Load supporting device

A load supporting device to facilitate transport of a load carrying unit along a supporting surface comprises a piston member having a restricted movement in a cylinder member towards and from the supporting surface, a recess open towards the supporting surface, and a spherical supporting member in said recess movable in relation to the piston member to a position partly out from the piston member a channel in the piston provides flow communicating between said recess and the end of the piston member opposite the end from which the spherical member can extend, and an inlet member through the cylinder member is connected to a gas source under pressure to supply gas to the end portion of the piston member adjacent the channel move the piston member and/or the spherical supporting member to a position in which the spherical supporting member contacts the supporting surface, in which position the gas may flow past the spherical supporting member while maintaining an increased pressure in the recess to produce a lifting movement of the load carrying unit from the supporting surface. A valve member is located in the channel to restrict the gas flow to the recess when the spherical supporting member is located in an extended position from the piston member without contacting the supporting surface.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a load supporting unit, for use with 
loading pallets, or similar units, used to support goods during transport 
and storage. The term "load supporting device" also includes other types 
of devices, e.g. units utilized to support objects during manufacture, 
which objects are to be moved between various assembly, control or test 
stations when manufactured. Also other types of load carrying units are 
included, intended to facilitate transport of a supported load. 
2. Description of the Prior Art 
With regard to loading pallets and similar types of load carrying devices, 
a transport operation, e.g. from a storage area to another location or to 
a transport vehicle, is carried out by means of a suitable lifting device, 
such as fork lift trucks, manually movable hydraulically operable lifting 
devices, or similar devices. Especially for short transport distances, 
manually movable lifting devices are used, e.g. for transport operations 
on the back of a lorry or for short transports within a warehouse for 
example. As a result, suitable devices must usually be carried on each 
transport vehicle, and corresponding devices must also be available in 
required number within the premises where transport is to be carried out. 
Load supporting units utilized for production in series may either be 
arranged by placing them on a suitable conveyor, such as a conveyor belt 
or a roller conveyor, or the units may be moved between the manufacturing 
stations by means of an air cushion, i.e. compressed air is supplied to 
each unit and directed towards the floor surface by nozzles, whereby the 
air jets directed towards the floor surface accomplish a lifting effect, 
intended to faciliate transport of the unit from one station to another. 
BRIEF SUMMARY OF THE INVENTION 
The object of the present invention is to provide a device, which can be 
used for various types of load carrying units, and which faciliates 
transport of a unit without need for any transport devices. The device is 
particularly suitable for short distance transport, e.g. within certain 
premises, on the back of a lorry when loading/unloading, for similar 
applications. The transport is achieved by application of a small manual 
force. The device according to the present invention is further based on 
the availability of compressed air, e.g. a small container of compressed 
air located on the load carrying unit, but the air consumption during a 
transport movement is considerably lower than previously known devices of 
the air cushion type, which means that a rather small volume of air is 
required for long transport distances, or repeated short transports. 
The device according to the present invention is intended to be used in 
connection with a load carrying unit, and facilitates transport of the 
load carrying unit along a supporting surface by means of application of a 
force in the intended direction of transport, and is mainly characterised 
in that a number of devices are located on the load carrying unit, each 
device including a piston member movable in a direction towards the 
supporting surface, said piston member having an open recess in the 
direction towards the supporting surface surrounding a spherical 
supporting member, and including an inlet member, communicating with a gas 
source under pressure and arranged to facilitate supply of said gas into 
an area adjacent to the end portion of the piston member opposite to the 
end portion where the spherical supporting member is arranged movable in a 
direction toward and from the recess. The device further includes a 
channel in flow-communication between the recess and the inlet adjacent to 
the end portion of the piston member, said spherical supporting member 
being arranged to facilitate a sliding movement to a position extending 
partly outside the adjacent end surface of the piston member, whereby 
supplied gas to the inlet member is arranged to cause a movement of the 
piston member and/or the spherical supporting member to a contact position 
for the spherical supporting member against the supporting surface, and in 
said contact position flow past the spherical supporting member, whereby 
the flowing gas removes the spherical supporting member from contact with 
surrounding wall portions in the recess.

DETAILED DESCRIPTION 
The embodiment shown in FIGS. 1-2 comprises a surrounding, cylindrical 
housing 1, in which a piston member 2 is slidable a limited distance. The 
housing 1 further includes an inlet member 3, communicating with a 
compressed air source. From the end surface of the piston member 2 
opposite the inlet member 3, a part spherical recess 4 is extends into the 
piston member 2. A spherical ball-shaped supporting member 5 is disposed 
in recess 2. A washer shaped abutment or retaining member 6 is attached 
against the end surface of the piston member 2 from which the spherical 
recess 4 extends, and the centrally located hole of the washer-shaped 
abutment member 6 has a diameter smaller than the diameter of the 
spherical ball-shaped supporting member 5, which thereby is held in a 
position substantially completely surrounded by the recess 4. From the end 
surface of the piston member 2 directed towards the inlet member 3, a hole 
7 extends in a adjacent the spherical recess 4, and at the inner end there 
is provided a channel 8, having conically enlarged end portions, which 
serve as valve seats for a longitudinally extending valve member 9 
extending through the channel 8. 
The above described embodiment is attached to a load carrying unit, e.g. as 
indicated in FIG. 4, which shows a loading pallet, as a complete unit 
denominated 10 having fixed on the side facing a floor surface, or a 
similar surface, supporting members 11, 11'. In each of the supporting 
members 11, 11' is provided a device of the type described with reference 
to FIGS. 1-2, having the inlet member 3 attached to a pipe system 12 
connected to a compressed air container 13, arranged with a flow 
restricting valve member 14. Each device is attached to the supporting 
members 11, 11' in such a way, that the spherical ball-shaped supporting 
member 5 is directed towards the floor surface or similar surface on which 
the load carrying unit is disposed. 
When the valve member 14 is in a position so that compressed air is not 
supplied to the inlet members 3 and the load carrying unit 10 is intended 
to take up a stationary position, each device takes up a first position as 
shown in FIG. 1, i.e. the load carrying unit 10 rests in a conventional 
way on the supporting floor surface on the free end surfaces of the 
supporting members 11, 11'. 
When it is desired to move the load carrying unit 10, the valve member 14 
is operated whereby compressed air is supplied to each unit from the 
compressed air container 13 via the pipe system 12, connected with the 
inlet members 3 of each device. As a result, the supplied compressed air 
flows through the hole 7 via the channel 8 into the spherical recess 4, 
whereby the spherical ball-shaped member moves towards the supporting 
surface located under the load carrying unit 10. When this movement take 
place, two alternative results may be accomplished. 
If the supporting surface is a completely plane floor surface, located 
immediately under the end surface of the support members 11, 11', the 
spherical ball-shaped member 5 takes up contact with the supporting 
surface in a position mainly corresponding to the first position shown in 
FIG. 1, and the supplied compressed air flows past the spherical 
ball-shaped supporting member 5 in a small surrounding air passage, formed 
between the member 5 and the surrounding washer-shaped member 6. The air 
pressure acting on the upper portion of the spherical ball-shaped 
supporting member 5 thus causes a lifting movement for the load carrying 
unit 10, whereby said supporting member 5, due to the surrounding flowing 
air, does not take up mechanical contact with surrounding parts, i.e. said 
supporting member 5 is arranged in a mainly non-frictional condition in 
relation to surrounding parts. The load carrying unit 10 can thus be moved 
by application of an extremely small manual force. 
As mentioned previously an alternative result can also be achieved, when 
the valve member 14 is operated, which result is also achieved during a 
transport movement when the supporting surface, e.g. a floor surface, has 
small irregularities. When the first sliding movement in relation to the 
piston member 2 of the spherical ball-shaped supporting member 5 does not 
cause the supporting member 5 to take up contact with the supporting 
surface, said sliding movement is performed until the portion of the valve 
member 9 adjacent to the inlet member 3 takes up a contact position 
against the co-acting valve seat in the channel 8, whereby air is no 
longer supplied to the spherical recess 4, but only to the hole 7 and 
adjacent end portion of the piston member 2. As a result, the piston 
member 2 is moved in towards the supporting surface to a position in which 
the spherical ball-shaped supporting member 5 takes up contact with the 
supporting surface. Since the spherical supporting member 5 in the moment 
of contact is not under the influence of any lifting force, caused by 
compressed air supplied to the surrounding recess 4, a continued sliding 
movement of the piston member 2 causes the spherical supporting member to 
influence the valve member 9, which is moved from its sealing contact 
position against the valve seat adjacent to the inlet member 3, whereby 
compressed air is supplied to the spherical recess 4 via the channel 8. As 
a result, a lifting position is achieved, in which the spherical 
ball-shaped supporting member takes up a mainly non-frictional condition 
as described before. 
During a transport movement, said piston member 2 thus takes up various 
relative positions in relation to the surround housing 1, in order to 
adjust to existing irregularities in the supporting surface. 
However, a further position may also exist, apart from the position in 
which the piston member 2 facilitates such a transport movement that the 
spherical supporting member 5 takes up contact with a supporting surface. 
This condition can also result when the load carrying unit 10 for example 
is to be moved over a supporting surface having a deep hole or groove, in 
which case it is desirous to prevent air leakage from the device 
concerned. As shown in FIG. 2, such a leakage is prevented partly because 
of the valve member 9 taking up contact against the valve seat at the 
channel 8 directed towards the inlet member 3, and due to the fact that 
the spherical ball-shaped supporting member 5 takes up contact against the 
washer-shaped abutment member 6. Air leakage is thereby completely 
elminated from a device, which for any reason does not contact a 
supporting surface, thus not serving as a supporting device for the load 
carrying unit 10. 
If a spherical supporting member 5 during a transport movement for any 
reason should be made subject to a sudden force, e.g. when passing a door 
sill or similar, the member 5 can obviously be rapidly moved in direction 
towards the bottom portion of the spherical recess 4, and such a movement 
is only for a short period of time, causing the surrounding air passage to 
be enlarged with excessive air leakage. However, this leakage is reduced 
due to the fact that the valve member 9 can also take up a sealing contact 
against the conical valve seat in channel 8 adjacent the spherical recess 
4, whereby air supply to said recess is intermittently interrupted, which 
also causes a reduced air consumption. 
In the above described embodiment, the recess 4, which surrounds the 
spherical supporting member, has been described as part spherical. In view 
of the fact that such a design from a manufacturing point of view is often 
costly and thus not preferred, FIG. 3 shows an example of a modified 
embodiment. This embodiment has basically correspondingly arranged parts 
to the above described embodiment, but said recess 4' has a cylindrical 
shape, and the washer-shaped abutment member 6' is thicker, having the 
internal edge portion of the centrally located hole provide with a curved 
surface adapted to substantially conform to the spherical supporting 
member 5. According to this embodiment, an air passage is achieved when 
compressed air is supplied between the spherical supporting member 5 and 
the cylindrical wall surface of the recess 4', and also between the 
spherical supporting member 5 and the centrally located hole in the 
washer-shaped abutment member 6'. The operation of this embodiment is as 
disclosed with reference to previous embodiments. 
During a transport movement, when the spherical supporting member 5 is 
rolling against a supporting surface, a side force may be imposed on the 
valve member 9, caused by existing friction between the part of the valve 
member 9 which is in contact with the spherical supporting member 5 and 
the outer surface of said member. Such a force exists, if the long axis of 
the valve member 9 corresponds with the center of the spherical supporting 
member 5. However, this problem can be overcome in various ways, e.g. by 
arranging the contact surface of the valve member 9 curved, in order to 
reduce the size of the contact surface, or by covering said contact 
surface with a suitable friction reducing material. A preferred 
alternative is, to move the center of the long axis of the valve member 9 
in relation to the rotary center of the spherical supporting member 5, 
whereby a rotary movement of the spherical supporting member 5 provides a 
rotary movement for the valve member 9, whereby the previously discussed 
side force is transformed into a rotary force acting on the valve member 
9. 
As previously discussed, there is no air leakage in those cases when the 
spherical supporting member 5 does not take up contact with a supporting 
surface, partly due to the valve member 9, and partly due to the contact 
of the spherical supporting member 5 against the washer-shaped abutment 
member 6. It should be realized, that the seal achieved between the 
spherical supporting member 5 and the washer-shaped abutment member 6 can 
be further improved, if the portion of the abutment member 6 which takes 
up contact with the spherical supporting member 5 is arranged with a 
coating of a suitable flexible sealing material, such as rubber, synthetic 
plastics or similar material. It should also be mentioned, that the above 
double security against leakage obviously is based on the fact that the 
valve member 9 in closed position no longer takes up direct contact with 
the spherical supporting member 5. 
The present invention is not restricted to the shown and described 
embodiments, since many modifications obviously can be made within the 
scope of the invention. 
Accordingly, the piston member 2 can be arranged as a unit comprising two 
joined members, which are joined in a position surrounding the spherical 
supporting members 5 whereby the previously discussed washer-shaped 
abutment may be excluded, since the recess 4, or 4' can be arranged with 
such a shape, that said member 6 is replaced. Furthermore, it has been 
stated that the piston member 2 is arranged slidable a restricted distance 
in a surrounding housing 1. In the described and shown embodiment this is 
accomplished by arranging the piston member 2 with two different 
diameters, defining a first guiding and sealing portion, and a second part 
with a smaller diameter, and the surface between said diameters being used 
as a movement restricting member in connection with a co-acting abutment 
surface in the housing 1. A corresponding restriction of movement can 
obviously by achieved by using other previously known means, whereby it 
would be possible to arrange the piston member 2 with a uniform external 
diameter, whereby manufacturing costs can be reduced. The housing 1 can 
also be an integrated part with the unit in which the device is to be 
arranged, preferably arranged as a cylindrical cylinder, in which the 
piston member 2 can be moved a restricted distance. For applications where 
a small air consumption is not primarily controlling, the valve member 9 
can also be excluded from the design, whereby sealing is only achieved in 
relation to the lower edge portion of the recess 6 surrounding the 
spherical supporting member 5. It should also be mentioned, that 
compressed air obviously can be supplied in other ways than from a 
container 13, located by the load carrying unit 10. Accordingly, 
compressed air can be supplied to the load carrying unit 10 by means of a 
hose connected to an available compressed air source. 
Since many modifications are possible, as indicated above, the present 
invention is in no way restricted to described and shown embodiments, 
which only serve as examples of embodiments within the scope of the 
invention and the following claims.