US 3827709 A
A fifth wheel coupling comprises a king-pin follower engageable with a bottom flange on a king-pin as it moves into a slot of a fifth wheel plate whereby the follower releases a lock which is spring-biased to locked position whereat a rear jaw confines the king-pin against a front jaw of the plate. The lock engages the rear jaw along complementary wedge surfaces which in conjunction with an elongated pivot pin hole in the rear jaw ensures snug fit of the king-pin within the jaws despite worn condition of the parts.
Description (OCR text may contain errors)
United States Patent [191 Madura et al.
[111 3,827,709 [451 Aug. 6, 1974 FIFTH WHEEL COUPLING  inventors: Francis Eli Madura, Whiting; John Allan Kent, Chesterton, both of Ind.
 Assignee: Amsted Industries Incorporated,
I Chicago, Ill.  Filed: Mar. 28, 1973  Appl. No.: 345,533
 US. Cl. 280/434  Int. Cl. B62d 53/12  Field of Search 280/434  References Cited UNITED STATES PATENTS 2,855,221 10/1958 Cochrane 280/434 2,861,818 11/1958 Kayler 280/434 2,885,222 5/l959 Walther et al. 280/436 2,977,137 3/1961 Durham 280/434 3,600,006 8/1971 Slaven 280/434 Primary Examiner-Leo Friaglia  ABSTRACT A fifth wheel coupling comprises a king-pin follower engageable with a bottom flange on a king-pin as it moves into a slot of a fifth wheel plate whereby the follower releases a lock which is spring-biased to locked position whereat a rear jaw confines the kingpin against a front jaw of the plate. The lock engages the rear jaw along complementary wedge surfaces which in conjunction with an elongated pivot pin hole in the rear jaw ensures snug fit of the king-pin within the jaws despite worn condition of the parts.
9 Claims, 18 Drawing Figures PATENTEH 51974 3.827.709
SHEE! 2 (If 3 I FIFTH WHEEL COUPLING This invention relates to a fifth wheel coupling mechanism as commonly utilized in coupling a tractor to a trailer of a highway vehicle.
A primary object of the invention is to devise an economical, dependable fifth wheel coupling mechanism capable of long life and consistent operation under service conditions.
Another object of the invention is to prevent closing of the mechanism unless the king-pin of the trailer is in proper position to be coupled to the tractor.
A further object of the invention is to compensate for wear in the king-pin and/or the coupling mechanism thereby ensuring a snug fit between the coupled parts despite such wear.
Still another object of the invention is to devise a novel operating rod and gravity safety latch to afford a lock-to-the-lock when the lock is in its locked position and to afford a lock-set position whereat the rear lock is held in open position before the mechanism is pulled away to remove the king-pin from the front jaw, a kingpin follower being provided to afford another lock-set position after the king-pin has cammed the lock during final separation of the king-pin from the mechanism.
The foregoing and other objectives and advantages of the invention will become apparent from the following specification and the accompanying drawings wherein:
FIG. 1 is a fragmentary top plan view of a fifth wheel embodying the invention;
FIG. 2 is a side elevational view of the structure shown in FIG. 1;
FIGS. 3 and 4 are sectional views taken respectively on lines 3-3 and 4-4 of FIG. 1;
FIGS. 5 8 illustrate the rear jaw in detail, FIG. 5
. being a top plan view thereof, FIG. 6 being a rear edge elevational view thereof, FIG. 7 being an end elevational view thereof, and FIG. 8 being a sectional view on line 8-8 of FIG. 5;
FIGS. 9 12 illustrate the lock in detail, FIG. 9 being a top plan view thereof, FIG. 10 being a rear elevational view thereof, FIG. 11 being an end elevational view thereof, and FIG. 12 being a sectional view on line l2-12 of FIG. 9;
FIG. 13 is a fragmentary top plan schematic view, partly in horizontal section showing the lock, rear jaw and king-pin follower in locked position with respect to the king-pin;
FIG. 14 is a fragmentary side elevational view showing the operating rod and gravity latch in position to hold the mechanism locked as shown in FIG. 13;
FIG. 15 is a view comparable to FIG. 13 but with the gravity latch and operating rod manually moved to their positions whereat the lock and rear jaw are held in unlocked and open positions respectively;
FIG. 16 is a view comparable to FIG. 14 but showing the gravity latch and operating rod in the position of FIG. 15
FIG. 17 is a view comparable to FIGS. 13 and 15 but showing the king-pin removed; and
FIG. 18 being a view comparable to FIGS. 14 and 16 but showing the gravity latch and operating rod in position to permit the lock to be snapped to its locked position when released by the king-pin follower in response to a king-pin entering the mechanism.
Describing the invention in detail and referring first to FIG. 1, the novel fifth wheel comprises a plate 20 slotted as at 22 to receive a king-pin 24 (FIG. 3) of a trailer vehicle (not shown). The plate 20 comprises a mounting bracket 26 at each side thereof for attachment as by pivot pin 28 to a saddle (not shown) of an associated tractor vehicle (not shown).
A front jaw 30 is integral with, or attached to, the plate 20, and a rear jaw 32 is pivoted to the plate 20 as by a pin or stud 33 and nut 34 which also attaches a support plate 36 to the plate 20. The support plate 36 is also attached to plate 20 by a pin or stud 38 and nut 40. Both studs 33 and 38 extend through elongated slots 40 of a king-pin follower 42 adapted to engage the bottom flange 44 (FIG. 3) of the king-pin 24, as hereinafter described, for releasing a lock 46 which is releaseably held (as hereinafter described) in open or unlocked position by the follower 42 as the king-pin enters the slot 22 and moves into engagement with the front jaw 30. During such movement of the king-pin, if its bottom flange 44 is at proper depth within the slot 22 the bottom flange 44 will disengage the follower 42 from the lock which then snaps to locked position under the action of a compression spring 48.
As the follower 42 is moved to its forward or release position by the bottom king-pin flange 44 as heretofore described, the follower compresses another compression spring 50 against a flange 52 of the support plate 36 When it is desired to release the king-pin from the jaws 30 and 32 the lock is manually retracted by an operating rod 54 having a handle 56. After the lock has been retracted, and the king-pin is moved out of the front jaw (as hereinafter described) spring 50 advances follower 42 until one arm 58 of the follower engages the outer end of the lock 46 along a bottom lug 68 thereof to hold it in unlocked position. As the lock 46 is retracted, spaced lugs 68 thereof engage flanges 70 of the rear jaw 32 pulling it to open position shown in FIG. 15.
Referring now to FIGS. 5 to 8 which show the rear jaw 32 in detail, it will be seen that this part is an elongated member having an arcuate king-pin engaging surface 72 on one lateral edge thereof and having on the opposite lateral edge thereof a wedge surface 74 engageable with a complementary surface (hereinafter described in detail) of the lock 46. The wedge surface 74 is partly defined by the beforementioned flanges 70. Adjacent one end thereof, the rear jaw 32 is formed with an elongated pin hole 76 to receive the pin 33 as heretofore described.
Thus when the rear jaw is urged to locked position by the lock 46, the wedge surface 74 and the elongated pin hole 76 permit the rear jaw to adjust for any wear in the king-pin 24 and the jaws 30 and 32, thereby ensuring a snug fit between these parts.
Referring now to FIGS. 9 to 12 which show the lock 46 in detail, it will be seen that this part is an elongated member having along one lateral edge thereof a wedge surface 78 for engagement, as best seen in FIGS. II and 4, with the rear jaw 32 along its complementary wedge surface 74 (FIGS. 5 and 6). The lock 46 along its opposite lateral edge has a bearing surface 80 adapted to slide along a complementary wall of the plate 20, said wall facing the wedge surfaces 74 and 78 and as seen in the top plan view of FIG. 1, said wall is arranged at an acute angle to said wedge surfaces. Opening at one end of the lock 46 is a spring pocket 82 terminating at its inner end in a spring seat 84 for the spring 48, and the inner end of the spring pocket 84 also communicates with a slot 86 for reception of a hook end 88 of the operating rod as best seen in FIG. 1. The end 88 is retained by pin 90 (FIG. 1) extending through aligned holes 92 (FIG. of the lock 46. Said lock, at its opposite end is provided with the beforementioned lugs 68.
Referring now to FIGS. 13 and 14 wherein the kingpin 24 is shown in its locked position with the rear jaw 32 held in its closed position by engagement of the lock 46 and the rear jaw 32 along their respective wedge surfaces 78 and 74, accidental unlocking of the mechanism is prevented by engagement of a shoulder 60 on the operating rod 54 with the safety latch 62 which has a weight 63 urging the latch by gravity to the position of FIG. 14. The operating rod 54 extends through a hole 21 of a depending flange 20a on the plate 20, and the-gravity latch 62 is pivoted at 66 to the flange 20a. The latch has a slot 64 which functions as hereinafter described.
When it is desired to release the king-pin 24, the latch 62 is moved manually to the position of FIGS. 15 and 16 and the rod 54 is pulled by its handle 56 to the position of FIGS. 15 and 16 whereat another shoulder 94 of the rod 54 is held against the flange 20a by the spring 48. As the tractor and the fifth wheel mechanism are moved forwardly to pull the mechanism from engagement with the king-pin 24, the rear jaw 32 is held open by engagement of the lock lugs 68 with the jaw flanges 70. When the inner end of the lock is cammed slightly toward the flange 20a by the king-pin upper collar 24a (FIG. 3) the rod shoulder 94 falls by gravity to the position of FIG. 18 after the king-pin follower arm 58 is in position to engage the bottom lock lug 68 to hold the lock in the lock-set position of FIG. 17, preparatory to reception of a king-pin into the position of FIG. 13 whereat the spring snaps the lock to locked position and jaw 32 to closed position as the rod 54 and its shoulder 94 move freely through the slot 64 and hole 21 until the rod reaches the position of FIG. 13 whereupon the latch 62 falls by gravity to the lockto-thelock position of FIG. 13.
As best seen in FIG. 1, the longitudinal axes of the springs 48 and 50 are substantially normal so that the force paths of the springs are approximately normal. Also the bearing surface 84 and the longitudinal axis of spring 48 are at an acute angle to the wedge surfaces 74 and 78 on the rear jaw 32 and the lock 46, respectively, thereby developing a wedging action along these wedge surfaces which in combination with the elongated hole 76 in the rear jaw causes the king-pin 24 to be snugly clamped by the jaws 30 and 32 above the king-pin flange 44 despite any wear which may have occurred along that portion of the king-pin which engages the jaws and despite any wear which may have occurred along rear jaw surface 72 and/or that portion of the front jaw 30 which engages the king-pin.
It should be noted that although the invention is disclosed as embodied in a right-hand fifth wheel, by an obvious reversal of parts the invention may be embodied in a left-hand fifth wheel.
What is claimed is:
1. In a fifth wheel; the combination of a plate having a slot terminating in a front jaw, a rear jaw pivoted to the plate for pivotal movement relative to the front jaw,
a lock moveable into locking position with respect to the rear jaw when it is in closed position, a U-shaped follower having spaced arms below said jaws at opposite sides, respectively, of said slot, said follower being moveable with respect to both jaws to a position whereat one arm of the follower holds the lock in an unlocked position when the rear jaw is in open position, and a king-pin confined against fore and aft movement between said jaws when the rear jaw is in closed position, said king-pin having means below said jaws for engaging said follower between its arms for releasing said one follower arm from the lock as the king-pin moves toward the front jaw.
2. A fifth wheel according to claim 1 wherein resilient means are provided for biasing the follower into engagement with the lock and wherein other resilient means are provided for biasing the lock into locking engagement with the rear jaw in its closed position.
3. A fifth wheel according to claim 2 wherein the first mentioned resilient means acts in a force path approximately normal to that of the second-mentioned resilient means.
4. In a fifth wheel; the combination of a plate having a rearwardly opening slot tenninating at its forward end in a front jaw, a rear jaw, means pivoting the rear jaw to the plate, a king-pin follower mounted on said plate for reciprocal movement, a lock having a wedge surface engaging a complementary wedge surface of the rear jaw, said lock mounted on said plate for reciprocal movement, a compression spring compressed against a spring seat carried by said plate and against a forwardly facing surface of said follower, another compression spring compressed against a spring abutment on said plate and against said lock, the compressional axes of said springs being approximately normal to each other, and said surfaces extending diagonally forwardly beneath said slot, said follower having means engageable with the lock in its unlocked position to releaseably hold the lock in said position whereat said wedge surfaces are separated from each other and said rear jaw is in open position.
5. In a fifth wheel having a plate with a rearwardly opening slot; the combination of a front jaw fixed to the plate at the forward end of the slot, a rear jaw pivoted to the plate for movement to open and closed positions, a lock moveable laterally of said slot into and out of locking position with respect to said rear jaw in its closed position, a king-pin follower beneath said jaws and moveable with respect to both jaws, said follower engageable with a bottom flange of an associated kingpin as it moves into said front jaw, said follower in retracted position, with the king-pin confined by said jaws, being disengaged from said lock to permit it to move into locking position with respect to said rear jaw, and said follower, in advance position with the king-pin rearwardly of said rear jaw, having means to latch the lock in an unlocked position whereat the rear jaw is in its open position, spring means for urging the lock toward its locked position, and spring means independent of the first-mentioned spring means for urging the follower toward said advance position thereof.
6. A fifth wheel comprising a plate with a slot, jaw means for coupling with an associated king-pin in said slot, lock means for locking said jaw means in closed position thereof with the king-pin therein, spring means for actuating said lock means to its locked position, an operating rod operatively connected to said lock means, a gravity latch pivotably connected to said plate beneath said rod, said rod having an inwardly facing shoulder held against said plate by said spring means in unlocked position of said jaw means, said rodextending through a hole of said plate, follower means releaseable by said king-pin for holding the lock in lock-set position whereat said shoulder is aligned with said hole with said spring means compressed against the lock means, said latch having an elongated slot receiving the rod and aligned with said shoulder when said lock is in said lock-set position, and said latch being moveable by gravity to a position whereat another, oppositely facing, shoulder on the rod is aligned with a solid portion of the latch when the lock means are in locked position.
7. A fifth wheel coupling comprising a plate with a slot terminating in a front jaw formed and arranged to receive a king-pin, a rear jaw pivoted to the plate, the rear jaw formed and arranged to engage the king-pin when the rear jaw is in closed position, a lock engageable with a rearwardly facing surface of the rear jaw to lock it in closed position, means on the lock and rear jaw for moving the rear jaw to closed position as the lock moves to locked position and for moving the rear jaw to open position as the lock moves to unlocked position, spring means for biasing the lock to locked position, and means for retracting the lock to unlocked position against the resistance of said spring means.
8. In a fifth wheel; the combination of a plate having a slot extending forwardly and having at its forward end an arcuate front jaw, a rear jaw pivotally supported by the plate for pivotal movement relative to the front jaw, said rear jaw having an arcuate area adapted to cooperate with the front jaw in confining an associated kingpin, said rear jaw having top and bottom flanges partly defining a surface along an edge of said rear jaw opposite said arcuate area, a hollow lock slideably supported by said plate and having a surface engaged with said jaw surface to hold the rear jaw in closed position, said flanges being recessed in said lock when the rear jaw is in closed position, and top and bottom lugs in said hollow lock engageable with respective flanges as the lock is moved to retracted position whereby the lugs pull the rear jaw to open position, the end of said rear jaw remote from its pivot point being recessed within the lock in the open position of said rear jaw, and means for moving the lock to retracted and locked positions.
9. A fifth wheel according to claim 8 wherein the surfaces extend diagonally rearwardly toward said remote end of the rear jaw when it is in locked position and wherein the lock is slideably engaged with a wall of the plate facing said surfaces and arranged at an acute angle thereto as seen in top plan view when the jaw is in locked position.