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Патент USA US2404121

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July 16, 1946.
I 2,404,] 2 1
J. J. BLACK
CASTER TRAILER
\- Filed April 17, 1944
r "
BY
4 Sheets-Sheét 1
QINVEN'IFIOR.v _
July 16, 1946.
‘
J. J. BLACK
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'
2,404,121
GASTER TRAILER
Filed April 17, 1944'
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BY/ZM
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4 Shéets-Sheyet 2
. a: ZINQENTOR. _
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July'16, 1946.‘
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' J. J. BLACK _
I
‘2,404,121
‘ CASTER TRAILER
Filed April _l'7, 1944
4 Sheets-Sheet 5
Jilly 16, 194.6.
,
-
J_ J. BLACK '
2,404,121
CASTER TRAILER
Filed April 17, 1944
'
J07
‘ 4 Sheets-Sheet 4
.
Patented July 16, 1946
2,404,121
UNITED STATES PATENT’ OFFICE"
James J. Black, (Cincinnati, Ohio; assignor to The
.Traiimobile Company, Cincinnati; Ohio, a cor}
poration of Delaware r'
Application April ‘17, 1944, Serial
5 Claims.
1
r
This invention relates to trailer vehicles of the
type which are edeptedite be towed by e treetbr:
The invention is directed, pertievlerly te- trailer
1 dividual ‘Wheels may be‘subjected are absorbed
by reason of their resilient mqunting. However‘;
if the'towingvehicle' is lodged heavily orif‘a.
heaiiy load isf‘imposed upon the casters from‘ the
vehicles in which the wheels at the front ends of
the structure are eestered Se thee-Whey do no tend 5V
to steer the vehicle but rather track behind the '
towing unit with its movements, and to facili
tate the positioning or parking of the trailer
when it is detached.
tow can‘: ch as'inight occur'if'the tow car starts
up a'rel vély 'abriiptincline before‘ the trailer
lias'rue'achedvthe incline, then movement of‘the
th' vehicle'ishijset bya countermovement equal
qne wheel which would'tend to alter the keel of
In, conventional structures employing caster
wheels mounted at the center oi the front ended
a trailer, a draw bar is attached directly between
the frame and thev pint‘lev hook of the towing car
so that the casters remain in contact with the
ground. The disadvantage of this type of struc
infestent'b'butobposite indirection;
_
siliently if the pivotal mobility is to be preserved.
A principal objective of the invention has been
to provide trailers having caster wheels at the
opposite sides of the "front ends of the structure
which are movable in up and down’ directions
but restrained as to movement so that a yield
able interconnection between the casters and the
body of the vehicle is provided. In this struc
ture the wheels yieldablyé are movable to {accom
modate themselves to local variations in the
roadway contour.
"
A further objective of the invention has been to
provide a mounting for the caster wheels in
which the vertical movement of a wheel at one
side of the vehicle is accompanied‘ by a substan
tially equal and opposite movement of the wheel
' 's to’ accommodate themselves" to local ir
_
the roadwayjand the shaft means
eale Lents interconnected with the levers “or wheel
niohzihngs ' whereby ‘ ‘independentwniqveinent ‘of
ease wheel is‘ 'resilien‘tly’controlled through'twistr
' ing'or sofoa'lled‘wvind-lupw thereof. ' whether;
means, however, béar'sAthe "weight loading "of
the vehicle and. is rotatable for impartin‘ghcni
pensa't'ing movements from one "wheélm-td‘the
omega“
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plates a structure in which the caster wheels are
yieldably mounted independently of one another
and also vequalized as to movement throngh cross
connection. The preferred mechanism‘ involves
the use of one or more shafts which are em
played as torsion members through which a re:
silient mounting is obtained by torsional twist
ing of the shafts and ‘through which equalization
isobtained by shaft rotation. Local minor var:
iations in the roadway contour to which the Lin-,
a
.
V
,
.
the easier Wheels witheyt'le Te ’ ens'atiiie'ifea
tn‘ , as 'wel'l‘assjtiiff shafts forv c mp'ensatioii 'of
"
3,0. a wneelswiihpey apiece "Yemeni
egf nee‘ feline
were eerie meuntirfg
is?121‘9vi1ie51 in Wale- Fee pitetsl movement "5f
the caste? wheelejiepieeeliied ihmighbiitifhei'i"
entnie ieirele 9f xetetebil'ity eminence with
control of their movements.
smetureihe Caster wheels are re- ‘
.ed‘ 1%1 farts; the .ferlse'jere swung
at the other side so that the body is maintained
In a further respect the invention ‘contem
..
vlOtihen' embodiments of the invention contem
plate the use of torsion shafts‘ rrggrmgmeor
YertieaHy 11.11.91} levers mounted 2.11
upon an even keel. In this respect va structure
is contemplated in which an equalizing mech
anism is employed to obtain the bene?ts of a
which
three-point
the load
type isofcarried,
supension
actually,
for upon
vehiclefour
" '
0 ions'x'lytfeferredto ‘isj'pne tr'more'rwistabie
with the towing vehiele- Even under most ever
able conditions the casters “?op” from one side to
the vother and thereby create a heavy ‘towing load.
Moreover, such wheels are 'dii?cult to mount re
'
the’pre'ferred embodiments" of the invention
the‘ caster wheels’ "are supportedi'individually 'upo'n
was" p'ivqitaiiy“ ‘intéliédn'nectewwith‘ the‘ name
whereby the wheels may move’i'n up and ‘down‘di
ture is that the wheels tend to plowinto the soft
center of a read and .de net fellow .22» direct eeuree
wheels or more.
5313406
(Cl. 28.0—33.4)
_. eterts a twisting rose 11115911 the elieéit
to spring the 0th? easier and ?cé @537” PF
‘ eetins to elieit to the ‘casters ‘at
,4
. .
nee}
ite. Delete thereon; or ihreqsfthle
use of smable" hell‘
the to‘ ileii Shaft
means is ‘eIe. ,_ teelet ‘as "e .ieemeen . ins .de l.
' From‘ the foregoing description’ of ‘the ipnnr.
eielee 11201; which the invention is ,Predieated
5.9 and from the"f.olloyying ‘detailed description of’
the deteyvgin W
~ 2,404,121
4
3
through which the nut may pass.
structure, the front end constructed in accord-‘
ance herewith and showing the organization of
the caster and control shaft means therefor.
j
It will be
observed that if the shaft I6 is torsionally rigid
then yieldability is provided primarily through
the compression spring 2|. However,in the al
ternative, part of the spring load, if desirable,
Figure 2 is a side viewv of the trailer shown in
‘
'
bolster channel having a clearance aperture
Figure 1 15a plan view of an entire trailer1
may be absorbed throughtwisting of ‘the shaft
and part through the compression spring.’ Neg‘
V Figure 1.
Figure 3 is an enlarged plan view‘ of the front
part ofthe trailer structure as shown in Fig-;
lecting any yieldability that may be provided
through the compression spring if it is employed,
Figure 4 is a side elevation of, a caster wheeli 170 ;it will be seen that the wheels are crossconnected
ure 1.
'
showing the lever connection thereof to thervehi- .
and sprung through a shaft l6 which is com
cle frame.
Figure 5 is a plan view similar to Figure 3, .
mon to them; 7
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V
» . To illustrate the operation of the device it may .7
showinga modi?ed form of the'inventionr:
bessupposed, 'for' example, that the wheel at the _ . V
.
Figure 6 is a side elevation showing the lever
,
‘
' mounting of the caster to. the frame and connece . - .
. tion therewith to the control shaft r'nea'n's'.
‘ "
15
. Figure 'Tis an end elevation» of another modi; '
:?ed form of the invention.
'
right-handof ‘the vehicle, as shown in Figure 4,
hits" an‘ obstruction and must move upwardly.
The shackles l2 and I3 permit this upward move"-_
ment and swing through arcs as indicated by
inasmuch as-Qnev of the
j, Figure 8 is a plan view/of therform shown ‘in 20 thearrows.» However,
shackles :18 1h rigid. connection with the cross.
.
1
f
shaft: Iii-this upward movement is imposed upon
Figures Qand 10 are views showing intercon
the cross shaft as .a‘twisting movement.v This
nection of the shaft means with the casters'or
shaft-therefore is twisted or loaded to'rsionally
levers _ as the case maybe, whereby failure of the
accordance with the upward movement of the
" shaft through torsional loading is prevented. " 25 in
caster‘as
governed, of course, by the weight load
The trailer in which thepresent improvements
ing-‘of
the
trailer.» The twisting movement also ,
arevutilized may be ofthe usual type as shown
may cause rotation of the shaft fl6'at its oppo
in Figures; 1 and 2 consisting of a frame 'I which»
site end which in turn exerts ' a lifting force
3 ' is stiffenedbycrossbolsters v2. The frame car
upon the-other wheel assembly. Therefore, 'dif
30
‘ ' ries the usual deck 3 upon which may be mount‘
ferences in the terrain 'over which the caster
ed the front boss. 4. :At the rear part of the
wheels \are moving: are accommodated by wind
trailer a stiff, axle 5 is provided to rotatably sup
ing or twisting of the shaft between the center
port the rear wheels 6, while caster wheels, des
fastening and shackle on each end.
T
ignated V1,;are located at the front end of the
In the apparatus shown‘ in Figure 5,:the casters
as
trailer, one at each side thereof.‘ Thesewheels
are mounted upon levers or shackles in the man
preferablyare smaller indiameter'than the rear
ner
described but,'in this case,,the cross shaft
wheels ;and are rotatably, supported upon, axles , I6 isjust
interconnectedwith the wheelunits at oppo
8 which are carried in forks 9, one for each wheel,
sitely idi'sposed’poi'nts'. For instance, the levers
"the; forks being ,‘con?gurated so that the axes
face in opposite directions, ‘one set to therfront
40
through ,thesha'fts ID are laterally offset from
and one set to the ‘rear'offthe trailer at suit
the axles 8>whereby pivotal action of the casters
able angles for interconnection of the cross shaft.
Figural;
is obtained.» ,
Connection sleeves l8 through'which the shaft is
mounted to each shackle are elongated and rotat
e
_ Shafts m are samba journalled in sleeves u
and each sleeve has aligned pairs of bosses ex-Q .
ably- pass through journals 24 "supported from’
tending in opposite directions from its outer pe 45 'therframeh Thus, if the wheel shown at the
riphery. “These bosses carry levers I2 and 13,
left'hand side of Figure 5 is raised the shaft I6
one ‘pair of levers at each side of the sleeve. In
is rotated in the .direc'tion'of the arrow and this
place of individual levers the upper and the
rotation in turn effects a'downward movement
lower pairs may be in the form of forks or shackles
of the wheel assembly‘ at thelleft hand side of
as shown in plan view in Figures: 1 ands. These to the
apparatus whereby the net effect upon the
shackles are rotatably connected through the
body of the vehicle is a lowering movement just
frame whereby the levers are free to swing and
half the distance which the left hand was raised.
permit the caster and wheel unit to move in an
If the raising movement is abrupt the shaft twists
up and. down direction as indicated by the ar
rows in Figure 4. Thus, one ofthe shackles, i. e. 55 to absorb the momentary shock whereby aresili- '
Vent effect is‘ displayed. It is preferableito star
I3,'is;connected to the vframe through a stub
bilize the central'portion' of the shaft l6 against
shaft 14 which extends from a pillow block l5
whipping'by
journalling it within a rubber bear
mounted on the frame, while the other of the
ing 25 or the like.
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’
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shackles, i. e. I2, is fastened'rigidly to ashaft
I6 which is journalled in a pillow block I‘! sup
co “Itis necessary that the cross shaft be pro
tected against torsional overloading. The‘ but
tress markedl? as shown in Figure’ 6 servesthis
ported by theframe, the shaft [6 constituting
the control shaft means through which vertical
function. As the wheel assembly moves in a
vertica1 direction the levers Or the shackles l2
movement of the caster is controlled. As shown
in Figure 3, shaft l6 forms' a rigid connection .
with theshackle throughla sleeve [8 and extends 65 and‘ll3' are swung on their pivotpoints where-V~
by the outer sleeve H in which the caster fork
across-the vehicle into connection with the other
is journalledv approaches‘ the ‘abutting face- 2'!
caster wheel assembly in the manner just de
scribed.'
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e
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of the member 26." This face therefore.'serves as
"
a positive stop ‘which after a predetermined
‘ At' the central part of the vehicle, shaft l6,
ifedesirable, may carryv ‘a supplemental'spri'ng
lever 19 which has aTrod 20 loosely connected
with it at its'fre'e end. The rod passes through
a; compression spring .2 l, which is seated, upon a
‘7 face of across bolster 2,2 of thejframe'while'the
. rod carries a nut '23 at another portion of the
amount ‘of movement'hastaken place limits fur- '
ther. movement to relieve thesuspensionsystem '
' of the wheels from further loading. ‘_ -
:A‘modi?edform OfLstructure is ‘shownin‘ Fig
"It
ures?and'
lHere thejshackles I12 and i3 eX-'_
tend in f'directions" laterally of vthe frame from
2,404,1 2,1
5
bolsters 28~whichiiare mounted on the‘. frame.‘
The connection15betwe'en1the free .ends of the
shackles and the bolstersis formed through. pins
which may be elongated 'to constitute shaftssub
jected to a twisting force commensurate with
vertical wheel movement. For cross connection
between the wheel’ units, these shafts‘ are pro.
videdwith bell cranks 29 mounted thereon rigid
ly, and the free ends of the bell cranks are inter
connected by means of a tie rod 3%). Inthe op
eration of this form of apparatusa lifting move.
6
minimum at a distance vspaced inwardly from the
end of the shaft. When the major diameter of
the tapered'bore, i. ’e., at its inward end equals
the diameter .of the shaft, then the pressure is
zero vat the point adjacent the major. diameter
and increases .to a maximum at the opposite end
of the connection.
. '
Asshown in Figure 9, a similar result is ob
tained'by con?gurating one of the parts, grad
ually, to weaken it, so that the pressure of en
gagement varies because of its weakness. Thus,
a sleeve '32 is shrunk upon the shaft either by
meansof heating itor by means of cooling the
shaft itself. ,This sleeve is chamfered or tapered
pin 31 _ on which the bell ‘crankl?l is" mounted.
The lower end‘lofT the crank 23 therefore moves 15 at oneend as at :33. At thispoint the wall thick
ness of. the. sleeve. is thinnest and it‘is, there.
toward‘ the left and the wheel at the opposite
foraincapa’ble :of embracing the shaft at the
side ofthe vehicle is lowered.
same pressure as that which occurs where the
If equalization of Wheel movements is desired
wall thickness is of fulldimension. By means
without torsional springing then the shafts 3!
of a shrink fit a ?rm connection between the
may be shortened to project just beyond the
caster brackets to carry the bell cranks 29; in ‘two members is established but in this embodi
ment, as in the other, there is still no abrupt
this embodiment the shafts are not long enough
variation in the pressure of engagement at which
to be twisted appreciably.
fatigue of a shaft may become localized.
Various torsion shafts adapted to be used as
In the structure shown in both Figures 9 and 10 ’
resilient members for absorbing shocks and pro
the members 34 connected to the shafts are
viding yieldability have been proposed in the
mounted upon the sleeves in a suitable manner,
past. However, the principal problem in the
use of them has been to avoid their failure, after _ "as by keying 35, or by shrink fit, or by welding.
It is to be observed that the sleeve forms a
a relatively short period of usage, through rup
ture or fatigue. In conventional practice a shaft 30 transition member through which the rigid con
ment of, say,-the caster unit at the-left hand side
of Figure 7», is accompanied by. rotationof the
which is to be subjected to torsion has an end
connection formed upon it, usually by forging,
nection is provided. It will be understood that ‘
the sleeves may be omitted .and that the members
34 will be connected directly to theshaft in the
in order that the shaft may be fastened rigidly
manner just described. It also will be understood
to a shackle or a lever. For instance the end
of the shaft is forged into a square and the 35 that the connection is established primarily
through pressure but that the parts also may be
shackle or the lever is connected to this por
welded, for instance, at the ends of the shaft as a
tion in order that the two will be hem together
further means of insuring permanence of the ‘
in non-rotatable relationship. Sometime the le
union. In such instances, however, the welding,
ver, shackle, or the like is fastened by welding.
In such instances, however, the metal structure 40 being located at the outer end of the shaft, is
not subjected to the main torsional loads and’
is altered and strains occur at localized areas at
therefore does not form a focal point at which
which the shaft eventually fails.
fatigue can occur.
It has been discovered, however, that fatigue
Aside from the fact that connections of this
and failure of the shaft for such reasons may
be avoided through connections which are char 4-5 type insure against shaft failure, they may be
formed more easily and economically than forged
acterized in that the engagement of the shaft
or welded connections of the type used in the
and the cooperating member is primarily a pres
past. ‘Thus, the shaft member may be of uni
sure engagement in which the pressure between
form diameter, preferably ground to a straight
the members, around any line peripherally of the
shaft, is substantially uniform but varies from 50 ?nish or it may be used in a cold rolled condi
tion without further machining although appro
maximum to minimum or zero over a substantial '
priate heat treating to provide toughness is de
distance in adirection longitudinally of the shaft.
sirable. The bore in the member which the
Representative connections of this type are shown
shaft is to receive may be drilled and reamed
in Figures 9 and 10. The pressure may be made
by means of a shrink ?t of one of the parts which 55 or taper reamed as the case may be, after which
the parts are ready to be united.
is appropriately weakened from end to end so
Having described my invention, I claim:
1. A trailer vehicle comprising a frame, caster
wheels located at opposite sides of said frame,
engagement, or the connection may be made
through a relative taper of one member with 60 levers pivotally interconnecting said casters with
said frame for movement of the casters in a
respect to the other.
substantially vertical direction, and shaft means
The joints of both type provide pressure forces
in common torsional connection with said levers
which are distributed over a substantial distance
and responsive to vertical movement of either one
of the shaft as measured in its longitudinal direc
tion. Thus focal points at which high stresses 65 of said casters, for exerting a compensating effect
that the pressure with which it embraces its
mating element varies throughout the length of
are localized are not present in such structures.
According to the arrangement shown in Fig
me 10 there is a relatively slight taper between
the shaft and the bore which is to receive it, that
upon the other.
2. A trailer vehicle comprising a frame, caster
Wheels located at opposite sides of said frame,
levers pivotally interconnecting said casters with
is, the bore is slightly larger at its inward end 70 said frame for movement of the casters in a sub- '
stantially vertical direction, and shaft means
than at the outer end. The shaft itself is uni
common to said casters and constituting a shaft
form in diameter. Therefore, when the shaft is
subjected to torsion through movement of said
pressed into the tapered bore the pressure of
casters in a vertical direction.
»
engagement between the two increases gradually
3. A trailer vehicle comprising a frame, caster‘ V
toward the outer end of the shaft and is at a 75
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r 2,404,121?
7
wheels located at opposite . sides .of saidframe,
levers pivotally interconnecting said casters with’
said frame for movement of the casters-in a sub
stantially vertical direction, and shaft means in
terconnecting said casters at respectively oppo
site points thereon whereby‘ vertical movement of
the caster at one side of the vehicle effects'move
ment of the caster at the otherside of the vehicle
in an opposite direction torsionally through ‘said
8
1
by said forks, said shaftconstituting across con;
‘motion between said forks which is subject to
torsion when one of the caster wheels tends to
'move upwardly or downwardly independently of»,
the other.
5. In a trailer vehicle having a frame, levers,
in pairs respectively mounted upon said frame at
opposite sides thereof, forks respectively pivotally
connected to the free ends'of said levers whereby
shaft means.
said forks are mounted upon said frame for move
4. In a'trailer vehicle having a frame, a shaft
rotatably supported on said frame, levers;con—'
nected with said shaft at opposite sides of saidv
frame, forks respectively pivotally connected
with said levers, additional levers spaced from 15
the ?rst pivotally interconnecting said forks with
ment in vertical directions, one of the levers of
said frame and'casterziwheelsrotatably supported -
each pair being connected in common by a tor
sion shaft extending crosswisely between them,
whereby movement of one fork independently of
the‘other is controlled by said shaft. 7’ i
' '
JAMES LLBLACK.
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