Note: Descriptions are shown in the official language in which they were submitted.
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The present inv~ntion relates to a con~eyor system of the type
comprising an overhead guiding rail supporting a number of driving units each
provided with a driving motor so as to be movable along the rail with means for
holding one end of a depending pulling rod operable to be connected with a load
carrier for driving the carrier along the path of the rail, and for a driving
unit for use in such a system.
Conveyor sys~ems of this type are used for driving a number of load
carriers along the path of the rail in order to move goods from one position
to another, e.g. in freight terminals. Normally the load carriers are floor
supported carts having a handle rod which can be hooked into and out of engage-
ment with the lower end of a pulling rod extending downwardly from each
driving member. However, in some systems the pulling rod hangs down from the
driving units so as to carry a hanging load. The self propelled driving units
include an elec~ric motor energized through a contact rail arrangement. This
motor operates under varying load conditions, from driving its associated driv-
ing unit idly to pulling a heavily loaded carrier and even pulling it along an
upwardly inclined path.
The mo~or and the driving wheel arrangement, of course, should be
designed so as to be operative at maximum load conditions, this involving a irm
frictional engagement between the driving wheel and the rail. Preferably the
driving units should be as light as possible, so normally the weight of the
driving unit is not sufficient to provide the necessary firm engagement. Con-
ven*ionally, therefore, the driving units are provided with counter pressure
wheels, and a spring arrangement is interposed between these wheels and the
driving wheels so as to urge the driving wheel against the rail with increased
force for providing the necessary friction there~etween. However, the fric-
tional engagement thus being permanently adapted to maximum load conditions,
this will involve a mechanical construction which is in fact amply dimensioned,
since maximum loaded conditions are normally encountered only sporadically.
Also the friction between the driving unit and the rail will be kept at a con-
stantly high level.
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It is the purpose of this invention to provide a driving unit and a
conveyor system of the ~ype referred to in which th~ describ~d disadvantages arecounteracted or eliminat~d.
According to the invention t~ere is provided a self propelled driving
unit for a conveyor system wherein, in ope:ration, self-propelled driving units
run along an overhead traction rail to transport loads either slung beneath
or towed by the driving units; said driving unit comprising a wheeled carriage
adapted to run along the rail and having wheels adapted to roll agains~ opposed
surfaces o~ the rail~ one of the carriage wheels constituting a traction wheel
for driving the carriage by frictional engagement with the rail and being
coupled with a prime mover to be rotated thereby~ and one of the carriage
wheels being mounted on a lever arm which is pivotally connec~ed to the carriage,
such as to be movable bodily relative to the carriage and mechanism serving
for the attachment of a load to the driving unit, said mechanism being coupled
with said lever arm and being operative to transmit the pull of the load to the
lever arm to urge said wheels, against the rail thereby to produce a contact
pressure between the traction wheel of the carriage and the rail which is depen-dent upon the magni~ude of the load, and said mechanism including means to
transmit to the lever arm components of said pull directed both normal to and
parallel to said rail.
It will be appreciated that in such a system the actual force of
engagement between the wheels and the rail will automatically adjust itself so
as to be low when no very firm frictional engagement is required and high only
when required, as determined by the pull or drag acting on the driving unit
through the pulling rod. Springs or other permanent sources of high clamping
forces can be entirely avoided so as to enable a simple construction of the
driving unit.
In the following the invention is described in more detail with refer-
ence to the accompanying drawing, in which:-
Figure 1 is a side view of a portion of a conveyor system according
to the invention,
Figure 2 is a perspec~ive view of a driving unit and the rail means,
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Figure 3 is a cross sectional v~ew thereof,
Figure 4 is a more detailed side v:lew o~ the dr~vlng ~mlt?
Figure 5 is a corresponding view o:~ a modified embodiment of the
driving unit, and
Figure 6 i5 a view corresponding to Figure 5, but showing the drlving
unit assuming an incllned positlon.
The system illustrated in Figures 1-4 comprises a rail 2 mounted under
the ceiling and serving to support a number of driving units 4 each provided
with a depending pulling rod 6 the lower end of which is connectable to the
outer end of a handle rod 8 of a load carrier cart 10 adapted to roll along
the floor. The pulling rods 6 are normally spring loaded so as to swlng
upwardly when they are not actually
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coupled together with a handle rod 8~ The rail 2 is made o~
profiled plate material which is self carrying between su-
spensiQn brackets secured to the ceiling. In the embodiment
shown the plate rail 2 is generally of inverted U cross sect-
ion, and the lower side portions thereo are profiled so as
to ha~e inwardly protruding box flanges 10 each having a top
side 12 and a bottom side 14. Preferably the rail side port-
ions are extended further downwardly at 16 and provided with
inwardly protruding bottom flanges 180 The interior vertical
surfaces of the box flanges 10 are designated 20a The flange
top sides 12 constitute the surfaces on which the driving
units are rollingly supported~ as described in more detail
below. In operation the dri~in~ units will be practically .
~otally enclosed within the plate rail, iOe. they are to~a
large degree protected from dust, and beside~ the entire rail .
system will have a very "clean" app2arance, also because the
current rails for energizing the driving motors may be mount-
ed inside the hollow rail, preferably underneath the ceilin~
thereof as shown at 22~ whereby the current rails are mounted
-20 or placed in a highly protected manner. The rail is o~ course
usable also in a complex system including rail junctions and
rail switch controlled rail branchings~
~ t intervals the rail is secured to suspension brackets
24 each comprising ~ top piece 26 connected to the ceiling in
any suitable manner and a pair of side pieces 28 made of flat
iron bent according to the main shape of the rail sides and
having a reinforcing flange 30. The flat iron 28 is secured
to the plate rail side by means of bolts 32,
The rail 2 holds a number of driving units of which one
is shown in fiys. 1-4. It comprises an elongated base chassis
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34 which is situated in the space betw~en the lower rail ~ide
portions 16 and provided wi.th an upstanding post 36 to the
upper end of which ther~ is pivotally secured one end of an
elongated upper chassis portion 38~ the other end of which
is pivotally secured to a vertical lever 40 to be described
in more detail below. On the upper chassis portion 38 is
mount~d a gear box 42 associated with an electric driving
motor 4a and having a crosswise arranged dri~ing sha~t 46
provided with a driving wheel 48 at either end thereo~ These
.
opposed driving wheels and therewith the entire driving unit
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are carried on the respëctive opposed top side portions o
the box ~langes 10 wi~h whic~~they are in ~rictional driving
engagement~ ~ ~~~
The base chassis 34 is provided with two upstanding rol-
- lers 50 generally or almost filling out the cross sectional
space ~etween the opposed slde wall portions 20 of the box
flanges 10 so as to act as guiding rollers guiding the driv-
ing unit longitudinally along the railO Moreover, the base
chassis 34 is provided with laterally arrang~d rollers 52
projecting under the bottom surfaces 14 of the box flanges 10
and rollingly enga~ing these surfaces so as to constitute
counter pressure wheeIs for the driving wheels 48.
The lever 40 extends ~rom the upper chassis 38 downwardly
~hrough a recess 54 in the Iower chassis, and at its lower
end it is connected to a bracket 56 to which the top end o~
the pulling rod 6 is pivotally secured. Preferably a hinge
58 ls interposed~between the elements 40 and 56 in order to
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allow ~or a limited transverse pivotin~ of the bracket 56~
On the upper chassis may be mounted a control box shown in
dotted lines at 60 and serving to house various control ele-
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ments and circuits such as destination code responsive motor
switch meansJ which7 however, shall need no further descript-
ion in the pr~sent connection. The box 60 may be provided with
upper sliding shoes 62 (see fig~ 3) engaging the current rails
64 and with a control signa1 transmitter and receiver unit
which is moved along a control rail 66 with which it communi-
cates in any convenient manner in order to be able to r~ceive
start/stop signals and to transmit eOgO rail switch actuating
signals for automatic operation.
The weight distribution about th~ transverse line of
engagement between the driving wheels 48 and the rail surface
portions 1~ is such that the upper chassis 38 tends to tilt
abo~t this line so as to lit the post 36 and therewith the
entire lower chassis 7~ whereby the counter pressure wheels 52
engage the rail surface portions 14 with an up~ard pressure,
which is only small as long as the driving unit is unloadedO
~en the pulling rod 6 is engaged to a cart and the driving
unit is started the pull transferred to the lever 40 will serve
to increase the force with which the post 36 and therewith the
wheels 52 are urged upwardly, or correspondingly the force
with which the driving wheels 4~ are urged downwardly, whereby
the frictional engagement between the wheels 48 and the rail
will increase~ .
The pulling direction being inclined, only the vextical
component of the pull will be active for producing the sai~
increas~ of the pressure of the driving wheels against the
railO As shown in fig. 4, however, the driving unit is pro-
vided with means for converting the horizontal component of
the pull into a downwardly directed force on the lever 40,
these means comprising a pin or roller 68 mounted on a side
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portion of the lever 40 and a block element 70 secured to
the lower chassis 34 inside the rocess 54 so as to have its
inir~lined front end 72 situated ~ust above the pin or roller
:~,
It will be understood that the ~orizontal component of
a counter traction pull in the pulling rod 6 will cause the
pin or roller 68 to be urged horizontally against the inclined
cam surface 72 of the block 70, whereby the lever 40 will be
urged correspondingly downwardly and thus contribute substan-
tially to th~ desired increase of the said frictional driving
engagement in response to the pulling *orce being increased.
As shown in ~ig. 4 another block member 74 is mounted
i~ front of the pin or roller 68 so as to have an inclined
cam surface portion 76 situated just abo~e the pin or roller
68 opposite to the cam portion 720 This arrangement shows the
important effect that the lever 40 will be drawn downwardly
also in response to a push being transferred through the
pulling~rod such as can be actual by a sudden stop~of the
driving unit or when the cart is moved along a downwardly
sloping floor portionO In these cases the motor 44 will act
as a positive braking device when the driving wheels 48 do
not slide along the rall, and the increased wheel friction
caused by the pin or roller 68 engaging the cam sur~ace 76
will thus secure a good braking effect~
Fig. 5 shows a modified embodiment in which the means
~or converting a horizontal pull or push in the lever 40 into
a vertical force are inverted of those shown in figO 4, viz~
comprising a cam member 68' mounted on the lever 40 and a pair
of pin~ or rollers 72' and 76' mounted in the recess 54.
The embodiment of figO 5 is used in fig. 6 for showing
that the invention is applicable also to conveyor systems in
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which the driving units are ~dapted to con~ey hanglng loads, In such systems,
of course, there are no problems. as to the ~rictional driving engagement
during movement in the horizontal direction, but the problems occur should
the driving unit move along upwardly or downwardly sloping rail sections, As
illustrated in Figure 6, however, tKe pull exerted by a load hanging in the
rod 6 will cause the lever 40 to be subjected to a pulling force component
parallel to the moving direction of the driving unit, whereby an increased
frictional driving engagement will be automatically obtained in the same
manner as described in connection with Figures 4 and 5, Correspondingly the
frictional braking engagement will be increased when the driving unit moves
through a downwardly sloping path.
The invention is not limited to the embodiments shown, since it will
be obvious that many modifications will be possible within the scope of the
invention in order to obtain the self adjusting clamping force between the
driving wheels and the rail, Thus, the driving wheels and the counter pres-
sure wheels should be urged away from each other if they are arranged so as
to engage with interfacing surface portions of the rail,
It will be understood that in the embodiments of Figures 1 - 5 the
desired amplification of the frictional engagement between the driving wheel
and the rail in response to an increased pull in the pulling rod is obtainable
already by virtue of the vertical force component in the member 40, since the
horizontal distance between the member 40 and the post 36 is larger than the
distance between the engagement point of the driving wheel 48 and the post 36.
A very high force amplification will be obtained if the wheel 48 is mounted
very close to the post 36, but in practice this arrangement requires that the
thickness of the rail should be extremely uniform throughout the length there-
of, as otherwise the upper chassis 38 and therewith the member 4 and the rod
6 would oscillate violently up and down, Placing the driving wheel 48 a
greater distance from the post 36 involves a reduced force amplification, but
this reduction is compensated for by means of the particular force converter
arrangement enabling also the hori~ontal force component to contribute to the
clamping force, and then the almost inevitable thickness variations of the
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rail become less criticall The said converter arrangèment, of course, is
especially important for causlng a braking action in case of a push being
transferred to the member 40 through the pulling rod 6,
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