Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to a triple axle trailer
with a walking beam frame.
In logging operations, triple axle trailers are
used to increase the load that may be hauled with a logging
truck. The trailer as typically found in the prior art has
a tandem rear axle and a forward axle which is spaced-apart
therefrom. A frame extends forwardly from the rear axles to
the forward axle. A turntable assembly is connected to the
frame and the forward axle is connected thereto, permitting
steering of the trailer. A drawbar connects the forward
axle to the truck.
In practice, it has been found that the use of
this frame presents problems. Logging trucks must operate
over extremely rough logging roads, resulting in a great
deal of movement of the wheels and axles as bumps are
encountered. This movement of the axles and the high
loading placed on the trailer by the logs being carried
result in high stresses being placed on the frame. After a
period of such rugged use, failure of the frame because of
metal fatigue is common.
The use of triple axle suspensions using two sets
of walking beams is found, for example, in United States
Patent, 3,253,838 to Hickman. However, a trailer as dis-
closed by Hickman stills employes a separate frame mounted
on the triple axle suspension and, therefore, offers no
solution to the problem of frame failure. ;
According to the invention, a triple axle trailer
comprises a forward axle assembly and a pair of spaced-apart
rear axle assemblies. Each of the axle assemblies comprises
a laterally extending, rigid axle with wheels rotatably
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mounted at each end thereof~ A pair of substantially
parallel, main walking beams extend longitudinally between
the forward axle assembly and the rear axle assemblies. A
pair of longitudinally extending, rear walking beams h~ve
forward and back ends, the rear axle assemblies interconnec-
ting the rear walking beams near the forward and back ends
thereof. Laterally extending rear connecting means is
pivotally connected to the main walking beams and to the
rear walkiny beams. Forward connecting means extends between
the main walking beams near the forward axle. There is
means yieldably connecting the forward connecting means to
each said main walking beam, permitting limited independent
pivoting of the main walking beams with respect to the rear
connecting means. Load bearing means is mounted on the main
walking beams. There is means pivotally connecting the
forward axle assembly to the forward connecting means for
rotation of the forward axle assembly about a vertical
steering axis. Drawbar means connects to the forward axle -
assembly for connecting the trailer to a haulage vehicle.
The present invention solues the problem of frame
failure by removing the frame itself. The present invention
is easily distinguishable from earlier trailers using triple
axle suspensions with two set of walking beams: in the
present invention, the walking beams, in effect, become the
entire trailer. The steerable front axle is connected
directly to the front of the elongate main walking heams.
The suspension of the trailer, accordiny to a preferred
embodiment of the invention, comprises the various rubber
bushings used throughout the trailer. Larger movement of
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the wheels is accomodated by movement of the walking beams
and the bushings. The highly flexible nature of the pre-
ferred form of the inventian removes hiyh stresses placed on
members of the trailer which result in metal fatigue. The
rubber bushings used in the preferred form of the invention
obviate the need for springs in the suspension system.
In drawings which illustrate embodiments of the
invention:
Figure 1 is a side elevational view of a triple
axle trailer, according to an embodiment of the invention,
connected to a truck;
Figure 2 is a top plan view of the trailer;
Figure 3 is a sectional view taken along line 3-3
of Figure 2;
lS Figure 4 is a sectional view taken along line 4-4
of Figure 3;
Figure 5, on the third sheet of drawings, is a
sectional view taken along line 5-5 of Figure 3;
Figure 6 is a sèctional view taken along line 6~6
of Figure 2;
Figure 7 is a sectional view taken along line 7-7 --~
of Figure 6; and
Flgure 8 is a sectional view taken along line 8-8
of Figure 2~.
Figure 1 shows a triple axle trailer 1 connected
to the back of a haulage vehicle or tractor, in this case, a
logging truck 2. The trailer has a forward axle a~sembly 4
and a pair of rea~ axle assemblies 6 and 8. Each of the
axle assemblies camprise~ a laterally extending, rigid axle
lO with rubber tired dual wheels 12 mounted at each end
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thereof.
A pair of substantially parallel, main walking
beams 14 and 16 extend longitudinally be-tween the forward
axle assembly 4 and the rear axle assemblies 6 and 8. Each
of the main walking beams 14 and 16 omprises a box girder
in the preferred embodiment. At their back ends, main
walking beams 14 and 16 are interconnected by the laterally
extending, rear connecting means or beam 18 which comprises
a steel tube. Beams 14 and 16 have downwardly curved rear
portions 20, best seen in Figure 7 for beam 14. The concave
end 22 of each of the beams 14 and 16, together with the cap
24 bolted thereto, form a trunnion receiving recess within
which the bushing 26, of a resilient material such as
rubber, is received. Portions of the tube 18 comprise
trunnions tightly fitted within each of the annular bushings
26. The rubber bushings 26 pro~ide yieldable means per-
mitting limited independent pivoting of the main walking
beams 14 and 16 about the tube 18.
The trailer 1 also has a pair of longitudinally
extending rear walking beams 28 and 30. As seen for beam 28
in Figure 7, each of the rear walking beams has a fronk end
32 and a back end 34. Referring to Figure 6, each of the
rear walking beams also has a pair of laterally extending
brackets 36 and 38 to which a pair of ~-bolks 40 and 42 are
connected. Portions of tube 18 comprise trunnions received
within the resilient annular bushings 44 ~hown in Figure 8
and the trunnion housings 46, which are held tightly against
the gussets 48 and the bottoms of the rear walking beams 2 a
and 30 by the U~bolts 40 and 42. By this arrangement, the
rear walking beams 28 and 30 are pivotally connected to the
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tube 18 with resilient bushings 44 therebetween,
Each of the rear walkiny beams 28 and 30 ha~ a
longitudinally extending tube 50 connected thereto and
extending forward and rearwardly therefrom. This is illus-
trated best in Figure 7. The forwardly and rearwardlyextending portions of the tubes 50 form trunnions at each
end of each rear walking beams extending along the hori-
zontal axis 52 of each rear walking beam. A pair of U-bolts
54 and 56, as shown in Figure 6, secure each end of each of
the rear axle assemblies 6 and 8 to an axle saddle 58. The
axle saddles 58 have cylindrical openings or recesses for
receiving the ends of the tubes 50. A resilient rubber
bushing 60 is tightly received between each of the axle
saddles 58 and the ends o the tubes 50. In this way, the
rear axles are yieldably connected to the trunnions at each
end of each of the rear walking beams 28 and 30.
The trailer 1 also includes a forward connecting
means or tube 62, best seen in Figure 3~ extending laterally
between the main walking beams 14 and 16 near the forward
axle assembly 4. Each of the main walking beams has a tube
64 extending forwardly therefrom as seen in Figure 4. The
tube 62 has axle saddles 66 secured to the bottom thereof
near each end by a pair of U-bolts 68 and 70. The axle
saddles 66 have cylindrical openings or trunnion receiving
means for the t.runnions comprisiny forward portions o~ -the
tubes 64. Resilient annular bushings 72 are t:ightly re-
ceived between the tubes 64 and the axle saddles 66 as shown
in Figure 3. Each of the bushings 72 comprises means
yieldably connecting the tube 62 to one of the main walking
beams 14 and 16 and permitting limited relative rotation
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between a main walking beam and the tube 62 about a hori-
zontal axis 74 extending longitudinally along the trailer,
as seen in Figure 4. The yieldable connection between the
tube 62 and each of the main walking beams permits limited
S independent pivoting of the main walking beams with respect
to the tube 18 near the rear of the trailer.
Referring to Figure S, the tube 62 is pivotally
connected to the forward axle assembly 4 by means of the
turntable assembly 76 which has an uppex portion 78 connec- -
ted to the tube 62 and a lower portion 78a connected to the
axle assembly 4. The turntable assembly 76 permits rotation
of the forward axle assembly 4 about the vertical steering
axis 77. A bolt 76a with nuts 76b and 76c compresses rubber
bushing 77a between washers 77b and 77c, compresses rubber
15 bushing 77g be~ween disc 77f and washer 77h and thereby
holds turntable poxtions 78 and 78a together. A thrust
bearing 77d is received between washer 77c and disc 77e.
A dra~bar assembly 79 is pivotally connected to
the forward axle assembly 4 for pivoting about the hori-
~0 zontal, laterally extending axis 81 and extends forwardlytherefrom. There is an eye connector 82 at the fo~7ard end
of a compensator bar 80 for connecting the trailer 1 to the
tractor 2 and permitting pivoting about the ~er-tical axis
83. Compensator 80 is telescopically connected to drawbar
assembly 79 to permit the eye connector to move rearwardly
when the trailer turns as shown in broken lines. This is
necessary when a load such as logs e~tend~ between the
tractor and trailer. When the trailer is empty, a pin is
fitted between the compensator 80 and drawbar assembly 82 to
prevent the telescoping.
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A load bearing means or bunk 84 is mounted on the
main walking beams 14 and 16. The bunk 84 is connected to
the upper portion 86 of a turntable assembly 88, best seen
in Figure 6, which permits rotation of the bunk about the
vertical axis 85. The lower portion 90 of the turntable
assembly 88 is connected to a laterally extendiny beam ~2.
Trunnion clamps 94 are connected to the bottom of beam 92
near each end thereof. ~runnions, comprising each end of
the tube 93, are received within the trunnion clamps 94.
Each of the beams 14 and 16 has a housing 95 and a pair of
U-bolts 97 for tightly receiving these trunnions of tube 93,
with resilient bushings 96 therebetween. The rubber bushings
96, shown in Figure 7 comprise means yieldably connecting
the bunk 84 to the main walking beams 14 and 16. The
bushings permit relative rotation of the walking beams about
the laterally extending axis 98 as well as limited movement
perpendicular thereto. This allows limited relative rota-
tion of the walking beams about tube 18.
Referring to Figure 1, the tractor or truck 2 is
equipped with a tractor bunk 100 rotatably mounted on the
tractor by means of a turntable assembly 102 for rotation
about the vertical axis 103. Logs 105, or other such
elongate loads, extend between the tractor 2 and the trailer
1 and are carried forwardly by the bunk 100 and rearwardly
by the bunk 84.
When compared with prior art triple axle trailers,
trailer 1 completely eliminates the need for a rigid Erame.
The yieldable connection~ employlng rubber bushings permit
movement of the main walking beam~ 14 and 16 instead of
subjecting them to varyiny loads which result in metal
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fatigue. The durability and simplicity of the trailer l is
enhanced by the complete elimination of conventiorlal sus-
pension components, such as springs, in favour of the
combination of walkiny beams and resilient rubber bushings
as described above. Independent vertical movement of the
front wheels is accommodated by the rubber bushings 72 at
the forward ends of the main walking beams and by the
bushings 26 between the main walking beams and the tube 18
adjacent the rear axle assemblies. At the same time, the
rubber bushings 96 connecting the bunk 84 -to the main
walking beams 14 and 16 allow this independent vertical
movement of the main walking beams and pivoting about the
tube 18. Relative vertical movement of the rear wheels at
opposite ends of the rear axle assemblies 6 and 8 is acco-
mmodated by the rubber bushings 60 connecting the rear axleassemblies to the rear walking beams 28 and 30 and by the
rubber bushings 44 connecting the rear walking beams to the
tube 18. Other stresses are absorbed by deformation of the
various rubber bushings either perpendicular to their
respective trunnions or shafts of by deformation of the
bushings along the trunnions.
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