Roller conveyor track

A roller conveyor track comprises a supporting structure in the form of a one-piece panel member providing a substantially flat surface from which U-shaped channels extend downwardly to accommodate rollers for movably supporting an article such as a freight container. The rollers project only slightly above the surface of the panel member. The rollers are rotatably carried by means of shaft portions at the ends thereof in snap-fitting mounting members which can be snap-fitted vertically downwardly into mounting openings in the side walls of the respective channel in the panel member.

BACKGROUND OF THE INVENTION 
Roller converor tracks are often used for example in freight loading 
systems in air freight traffic for conveying freight containers or other 
articles within the interior of the freight compartment of freight 
aircraft. Typically, a roller conveyor track which may be used in that 
situation comprises a plurality of rollers which are free-running and/or 
driven by an electric motor, disposed in succession at a spacing from each 
other in the direction of conveying movement, with their axes of rotation 
transverse relative to the direction of conveying movement. At least the 
free-running rollers are releasably mounted by means of shaft portions at 
the ends thereof, in openings provided in vertical side walls of an 
upwardly open channel configuration in a supporting structure. The 
supporting structure may comprise a plurality of upwardly open, U-shaped 
metal members which are anchored in mutually parallel relationship in the 
direction of conveying movement, to the bottom of the freight compartment. 
Provided in the side walls of the metal members and arranged in pairs in 
oppositely disposed relationship are rows of bores or holes in which the 
shaft portions on the conveyor rollers are suitably fixed. 
One possible form of the arrangement for fixing and mounting the conveyor 
rollers in such a roller conveyor track is to be found in German patent 
specification No. 3 210 204. As the two side walls of the U-shaped members 
are fixed at a spacing relative to each other, that arrangement provides 
that the shaft portions which project away from the two axial ends of each 
roller are arranged to be such that they can be pushed axially into the 
roller so that the roller can be fitted into the U-shaped member by 
retracting the shaft portions in that way, with the two shaft portions 
then being fixed in the respective holes for receiving same. Fixing of the 
respective rollers is effected by a procedure which provides that, after 
the shaft portions have been pushed in, the roller is firstly fitted into 
position between the two side walls of the U-shaped member, and then a 
screw bolt is inserted from the outside of the side wall, through the 
bore, and screwed into an axial screwthread in the corresponding shaft 
portion of the roller so that the shaft portion is drawn into the opening 
in the side wall of the U-shaped member, and fixed in position therein. 
A construction of that kind has a large number of mechanically movable 
components which are also of a really complicated configuration so that in 
general terms, besides a high level of manufacturing costs, that 
arrangement is also of a substantial weight which is a highly undesirable 
consideration, precisely in relation to use in an air freight system. In 
addition it is also essential that the outer side walls of the U-shaped 
members are kept freely accessible so that the rollers can be fitted or 
replaced by screwing the screw bolts in or releasing them, from the 
outside. 
The need for the outside walls of the U-shaped members to be kept freely 
accessible thus means that the roller conveyor track is of a design 
configuration in which the individual U-shaped members project upwardly 
from the floor of the freight compartment, which in itself is a flat 
floor, thus resulting in a floor surface which is so-to-speak cluttered up 
with impediments and obstacles, in the form of the U-shaped members. In 
addition, there is always the risk of damage to the individual roller 
tracks as they project upwardly from the floor of the freight compartment 
in a free-standing and thus essentially unprotected fashion. 
Entirely similar problems also arise in relation to drive roller units of 
such a roller conveyor track, which are provided at various points in the 
roller tracks, for driving the freight containers and the like which are 
to be conveyed thereon. 
SUMMARY OF THE INVENTION 
An object of the present invention is to provide a roller conveyor track 
which is of a simpler structure than previous such arrangements. 
Another object of the present invention is to provide a roller conveyor 
track which provides a greater degree of structural integrity. 
Still another object of the present invention is to provide a roller 
conveyor track which does not require a large number of mechanically 
movable components of complex configuration whereby the roller conveyor 
track can be produced at lower cost and at lower weight. 
A further object of the present invention is to provide a roller conveyor 
track which is of such a construction that components thereof can be more 
readily interchanged and replaced as required. 
Yet a further object of the present invention is to provide a roller 
conveyor track which has a substantially flat upwardly facing surface with 
support rollers projecting only slightly thereabove. 
In accordance with the invention these and other objects are achieved by a 
roller conveyor track comprising a plurality of rollers which are arranged 
in succession at spacings from each other in the direction of conveying 
movement on the conveyor track, with their axes of rotation disposed at 
least substantially tranversely with respect to the direction of conveying 
movement. The rollers include rollers which are driven by electric motor 
means as well as freerunning rollers. At least some of the rollers, 
preferably at least the free-running rollers, are releaseably mounted by 
means of shaft portions projecting axially away from the respective roller 
at the two end faces thereof, rotatably in openings in vertical side walls 
of an upwardly open channel configuration of a supporting structure, the 
side walls extending at a spacing from each other and at least 
substantially parallel to each other in the direction of conveying 
movement. The supporting structure comprises a panel means formed from 
plate material and including horizontal upper cover plate portions and at 
least one channel which is shaped to project downwardly therefrom and 
which is open to the plane of the cover plate portions. Mounting openings 
are provided in the side walls of the channel configurations, starting 
from the upper region of the side walls and extending beyond the 
connecting edge at which the respective side wall is connected to the 
adjoining cover plate portion. Snap-fitting mounting means of resiliently 
deformable material are provided to be inserted by a snap-fitting action 
into respective ones of the mounting openings. Each said holding means 
includes a horizontal bore which fits on to the respective shaft portion 
of a respective said roller, the mounting means being adapted to be fitted 
into the mounting openings in a downward direction from above the cover 
plate portions and the channel configuration. 
That roller conveyor track configuration in accordance with the invention 
therefore makes it possible for a roller to be fitted from above into the 
channel in the panel means, by virtue of the holding means which are 
fitted on to the shaft portions of the respective roller being suitably 
fitted downwardly into the respective mounting openings, without any need 
for the outsides of the side walls of the channels having to be kept 
accessible for assembly purposes. The panel means can therefore be 
provided with continuous cover plate portions thus generally providing a 
substantially flat and unencumbered freight compartment floor, above the 
top surface of which the rollers project only slightly. That arrangement 
not only substantially reduces the risk of damage and fouling under the 
rough conditions encountered in freight loading operations, but the 
arrangement of the invention also generally provides a design 
configuration which is very simple from a structural point of view and 
which involves a small number of components which in addition can be 
produced at an ecomonical level and which are of light weight. 
In a preferred feature of the invention, each snap-fitting mounting means 
provides a lower opening or recess which, in the fitted condition thereof, 
embraces the lower edge portion of a respective mounting opening on both 
sides thereof, and an upper opening or recess with a horizontal locking 
shoulder which, in the operation of fitting same into position, snaps 
lockingly under a rearward edge of the mounting opening in a said cover 
plate portion. That construction ensures that the snap-fitting mounting 
means fixes the roller shaft portion which is inserted therein not only in 
a vertical direction but also in both directions axially of the respective 
roller and in a direction transversely thereto, in the channel 
configuration of the panel means. 
A further preferred feature of the invention provides that the cover plate 
portions and the channel in the panel means are formed in one piece with 
each other, while preferably the horizontal cover plate portions form a 
substantially flat surface. 
In such a design configuration, it is particularly advantageous for the 
panel means to be formed from a composite material such as fiber 
reinforced plastic material. That not only provides a low level of 
manufacturing costs but also gives low weight which is an advantageous 
consideration precisely in connection with air freight traffic. 
The roller conveyor track in accordance with the invention also has rollers 
which are driven by electric motor means, for driving articles such as 
freight containers to be conveyed thereon, at various mounting locations 
in the channel configurations. Driven rollers of that nature may be fitted 
into the mounting openings in the same manner as the free-running support 
rollers referred to above, by means of corresponding snap-fitting mounting 
means. So that that can be achieved without the need to make the outward 
side walls of the channel configurations accessible from the outside, it 
may be provided in accordance with a further feature of the invention 
that, to provide for a supply of power to the driven rollers, conductor 
track bars are embedded insulatedly into at least one side wall of the 
channel configuration. The bars are exposed in the region beneath the 
mounting openings, towards the interior of the channel configuration, to 
constitute contact portions which co-operate with resilient contact means 
of a driven roller. That configuration makes it possible to fit the driven 
rollers at any desired mounting locations, to meet the individual 
requirements of any specific situation. It is only necessary for the shaft 
portions of the driven roller to be fitted into the appropriate 
snap-fitting mounting means and for the resulting assembly then to be 
fitted by a snap-engagement action into the respective mounting openings 
in the conveyor track structure. At the same time, that produces a 
conducting connection between the resilient contact portions of the driven 
roller in question, and the conductor track bars of the conveyor 
structure, to provide the supply of power to the driven rollers. 
A preferred embodiment of the track arrangement according to the invention 
provides that each snap-fitting mounting means has a hole or aperture 
which is accessible from above in the fitted condition thereof, for the 
insertion of a tool for releasing the locking engagement of the 
above-mentioned locking shoulder under the co-operating edge of the 
mounting opening, by producing resilient deformation of the body of the 
mounting means, so that the roller can be removed from the channel in an 
upward direction at any time. 
Further objects, features and advantages of the present invention will be 
apparent from the following description of a preferred embodiment thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring firstly to FIG. 1, shown therein in a somewhat simplified 
perspective view is a part of an embodiment of a roller conveyor track in 
accordance with the invention. The roller conveyor track comprises a 
support structure with which the roller conveyor track can be fixed in 
position for example on the floor of a freight compartment of an aircraft, 
the support structure comprising an elongate panel configuration which 
includes a plurality of cover plate portions 20a, 20b and 20c which are 
disposed horizontally in a plane. Formed between each two adjacent plate 
portions 20a through 20c in downwardly projecting relationship are 
U-shaped channels 10 which are open in an upward direction, with 
substantially vertical side walls 12 and a bottom wall 11 which connects 
the side walls 12 of each channel at the lower end thereof. In practical 
use the bottom walls 11 of the channels 10 rest on and are secured to the 
floor of the freight compartment. 
The entire panel structure 1 with plate portions 20a, 20b and 20c and the 
channels 10 which are matched to the practical requirements of any 
individual situation in regard to the number thereof and the relative 
spacing thereof is formed in one piece from a plate-like material 
comprising for example a composite material such as fiber-reinforced 
plastic material. 
Formed along the length of the channels 10 in pairs in oppositely disposed 
relationship and at spacings from each other in the longitudinal direction 
of each channel 10 are mounting openings or cut-outs as indicated at 20, 
the configuration of which can be clearly seen from FIG. 2. Referring 
therefore to FIG. 2, each mounting opening 40 comprises a generally 
rectangular aperture which begins in the upper region of the side wall of 
the respective channel 10, having a lower edge as indicated at 44. The 
aperture extends beyond the upper longitudinal edge of the side wall 12 
and thus into the adjacent plate portion as indicated at 20a in FIG. 2, 
terminating therein with a rearward edge 43. The mounting opening 40 is 
thus in the form of a generally rectangular opening which extends entirely 
through the material of the panel structure 1 and which extends beyond the 
edge at which the side wall 12 of a channel 10 and the adjacent plate 
portion 20a meet. The mounting openings 40 serve to accommodate the 
snap-fitting mounting members 50 which are described in greater detail 
hereinafter and in which individual rollers as indicated at 30 in FIG. 1 
of the conveyor track arrangement are mounted. 
Referring still to FIG. 1, also provided in side walls 12 of the channels 
10 at different locations are fixing holes 80 which are disposed in pairs 
and which serve for mounting clamps (not shown) by means of which articles 
such as freight containers can be fixed in position at a desired location 
on the roller conveyor track, once transportation movement thereof on the 
track has been concluded. 
In addition, disposed at spacings from each other along the side edge of 
the panel structure 1 which is shown at the right in FIG. 1 are a 
plurality of guide jaws 100 which serve to guide an article such as a 
freight container as it is conveyed along the conveyor track as well as 
for fixing the freight container in position in a lateral direction, in 
the condition of storage thereof on the conveyor track. The guide jaws 100 
are in the form of an inverted L-shaped member, with the free limb portion 
of the L-shape being intended to engage over a longitudinally extending 
flange portion which is in projecting relationship at the side edges of 
the bottom of each of the freight containers. 
The individual rollers of the conveyor track are of a conventional 
construction for example in the form of free-running support rollers. As 
shown in FIG. 4, they comprise a generally hollow cylindrical roller body 
32 having rolling bearing assemblies (not shown) disposed in concentric 
relationship in the two axially facing end surfaces of the roller body. 
The inner bearing race of each rolling bearing assembly is provided with 
an axially outwardly projecting bearing shoulder or collar as indicated at 
33 in FIG. 4, and is carried on a shaft portion 34 which also projects 
radially outwardly from the roller body. The above-indicated arrangement 
of each rolling bearing assembly provides that the roller body 32 is 
freely rotatable relative to the shaft portion 34, while the shoulder or 
collar 33 ensures that the roller body 32 is held at a suitable spacing 
relative to the adjacent supporting structure, in that case the side wall 
12 of a channel as indicated at 10. 
Instead of a free-running support roller of that kind, individual locations 
at which rollers are provided in the roller conveyor track may be 
provided, as necessary according to the requirements of any individual 
situation, with a respective drive roller unit which is adapted to be 
driven for example by means of an electric motor and which is externally 
the same in terms of its dimensions to a free-running support roller but 
which includes a mechanism for driving the roller, serving to convey a 
freight container on the roller conveyor track. Drive roller units of that 
kind are described in greater detail in co-pending application U.S. Ser. 
No. 160,427, filed Feb. 25, 1988 the content of which is thereby 
incorporated by reference thereto. 
As already mentioned, the individual rollers 30 are mounted by means of 
snap-fitting mounting members 50 in the mounting openings 40 in the panel 
structure 1. 
Referring now to FIGS. 3 through 5, a mounting member 50 of that nature has 
a body 51 which is of a cross-section such as to taper inwardly in a 
downward direction as viewed in for example FIG. 3, thus providing a 
generally wedge-shaped member, through the associated axis of rotation of 
a roller 50. In the lower portion of the vertical side of the body 51 
which is towards the roller 50, the body 51 has a generally annular 
projection as indicated at 52 for example in FIG. 3. Formed in the region 
of the projection 52 and within same is a large-diameter bore 54 which is 
adjoined inwardly of the body 51 and in concentric relationship by a 
smaller-diameter bore as indicated at 53 which in the illustrated 
embodiment terminates as a blind bore. The larger-diameter bore 54 is 
approximately matched in terms of depth and diameter to the mounting 
shoulder or collar 33 on the roller 30 while the smaller-diameter bore 53 
approximately corresponds in respect of depth and diameter to the free 
projecting part of the shaft portion 34 of the roller 30. As can be seen 
from FIGS. 4 and 5, in the lower part, under the bores 53 and 54, each 
mounting member 50 has a lower recess or groove which extends transversely 
with respect to the bores 53 and 54 and which is of rectangular 
cross-section, the configuration of the recess or groove 58 being adapted 
to the configuration of the lower edge 44 of the mounting opening 40 so 
that in the fitted condition of the mounting member 50, the recess or 
groove 58 embraces the edge 44. 
Formed in the upper edge of the tapered body 51, which is remote from the 
annular projection 52, is an upper recess as indicated at 55 in FIG. 3, 
which is defined by a vertical surface indicated at 57 in FIG. 5 and a 
horizontal surface indicated at 56, thus forming a locking shoulder 
co-operable with the rearward edge 43 of the respective mounting opening 
40. 
The entire mounting member 50 is made in one piece as by molding and 
comprises a resiliently deformable material, for example a plastic 
material. 
For the purposes of fitting and mounting a roller 50 in a channel 10 in the 
panel structure 1, a mounting member 50 is firstly fitted on to one of the 
two shaft portions 34 of the respective roller 30 in such a way that the 
shaft portion 34 in question is accommodated in the smaller-diameter bore 
53 while the mounting shoulder or collar 33 extends into the 
larger-diameter bore 54. The roller 30 with two mounting members 50 fitted 
thereon in the above-described manner is introduced downwardly into the 
channel 10 in such a way that the two mounting members 50 pass with their 
tapered end downwardly into the two mutually oppositely disposed mounting 
openings 40 in the channel 10. By applying a vertical force in a downward 
direction the outer inclined surfaces of the tapered body 51 of the 
respective mounting members 50 slide along against the rearward edge 43 of 
each mounting opening 40, with the tapered body 51 being resiliently bent 
towards the roller in the upper region thereof, in the manner shown for 
example in FIG. 5. Finally, that fitting movement causes the lower recess 
or groove 58 of the body 51 to embrace the lower edge 44 of the mounting 
opening 40, while the locking shoulder 56 defined by the upper recess 55 
engages under the underside of the edge 43 of the opening 40 so that it 
snaps into position under that edge 43, due to the resiliency of the body 
50 which has been deformed towards the roller 30, as indicated above. In 
that condition, the mounting member 50 and therewith also the roller 30 
carried thereby are fixed in position in the radial direction relative to 
the axis of rotation of the roller by virtue of the lower recess 58 and 
also in a vertical direction upwardly by the locking shoulder 56, and 
finally, in the direction of the channels 10, by the vertical side walls 
of the mounting opening 40 which are disposed with a slight clearance 
against the corresponding side surfaces of the mounting member 50. 
To release the mounting member 50 and to remove the roller 30 from the 
channel, the mounting member 50 has a blind hole 66 which is formed in the 
upper part thereof and which is exposed in the upper horizontal surface of 
the mounting member 50, in the fitted condition thereof, as can be most 
clearly seen from FIG. 4. FIG. 5 shows that the hole 66 is intended to 
accommodate a suitable tool 99 with which the body of the mounting member 
50 can be resiliently bent in its upper region towards the roller 30 in 
such a way that the locking shoulder 56 comes free from its position of 
engagement against the underside of the rearward edge 43 of the mounting 
opening 40 so that the roller can be drawn upwardly out of the channel 10, 
together with the two mounting members 50 which carry it. 
In that way individual rollers can be easily replaced, for example for the 
purposes of maintenance of in the event of damage thereto, or can be 
exchanged for drive roller units. That means that the roller conveyor 
track in accordance with the invention may be adapted to the requirements 
of any individual situation at any time without involving a substantial 
amount of work. 
As can be seen in particular from FIGS. 2 and 6, conductor track bars 90 
which extend in mutually parallel relationship in the longitudinal 
direction of the roller conveyor track and which comprise electrically 
conductive material are insulatedly embedded in a side wall of a channel 
10. The bars 90 serve to supply power to driven drive roller units, as 
described in greater detail in the above-mentioned co-pending application. 
The bars 90 extend over the major part of their length within the material 
of the respective side wall 12, as shown in FIG. 6, so that in that region 
they are embedded in a completely insulated fashion. It is only in the 
region beneath each mounting opening 40 that the bars 90 are brought out 
to the interior of the respective passage 10 so that the surface of the 
respective bars 90 is exposed in an un-insulated condition at that 
location, constituting contact portions 91. When a drive roller unit of 
the above-indicated kind is fitted into position at the corresponding 
roller mounting location, resiliently biased contact portions which are 
carried by the drive roller unit come to bear against the contact portions 
91 so that the drive roller unit is readily electrically connected to the 
power supply through the bars 90, in the operation of fitting the drive 
roller unit into position. In that way free-running support rollers and 
drive roller units may be fitted at any appropriate locations in the 
roller conveyor track in accordance with the invention, without involving 
electrical connecting operations to provide for the supply of power to the 
driven rollers. 
It will be appreciated that the above-described arrangement has been set 
forth solely by way of example and illustration of the present invention 
and that various modifications and alterations may be made therein without 
thereby departing from the spirit and scope thereof.