X-ray device for checking the contents of closed cargo carriers

An x-ray examination device for checking the contents of closed cargo carriers having two steerable single-track carriages disposed parallel to each other, wherein the carriages each support a vertical column. The free ends of the columns are connected to each other by means of a yoke spanning the space between the carriages, which corresponds to the maximal possible width of the cargo containers. The yoke can be raised and lowered on the two columns. Cantilevers are aligned horizontally, and parallel relative to each other, and are arranged on the yoke. The free ends of the cantilevers support a cross bar. Connected to one end of the cross bar are supports for supporting the x-ray equipment. The x-ray equipment includes an x-ray emitter and an x-ray receiver. Moreover, one or more screen vehicles having leaded mesh screens for surrounding the cargo containers are provided to shield against harmful x-rays outside the cargo container area.

BACKGROUND OF THE INVENTION 
Field of the Invention 
The invention relates to a device for checking the content of closed cargo 
carriers or containers, through use of x-rays. 
SUMMARY OF THE INVENTION 
The present invention provides a device for x-raying containers, which is 
capable of traveling along the parked containers at their storage site. 
These containers are stacked one on top of each other. The x-ray device is 
designed to drive past these containers while checking their contents. 
In the invention, two steerable single track carriages are disposed in 
parallel with each other, each supporting a vertical column. The free ends 
of the columns are connected to each other by means of a yoke spanning the 
spacing between the carriages. This spacing corresponds with at least the 
maximal possible width of each container, whereby the yoke is guided on 
two columns in such a way that it can be raised and lowered. In addition, 
supporting elements for a cross bar are arranged on the yoke, wherein the 
cross bar bridges the space between the carriages. The cross bar has x-ray 
equipment supports on the end sides. These supports allow an x-ray 
apparatus in the form of radiation source on one side, and an x-ray 
receiving screen attached to the other side. 
The device is capable of traveling along rows of stored and stacked 
containers like a gantry crane, typically used for handling the 
transloading containers. The carriages are driven along both sides of a 
container, or a stack of containers, and the yoke is guided across the top 
side of these containers. Two columns are each arranged in the center of 
their associated carriages and carry the supporting elements for 
supporting the cross bar. The cross bar contains the supports for carrying 
the components of the x-ray machine. 
Each column consists of a fixed segment, and at least one displaceable 
segment. The displaceable segment can extend longitudinally on the fixed 
segment like a telescope, whereby the displaceable segments of the two 
columns are connected to each other by the yoke. The height of the yoke 
can be adjusted by longitudinally extending the sliding displaceable 
segments relative to the fixed segments. Because these segments are 
longitudinally displaceable, they can be used to guide the x-ray equipment 
supports along the vertical expanse of one or a plurality of containers. 
The movability of the entire device allows it to be driven with the x-ray 
machine along the containers in a longitudinal direction. 
The supports carrying the components of the x-ray equipment can be lowered 
by longitudinally displacing the sliding segments of the columns. This is 
necessary because containers are deposited, in most cases, on the ground 
of the storage site on which the device is driven. The ground clearance 
required for the carriages limit the downward travel of the displaceable 
segments and consequently also the extent to which the supports of the 
x-ray equipment can be lowered in the direction of the ground. This is 
because the displaceable segments are normally downwardly extendible only 
to the footing of the fixed segments. 
To increase the displacement distance of the displaceable segment towards 
the ground, each carriage is designed so that the surface of each of the 
displaceable segments is capable of extending over the carriage. These 
ends have release mechanisms on both sides. 
To make the carriage sufficiently stiff so that it will hold its track when 
driven, each column has a rectangular shape, whereby the longitudinal 
sides of the column sections are aligned parallel with the longitudinal 
axis of the carriages. The displaceable segments are designed to slide 
along with the fixed segments. In one embodiment, the displaceable 
segments can be designed as rectangular sections dimensioned to 
accommodate the fixed segments within themselves. In another embodiment, 
the inner surface of each displaceable segment is guided on the outer 
surface of each fixed segment with sliding and guiding elements. 
The supporting elements are arranged on the yoke. However, the supporting 
elements could be arranged also on the displaceable segments. 
Using larger track widths of the device, it is possible to bring the cross 
bar close to the columns. In this case, the cantilever supports 
representing relatively short lever arms can be mounted on the columns 
through the support elements. However, if the track width of the device is 
rather narrow and extends only slightly beyond the width of the container, 
additional projecting support elements are required. The components of the 
x-ray equipment, namely the emitter and the receiver, must have a 
predetermined spacing between each other, so that the range of the x-rays 
can fan out adequately. If the spacing between the components of the x-ray 
machine requires certain projections beyond the track width, then the 
cantilevers can extend behind one end of the device. In this way, the 
supporting elements are aligned substantially horizontal and parallel, 
relative to each other and hold the components of the x-ray equipment so 
that they are disposed behind one end of the device. Therefore, the x-ray 
equipment can be placed practically behind or in front of the carriages, 
depending on the driving direction. In this way the x-ray equipment does 
not need to project beyond the track width. 
Furthermore, if the operator is positioned at the opposite end of the 
device, he minimizes his risk of exposure by outstretching the 
cantilevers. As the cantilevers project outwardly bending moments can 
occur. To counteract these forces, platforms can be arranged on the yoke 
on the side facing away from the cantilevers. In addition, the platforms 
can support the operating controls, the control or power supply of the 
x-ray apparatus, and an operator's cabin. Such devices on the platforms 
form a counterweight for the cantilevers, so that there are little 
unilateral bending stresses on the columns. 
Each cantilever is designed in the form of a rod to reduce the weight of 
the cantilevers, and to obtain an adequately stiff steel construction. The 
crossbeam with the x-ray equipment supports is rotatably supported on the 
supporting elements, on the points of the cantilevers, turning around a 
horizontal axle. In this way, the center of gravity of both the x-ray 
equipment supports, and the x-ray equipment is disposed behind the free 
ends of the supporting elements, spaced away from the axis of rotation. 
It is advantageous to provide at least one support counteracting rotation 
relative to the associated column or to the yoke. A vibration damper, or a 
damping element can then be integrated in this support, so that the x-ray 
machine is prevented from swinging due to acceleration forces. The support 
may comprise at least one connecting bar to connect with the associated 
column or yoke, with the connecting bar having at least one damping 
element, and being under tensile load when rotating. 
Each supporting element, and in particular, each cantilever may be formed 
by a rod with joint elements. Such a rod is equipped with operating 
cylinders permitting forced rotation the x-ray equipment supports around 
the axis of rotation. The components of the x-ray equipment could be 
driven into predetermined positions with the help of controlling and 
adjusting elements by extending or retracting the operating cylinders or a 
driving means. 
The rod mechanism for a cantilever can be designed similar to a 
parallelogram steering linkage. In this case, the x-ray equipment carrier 
or support can be adjusted relative to the column, parallel with the 
longitudinal direction of the carrier. 
One advantage of the device is that the assemblies and components can be 
mounted or dismantled in a quick and simple way, which facilitates the 
shipping of individual parts. The assemblies are, for example, the 
columns, the carriages, the yoke, and the cantilevers. 
A screening system is used to prevent scattered x-rays when the device is 
in operation. This screening system covers predetermined areas of a 
container on both sides of the plane of radiation. The plane of radiation 
extends between the emitter and the receiver of the x-ray apparatus, or 
within the cone of x-rays formed when the radiation energy fans out from 
the emitter. For example, the screening device may be a hood, which can be 
put over a container. The hood has a gap corresponding with the plane or 
cone of radiation, so that there is free passage of the rays within the 
zone of the gap. 
The hood is designed in the form of a tunnel-shaped hood, so that it can be 
moved together with the device across a container. The walls of each 
tunnel-shaped hood consist of a screening material in the form of plates, 
mats or the like that are preferably made of lead. 
Each screening device is equipped with carriages. It can be driven 
separately or jointly with the device when the latter is in operation. 
Each screening device can be designed in the form of a self-propelled 
system with its own drive and its own steering. However, it is possible 
that the screening device may consist of a number of tunnel hoods coupled 
together, that are pulled along by the device when it travels along a 
container. However, engineering problems can arise if the device is 
designed so that it can support the heavyweight screening devices, since 
the screens may comprise several tons of lead. It is advantageous if the 
screening device is designed in the form of a so-called self-propelled 
system. 
A synchronization system can be incorporated into the invention to 
coordinate drives and controls or steering systems of the screening 
device, or of individual tunnel hoods, so that there is a completely 
uniform driving mode of all carriages. The individual tunnel hoods can be 
synchronized to drive uniformly, so that their driving motion is 
completely synchronized with the driving mode of the device carrying the 
x-ray equipment. 
To enhance the screening effect, the walls of each tunnel hood extend 
downwardly by means of screening aprons on the side of the tunnel hood 
facing the receiving screen of the x-ray apparatus. These aprons assure 
that a screening effect is obtained also within the zone of the "ground 
clearance" required for driving. This zone is between the carriages, which 
is limited at the bottom by the surface of the driving lane (ground), and 
at the top, by the lower edge of the respective wall of a tunnel hood. 
The invention can also contain an actuating device for aprons designed like 
Venetian blinds, wherein the aprons can be moved in pre-determinable 
screening positions. For example, each apron can be guided with vertical 
mobility in suitable guides on a tunnel hood, whereby there is at least 
one drive for the sliding movement along the guides. Each apron may be a 
plate made of screening material, for example lead, and can be raised or 
lowered in suitable lateral guides. Each drive can be an operating 
cylinder. However, other types of drives are also possible, for example 
hoists with toothed racks, ropes, sprocket chains, etc. 
The cone of radiation or radiation plane present during operation between 
the emitter and the receiver of the x-ray apparatus extends through a 
corresponding slot in the screening device. The slot is formed by a 
separation joint between two tunnel hoods driving in "tandem", one after 
the other. The occurrence of scattered x-ray is the greatest in zones 
adjacent to the separation joints, where an adequately safe screening 
effect is required. For this reason, the greatest thickness of the 
screening material is provided in these zones. The increase in weight 
caused by this material accumulation requires a corresponding increase in 
load capacity of the carriages. Twin wheels mounted on one axle would be 
sufficient to increase the load capacity. However, in this design an 
undesirable result is that the track width of these carriages would be 
reduced by these wheels. Therefore, the carriage of each tunnel hood has 
multiple-axles within the zone where the device's own weight is the 
highest.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to FIG. 1 there is shown a single-track carriage 1 comprising an 
carriage support 2, which has a dropped center, and includes a pair of 
front wheels 3, and rear wheels 4. A driver's cabin 5, is disposed in the 
front of carriage support 2, and located on the front side of device 100. 
A vertical column 6 is arranged in the center of carriage support 2, and 
consists of an inner fixed segment 7, that is connected on the floor of 
carriage 2, and includes an outer displaceable segment 8. In this case, 
fixed segment 7 accommodates displaceable segment 8 which is guided in the 
longitudinal direction of fixed segment 7 through a driving means. 
A cantilever 9, serving as a support element, is designed as a rod as shown 
by rods 10 and 11. The free end of cantilever 9, supports a cross bar 12 
for arranging the components of an x-ray apparatus. The x-ray apparatus 
includes radiation source 13, on one side, and receiving screen 24 on the 
other side, (See FIG. 4). 
Cross bar 12 is rotatably supported on an end point of cantilevers 9, and 
rotates around a horizontal axle 15. In addition, there is at least one 
connecting bar 16 connected with associated column 6. This connecting bar 
is subjected to tensile stress when rotating. Connecting bar 16 may be 
equipped with a damping element 17. 
On the side opposite cantilever 9 is platform 18 projecting from column 6. 
Platform 18 carries equipment 19 comprising the operating controls, and 
the control or power supply for the x-ray apparatus. In addition, the 
operator's cabin 20 is located on platform 18. 
Driver's cabin 5 can be omitted and may be integrated in operator's cabin 
20, or vice versa, while operator's cabin 20 may be integrated in driver's 
cabin 5. 
FIG. 2 shows device 100 according to FIG. 1 in an operating position, in 
which displaceable segment 8 of column 6 is extended upwardly relative to 
fixed segment 7. The outlines of the two stacked containers 14, and 14', 
are indicated by dash-dotted lines. In this operating position, the x-ray 
equipment, as shown by radiation source 13, can be driven also along top 
container 14'. 
FIG. 3 shows a front view of device 100 according to FIG. 2, wherein the 
free ends of columns 6 and 6' are connected to each other by means of a 
yoke 21 bridging or spanning the space between carriages 1 and 1'. In this 
case, the spacing approximately corresponds with the maximum possible 
width of a container 14 or 14'. 
FIG. 4 is a rear side view of device 100 opposite driver's cabin 5. In FIG. 
4, a cross bar 12 is connected to x-ray equipment supports 22, and 23. 
Support 22 supports radiation source 13 on one side of device 100 and 
support 23 supports receiving screen 24 on the other side. The fanned-out 
beam emitted by radiation source 13 is indicated by dash-dotted lines 25. 
FIG. 5 shows an additional embodiment of cantilever 9 with x-ray equipment 
support 22 on cross bar 12. In this embodiment, the rod mechanism 
comprises a lower guide rod 26 as well as an upper guide rod 27. With 
their articulation points on a head 28 holding cross bar 12, these guide 
rods form a parallelogram. Upper guide rod 27 is equipped with a damping 
element 17. A diagonal rod 29 is designed in the form of an operating 
cylinder, so that by actuating both the detecting damping device and the 
operating cylinder of diagonal rod 29, x-ray equipment support 22 can be 
both swivelled, and raised and lowered in the directions of the double 
arrows shown in FIG. 5. 
FIG. 6 shows a schematic front view of an additional embodiment of device 
100. In this embodiment two carriages 1, and 1' with columns 6, and 6' and 
top yoke 21 connect the columns and form a carriage designed similar to a 
gantry crane. In front of yoke 21, cross bar 12 is supported by supporting 
elements 30 and 30' (FIG. 7) and project out from the plane of the 
drawing. On the left side of FIG. 6, x-ray equipment support 22 is 
connected at its top end to cross bar 12 and to radiation source 13 at its 
bottom end. The right side of FIG. 6 shows the section of cross bar 12 
facing supporting element 30, and has the x-ray equipment support 
(carrier) 23. Support carrier 23 is substantially shortened in this 
embodiment as compared to the design in FIG. 4. Receiving screen 24 of the 
x-ray machine is mounted on a flanged surface on equipment support 23. The 
range of the radiation cone or radiation plane emitted by the radiation 
source is indicated by dash-dotted lines 25. 
Because of the increased track width of device 100, a screening device 31 
can drive under the gantry-type carriage formed by yoke 21, columns 6, and 
6' and carriages 1, and 1'. 
Screening device 31 comprises one or a plurality of tunnel hoods 32, and 
32' (FIG. 7) covering one or a plurality of containers 14, 14'. The walls 
of these tunnel hoods are in areas provided with linings made of material 
screening x-rays. In FIG. 6, tunnel hood 32 is outlined by dash-dotted 
lines 35 indicating its left side wall 33, right side wall 34, and upper 
cover wall 35. Lead in the form of plates, mats or the like can be used as 
a screening material. 
The dead weight of lead screening device 31 is considerably high. 
Therefore, to reduce the weight on carriages 1 and 1', the screening 
device 31 is made free standing, and is equipped with separate 
under-carriages 111 and 111'. This means that each screening device 31 is 
a self-propelled device with its own drive and separate controls. The 
invention also contains a device located with components 19 and with 
screening device 31 for synchronizing the driving modes of device 100 and 
screening devices 31. Therefore with the use of a cable or by radio 
control screening device 31 can be driven in sync and in parallel with 
device 100. FIG. 6 indicates that device 100 and tunnel hoods 32, 32' of 
screening device 31 drive along container 14 in the longitudinal 
direction. 
The lower wall areas of each tunnel hood are formed by walls 33, 34, 35 
that are disposed directly adjacent to receiving screen 24 of the x-ray 
apparatus, and are extendible by means of vertically movable screening 
aprons 36. Each apron 36 is formed by a plate 37, 37' guided in vertical 
guides. A drive for sliding motion along the guides is associated with 
each apron 36. FIG. 6 shows a downwardly lowered apron 37 and an apron 37' 
raised into the driving position. Operating cylinders can serve as drives 
to raise and lower aprons 36. 
FIG. 7 is a top view of device 100 of FIG. 6 and shows second supporting 
element 30' for cross bar 12. This view shows that screening device 31 
consists of two separate tunnel hoods 32 and 32' driving one after the 
other. On their end sides facing each other, tunnel hoods 32 and 32' are 
beveled, and are held apart from each other. In this way, cross bar 12 is 
supported on yoke 21, and the x-ray equipment carried by cross bar 12 is 
freely and independently movable up and down in gap 137. 
FIG. 8 shows a side view of a supporting element 30. On the end side, cross 
bar 12 is provided with a head 28 ending in a lever arm 38. Cross bar 12 
with head 28 and lever arm 38 is rotatably supported in a pivot bearing 
39. Pivot bearing 39 rotates about an axle 15, and extends parallel with 
the longitudinal central axis of cross bar 12. When x-ray equipment 
supports 22 and 23 vibrate, this causes a swinging motion of cross bar 12 
around the axis of rotation 15. 
Damping elements 17 and 17' are disposed between lever arm 38 and 
supporting element 30. These damping elements absorb the oscillations of 
cross bar 12 or the lever forces of lever arm 38 transmitted to damping 
elements 17, and 17' . 
FIG. 9 shows a front view of another embodiment of screening device 31. In 
this case, the upper struts forming the ceiling wall 35 of a screening 
device 31 consist of struts that are guided within each other, so that the 
track width can be changed by telescope-like extension or shortening. In 
addition, apron 36 is shown in its center position, and can be raised or 
lowered. 
FIG. 10 shows a schematic side view of screening device 31. Screening 
device 31 is comprised of two tunnel hoods 32 and 32' running one after 
the other. These tunnel hoods are independently and separately driven and 
keep a spacing between each other. This spacing is shown as clear gap 137, 
in which the x-ray apparatus can be driven into its operating positions. 
Hydraulic cylinders 40 are provided to adjust the track width by means of 
the strut sections (FIG. 9) within the zone of ceiling wall 35. 
The screening walls of each tunnel hood 32 and 32' of screening device 31 
are thicker in the areas adjacent to the x-ray equipment than in the 
remote areas of the walls. Therefore, the weighted load acting on the 
carriages of tunnel hoods 32, 32' is considerably higher in the x-ray 
equipment areas. Thus, the carriages of tunnel hoods 32 and 32' are 
designed in the form of multi-axle arrangements in the areas with the 
highest dead weight. As shown in FIG. 10., the carriages adjacent to the 
gap are designed in the form of twin-axle carriages. 
FIG. 11 shows a schematic top view of screening device 31 comprised of two 
tunnel hoods 32 and 32', with a gap 137 disposed in between. Hydraulic 
cylinders 40 are designed to adjust the track width of each tunnel hood. 
In the present embodiment, the piston rods of cylinders 40 are shown fully 
extended, which means the maximal possible track width of tunnel hoods 32 
and 32'. 
In addition, device 100 contains operating cylinders 41 and 41' for raising 
and lowering the aprons. As indicated in the present figure, cover or 
ceiling wall 35 consists of lead plates that prevent scattered x-rays from 
exiting upwardly from tunnel hoods 32 and 32' or screening device 31. 
While several embodiments of the present invention have been shown and 
described, it is to be understood that many changes and modifications may 
be made thereunto without departing from the spirit and scope of the 
invention as defined in the appended claims.