Note: Descriptions are shown in the official language in which they were submitted.
CA 02704272 2010-05-13
1
TITLE OF THE INVENTION
DETACHABLE GOOSENECK FOR HEAVY HAUL TRAILERS
FIELD OF THE INVENTION
This invention relates to hydraulic gooseneck hitches for heavy haul trailers.
In
particular, this invention relates to an articulation mechanism for a
gooseneck
arm, to means for hitching the gooseneck and hitch assembly to a low bed
trailer
1o deck or to a towed vehicle, to means for transitioning between the low bed
mode
and the towed vehicle mode, and to means for locking the gooseneck and hitch
assembly to a low bed trailer deck.
BACKGROUND OF THE INVENTION
Sliding fifth wheel and gooseneck assemblies have been a common feature of
heavy haul low bed semi trailers for several decades. They are found on every
type of truck and trailer combination from on-road 30 ton single axle jeeps to
off-
road 200 ton mine trailers. The sliding assemblies are used to move the down
or bearing point of the semi-trailer forward or backward to change the weight
distribution on the tractor vehicle, in some cases to accommodate a transition
from towing a low bed deck to towing an incapacitated vehicle. Such an
assembly must also be capable of lowering the hitch assembly to allow it to be
attached to a low bed deck, and of raising it to provide ground clearance when
the deck is unhitched.
Examples of sliding fifth wheel and gooseneck assemblies are provided in
Canadian Patent No. 2,080,446 and in the trailers manufactured by Kalyn
CA 02704272 2010-05-13
2
Siebert, Peerless Limited, Scona Trailer Manufacturing, XL Specialized
Trailers
Inc., Cozad Trailers Sales LLC, Trail King Industries and Murray Trailer.
While several variations of sliding fifth wheel and gooseneck assemblies
exist,
they are all subject to a significant limitation - they can get stuck. Heavy-
haul
low bed trailers work in sometimes very harsh environments such as mines and
they spend the majority of their life unprotected from the elements and from
local
debris. As a result, it is common for the sliding mechanisms to become
contaminated with moisture that can freeze or rust the mechanism, or with
rocks,
io dust or other debris that can create resistance or jam the unit completely.
As the
sliding mechanism is located atop the tractor vehicle, it is effectively out
of reach
on larger mine trucks and therefore it is difficult for an operator to inspect
it prior
to or during operation, thereby making it inconvenient to keep the mechanism
free of debris.
Some prior art mechanisms get stuck without the introduction of contaminants.
Simple sliding mechanisms comprised of a rectangular plate in a slightly
larger
rectangular track can become jammed as a result of misalignment of the two
pieces. The fact that such units are continually connected and disconnected
from a very large pieces of equipment and that they carry a very large load
increases the risk of bending and distortion of the sliding track components.
It is therefore an object of the present invention to provide an articulation
mechanism for a hydraulic removable gooseneck that avoids the jamming that
characterizes sliding fifth wheel and gooseneck assemblies.
It is a further object of the invention to provide a connection between the
gooseneck and the tractor vehicle that provides three degrees of freedom of
CA 02704272 2010-05-13
3
movement between them in the low bed mode and that restricts those three
degrees of freedom in the vehicle towing mode.
The transition between the low bed mode and the vehicle towing mode involves
moving the gooseneck between a forward and an aft position on the tractor
vehicle. The transition typically involves considerable stresses on the
sliding
mechanism and on the sub-frame that is installed on the tractor vehicle bed to
support the gooseneck and the associated components. It is a further object of
the present invention to minimize the stresses on the articulation mechanism
and
sub-frame of a gooseneck during the transition between the low bed mode and
the vehicle towing mode.
As the gooseneck connection is detachable from the low bed trailer deck, a
locking mechanism is usually provided to secure the hitching mechanism when
1s the low bed deck is hitched to the gooseneck and hitch assembly. Providing
such a lock is prudent from a safety standpoint, but the lock mechanism does
not
provide significant additional strength to the gooseneck connection. 'Some
prior
art systems attempt to assist the gooseneck in connecting to the trailer by
applying a pulling force during connection to bring the two parts of the
connection
(trailer and tractor vehicle) closer together to complete a snug connection.
That
is not easy to achieve with the large equipment involved unless the design,
manufacturing, operation, and environment are very specific. In practice,
attempts to force the gooseneck and trailer together result in additional
stresses
being added to the connection and part failure, due in part to the fact that
the size
and power of the lock assemblies are significantly less than those of the
gooseneck and trailer (especially a loaded trailer).
CA 02704272 2010-05-13
4
It is therefore a further object of the present invention to provide a simple
but
effective locking mechanism for a gooseneck to low bed deck hitch.
These and other objects of the invention will be better understood by
reference to
the detailed description of the preferred embodiment which follows. Note that
not
all of the objects are necessarily met by all embodiments of the invention
described below or by the invention defined by each of the claims.
SUMMARY OF THE INVENTION
The present invention avoids the use of a sliding gooseneck assembly to
transition between forward and aftward positions by instead pivoting the base
of
the gooseneck at the end of a pivoting member so that the base of the
gooseneck travels along an arcuate path. This reduces the point of moving
contact between the tractor and the gooseneck to one or more coaxial pivot
points rather than through a slide track, thereby minimizing the opportunity
for
jamming through debris or other contaminants.
According to the preferred embodiment, a pivoting arm assembly is mounted to
the tractor and the forward end (base) of the gooseneck is attached to a
portion
(preferably the end) of the pivoting arm assembly that undergoes arcuate
travel.
Apart from avoiding the problems inherent in the use of sliding mechanisms in
contaminant-laden environments, the pivoting arm assembly articulation enables
the rear of the gooseneck and hitch assembly to be supported on the ground
while the gooseneck is moved between the two positions. This significantly
decreases the load that the articulation mechanism needs to support.
CA 02704272 2012-10-26
4A
In one aspect, the invention comprises a gooseneck hitching apparatus for
mounting on a tractor vehicle to enable a releasable connection between a
gooseneck mounted on the tractor vehicle and a heavy-haul low bed trailer
deck.
The apparatus comprises a gooseneck selectively positionable in an aftward
position for hitching said apparatus to the heavy-haul low bed trailer deck or
in a
forward position for towing a vehicle. The transition of said gooseneck
between
the aftward and forward positions is effected by arcuate movement of a forward
end of the gooseneck in relation to the tractor vehicle. Means are preferably
provided for securing the gooseneck against articulation when it is in the
forward
1o position.
In another aspect, the forward end of the gooseneck is operatively coupled to
a
pivoting arm having a pivot axis that is fixed in relation to the tractor
vehicle and
the arcuate movement is actuated by pivoting of the arm.
In another aspect, in low bed mode, the forward end of the gooseneck is
pivotable in relation to the tractor vehicle about a vertical axis, about an
axis that
is transverse to the tractor vehicle and about a longitudinal axis of the
tractor
vehicle.
The forward end of the gooseneck may be operatively coupled to the pivoting
arm by a pivot member that is pivotally secured to the arm about the
transverse
axis. The pivot member may include a vertical pin providing the said vertical
axis.
In another aspect, the forward end of the gooseneck is operatively coupled to
at
least one horizontal pivot element defining the longitudinal axis.
CA 02704272 2012-10-26
4B
In another aspect, the invention includes a vertical hitch pin for use in
towing a
vehicle.
In another aspect, the apparatus further comprises at least one hydraulically
operated lifting arm for lowering, raising or supporting an aft portion of the
gooseneck.
In yet another aspect, the lifting arm comprises a lateral flange for
restricting
pivoting of the gooseneck about the vertical axis when the gooseneck is
1o supported by the lifting arm.
In a method aspect, the invention applies to a tractor vehicle having a
gooseneck
hitching apparatus mounted thereon for enabling a releasable connection
between a gooseneck mounted on the tractor vehicle and a heavy-haul low bed
trailer deck. A transition of the gooseneck hitching apparatus between an
aftward position and a forward position is effected by arcuate movement of a
forward end of the gooseneck. The method in question comprises effecting such
transition by lowering an aft portion of the gooseneck hitch assembly to rest
on
the ground and effecting the arcuate movement while the aft portion is in
contact
with the ground.
In another method aspect, the tractor vehicle is also placed in neutral gear
prior
to actuating the arcuate movement.
CA 02704272 2010-05-13
In another aspect, the invention comprises a locking mechanism for the deck
hitch of a detachable gooseneck trailer. The locking mechanism comprises a
locking member that pivots from a pivot point that is rearward of an aftward-
opening hitch recess. In a more particular aspect, the hitch recess is
provided on
5 a hitch assembly that is pivotally attached to the end of the gooseneck. In
a
further aspect, the locking member has a substantially flat surface for
abutting a
hitch shaft of a trailer deck.
In a further aspect, the locking member is actuated by a hydraulic cylinder
that
io actuates a rotating member. A second link is pivotally attached to the
rotating
member and to the locking member. When the locking member is in the lock
position, three pivot points are substantially aligned: the pivot point of the
rotating member, the pivot between the rotating member and the second link,
and the pivot between the second link and the locking member. The aligned
pivots provide mechanical resistance to articulation of the locking member
thereby offering a failsafe if the hydraulic cylinder fails.
In another aspect of the invention, the forward end of the gooseneck is
pivotable
in relation to the tractor about a vertical axis, about an axis that is
transverse to
said tractor vehicle and about a longitudinal axis of the tractor.
The foregoing was intended as a broad summary only and of only some of the
aspects of the invention. It was not intended to define the limits or
requirements
of the invention. Other aspects of the invention will be appreciated by
reference
to the detailed description of the preferred embodiment and to the claims.
CA 02704272 2010-05-13
6
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described by reference to the detailed description of
the
preferred embodiment and to the drawings thereof in which:
Fig. I is a side elevation of the preferred embodiment of the invention,
showing a tractor vehicle, gooseneck and hitch assembly and a low bed
deck, in low bed mode;
Fig. 2 is a side elevation of the preferred embodiment showing a tractor
vehicle, gooseneck and hitch assembly and towed vehicle, in vehicle
towing mode;
Fig. 3A is an oblique projection of the gooseneck of the preferred
embodiment;
Fig. 3B is a plan view of the gooseneck of the preferred embodiment;
Fig. 4A is a plan view of the tractor vehicle and associated structures of
Fig.2;
Fig. 4B is a plan view of the tractor vehicle and associated structures of
Fig. 1;
Fig. 5A is a vertical section taken along line 5A-5A of Fig. 4A;
Fig. 5B is an exploded view of the pivot plate, base plate and forward
portion of the gooseneck;
CA 02704272 2010-05-13
7
Fig. 6 is a vertical section of the tractor vehicle taken along line 6-6 of
Fig.
4B, with the gooseneck removed;
Fig. 7A is a vertical section of the gooseneck taken along line 7A-7A of Fig.
3B;
Fig. 7B is a front view of the forward portion of the gooseneck;
Fig. 8A is a plan view of the pivot plate;
Fig. 8B is a side view of the pivot plate;
Fig. 9A is a plan view of the pivoting arm assembly;
Fig. 9B is a view taken along line 9B-9B of Fig. 9A;
Fig. 10 is the view of Fig. 6, but with the pivoting arm assembly in an
intermediate position between the low bed mode and the vehicle towing
mode;
Fig. 11 is the view of Figs. 6 and 10, but with the pivoting arm assembly in
position for the vehicle towing mode;
Fig. 12A is a plan view of the sub-frame;
Fig. 12B is a view taken along lines 12B-12B of Fig. 12A;
CA 02704272 2010-05-13
8
Fig. 13A is a plan view of the support arm assembly;
Fig. 13B is a side elevation of the support arm assembly;
Fig. 14A is a vertical section of the gooseneck and hitch assembly with the
locking paddle in lock/latched position;
Fig. 14B is a vertical section of the gooseneck and hitch assembly with the
locking paddle in unlocked position;
Fig. 15 is a rear view of the hitch assembly only taken from approximately
lines 15-15 of Fig. 14B.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the following description, the preferred embodiment of the invention will
be
described. However, it will be appreciated that alternative embodiments that
do
not necessarily embody the same constructional and design features may be
implemented while still applying the broader principles of the invention.
As is the case for many prior art detachable gooseneck trailers, the tractor,
gooseneck and hitch assembly according to the preferred embodiment may be
operated in two modes: the low bed mode illustrated in Fig. I and the vehicle
towing mode illustrated in Fig. 2.
The base of a gooseneck 10 is mounted behind the cab of a tractor vehicle 12.
The gooseneck 10 terminates at a pivot 14 to which a hydraulically-actuated
hitch assembly 16 is pivotally attached.
CA 02704272 2010-05-13
9
In low bed mode (Fig. 1), the gooseneck 10 is in an aftward, rearmost position
relative to the tractor vehicle, defining a space L between the rear of the
hauling
vehicle 12 and the front of the low bed 18. This allows clearance for rotation
(about a vertical axis) between the low bed deck and the tractor vehicle. The
hitch assembly 16 is designed to be attached to a horizontal hitch pin 20
provided on the front of the low bed 18, and a bearing surface 22 of the hitch
assembly is brought into contact with a bearing portion 24 of the low bed at a
position aft of the hitch pin 20. As is known, this enables the gooseneck to
raise
to the front of the low bed deck 18 by applying torque between the hitch pin
20 and
the bearing portion 24 of the low bed deck.
In vehicle towing mode (Fig. 2), the gooseneck 10 is in a forward position
such
that the vertical portion 26 of the gooseneck is tucked into the rear of the
tractor
vehicle in comparison to distance L in the low bed mode. This allows support
arm 92 to provide the lifting force to lift the towed vehicle, and "captures"
the
neck, restricting its three degrees of freedom. The towed vehicle is hitched
to a
vertical hitch pin 28 that is provided at the rear of the hitch assembly 16.
Referring to Figs. 2, 3A, 3B and 4A, the gooseneck 10 consists of two parallel
L-
shaped members 30, 31 each comprising a generally horizontal portion 32 and a
vertical portion 34. Cross-members 36, 38 and 40 and shaft 42 extend between
the L-shaped members 30, 31.
As best appreciated by reference to Fig. 5A, the forward end of the gooseneck
10 is supported by an articulated support assembly 44. Fig. 5B provides an
exploded view of a pivot plate 46 and a base plate 47 as well as longitudinal
axis
pivot pins 49. Fig. 6 is a vertical section taken along lines 6-6 of Fig. 4B
but
CA 02704272 2010-05-13
wherein the gooseneck 10 has been removed. The gooseneck support
assembly 44 consists generally of a pivot member in the form of pivot plate
46, a
pivoting arm assembly 48 and a hydraulic cylinder 50. One end of hydraulic
cylinder 50 is secured to a forward cross-member 52 of a sub-frame 54 (which
5 will be described in more detail below). The other end of the cylinder 50 is
attached to a lug on central cross-member 56 of the pivoting arm assembly 48.
The pivot plate 46 is shown in more detail in Figs. 8A and 8B. A vertical
pivot pin
58 extends centrally of a plate 60, along a transverse axis of the tractor
vehicle.
to The forward end of the gooseneck 10 is pivotally engaged to the pivot pin
58
enabling rotation of the gooseneck in the plane of plate 60, i.e. within the
horizontal plane and about a vertical axis (designated as the z-axis in Fig.
5B).
The bottom of the plate 60 includes two opposed flanges 62 each of which has a
pivot aperture 64. Pivot apertures 64 are threaded by pivot shaft 66 of
pivoting
arm assembly 48, thereby enabling pivoting of the gooseneck in the vertical
plane about an axis that is transverse to the tractor vehicle (designated as
the y-
axis in Fig. 5B).
Referring to Figs. 9A and 9B, pivoting arm assembly 48 includes two arms 68,
70
joined by a central cross-member 56. Pivot shaft 66 extends between arms 68,
70. Each pivoting arm 68, 70 includes a pivot aperture 72 for receiving pivot
pins
76 attached to sub-frame 54. Through such attachment, the pivot axis for the
pivoting arm assembly is fixed in relation to the tractor vehicle. A hydraulic
cylinder 73 actuates the extension or retraction of lock pins 75 to lock the
rotation
arm assembly 48 into position prior to use, as will be described below.
Referring to Fig. 5B, pivoting of the gooseneck about the longitudinal axis of
the
tractor vehicle (the axis designated as x-axis in Fig. 5B) is enabled by
horizontal
CA 02704272 2010-05-13
11
pivot elements in the form of pins 49 mounted in bearings 51, 53 within lugs
55
that extend upward from a base plate 47.
The support assembly 44 in conjunction with the x-axis pivot pins =49 provide
three degrees of freedom of movement of the gooseneck: pivoting about an axis
that is longitudinal to the tractor vehicle, pivoting about an axis that is
vertical and
pivoting about an axis that is transverse to the tractor vehicle.
In operation, when cylinder 50 is fully extended as shown in Fig. 6, pivoting
arm
io assembly 48 is pivoted to the rearmost position, corresponding to the low
bed
mode of Fig 1. Fig. 10 shows the cylinder 50 with its piston partially
retracted
and pivoting arm assembly 48 in an intermediate position. When the piston is
fully retracted (Fig. 11), pivoting arm assembly 48 is in its forward most
position
corresponding to the vehicle towing mode of Fig. 2. This arcuate motion
arrangement avoids any slide track that might be contaminated by debris and it
limits the moving connection between the tractor vehicle and the gooseneck to
the two pivots points 67, 69 (see Figs. 6 and 9A) on the pivoting arm assembly
48.
Sub-frame 54 (Figs. 12A and 12B) provides the interface between the tractor
vehicle and the gooseneck support assembly and the support arm assembly 92.
Sub-frame 54 comprises two generally L-shaped members 82, 84 connected by
cross-members 86, 88 and 90. Pivot pin 76 is threaded through pivot apertures
72 of pivoting arm assembly 48. Shaft seats 85, 87, 89 and 91 provide seats
for
the pivoting arm of arm assembly 48 in its forward most and rearmost
positions.
The aft portion of the gooseneck 10 is supported by a support arm assembly 92
(Figs. 13A and 13B) consisting of two support arms 94, 96 joined at the rear
by a
CA 02704272 2010-05-13
12
cross-tube 98. Cylinder mounting lugs 100 are provided at each end of cross-
tube 98. The forward ends of support arms 94, 96 are pivoted on cross-member
88 of sub-frame 54. Referring to Figs. 11 and 5A, support arm assembly 92 is
used to selectively raise or lower the gooseneck 10 by means of a pair of
hydraulic cylinders 102 first ends of which are secured to cross-member 90 of
sub-frame 54 and the other ends of which are attached to lugs 100. Support arm
assembly 92 is used to raise the gooseneck 10 when in vehicle towing mode to
lift the front of the towed vehicle. It also supports the gooseneck and hitch
assembly when the low bed trailer deck is not hitched.
The hitch assembly 16 will now be described by reference to Figs. 14A, 14B and
15. Two parallel vertical arms 110, 112 are joined at their base by an aft
ward
extension 114. Parallel arms 110, 112 are also joined by cross member 111 and
by upper web 113. Aftward-opening C-shaped recesses 117, 119 at the bottom
of each arm 110,112 accommodate a horizontal hitch shaft 20 on the low bed
deck. Hydraulic cylinder 116 pivots the hitch assembly 16 about shaft 42 at
the
end of the gooseneck. Preferably a pair of side by side cylinders 116 is
provided.
When the user wishes to hitch the tractor vehicle to a low bed deck, if the
gooseneck is not already in the rearmost position shown in Fig. 1, the piston
of
cylinder 50 is extended to cause pivoting arm assembly 48 to rotate toward the
rearmost position until extensions 13, 15 of shaft 66 of the pivoting arm
assembly
are seated in seats 87, 91. As the pivoting arm assembly 48 supports the pivot
plate 46 which in turn supports the forward end of the gooseneck, the forward
end of the gooseneck undergoes an arcuate movement 49 from the forward most
to the rearmost position. Locking pins 75 are then engaged into apertures 77
provided In the seats 87, 91. Movement of the locking pins 75 is actuated by
hydraulic cylinder 73. Preferably, movement of the gooseneck from the forward
CA 02704272 2010-05-13
13
to the aft position is done with the base of the hitch assembly resting on the
ground and with the tractor vehicle in neutral, so as to minimize stress on
the
gooseneck support assembly. The gooseneck support arm assembly 92 is then
positioned to provide an appropriately low clearance for the hitch assembly 16
to
engage the hitch shaft 20 of the low bed. Once properly positioned, the
tractor
vehicle is backed up to the low bed so as to fully engage the recesses 117,
119
about the hitching shaft 20. Once the hitching shaft is fully seated in the
recesses 117, 119, a locking member 120 is rotated downward to the lock
position.
Referring to Fig. 14A, a locking member in the form of paddle 120 is pivoted
from
a point 122 on hitch assembly 16 that is located aft of the recesses 117, 119.
The forward end of paddle 120 includes a substantially flat surface 124 for
abutting the aft side of the hitching shaft 20 to retain hitching shaft 20 in
recesses
117, 119 when the trailer is being towed. A cylinder 126 actuates pivoting of
the
paddle through an over center cam rotating member 128 pivoted on pivot shaft
42. Over center cam member 128 is pivotally attached to link member 125 at a
point 127 and is pivotally attached to the piston of cylinder 126 at a point
129 that
is angularly displaced in relation to point 127. Link member 125 is pivotally
attached at point 131 on a lug on paddle 120. When the piston of cylinder 126
is
fully extended, paddle 120 is pivoted to engage the hitching shaft 20 and the
over
center cam member 128 is rotated to a latched position in relation to the
paddle.
When the paddle 120 is in the lock position, three pivot points are
substantially
aligned: the pivot point 42 of the over center cam member, the pivot 127
between the over center cam member 128 and the link member 125, and the
pivot 131 between the link member 125 and the paddle 120. The aligned pivots
CA 02704272 2010-05-13
14
provide mechanical resistance to articulation of the paddle thereby offering a
failsafe if the hydraulic cylinder fails.
The piston of cylinder 116 is then extended to pivot the hitch assembly 16
about
the pivot 42 causing bearing surface 22 to bear down against the surface of
the
low bed at point 24 that is aft of the hitching shaft 20. This raises the
front of the
low bed and provides a secure hitch. Once the deck is properly secured,
support
arm assembly 92 is lowered to its lowest position to allow full play to the
vertical,
longitudinal and transverse axis pivotability of the forward end of the
gooseneck.
The low bed deck 18 may be disengaged from the gooseneck assembly by
retracting the piston of cylinder 116 to relieve the torque between the
hitching
shaft 20 and point 24 on the deck, retracting the piston from cylinder 126 to
disengage the paddle lock, raising the support arm 92 to support the gooseneck
9s and driving the tractor vehicle away from the deck 18.
In order to attach the tractor vehicle and gooseneck assembly to a vehicle to
be
towed, pivoting arm assembly is rotated to the forward most position, with
extensions 13, 15 of shaft 66 seated in seats 85, 89 of sub-frame 54. This
moves the vertical portion of the gooseneck forward toward the rear of the
tractor
vehicle. Locking pins 75 are engaged into apertures 79 in seats 85, 89.
Preferably, this is done with the tractor vehicle in neutral and the base of
the
hitch assembly resting on the ground (support arm assembly 92 fully lowered).
Once the gooseneck is in the forward position, support arm 92 is then raised
to
lift the hitch 16 just clear of the ground. The tractor vehicle is then
reversed to
position the vertical hitch pin 28 under the vehicle to be towed. Support arm
assembly 92 is then raised to raise the gooseneck and the attached hitch
assembly and to lift the front end of the towed vehicle. Once supported by
CA 02704272 2010-05-13
support arm 92, gooseneck articulation is restricted in the x-axis by arm 92
bearing on gooseneck members 30, 31 and in the y-axis by the 3 points of
contact (arm 92 on members 30, 31, and plate 47 on plate 60) and in z-axis by
the flanges 133, 135 on the ends of support arm 92. These flanges capture
5 members 30, 31 and restrict z-axis rotation. There nonetheless remain the 3
degrees of freedom inherent in the hitch 28 to allow the required movement
between the tractor and the towed vehicle.
As noted above, in order to effect a transition of the gooseneck and hitch
is assembly from the low bed mode to the vehicle towing mode, support arm
assembly 92 may be lowered fully so that the base of the hitch assembly 16
rests
on the ground. The tractor vehicle is then put into neutral gear. The piston
of
hydraulic cylinder 50 is then retracted to rotate the pivoting arm assembly 48
from the rearmost to the forward most position. As the pivoting arm assembly
15 48 completes its travel through the arc, the bulk of the weight of the
gooseneck
and hitch assembly is borne by the ground. As the pivoting arm assembly 48
travels between its two extremes, the tractor vehicle may be urged rearward to
track the movement of the pivoting arm assembly. The reverse sequence is
used to transition from the vehicle towing mode to the low bed mode. This
mechanism and method of transitioning between the two modes presents
considerably less stress on the gooseneck support assembly than would be the
case by simply articulating the entire weight of the gooseneck and hitch
assembly without laying the hitch assembly 16 on the ground.
The invention therefore provides a mechanism for arcuate travel of the
gooseneck support assembly (and therefore the forward end of the gooseneck)
that not only limits the ability of contaminants to jam the assembly, but it
also
provides three degrees of freedom of movement for the gooseneck in relation to
CA 02704272 2010-05-13
16
the tractor vehicle in low bed mode and restricts those degrees of freedom in
vehicle towing mode. The locking member arrangement provides an inherent
failsafe for securing the low bed deck hitch shaft into the hitch assembly.
s It will be appreciated by those skilled in the art that the preferred and
alternative
embodiments have been described in some detail but that certain modifications
may be practiced without departing from the principles of the invention.
