angled with respect to an arbitrary vertical plane. A fifth wheel coupling as claimed in Claim 1 including first and second gussets (79) fixedly mounted within respective channels (5), and having end faces (80) extending between and aligned with respective windows (75), to define interior guides in which the plungers (9) are reciprocated. A fifth wheel coupling as claimed in Claim 2 in which the gusset end faces (80) have a lower edge (81) positioned slightly above upstanding teeth in the respective racks (11). A fifth wheel coupling as claimed in claim 2 or claim 3 in which the gussets (79) have sides and ends welded to the respective channels (5). A fifth wheel coupling as claimed in any one of claims 2 to 4 in which the windows (75) and interior plunger guides have a width slightly greater than the width of the plungers (9). A fifth wheel coupling as claimed in any one of the preceding claims including stops (l2) connected with the plungers (9), and positioned to abut the racks (ll) in the locked position to positively maintain the plungers in a preselected, engaged relationship with the respective racks (ll). A fifth wheel cou pling as claimed in claim 6 in which the stops (l2) are adjustably mounted in the plungers (9). A fifth wheel coupling as claimed in claim 7 in which the stops (l2) comprise studs threadedly mounted in the exterior ends (62) of the plungers (9) for adjusting the stops in substantially infintesimally small increments. A fifth wheel coupling as claimed in any one of the preceding claims including means (l3, 90) which diverge the plungers (9) into an unlocked position. A fifth wheel coupling as claimed in any one of the preceding claims including means (83) which converge the plungers (9) into a locked position. A fifth wheel coupling as claimed in any one of claims l to 8 including means (83) for resiliently biasing the plungers (9) into a converged, normally locked position with the racks (ll); a first lever arm (95) having a first end (96) pivotally connected with one of the plungers, and a second end (l02) adapted for applying a lateral release force thereto; a second lever arm (97) having a first end (98) pivotally connected with the other one of said plungers, and a second end (99) pivotally connected with a medial portion of the said first lever arm (5), whereby selective rotation of the said first lever arm diverges the plungers into an unlocked position. A fifth wheel coupling as claimed in claim ll in which the second end (99) of the second lever arm (97) is connected with the first lever arm (95) at a point thereon which causes the arms to assume an over-centred relationship in the unlocked plunger position, and including a stop (l0l) mounted on one of the lever arms and positioned to abut the other of the lever arms in the unlocked plunger position to retain the same therein.

Inventors: BAKKER, FREDERICK JAY, BUSH, JAMES HARVEY, GISINGER, JACK LORIN, HUNGERINK, GERALD WESLEY, MARTIN, SAMUEL ALBERT
Applicants: HOLLAND HITCH COMPANY
Application year: 1983
Main classification: B62D53
IPC codes: B62D53