U.S. patent number 3,856,344 [Application Number 05/341,874] was granted by the patent office on 1974-12-24 for orthotropic trailer.
This patent grant is currently assigned to Ameron, Inc.. Invention is credited to Frederick W. Loeber.
United States Patent |
3,856,344 |
Loeber |
December 24, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
ORTHOTROPIC TRAILER
Abstract
A highway trailer has a relatively low-weight, high-strength
load-support bed which includes a pair of longitudinally extending,
parallel, inverted T-beams, and a series of side-by-side transverse
compound channel members, or pans, welded to the vertical webs of
the T-beams in an orthotropic design. Preferably, each pan is
substantially J-shaped in cross-section, and comprises a
load-supporting horizontal top flange, a horizontal bottom flange,
and a vertical web between the top and bottom flanges. The bottom
flange and vertical web of each pan are slotted so the bottom of
each top flange rests on the top edge of the T-beams. The top
flanges are welded together to provide a continuous unitary deck
surface extending the length of the T-beams. The top flange, bottom
flange, and web of each pan are welded to the T-beams to provide
shear continuity between the top deck flanges and the T-beams. A
row of spaced apart longitudinal depressions are formed in each top
flange to add stiffness to the top deck flanges.
Inventors: |
Loeber; Frederick W. (Downey,
CA) |
Assignee: |
Ameron, Inc. (Monterey Park,
CA)
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Family
ID: |
26915936 |
Appl.
No.: |
05/341,874 |
Filed: |
March 16, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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221608 |
Jan 28, 1972 |
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Current U.S.
Class: |
296/204; 105/422;
52/674; 280/789 |
Current CPC
Class: |
B62D
53/0842 (20130101); B62D 33/02 (20130101); B62D
25/2054 (20130101) |
Current International
Class: |
B62D
33/02 (20060101); B62D 25/20 (20060101); B62D
53/08 (20060101); B62D 53/00 (20060101); B62d
033/02 () |
Field of
Search: |
;296/28M,28F ;280/16T
;105/422 ;52/579,656,668,673,674,732 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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771,298 |
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Mar 1957 |
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GB |
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108,279 |
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Aug 1939 |
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AU |
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Primary Examiner: Sheridan; Robert G.
Assistant Examiner: Paperner; Leslie J.
Attorney, Agent or Firm: Christie, Parker & Hale
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This is a continuation-in-part of my application Ser. No. 221,608,
filed Jan. 28, 1972, now abandoned.
Claims
I claim:
1. In a highway trailer, a load-support bed including a pair of
spaced apart and generally parallel, rigid, elongated open-section
metal beams each having at least a vertical web and a bottom
flange, and a series of rigid, elongated open-section load-support
members each being made of metal and shaped to provide a top
flange, a bottom flange below the top flange, and a web integral
with and extending between the top flange and the bottom flange,
the series of load-support members being mounted on the beams in a
side-by-side relation with the bottom of each top flange being in
substantially continuous contact with the top of each beam and
being rigidly bonded to each beam, the web and the botton flange of
each load-support member also being rigidly bonded to each beam,
the top flanges of the load-support members being rigidly bonded
together to form a continuous rigid panel extending lengthwise
relative to the beams for providing a load-supporting deck and also
serving as a compression flange for the vertical webs of the beams
and a tension flange for the webs of the load-support members to
form a stiff, unitary load-support bed of orthotropic design.
2. Apparatus according to claim 1 including a series of spaced
apart depressions formed in each top flange to stiffen the top
flanges.
3. Apparatus according to claim 1 in which each beam is inverted
T-shaped in cross-section and including slotted openings in the web
and bottom flange of each load-support member to permit the
vertical web of each beam to fit into the slotted openings, with
the top edge of the vertical web of each inverted T-shaped beam
continuously supporting the bottom surface of each top flange.
4. Apparatus according to claim 1 in which the web and bottom
flange of each load-supporting member is bonded to both sides of
the vertical flange of each beam
5. Apparatus according to claim 1 including a series of spaced
apart openings formed in the web of each load-supporting
member.
6. Apparatus according to claim 1 including several stiffening
members for providing additional stiffness at longitudinally spaced
apart points in the bed, each stiffening member being rigidly
secured between a pair of adjacent loadsupport members and shaped
so it cooperates with at least one of the load-support members to
form a closed-section beam extending parallel to the load-support
members.
7. Apparatus according to claim 1 in which the load-support members
are made of work hardening steel.
8. In a highway trailer, a load-support bed including a pair of
spaced apart rigid, elongated open-section metal beams, a series of
rigid, elongated open-section load-support members each being made
of metal and shaped to provide a substantially planar top flange, a
bottom flange below the top flange, and a web integral with and
extending between the top flange and the bottom flange, the series
of load-support members being mounted on the beams in a
side-by-side relation with the bottom of each flange being bonded
to each beam, the web and bottom flange of each load-support member
also being bonded to each beam, and the top flanges of the
load-support members being bonded together to form a continuous
rigid load-supporting deck panel extending lengthwise relative to
the beams, and several stiffening beams mounted on the open-section
beams for providing additional stiffness at longitudinally spaced
apart locations in the trailer bed, each stiffening member being
disposed between a pair of adjacent load-support members and having
a load-supporting top flange, and a web transverse to the top
flange, the top flange of each stiffening beam being in the same
plane as the top flanges of the adjacent load-support members, and
including means bonding the top flange of each stiffening beam to
the top flange of its adjacent load-support members, the bottom
flange of at least one adjacent load-support member being bonded to
the web portion of the stiffening beam so that said one adjacent
load-support member and the stiffening beam cooperate to form a
transverse closedsection beam, the entire composite structure
forming a stiff, unitary load-support bed of orthotropic
design.
9. Apparatus according to claim 8 including a series of spaced
apart openings extending through the web of the stiffening
member.
10. In a highway trailer, a load-support bed including a pair of
spaced apart and generally parallel, rigid, elongated open-section
beams which are inverted T-shaped in cross-section and define a
vertical web and a bottom flange, the open-section beams being made
of a material having a Young's modulus on the order of that of
steel, and a series of rigid, elongated open-section load-support
members each being made of a material having a Young's modulus on
the order of that of steel and being shaped to provide a top
flange, a bottom flange below the top flange, a web integral with
and extending between the top flange and the bottom flange, and a
series of spaced apart depressions formed in each top flange to
stiffen the top flanges, each load-support member having slotted
openings in the web and bottom flange thereof, the series of
load-support members being mounted on the beams in a side-by-side
relation with the vertical web of each beam fitting into the
slotted openings of the load-support members, and the bottom of
each top flange being in substantially continuous contact with the
top edge of the vertical web of each beam, the bottom of each top
flange being bonded to the web of each beam, the web and bottom
flange of each load-support member being bonded to each beam, and
the top flanges of the load-support members being bonded to each
other to form a continuous, rigid panel extending lengthwise
relative to the beams for providing a load-supporting deck and also
serving as a compression flange for the vertical webs of the beams
and a tension flange for the webs of the load-support members to
form a stiff, unitary load-support bed of orthotropic design.
11. Apparatus according to claim 10 in which the web and bottom
flange of each load-support member is bonded to both sides of the
vertical web of each open-section beam.
12. Apparatus according to claim 10 including a series of spaced
apart openings formed in the web of each load-support member.
13. Apparatus according to claim 10 including several stiffening
members mounted on the open-section beams for providing additional
stiffness at longitudinally spaced apart points in the bed, each
stiffening member being rigidly secured between a pair of adjacent
load-support members and being shaped so it cooperates with at
least one of its adjacent load-support members to form a
closed-section beam extending parallel to the load-support
members.
14. Apparatus according to claim 13 in which each stiffening member
has a load-supporting top flange, and a web transverse to the top
flange, the top flange of each stiffening member being in the same
plane as the top flanges of its adjacent load-support members, and
including means bonding the top flange of each stiffening member to
the top flanges of its adjacent load-support members, the bottom
flange of at least one adjacent load-support member being bonded to
the web portion of the stiffening member so that said one adjacent
load-support member and stiffening member cooperate to form a
transverse closed-section beam.
15. Apparatus according to claim 14 including a series of spaced
apart openings extending through the web of the stiffening member.
Description
BACKGROUND OF THE INVENTION
This invention relates to highway trailers, and more particularly
to a relatively low-weight and high-strength trailer bed.
All states have laws which limit axle loads imposed by vehicles
using public highways and streets. Thus, there is a strong economic
incentive for truck and trailer manufacturers and companies
shipping cargo on fleets of trucks to minimize tare weights of the
vehicles so as to maximize pay loads. Substantial economic
advantages are gained by reducing the tare weight of trucks
carrying maximum pay loads during a large percentage of their total
mileage.
Besides the increased pay load resulting from highway tractors and
trailers of reduced weight, a low-weight vehicle also produces
lower running costs in the form of less maintenance, increased tire
life, and an overall increase in fuel economy.
Thus, a trailer having a weight reduction of 1,500 lbs. to 2,000
lbs, can produce substantial cost savings, which can be in the
neighborhood of several hundred dollars per week.
SUMMARY OF THE INVENTION
This invention provides a highway trailer having a load-support bed
of orthotropic design which is extremely low in weight and easily
fabricated from a few similar parts.
Briefly, the trailer bed includes a pair of spaced apart,
elongated, rigid open-section beams, and a series of rigid,
open-section load-support members rigidly secured to the beams in
an orthotropic design to provide a unitary deck for the trailer
bed. Each load-support member includes a horizontal top flange, a
bottom flange spaced below the top flange, and a vertical web
integral with and extending between the top and bottom flanges. The
load-support members are mounted on the open-section beams in a
side-by-side relation, with the bottom of each top flange resting
on the top of each beam. The top flanges of the load-support
members are rigidly secured together to form a substantially
continuous unitary deck panel extending lengthwise relative to the
beams. The top flange, bottom flange, and web of each load-support
member are rigidly secured to the open-section beams to provide
"shear continuity," i.e., continuous load-carrying capacity
uninterrupted by elastic losses, between the open-section beams and
the continuous deck panel formed by the top flanges. Moreover, the
orthotropic design of the trailer bed enables the continuous deck
panel to act as both a compressive member and a tensile member
capable of resisting bending in two mutually perpendicular
directions. That is, the deck panel acts as the compressive flange
of the longitudinal open-section beams to resist bending about a
transverse axis through the load-support bed, and also acts as the
tensile flange of the vertical webs of the load-support members to
resist bending about a longitudinal axis through the load-support
bed.
The trailer bed provided by this invention is relatively low in
weight and high in strength because of the shear continuity between
the structural components of the bed and the ability of the
integral deck panel to resist bending in two directions.
In a preferred form of the invention, a series of laterally spaced
apart depressions are formed in each top flange. The depressions
provide additional stiffness for the top flanges of the
load-support members, thereby increasing the ability of the deck
panel to carry planar compressive loading.
Additional strength also is provided by several closed-section
stiffening members rigidly secured between certain load support
members in the bed.
Thus, the trailer bed has high strength and low weight, which makes
it possible to carry pay loads of increased weight, thereby
providing substantial cost savings for companies shipping cargo on
public highways and streets. Moreover, the design of the bed lends
itself to fabrication from only a few similar parts, which provides
substantial cost savings for trailer manufacturers.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects of the invention will be more fully
understood by referring to the following detailed description and
the accompanying drawings in which:
FIG. 1 is a fragmentary perspective view showing a highway
trailer;
FIG. 1A is an elevation view, partly in section, taken on line
1A--1A of FIG. 1;
FIG. 2 is a fragmentary perspective view showing a loadsupport
member from which the bed of the trailer is constructed;
FIG. 3 is a fragmentary plan elevation view taken on line 3--3 of
FIG. 2;
FIG. 4 is a fragmentary plan elevation view taken on line 4--4 of
FIG. 3;
FIG. 5 is a sectional elevation view taken on line 5--5 of FIG.
4;
FIG. 6 is a fragmentary sectional elevation view taken on line 6--6
of FIG. 3;
FIG. 7 is a fragmentary elevation view showing the construction of
the longitudinal T-beams which support the load-support
members;
FIG. 8 is a fragmentary plan elevation view taken on line 8--8 of
FIG. 7;
FIG. 9A is a fragmentary sectional elevation view taken on line
9A--9A of FIG. 8;
FIG. 9B is a fragmentary sectional elevation view taken on line
9B--9B of FIG. 8;
FIG. 9C is a fragmentary sectional elevation view taken on line
9C--9C of FIG. 8;
FIG. 9D is a fragmentary sectional elevation view taken on line
9D--9D of FIG. 8;
FIG. 10 is an enlarged sectional elevation view showing means for
stiffening the load-support members;
FIG. 11 is a fragmentary sectional elevation view taken on line
11--11 of FIG. 10;
FIG. 12 is a fragmentary sectional elevation view showing means for
welding the load-support members to the T-beams; and
FIG. 13 is a fragmentary sectional elevation view taken on line
13--13 of FIG. 12.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2, a highway trailer 20 is supported on a
conventional rear running gear 22. Preferably, the weight of the
running gear is reduced by using forged disk aluminum wheels 24.
During use of the trailer, a king pin 25 (see FIG. 7) at the front
of the trailer is connected to a conventional highway tractor (not
shown).
Trailer 20 has a high-strength, low-weight load supporting bed 26
of orthotropic design. The bed includes a pair of longitudinally
extending, parallel open-section inverted T-beams 28, each T-beam
having a vertical web 30 and a horizontal bottom flange 32. The
T-beams comprise the main load-carrying structural members of the
trailer bed.
A series of side-by-side elongated transverse load-support members
or pans 34 are mounted on the top edges of webs 30 of the T-beams.
The pans are open-section members rigidly secured to the T-beams in
an orthotropic design. Each pan is formed from sheet metal to
provide a substantially J-shaped cross-sectional configuration
which includes a vertically extending web 36, and a relatively
wide, downwardly opening top channel having a flat, horizontal top
flange 38 integral with the top edge of web 36 and a downwardly
turned marginal lip 40 at the remote edge of top flange 38. Each
pan also includes a relatively narrow, upwardly opening bottom
channel having a flat horizontal bottom flange 42 integral with the
bottom edge of web 36. Bottom flange 42 extends away from web 30 in
a direction opposite that of upper flange 38. An upwardly turned
marginal lip 44 extends along the remote edge of bottom flange
42.
A pair of laterally spaced apart, parallel, slotted openings 46 are
formed in web 36, bottom flange 42, and lip 44. A separate pair of
laterally spaced apart and parallel slotted openings 48 are formed
in lip 40. Each slot 46 is aligned longitudinally with a respective
one of slots 48 so that each pan can slip over webs 30 of the
T-beams, with the bottoms of top flanges 38 resting on the top
edges of webs 30.
Thus, top flanges 38 of the adjacent pans provide a continuous deck
panel extending the length of the T-beams.
As shown best in FIG. 1 the pans are mounted on T-beams 28 so that
lip 40 of each top flange 38 abuts against the top portion of the
web of the neighboring pan continuously for the width of the
trailer bed. The abutting portions of the adjacent pans are rigidly
bonded together by stitch-welding 50 (see FIGS. 1, 8 and 12) so the
top flanges provide a rigid load-supporting unitary deck panel.
Preferably, each weld 50 is about 11/2 inches wide, and has a
naturally V-shaped configuration which substantially prevents
fatigue or localized stress occurring in the weld as a result of
loads on the deck panel. The purpose of the welds at 50 is to
interconnect top flanges 38 so they form the equivalent of a
continuous, rigid load-supporting deck panel. It is critical to the
orthotropic design of the load-support bed to maintain the
structural continuity of the top flanges. For example, certain
methods of bolting the top flanges together would be unacceptable,
if they would produce elastic losses at the joints which, in turn,
would prevent the top flanges from acting as a continuous, rigid
flange.
As shown in FIG. 12, the bottom of each top flange 38 is rigidly
bonded by stitch-welding 50a to both sides of each T-beam web 30.
This rigid connection provides "shear continuity" between the top
deck panel and the webs of the main load-carrying T-beams. "Shear
continuity" between structural members is defined herein as the
capability of maintaining load-carrying ability with stiffness,
uniterrupted by elastic losses, between component structural
members such that the resulting composite structure has stiffness,
or rigidity, equal to that of the basic structural members. For
example, the load-carrying top flanges 38 rest on the tops of
T-beam webs 30, and are rigidly bonded thereto as an integral unit.
This provides shear continuity between flanges 38 and webs 30. On
the other hand, shear continuity between these members would be
destroyed if (1) the top flanges were bolted to the webs 30 in a
manner which would result in elastic losses at the joints, (2) the
load-supporting plane of the top flanges is spaced apart from webs
30, or not bonded to the webs, or (3) a material such as aluminum
or wood having a substantially lower Young's modulus than that of
the steel top flanges and webs is interposed between the top
flanges and the webs. In the latter instance, loading on the
trailer bed would cause the material of lower modulus to develop
shear between the deck panel and the T-beam webs which would absorb
energy and therefore would prevent the transmission or continuity
of shear between the load-supporting deck panel and the T-beams. In
the trailer bed this invention, the T-beams, pans, and other
transverse members between the pans are made of steel or other
structural metal having a modulus equivalent to that of steel,
i.e., in the neighborhood of 30 .times. 10.sup.6 psi.
Referring to FIGS. 12 and 13, the vertical web 36 of each pan is
rigidly bonded by stitch-welding 50b to each side of each T-beam
web 30. This rigid connection provides shear continuity between top
deck panel flanges 38 and webs 36.
Bottom flange 42 of each pan is rigidly bonded by stitch-welding
50c to each side of each T-beam web 30. This rigid connection
provides shear continuity between webs 36 and bottom flanges
42.
The structural integrity of load-support bed 26 enables the
continuous deck panel to act as both a compressive member and a
tensile member capable of resisting bending in two mutually
perpendicular directions. For example, the deck panel acts as the
compressive flange of the longitudinal T-beams to resist bending
about a transverse axis through the load-support bed, and it also
acts as the tensile flange of the vertical webs of the pans to
resist bending about a longitudinal axis through the load-support
bed. Moreover, bottom flanges 42 also have compressive and tensile
continuity under loads imposed on the load-support bed.
Referring to FIGS. 1 and 1A, a pair of elongated side channel
members or rub rails 52, each having a substantially C-shaped
cross-sectional configuration, are fitted over the ends of pans 34.
Preferably, the rub rails are formed from 10-gauge sheet metal, and
may take a variety of suitable shapes for fitting over the ends of
the channel members to protect them from impact damage and
abrasion. FIG. 1A shows a typical rub rail configuration which
includes an upwardly turned, diagonally extending top flange 52a
and a substantially horizontally extending and inwardly projecting
bottom flange 52b which is turned back on itself to provide a
channel which makes a tight friction fit over the ends of the pans.
Rub rail 52 is the main support member for a variety of auxiliary
load supporting equipment such as load hooks 53a (see FIG. 1A),
cargo winches 53b, stake pockets 53c, reflectors 53d, running
lights 53e, and the like. The rub rail is also welded in place so
it can serve as the top flange of the trailer deck panel.
The detailed construction of pans 34 is understood best by
referring to FIGS. 3-6. The pans are formed from 14-gauge sheet
steel, preferably carbon steel capable of work-hardening. The pans
are preferably 8 feet long, with each pan being continuous for the
width of the trailer bed. Top flange 38 is preferably 101/2 inches
wide, web 36 is preferably 4 inches deep, and bottom flange 42 is
preferably 13/4 inches wide. Each return lip 40 and 44 is about
three-fourth inch in depth. The bending of the sheet steel to form
the substantially J-shaped configuration work-hardens the steel and
thereby increases its physical strength.
A series of laterally spaced apart, parallel, longitudinally
extending and downwardly projecting elongated depressions or
dimples 54 are formed in top flange 38 of each pan. Depressions 54
are continuous for most of the width of the top flange, and are
substantially V-shaped in cross-section, as viewed in FIG. 6. Each
depression is about three-eighth inch deep. The depressions are
uniformly spaced apart, except that depressions are omitted in
those portions of the top flange supported by vertical webs 30 of
the T-beams.
During use of trailer bed 26, loads carried on the bed put top
flanges 38 in compression. When the trailer bed carries heavy
loads, particularly loads which maximize the pay load capacity of
the vehicle, there is a natural tendency for the top flanges to
buckle or sag. However, the T-beams directly support the continuous
load-carrying deck panel provided by the top flanges, and thereby
act as transverse stiffening members to keep the top flanges in a
common load-supporting plane, thereby resisting the tendency of the
flanges to buckle. The working of the steel to form depressions 54
work-hardens the steel to provide additional strength for the top
flanges, which increases their ability to stay in a flat plane
resisting the tendency to buckle. The work-hardening of the steel
increases the strength of the pans to such a degree that additional
transverse stiffening members, such as additional T-beams, or
closed-section beams, are not needed to prevent buckling of the
pans. Thus, a substantial savings of weight results from the use of
the high-strength, work-hardened pans.
A series of laterally spaced apart lightening holes 56 are punched
through web 36 of each pan. As shown best in FIGS. 3 and 4, each
lightening hole preferably is aligned longitudinally with a
respective one of the depressions 54. The holes are punched so that
the metal surrounding each hole bends away from the plane of web 36
to form a circular flange or lip 58 bordering the hole. The bending
of the steel during forming of the holes work-hardens the steel to
provide additional strength for the web of each pan. Moreover, the
lightening holes produce a considerable weight reduction for the
pans.
During use of the trailer bed, loads on the bed put bottom flanges
42 in tension. Bottom flanges 42 provide transverse beam strength
for the trailer bed when the bed is subjected to heavy loading. The
strength of the bottom flanges 42 is enhanced by return lip 44
which stiffens the edge of each bottom flange to prevent it from
deforming under loading. Each bottom flange also includes several
laterally spaced apart drain holes 60.
The presently preferred J-shaped configuration of the pans is shown
in the drawings. The pans also can be substantially C-shaped (i.e.,
by turning bottom flange 42 in an opposite direction) without
departing from the scope of the invention. The J-shaped
configuration is preferred because it is easier to fabricate.
The geometry of the pans also can be varied to increase the
capacity for localized loading. For example, changes such as (a)
depth increase, (b) increase in the width of bottom flange 42, (c)
decrease in the width of top flange 38, (d) increase in metal
thickness, and (e) increase in the density of depressions 54 can be
made to increase the capacity of the pans for given localized
loading situations. Consideration of the above changes together
with attendant fabrication advantages can yield an optimum
cost/weight profile to suit a given application.
The detailed construction of the trailer bed lower support
structure is best understood by referring to FIGS. 7 and 8. The
front of the trailer is supported independently of the tractor on a
conventional telescoping landing gear 62. A series of spaced apart
lightening holes 64 are punched through web 30 of each T-beam
rearward of the landing gear. Holes 64 serve substantially the same
purpose as holes 56 in the pans. Each lightening hole 64 is formed
by bending the metal surrounding it away from the plane of flange
30 to work-harden the steel and thereby provide additional strength
for the T-beams. Moreover, each lightening hole 64 provides a
substantial weight savings.
As shown best in FIG. 8, the vertical dimension of each T-beam web
30 is relatively narrow at the front end of the trailer, tapering
wider toward the load-bearing intermediate portion of the trailer,
and tapering narrower toward the end of the trailer. Two series of
holes 64 are formed in the wide intermediate portion of web 30,
with a single series of the holes being formed in the narrower
front and rear portions of the web. Alternatively, a single series
of wider holes 65 (shown in FIG. 1) may be formed in webs 30,
although it is preferred to use a large number of smaller holes, as
shown in FIG. 7, because the additional working of the steel
provides greater work-hardening and therefore a stronger structural
member.
Each bottom flange 32 of the T-beams is fabricated from alloy steel
and bent at several longitudinally spaced points to conform to the
lower edge contour of web 30. The two members are then welded
together continuously to provide shear continuity between web 30
and flange 32. Preferably, web 30 is sheared out of 10-gauge sheet
steel, preferably a type of carbon steel capable of
work-hardening.
As shown best in FIG. 8, the front portions of flanges 32 are
interconnected by a continuous flat, horizontally disposed plate
section 66. The plate section supports a king pin mounting bracket
assembly 67.
FIGS. 9A through 9D, 10, and 11 show the detailed construction of
the trailer bed, including means for providing additional stiffness
for the bed. The front of the trailer bed includes a rearwardly
opening, substantially C-shaped elongated transverse channel member
68 extending the width of the bed. Channel member 68 is slotted in
a manner identical to pans 34 so the channel member fits over webs
30 of the T-beams. The top flange, bottom flange, and web of member
68 are welded to T-beam flange 30 in a manner similar to that of
pans 34 to maintain the desired shear continuity.
Referring to FIG. 9A, additional stiffness in the area of king pin
25 is provided by a vertical stiffening plate 70 extending
laterally between vertical webs 30 of the T-beams. The top edge of
the plate is stitch-welded to the bottom edge of web 36 of a pan
forward of king pin 25. The bottom of plate 70 is stitch-welded to
the top of horizontal plate section 66. An identical vertical
stiffening plate 72 is spaced rearwardly from plate 70 and rigidly
secured between webs 30 of the T-beams at a point behind king pin
25. Stiffening plates 70 and 72 stiffen the bed in the area of the
king pin which is subjected to substantial stress when the trailer
is hitched and pulled by a tractor.
FIG. 9B shows means for providing additional stiffness for the
trailer bed on both sides of landing gear 62. A narrow, vertically
extending transverse, elongated stiffening channel 74 is sandwiched
between a pair of pans 34. Stiffening channel 74 extends the width
of the trailer bed and is located forward of the landing gear. An
identical stiffening channel 76 is sandwiched between a pair of
pans to the rear of the landing gear.
As shown best in FIGS. 10 and 11, each stiffening channel has an
intermediate portion 77 which includes a vertical web 78, and a
downwardly opening top channel which includes a horizontal top
flange 80 integral with the top edge of web 78 and continuous for
the width of the trailer bed, and a downwardly turned marginal lip
82 along the remote edge of top flange 80. The stiffening channels
also include an upwardly opening bottom channel having a horizontal
bottom flange 84 integral with the bottom edge of web 78, and an
upwardly turned marginal lip 86 extending along the remote edge of
bottom flange 84. Top and bottom flanges 80 and 84 extend in the
same direction from the plane of web 78 to form a substantially
C-shaped configuration when the intermediate portion of the
stiffening channel is viewed in transverse cross-section.
As shown best in FIG. 11, top flange 80 is continuous for the
entire width of the trailer bed. Top flange 80 is welded to the top
flanges of the adjacent pans 34 to maintain the desired structural
integrity of the deck panel. The bottom of top flange 80 is welded
to the top of T-beam webs 30 to maintain the desired shear
continuity.
The intermediate portion of each stiffening channel is continuous
between webs 30, and is supported at its bottom by a pair of
horizontal support plates 88 welded to the inner vertical side
walls of webs 30. Stitch-welds 90 (see FIG. 10) rigidly secure the
bottom of each intermediate portion 77 to support plates 88.
Support plates 88 prevent fatigue failure of the connection of
vertical web 78 to main web 30.
Each stiffening channel also has a pair of outer portions 91 each
including a vertical web 92 extending downwardly from the edge of
top flange 80 in the same plane as vertical web 78. Each web 92 is
separated from web 78 by a respective slotted opening 94 which
receives a web 30 of a respective T-beam. Webs 92 are welded to the
sides of webs 30 to maintain the desired shear continuity.
Several vertically spaced apart and horizontally extending series
of lightening holes 96 are formed through vertical web 78 of each
stiffening channel. A single row of laterally spaced apart
lightening holes 98 are formed through outer vertical webs 92 of
the stiffening channels. The purpose of holes 96 and 98 is
identical to that of the lightening holes 56 in the pans, i.e.,
they reduce weight and provide added strength because of the
work-hardening of the steel surrounding the holes.
As shown best in FIGS. 9B and 10, stiffening channel 74 cooperates
with web 36 and bottom flange 42 of the pan to its rear to form the
equivalent of an elongated closed-section transverse stiffening
beam extending the width of the trailer bed at a point forward of
landing gear 62. Stiffening member 76 forms an identical
closed-section stiffening beam rearward of the landing gear. Each
closed-section stiffening beam is formed by rigidly securing the
top of web 78 to upper lip 40 of the neighboring pan forward of the
stiffening channel by stitch-welds 100. Stitch-welds 102 rigidly
secure the rear face of web 78 to bottom lip 44 of the neighboring
pan rearward of the stiffening channel. Stitch-welds 104 rigidly
secure upper lip 82 of the stiffening channel to the top of the web
36 of the neighboring pan to the rear of the stiffening channel.
The closed-section stiffening beams provide additional physical
strength in the areas of the trailer bed which are subjected to
heavy loading when the trailer rests on landing gear 62.
FIG. 9C shows means for stiffening the trailer bed to withstand
heavy loading above rear running gear 22. A stiffening channel 106
(identical in construction to channels 74 and 76) is rigidly
secured between a pair of adjacent pans, in a manner identical to
that described above for stiffening channels 74, 76, to form a
closed-section stiffening beam above a spring hanger 108 forward of
the front set of wheels. A second identical stiffening channel 110
is identically welded between a pair of pans above an intermediate
spring hanger 112 to form a closed-section stiffening beam between
the front and rear set of wheels.
FIG. 9D shows the detailed construction of the rear of trailer bed
26. A substantially C-shaped transverse channel member 114 spans
the width of the trailer bed at the rear of the trailer. A
substantially J-shaped transverse channel member 116 rigidly
connects the forward or free end of rear channel member 114 to the
rearwardmost pan 34 of the trailer bed. Channel member 116 is
slotted so it fits over webs 30 of the T-beams, with its top flange
acting as part of the deck surface. Channel member 116 is welded to
web 30, its neighboring pan 24, and channel 114 in a manner
identical to that described above for pans 24 to provide the
desired shear continuity.
The equivalent of a closed-section beam stiffens the rear of the
trailer bed above a rear spring hanger 118. The rear stiffening
beam includes a substantially Z-shaped transverse channel member
120 extending laterally between the vertical webs of the T-beams.
Channel member 120 has a top flange rigidly secured to the bottom
edge of channel member 114, and a bottom flange rigidly secured to
the inner portions of flanges 32 of the T-beams. An upright
diagonally upwardly extending plate 122 extends between a bottom
flange 123 of channel member 120 and a downwardly extending lip 124
at the front of rear channel 114. Plate 122 has several series of
vertically spaced apart and horizontally extending rows of
lightening holes 125 formed through it to work-harden the metal for
strengthening the plate sufficiently to provide additional strength
for the rear of the trailer. Channel member 120 is so constructed
to allow for protecting flush mounting of lights, signals and
license plates.
The trailer bed deck panel may have a variety of surfaces to resist
abrasion and the like from loads carried on the deck. The deck
surface can be a coating (not shown) of epoxy, urethane, or similar
material loaded with abrasive material such as sand, carborundum
dust, or like media. Alternatively, the deck can be covered with
plywood (not shown) treated to withstand abuse, weather conditions,
and so forth. As a further alternative, the deck can have a
non-skid tape (not shown) applied selectively over critical
portions.
The structural members of the load-supporting bed are made of
work-hardening steel. Preferably, a medium strength steel such as
high manganese/silicon steel, is used as the initial material. The
rolling, bending, and dimpling of the steel work-hardens it to such
an extent that the members are of high strength steel when
work-hardening is completed. The structural members of the bed are
better able to take heavier loads and resist dents and the like
because of the work-hardening. Moreover the use of medium strength
work-hardening steel as the starting material provides substantial
cost savings when compared with the use of high strength carbon
steel.
Thus, highway trailer 20 has relatively high strength and low
weight because of the work-hardened open-section transverse
structural members of orthotropic design which are low in weight
and have good physical strength. Moreover, the pans of the trailer
bed are supported on only a pair of longitudinal open-section beams
which are themselves low in weight and work-hardened to provide
good physical strength. Thus, the need for a large number of
structural members to support the compound channel members is
eliminated, which provides a substantial savings in weight.
An additional weight savings is provided by the welded unitary
construction of the bed, which eliminates the need for cross-ties
or other similar means for rigidly holding the deck-forming
structural members in place.
The trailer also exhibits greater stiffness than conventional
designs. The open-section pans are supported by the T-beams so that
top flanges 38 of the pans provide the equivalent of a stiff
orthotropic deck panel which resists bending in longitudinal and
transverse directions. Thus, the continuous deck plate provided by
top flanges 38 acts as a combination compression flange-tension
flange which reduces substantially the structural members required
to support loads without buckling, which also is a factor in the
reduced weight of the trailer bed. The orthotropic design provides
good stiffness vertically and laterally, while remaining
torsionally flexible. Thus, the trailer is able to carry maximum
pay loads, and yet is flexible enough in torsion to resist the
tendency to buckle under heavy loads and prevent shock from being
transferred to the load.
The trailer also is relatively inexpensive to fabricate because it
is manufactured from a few similar parts.
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