JPH0510264B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an AAR standard E-type coupler for railway vehicles (an E-type coupler approved as a standard by the U.S. AAR, hereinafter simply referred to as an "E-type coupler"). (hereinafter simply referred to as the "yoke") for the coupling yoke (hereinafter simply referred to as the "yoke"), with a length of 3 1/2 inches, specifically to facilitate removal of the yoke together with the traction equipment from the rail vehicle. (88.9mm) to have a blunt (less sharp) nose and, if desired, to avoid deformation in the key slot area adjacent to the nose of the yoke. The present invention relates to a coupler yoke, characterized in that the nose of the yoke is formed with a uniformly thick wall having a smooth convex outer surface, in order to strengthen the yoke and improve the service life of the yoke.

BACKGROUND OF THE INVENTION For convenience of explanation, the following description will use reference numerals of various parts attached to the accompanying drawings showing embodiments of the present invention.

A coupler used to connect two railway cars is coupled to each car via a coupler yoke 15. A central sill 18 having an inverted U-shaped cross section and opening downward is fixed to each vehicle.

Hitch yoke 15 is formed with a traction device receiving pocket for receiving a traction device 24 for damping the pulling and pushing forces transmitted between the hitch head 10 and the vehicle.
The AAR standard E-type coupler yoke is a one-piece casting with a symmetrical shape about a longitudinal center plane. The cast yoke 15 consists of a rear end portion 35 forming a towing device receiving rear seat 37, a yoke head 40, a top strap 38 and a bottom strap 39 extending therebetween, and a wall of the yoke head 40. forms a towing device receiving front wall 42 facing the towing device receiving rear seat 37. the towing device receiving front wall 42;
The area bounded by the towing device receiving rear seat 37 and the top strap 38 and bottom strap 39 defines a towing device receiving pocket. Within this pocket, the traction device 24 can serve to dampen the pushing and pulling forces that occur during the running of the train.

The yoke 15 and the traction device 24 inserted into its said pocket are inserted into the U-shaped cavity of the sill 18 so that the abutting end 35 of the yoke abuts the traction lug 26 secured to the sill 18. York 15
is supported from below by a yoke strap carrier 25 bolted to the sill 18.

A cast striker 17 is also fixed to the central sill 18 of the railway vehicle. A traction device follower 27 (cubic metal block) is interposed between a front traction lug 28 fixed to the rear of the striker 17 and the traction device 24. It engages the front follower 27 to transmit the force from the device 24.

The shaft 11 of the coupler is inserted into the striker 17 so that the abutting end 12 of the shaft 11 abuts against the follower (also referred to as "follower block") 27. The coupler shaft 11 inserted into the striker 17 is supported by the bottom wall of the striker 17 or the coupler carrier 32 . Striker 1
The coupler carrier 32 of 7 is an integral part of the striker 17.

The key slot walls 41 of the head portion 40 of the yoke 15 flare outwardly on each side of the yoke 15.
Each key slot wall 41 has a key slot 13 extending generally parallel to the top and bottom straps 38, 39 of the yoke. The key slot 13 is for receiving a horizontally arranged towing key 14 for connecting the coupler shaft 11 inserted into the striker 17 to the yoke 15. The ends of each key slot 13 are semicircular in shape to avoid the tow key 14 exerting concentrated local forces on the cast yoke 15. The head portion 40 of the yoke has a nose 43 extending forwardly from the key slot wall 41 and projecting into the central space of the cast striker 17.

Problems to be Solved by the Invention The Y40 and Y41 standard yokes 15 for E-type couplers provide a significant improvement in operation in railway vehicles by improving the structure of the nose 43 to solve two problems. be able to.

The first problem among the above problems is that the yoke 15 is
Removal of the type coupler together with the towing device 24 as an integral unit from the vehicle is often difficult and cumbersome. This is because the yoke 15 protrudes too far forward of the vehicle, so the nose 43 of the yoke
and the coupler carrier 32 of the striker 17 interfere with each other during the above-mentioned removal operation (although such interference should not occur due to the design of the standard parts).

At times, it is necessary to remove the traction device 24 from the center sill 18 of the rail vehicle for maintenance service or replacement. In order to be able to remove the traction device 24 from the yoke 15 on the side far from the railway vehicle, the yoke must first be removed from the center of the vehicle together with the traction device 24 and follower block 27 mounted in its traction device receiving pocket. It must be removed from the sill 18. If the condition is normal, pull out the shaft part 11 of the coupler from the striker 17 and yoke 15, and remove the bolted yoke trap.
If carrier 25 is removed from sill 18, yoke 15
and the traction device 24 can be slid downwardly through the open bottom of the central sill 18 between the traction lug 26 and the hitch carrier 32, both of which are fixed. However, as is well known in the art, the traction system 24 is subjected to enormous loads while transmitting pulling and pushing forces while the train is in motion.
If the yoke 15 is deformed or expanded under a large tensile load, the yoke 1
5 and traction device 24 downwardly through the open bottom of the central sill 18.
3 gets caught in the coupler carrier 32 of the striker 17 (interferes with it) and cannot pass through.
The load that the yoke receives while the train is running is extremely large, so the clearance specified by the design is
Even though manufacturing tolerances are set, they actually vary. Therefore, the cast yoke 15 is significantly elongated, with the result that the design clearance required to remove the yoke together with the traction device 24 is reduced to such an extent that removal of the yoke is impossible. In that case, the operator would conventionally cut off a portion of the coupler carrier 32 to create sufficient clearance. However, this would weaken the coupler carrier 32 and the striker 17 and deteriorate their quality.

The yoke and traction device combination can be attached to the center sill 1 without cutting a portion of the coupler carrier 32.
8 to create sufficient clearance between the front traction lug 28 and the rear traction lug 26 of the center sill 18 and the yoke/traction device combination to allow it to slide freely downwardly through the open bottom of the sill 18. To do this, place the towing device 24 in the 1/8 inch
mm) or more. The traction device 24 typically includes a compression jack inserted into an opening between a pair of key slot walls 41 such that one portion of the jack compresses the front follower block 27 and thereby the traction device 24. compressed by making it possible to press on the telescoping member of. The compression jack is attached to the key of the yoke.
Support is provided to the yoke by means of a cross member inserted through the key slot 13 of the slot wall 41. Interference occurs between the nose 43 of the yoke and the coupler carrier 32 of the striker 17, causing the traction device 2
4 and yoke 15 to the coupler carrier 32
If it interferes with processing through the rail, the yoke must be moved to the rear of the railway vehicle. Previous attempts to eliminate such interference problems have included adding shims of appropriate thickness, typically 3/8 inch (9.525 mm) or thicker, to the rear of the towing device 24 and the yoke 1.
It was necessary to insert it between the towing device receiving rear seats 37 of No. 5 and to provide a gap between the two. Such a gap must be created by pushing the yoke rearward in a manner that simulates the pushed-in condition of the traction device 24. Forces tending to compress the traction device 24 are resisted by the rear traction lug 26 of the center sill 18 and the traction lug 28 of the striker 17, which are in force transmission relationship with the traction device via the traction device follower 27. Ru.
The purpose of the shim or spacer inserted between the yoke and the rear seat 37 is to limit forward movement of the yoke when operating the compression jack to compress the traction device 24. During compression of the towing device using a compression jack, the spacer holds the yoke in a rearward position to relieve the compressive force exerted by the towing device on the front and rear traction ears 28 and 26. play a role. However, this method is not successful because the clearance between the nose 43 of the yoke and the coupler carrier 32 of the striker 17 may still be insufficient, for example because the yoke 15 has been stretched during use. There are cases. To move the yoke further rearward, the traction device 24 is placed in front of the front traction ear 28 and the follower 27 to provide sufficient clearance between the nose 43 of the yoke and the coupler carrier 32. must be sufficiently compressed to allow insertion of a spacer between them. The compression jack must then be released to lock the traction device 24 between the rear traction ear 26 and the spacer, thereby sliding the yoke 15 rearwardly relative to the striker 17. A spacer of sufficient thickness to provide the required clearance between the nose 43 of the yoke and the coupler carrier 32 of the striker 17 is then placed between the rear of the traction device 24 and the traction device receiving rear seat 37 of the yoke. must be inserted into. Thereafter, the traction device 24 is compressed to move the traction device out of compressive engagement with the front and rear traction ears 28 and 26, allowing the spacer to be removed. This operation is time consuming and expensive and must be carried out under difficult working conditions. This is because the yoke must be held in the downwardly facing pocket of the center sill 18 to provide operator access to the spacer and shim for insertion and removal.

The second problem is that the load of the towing key 14 is concentrated on the peripheral rib 44 of the key slot 13 of the cast yoke 15, causing the key slot 1 of the yoke to
Deformation occurs at the periphery of the key slot 13 and sometimes cracks occur in the yoke at the front end of the key slot 13. Therefore, in the conventional yoke structure, deformation occurs in the front of the key slot 13 in the nose 43 of the yoke, and as a result, the key slot 13
The surrounding wall of the yoke was damaged and the entire yoke had to be replaced.

The service life of a yoke can be extremely short, especially when installed in a coal car of a single freight train. Deformation of the front portion (nose portion 43 side) of the key slot 13 of the yoke may be severe enough to require replacement of the entire yoke. The type of deformation that has been observed to occur is that formed in the key slot wall 41 of the yoke and in the key slot 13 for receiving the horizontal key 14 for coupling with the coupler shaft 11. This is caused by a localized load being applied to the peripheral wall by the key 14.

As railroad freight cars are subject to shaking and varying rail conditions such as curves during travel, the coupled coupler between the freight cars may tilt with respect to the freight car, causing twisting and pulling forces or rubbing against the coupler's traction device 24. Add force. Torsional forces create relative torsional slopes between interconnected parts. Both parts are free to tilt until no further twisting is possible due to the disappearance of the clearance.

The coupler may impose rotational motion on the tow key 14, which is restrained within the key slot 13 of the yoke. Metal-to-metal contact between the key 14 and the peripheral wall of the key slot 13 of the yoke (metal-to-metal contact)
If the coupler continues to rotate even after this, the yoke itself will rotate and the straps 38, 39 of the yoke will rotate.
Interference (contact) occurs between the follower block 27 (top wall and bottom wall). According to the data regarding the normal running load of 2000001b (90600Kg), the resistance to twisting of the yoke creates a friction force of 400001b (18120Kg) when the friction coefficient is 0.2. This frictional force is distributed to the contact between the follower 27 and the traction lug 28 of the striker 17, thereby preventing further twisting of the follower.
In the case of the AAR standard E-type coupling shaft 11 and yoke combination, the maximum angle of inclination that the key 13 experiences under the above conditions is about 5.25° and the minimum is about 0.75°. Comparing the maximum and minimum tilting of the tow key 13 with the tilting of the wagon bolsters and side beams that can occur on uneven, low-quality rails, if two coupled wagons swing in opposite directions. , the maximum inclination of the bolster with respect to the rail is 7.393°,
The maximum tilt for the bearing adapter is 15°. Therefore, the maximum distance between the connected freight cars
A tilt of 22.39° can occur. Since the torsional slopes of the couplers are mutually limited, the remaining torsional slope of the 22.39° must be tilted by the entire system. The combination of torsional tilt and vertical tilt causes the tow key 13 to stick to the ribs 44 around the key slot 13 and become stuck.
A point load will be applied to the circumferential surface of the rib.

The present invention addresses the first problem described above, which is associated with the removal of the yoke from a railway vehicle, and also solves the problem of removing the key slot 13 of the yoke after a relatively short period of use, particularly in the nose section 4.
For the nose 43 of the yoke 15, in order to simultaneously solve at least one or both of the above second problems, i.e. the problem of deformation of the key slot wall, causing distortions and even cracks at the yoke 15. The objective is to provide an improved structure for.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an improved structure of the yoke nose 43 of the AAR standard E-type coupling in order to avoid the problems and disadvantages mentioned above.

Means for Solving the Problems The present invention provides a means for solving both the first problem and the second problem described above.
In order to prevent the front part of the key slot 13 of 3 from being deformed and to facilitate the removal of the yoke from the center sill 18 of the vehicle, the nose is shortened and has a non-sharp, blunt, solid form. To provide an improved structure of the AAR standard E-type yoke for the E-type coupler shaft portion 11, which is characterized by the following.

That is, the present invention includes a top strap 38 and a bottom strap 39 extending parallel to each other and spaced apart, and a towing device receiving rear seat 37 at right angles to the top and bottom straps. an abutting end portion 35 having an abutting end portion 35 and a towing device receiving front wall 42 facing the rear seat 37;
and a yoke head portion 40 having a pair of key slot walls 41, 41 extending from the front wall and the top strap 38 and bottom strap 39 and gradually flared outwardly, the towing device receiving rear portion Seat 37 and towing device receiving front wall 42
, top strap 38 and bottom strap 39
In the coupler yoke 15 by which a towing device receiving pocket is defined, each said key slot wall 41 includes an elongated key slot 13 having a semi-circular shaped front end and extending from the front end of the key slot. Nose 4 extended forward
3, and the nose has a length from a point on the forwardmost surface of the semicircular front end of the key slot to the forwardmost end of the nose that is less than 3 1/2 inches (88.9 mm). To provide a coupler yoke characterized by having a blunter profile than that of a standard yoke due to its shortened length.

The invention also includes an abutting end portion 35 having a top strap 38 and a bottom strap 39 extending parallel to each other and spaced apart, and a tow device receiving rear seat 37 at right angles to the top and bottom straps; a towing device receiving front wall 42 facing the rear seat 37, said front wall 42) and said top strap 38 and bottom strap 3;
A pair of keys extending from 9 and gradually expanding outward.
a yoke head portion 40 having slot walls 41, 41, the towing device receiving rear seat 3;
7 and a hitch yoke 15 having a towing device receiving pocket defined by a towing device receiving front wall 42, a top strap 38 and a bottom strap 39; The key slot 13 includes an elongated key slot 13 having a semi-circular rear end spaced apart from the front receiving wall 42 and a semi-circular front end.
A nose 43 extends forward from the front end of the slot, the nose having a generally semicircular edge 45 centered at a point within the key slot to reduce the length of the nose. The nose is defined by a convex continuous outer surface extending rearwardly and connected to a rib 44 projecting from the key slot wall 41 and extending along both longitudinal sides of the key slot 13. A coupler yoke is provided.

This configuration provides a particularly robust yoke. Preferably, the nose 43 of the coupler yoke 15 extends beyond the key slot 13.
It is composed of a solid wall 46 having a trapezoidal cross section and a smooth convex outer surface and a smooth inner surface. The convex, continuous outer surface of each nose 43 defines the tow key 1.
4 extends rearwardly beyond the semicircular front edge of key slot 13 by a small distance sufficient to withstand the torsional force exerted on the front portion of the peripheral wall of key slot 13 by It is connected (merged) with the side protruding rib 44. Outward protruding rib 44
inserts the key into both sides of the key slot from its front edge.
Towing device receiving rear seat 37 along slot
It extends towards. Thus, by forming the nose 43 of the key slot wall 41 with a smooth convex outer surface and by forming the outwardly projecting ribs 44 along both sides of the key slot 13, the key of the key slot wall 41 is - Stepped recesses are formed on both sides of the slot 13.

Effects of the Invention As described above, according to the present invention, by shortening the nose portion 43 of the yoke 15, the outline of the nose portion is made into a blunt shape without being sharp. When removing the yoke 15 and traction device 24, the yoke can be easily removed without having to shift the yoke rearwardly along the sill 18 to avoid interference between the nose 43 of the yoke and the coupler carrier 32 of the striker 17. The result is a yoke head portion 40 that is not only easily removable, but also strong enough to withstand the torsional forces exerted by the tow key 14 on the front of the peripheral wall of the key slot 13.

The above and other features and advantages of the invention will become more apparent from the following description taken with reference to the accompanying drawings.

DESCRIPTION OF THE EMBODIMENTS Referring to FIG. 1, the E
The type train coupling device has a coupler head 1 of a well-known structure.
0, and a coupler shaft 1 extending rearward from the head.
1. The shaft portion 11 is the shaft portion of the E-type coupler.
It complies with AAR standards, and the butt end 12
have. The shaft portion 11 has a horizontal key slot 13 formed in front of the abutting end. The tow key 14 is located in the key slot 13
and projects outwardly from both sides of coupler shaft 11 through a key slot opening formed in the nose of yoke 15, as will be described below. The ends of the towing key 14 also project through the key slot opening 16 of the cast striker 17. The cast striker 17 is preferably made of welded metal, as shown in FIG.
Central sill (cradle) in the manner described in No. 4445617
It is fixed at 18. Sill 1 shown in Figure 2
8 is a Z-shaped sill consisting of two Z-shaped pieces;
Each Z-shaped piece has a flange portion 19 and an upright side wall 2.
1 and a top wall 23. A horizontal slot 22 is formed in the side wall 21 to receive the horizontal rib of the striker. The cast striker 17 is welded to the sill 18 at the periphery of ribs on both sides of the striker. The top walls 23 and 23 of the two halves of the sill 18 are welded together along their longitudinal edges to form a pocket for receiving the cast striker 17, and Also located within the pocket is a yoke 15 and a traction device behind the striker 17.

The yoke 15 is held within the pocket of the Z-sill 18 by a yoke strap carrier 25. The rearmost ends of the traction device engage rear traction ears 26 projecting from the inner surfaces of the side walls 21.
The front end of the traction device presses against a follower 27 which is supported by a front traction lug 28 formed at the rear of the cast striker 17. Projecting from the forward end of the Z-shaped sill 18 is a generally rectangular continuous striker surface 29. Striker surface 29 is part of spaced apart sidewalls 30 of sill 18 . Both side walls 3
0,30 are connected by a top wall 31 and a bottom wall 32, referred to in the art as a coupler carrier. As shown in FIG. 1, the coupler carrier 32 engages the bottom surface of the coupler shaft 11;
It supports the coupler during lateral (left-right) and longitudinal (back-and-forth) movements of the shaft.

3-5, a coupler yoke 1 according to the invention is shown.
The details of the structure of 5 are shown. This yoke is
A towing device receiving rear seat 37 with a generally flat surface has an abutting end portion 35 with weight reduction pockets 36 on each side thereof. A top strap 38 and a bottom strap 39 extend forwardly from the abutting end portion 35 to the yoke head 40. As will be apparent to those skilled in the art, in FIG. 3 the yoke 15 has been rotated 90 degrees from the position of the yoke when assembled within the center sill 18 of the railroad vehicle as shown in FIG. It is shown as. Referring again to FIG. 3, the yoke head 40 includes a key slot wall 41 that gradually flares outwardly from a towing device receiving front wall 42 forward to a nose 43. The yoke defines a towing device receiving pocket surrounded by a towing device receiving rear seat 37, a towing device receiving front wall 42, a top strap 38, and a bottom strap 39. Each key slot wall 41 has a key slot opening extending longitudinally of the yoke, ie, parallel to top straps 38 and 39, and is provided with a raised rib 44. Both the rear end of each key slot adjacent to the traction device receiving front wall 42 and the front end located on the nose 43 have a semicircular shape. The length of nose 43, defined as distance It has been shortened to Preferably, distance X is approximately 3 inches. The shortened length of the nose causes the profile defined by edge surface 45 to be blunt rather than sharply pointed. This edge surface 45 preferably extends approximately 1/2 inch rearwardly from the forwardmost surface of the semicircular front end of the key slot.
It shall be defined by a radius of curvature centered at a 4 inch point and may be formed to match the standard yoke profile of E-type couplers referred to as the Y40 and Y41 types. The Y40 yoke has a traction device receiving pocket that is 25 5/8 inches long, while the Y41 yoke has a traction device receiving pocket that is 36 3/8 inches long. Reducing the length of the yoke nose 43 eliminates various of the problems listed above and is sometimes necessary in the past to allow removal of the coupler yoke from the center sill. , it is not necessary to cut out a portion of the rear portion of the striker carrier 32 (FIGS. 1 and 2) using a cutting torch or the like. Conventionally, the existence of such defects due to partial removal of the striker carrier may be overlooked during yoke replacement work, and as a result, sufficient support for the coupler cannot be obtained due to weakening of the coupler carrier. Something happened.

As can be seen in FIGS. 3-5, the nose portion 43 extending beyond the key slot opening of the key slot wall 41 has a trapezoidal cross section (FIG. 5) having a smooth convex outer surface and a smooth inner surface. ) is defined by a wall 46. The trapezoidal cross-sectional shape of each wall 46 extends rearwardly, preferably a small distance along the key slot beyond the semi-circular front edge of the key slot opening, to the point where the wall thickness smoothly articulates with the rib 44. It extends to. This articulation point is located far enough rearward to increase the strength of the forward portion of the key slot wall to prevent deformation as shown in FIGS. 6 and 7. Each nose part of the yoke 4
The uniform wall thickness extension 3 terminates in a wall section 46 extending transversely to the length of the key slot.

As a contrast to the yoke of the present invention, FIG. 6 shows a standard AAR standard E coupler.
A Y40 coupler yoke is shown. The nose of the yoke includes a single raised rib 48 extending from the semi-circular rib portion at the front end of the key slot to the front end of the yoke. The wall thickness of the upper and lower yoke nose end portions of rib 48 is not strong enough to prevent distortion of the forward portion of the key slot opening as shown in FIG. As shown exaggerated in FIG. 7, the front lower surface of the key slot may be deformed by the combination of torsional and vertical bending actions of the coupler, resulting in traction The key sticks to the rib of the key slot and does not move, causing the key to become stuck at point 4 on the circumference of the rib.
9 induces a point load condition. This condition, which is shown exaggerated in FIG. 7, has been found to result in the cast yoke breaking due to the formation of cracks, such as those indicated by reference numeral 50.

[Brief explanation of drawings]

FIG. 1 is an elevational view, partially in section, of an E-coupler assembly including a coupler yoke embodying features of the present invention. FIG. 2 is a perspective view of a striker and Z-sill for a railroad car forming part of the coupler assembly shown in FIG. 1; FIG. 3 is a perspective view of an E-coupler yoke embodying features of the present invention. 4 is a diagram showing a key slot provided in the head portion of the yoke of the present invention shown in FIG. 3; FIG. FIG. 5 is a view taken along the line - in FIG. 4. FIG. 6 is a view similar to FIG. 4, but showing the head portion of a standard Y40 coupler yoke for a standard AAR standard E coupler. FIG. 7 is an enlarged partial view of the key slot in the key slot wall shown in FIG. 6, exaggerating the distortion of the key slot wall. 15: York, 16: Key slot, 17:
Striker, 18: Sill, 35: Butt end portion,
37: Towing device receiving rear seat, 38: Top strap, 39: Bottom strap, 40: Yoke head, 41: Key slot wall, 42: Towing device receiving front wall, 43: Nose, 44: Rib, 4
5: Edge surface, 46: Wall with trapezoidal cross section.

Claims (1)

Claims: 1. An abutted end portion 3 having a top strap 38 and a bottom strap 39 extending parallel to each other and spaced apart, and a traction device receiving rear seat 37 at right angles to the top and bottom straps.
5, a towing device receiving front wall 42 facing the rear seat 37, and a pair of key slot walls extending gradually outwardly from the front wall and the top strap 38 and bottom strap 39. 41,4
1, a towing device receiving rear seat 37, a towing device receiving front wall 42, and a towing device receiving pocket defined by a top strap 38 and a bottom strap 39. In the yoke 15, each key slot wall 41 includes an elongated key slot 13 having a semicircular front end, and a nose 43 extending forward from the front end of the key slot.
and the nose has a length less than 3 1/2 inches (88.9 mm) from a point on the forwardmost surface of the semicircular front end of the key slot to the forwardmost end of the nose. A coupler yoke characterized in that it has a blunter profile than that of a standard yoke due to its shortening. 2. The coupler yoke of claim 1, wherein the shortened length of the nose portion 43 is 3 inches (76.2 mm). 3. The coupler yoke according to claim 1, wherein the nose portion 43 has an outer wall surface that is convex in a direction transverse to the length of the coupler yoke. 4 The nose portion 43 has a trapezoidal cross-sectional shape.
A coupler yoke as claimed in claim 1 defined by paired wall portions (46). 5 Each wall portion 46 having the trapezoidal cross-sectional shape
extend toward the towing device receiving rear seat 37 to a point along the key slot 13 to form outwardly projecting ribs 44 on either side of the key slot.
A coupler yoke according to claim 4, which is connected to a coupler yoke. 6 an abutting end portion 3 having a top strap 38 and a bottom strap 39 extending parallel to each other and spaced apart and a towing device receiving rear seat 37 at right angles to the top and bottom straps;
5, a towing device receiving front wall 42 facing the rear seat 37 and extending from the front wall 42 and the top strap 38 and bottom strap 39;
A pair of key slot walls 4 that gradually expand outward
1 and 41, the towing device receiving rear seat 37, the towing device receiving front wall 42, the top strap 38 and the bottom strap 39 defining a towing device receiving pocket. In the coupler yoke 15, each key slot wall 41 is an elongated key slot having a semi-circular rear end spaced apart from the towing device receiving front wall 42 and a semi-circular front end. slot 13, the key
A nose 43 extends forward from the front end of the slot, the nose having a generally semicircular edge 45 centered at a point within the key slot to reduce the length of the nose. The nose is defined by a convex continuous outer surface extending rearwardly and connected to a rib 44 projecting from the key slot wall 41 and extending along both longitudinal sides of the key slot 13. A coupler yoke characterized in that: 7. The coupler yoke of claim 6, wherein the shortened length of the nose portion 43 is 3 inches (76.2 mm). 8 The nose portion 43 has a trapezoidal cross-sectional shape.
7. A coupler yoke as claimed in claim 6 defined by paired wall portions 46. 9 Each wall portion 46 having the trapezoidal cross-sectional shape
extend toward the towing device receiving rear seat 37 to a point along the key slot 13 to form outwardly projecting ribs 44 on either side of the key slot.
9. A coupler yoke according to claim 8, which is connected to the coupler yoke of claim 8. 10 an abutting end portion 35 having a top strap 38 and a bottom strap 39 extending parallel to each other and spaced apart, a towing device receiving back seat 37 at right angles to the top and bottom straps, and facing the back seat 37; a yoke head portion 40 having a towing device receiving front wall 42 and a pair of key slot walls 41, 41 extending progressively outwardly from the front wall 42 and the top strap 38 and bottom strap 39; a towing device receiving pocket defined by the towing device receiving rear seat 37, the towing device receiving front wall 42, the top strap 38 and the bottom strap 39; The key slot wall 41 includes an elongated key slot 13 having a semicircular rear end spaced apart from the towing device receiving front wall 42 and a semicircular front end.
A nose 43 extends forwardly from the front end of the slot, the nose having a generally arcuate edge 45, and the nose extends rearwardly and projects from the key slot wall 41. A coupler yoke, characterized in that it is defined by a convex continuous outer surface connected to the ribs 44 and extending along both longitudinal sides of said key slot 13 and forming a trapezoidal wall section.