Note: Descriptions are shown in the official language in which they were submitted.
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GGING TRAILER
This invention relates to an extended trailer,
especially a trailer for use in logging.
In logging a trailer able to carry long loads is
required. The typical arrangement used is a tractor trailer
combination in which the trailer is of simple construction.
The load is, of course, self-supporting. The trailer has a
central tubular reach able to attach to the tractor, with two
axles at the rear, remote from the tractor. There are
upstanding members to restrain the load from sideways
~; movement and these upstanding members typically are mounted
on pivotal bunks.
The trailer length is restricted by the small
maneuvering capability of a long, simple structure and by
highway regulations. These regulations restrict vehicle
weight and load-carrying capacity, the latter usually
depending on the number of axles, wheels and the spaces
between axles.
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Examples of prior art structures known to applicant
include United States Paten-ts 4,219,210 to Genberg; 2,034,842
-to S-tra-tton; 4,496,166 to Anderson and 2,112,201 tc) Larison.
Of the above Genberg discloses a logging -trailer in
which an auxiliary trailer is -towed behind a main trailer.
The auxiliary trailer has a pivot point that allows it to be
carried by -the main trailer.
Stratton shows a struc-ture for self-loading the trailers
of logging trucks. Anderson relates to a translotor log
trailer of complicated structure. Larison again shows a
complicated means of loacling a trailer onto a truck.
The above demonstrate the complicated structureæ -that
are available in logging once the simple, poorly
maneuverable, conventional trailer is to be extended.
The present invention seeks to provide a trailer that is
longer than conventional trailers and thus of increased load-
carrying ability. The trailer of the invention is of an
improved maneuverability and, in a preferred embodiment, has
a leading axle on which the wheels are self-steering.
Accordingly the present invention is an extended trailer
to attach to a tractor and comprising:
a main reach;
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means Eormed a-t the end of -the main reach to a-ttach
to a tractor;
a bridge extending over the main reach;
a forward self steering axle for the ex-tended
trailer;
steerable mountings for wheels on the forward axle,
the mounting having castor and camber;
resilient means extending forward from the bridge to
0 the forward axle;
an intermediate axle on the extension;
a rear axle on the extension; and
a subframe carrying the in-termediate and rear axles
10 pivotally attached to the bridge.
In a preferred embodiment the trailer has a steering
arm extending from one wheel mounting means;
a spring abutment on the axle, spaced from the
steering arm; a spring arm extending from the steering
arm and slidably received in the spring abu-tmen-t; a
spring received on the steering arm on ea~h side of the
spring abutment plate;
whereby the springs allow wheels attached to the
forward axle to -turn on application of a turning force
but urge the wheels back to a straight ahead position in
the absence of a turning force.
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Aspec-ts of the inven-tion are il:lus-trated, merely by
way of example, in the accompanying drawings in which:
Figure 1 is a side elevation of a trailer according
to the present invention;
Figure 2 is a plan view o:f -the trailer of E'igure l;
Figure 3 is a front elevation of -the -trailer
according to the present invention;
Figure 4 is a detail on the line 4-4 of Figure 3;
Figure 5 illustrates a detail of the preferred
embodiment of -this invention;
Figure 6 is an end elevat:ion of -the -trailer of
Figure l; and
Figure 7 is a partial side eleva-tion of the -trailer
of Figure 6.
The drawings show an extendéd trailer 2 to attach to
a tractor 4. The trailer comprises a main reach 6 with
means formed at the end of the main reach to attach to
the tractor 4; a simple hook 8 is shown in ~igure ~. A
bridge 12 extends over the main reach 6. The bridge 12
comprises longitudinally spaced members 14 linked by
cross memhers 16 although the details of its structure
are immaterial. Bridge 12 is rigidly attached to the
main reach 6 as shown most clearly in Figure 4.
There is a forward axle 18 for the extended trailer
and resilient means in the form of leaf springs 20, as
most clearly shown in Figures 3 and 4, ex-tend forwardly
from the
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bridge 12 to the forward axle 18. The leaf springs are
located by U-bol-ts 22 at each end.
There is an intermediate axle 24 on the trailer 2
and a rear axle 26. Both tnese axles 24 and 26 are
provided wi-th wheels 23 at each end. 'l'he wheels 28 are
freely rotatable on -the axles 24 and 26, avoiding the
necessity of a differential or the like.
There is a sub-frame to carry the interrnediate and
rear axles 24 and 26 pivotally attached to the bridge 12.
This sub-~rame comprises longitudinal members 30 linking
the intermediate and rear axles at both sides of the
reach 6. There are support members 32 ex-tending from the
longitudinal members 30 to the bridge 12. The support
members 32 and the longitudinal members 30 are at-tached
at 34. The support members 32 are attached -to a mounting
plate 36 spaced from bridge 12, typically by about 2
inches. There are bearing blocks 38 attached to the
mounting plate ~6 to receive pivot pins 40, which are
: attached to the bridge 12. The bearing blocks 38
comprise upper member 42 and lower members 44, the lower
members 44 being attached to the upper members 42 by nuts
46 received on studs 48. This is a conventional
arrangement. The pivot pins 40 are then received with a
bearing fit within the bearing blocks 38.
There are load support means 50 ex-tending ~rom the
25 bridge 12 and, in conventional manner, pivotally
attached to
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a bunk 52 mounted on the bridge :L2. I'he arrangement is
most clearly shown in Figures 1 and 7 ~u-t is no-t par-t of
the present invention. These load support members S0 and
the bunks 52 that permit their rotation are prior art.
The forward axle 18 includes steerable mountings for
wheels 54 mounted on axle 18. The arrangement is such
that the wheels 54 are self-steering, ra-ther -than being
activated by a linkage extending -to -the driver's cab. In
conventional manner the steerable wheels 54 are pivotal
on the axle 18 by the use, for example, of steering or
king pins 56 extending from housings 58 on the hubs of
wheel 54 through a bushing in forward axle 18. There :is
a steering link 60 extending be-tween the hubs of wheels
54 in conventional manner to ensure tha-t the wheels move
in unison about the pivotal steerable mountings 58.
The steering action is control~ed by the provision
of a steering arm 62 extending from one wheel mounting as
shown most clearly in Figures 4 and 5. There is a spring
abutment 64 on'the axle 18, spaced from the steering arm.
A spring arm 66 extends from -the steering arm 62 and is
slidably received in the spring abutment 64. Spring 68
is received on the steering arm 66 on each side of the
spring abutment 64. Springs 68 act to damp -the wheel
movement, acting to prevent the wheels changing steering
direction on encountering a bump
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and also acting to stab:Lilize the wheels in -the straight-
ahead position when the trailer is not turning.
Wheels 54 are self steering. They have cas-tor and
camber so that they can turn as the vehicle turns and -thus
applies a turning force to the wheels 54. Their mounting is
thus designed to allow castor and camber action to s-teer them
as the trailer turns.
A shock absorber or damper 70, preferably hydraulic,
extends from the steering arm 62 to damp the action of
sppring 68. As shown in Figure 5 it may be attached to the
steering arm 62 at one end and the body or piston of the
shock absorber is attached to the spring abutment 64 at its
inner end.
The trailer of the present invention permits the
carrying of loads of increased length and weight. The
provision of pivotal joints and, in particular, the provision
of greatly increased wheel area permits greater loads than a
conventional trailer. The use of pivotal joints between the
bridge and the sub-frame means that the trailer maintains
contact with the road at all times.
The trailer is made of conventional materials in the
art, bearing in mind that the trailers are subjected to
considerable loads and forces.
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