NL2035721B1

NL2035721B1 - A strut device

Info

Publication number: NL2035721B1
Application number: NL2035721A
Authority: NL
Inventors: Maarschalk Jan-Pieter; Kikkert Jelle
Original assignee: Zamqua Holding B V
Priority date: 2023-09-01
Filing date: 2023-09-01
Publication date: 2025-03-13
Also published as: WO2025046532A1

Abstract

_19_ A strut device An extendable strut device (1), comprising a tool housing (21) and an extendable tool member (2) having a first part (3) and a second part (4) which are axially displaceable relative to each other between a compact first state and an extended second state of the tool member (2). Between the first part (3) and the second part (4) a pressure chamber (5) is operatively coupled with an inlet (6) for a pressurized pneumatic gas capable and configured to drive the first and second part apart from within the pressure chamber (5). An internal reservoir (7) is provided therein, having an inlet and/or an outlet (71) and being configured to contain a supply of compressed pneumatic gas at an elevated pressure. Said internal reservoir (7) is coupled to the pressure chamber (5) by means of a valve device (8), comprising one or more valve members, and in that control means (82) are provided to enable a user to operate said valve device (8). Fig. 2

Description

A strut device

The present invention relates to an extendable strut device, comprising a tool housing and an extendable tool member having a first part and a second part which are axially displaceable relative to each other between a compact first state and an extended second state of the tool member, wherein between the first part and the second part a pressure chamber is operatively coupled with an inlet for a pressurized pneumatic gas capable and configured to drive the first and second part apart from within the pressure chamber.

An extendable strut device of this type is often used in emergency situations to stabilise a relatively heavy load, for example a vehicle or a wall of a pit. This enables a safety worker to work in the region of the load without a risk of harm being caused by collapsing of the load. To stabilise the load, the strut device may be placed between the load and a support with one side of the strut device pushing against the support and an opposing side against the load. In order to accommodate for variation in distances between the support and the load, the strut device has a first part and a second part which can extend relative to one another to either extend or retract the strut.

These parts are extendable by either supplying or releasing compressed air to or from the strut device. To that end the strut device is connected to a compressed air cylinder with a number of hoses. The hoses are provided with operation means. The operation means comprise controls which allow a user to control supply of compressed air to and from the strut device.

Requiring a compressed air cylinder to be connected to the strut device by means of hoses poses a number of drawbacks. In particular, the compressed air cylinder and hoses consume valuable space in an emergency vehicle and at an emergency scene.

Moreover, the deployment of the hoses and compressed air cylinder at the emergency requires valuable time. Furthermore, the presence of these connections may hinder operation by the emergency persons involved.

The present invention thus seeks, among other things, to provide a strut device that alleviates these aforementioned drawbacks. in order to achieve the above-stated object, an extendable strut device of the type described in the opening paragraph, according to the invention, is characterised in that an internal reservoir is provided therein, having an inlet and/or an outlet and being configured to contain a supply of compressed pneumatic gas at an elevated pressure, in that said internal reservoir is coupled to the pressure chamber by means of a valve device, comprising one or more valve members, and in that control means are provided to enable a user to operate said valve device.

The strut device, comprising an internal reservoir for a supply of the pneumatic gas, allows for the strut device to store a supply of compressed pneumatic gas in itself, alleviating the need for a remote compressed gas cylinder. With a supply of compressed pneumatic gas stored in said internal reservoir an energy source required for operation of the strut device is available to the strut device from within the strut device. This allows the strut device to be a self-sustaining device.

Said internal reservoir being connected to the pressure chamber by means of the valve device allows the connection between said internal reservoir and the pressure chamber to be operated as desired. This allows a user to fill said internal reservoir with a supply of compressed gas and close the valve device to retain the gas in said internal reservoir for later use. When the gas is required to operate the tool member, the valve device can be operated to allow gas to flow from said internal reservoir to the pressure chamber in order to operate the tool member. Accordingly, a user is able to only release such an amount of gas from said internal reservoir as needed to operate the tool member in a specific manner whilst retaining a remaining supply of gas in said internal reservoir for later use.

A preferred embodiment of the strut device according to the invention is characterised in that the first part and the second part are co-axially engaged and extendable relative to each other, and that said internal reservoir extends within the tool co-axially with the first part and the second part. With said internal reservoir within the tool, available space within the tool may be used for said internal reservoir. The tool enclosing said internal reservoir allows said internal reservoir to be protected from impact or the like.

Furthermore, the tool may maintain a sleek exterior.

A preferred embodiment of the strut device according to the invention is characterised in that an elongated shaft extends within at least one of the first part and the second part, and that said internal reservoir is provided within the shaft. In this embodiment use is made of a hollow shaft to accommodate said internal reservoir. As a result said internal reservoir requires no, or hardly no, additional space.

To efficiently use space within the tool, a further embodiment of the strut device according to the invention is characterised in that an elongated shaft extends within at least one of the first and second parts, and that said internal reservoir is provided around the shaft. The shaft forms a central core of said internal reservoir that may be created to suite a desired volume by extending its external diameter.

A preferred embodiment of the strut device according to the invention is characterised in that de-activateable blocking means are provided between the first part and the second part which prevent retraction of the first and the second part from an at least partially extended state, that pneumatically operable de-blocking means are provided which, when energised, disable the blocking means, and that said internal reservoir is coupled to the de-blocking means by means of the valve device. Said internal reservoir is coupled to the de-blocking means to allow the de-blocking means to be operated as well from within the strut device itself. This alleviates the need for a separate gas supply source coupled to the strut device in order to operate the de-blocking means. The valve device allows a user to control the de-blocking means.

A further aspect of the invention provides for strut device comprising a cylindrical extension body in which a body cavity extends longitudinally, which extension body is functionally connectable to an end of a further strut device to provide an extension thereto, characterised in that the body cavity comprises an internal reservoir with an inlet and/or an outlet, in which a supply of compressed pneumatic gas is containable at an elevated pressure, wherein a valve device is connected to the inlet and/or outlet of said internal reservoir, and that control means are provided to enable a user to operate the valve device

One or more of these extension bodies may be used to bridge a total length between a load to be supported and a fixed, stable basis. This extension body, having a body cavity which comprises an internal reservoir, allows for available space within the extension body to be used. Said internal reservoir allows for a supply of compressed pneumatic gas to be stored within the extension body. This compressed gas may be used to operate pneumatic eguipment, for example, a pneumatic cushion or otherwise a lifting system. This reduces the need of dedicated compressed gas cylinders at an emergency site for feeding necessary pneumatic equipment.

A preferred embodiment of the strut device according to the invention is characterised in that one or more pneumatic connections are provided externally to said housing, comprising a pneumatic connection to the inlet and/or outlet of said internal reservoir.

The pneumatic connections allow for pneumatic gas to be supplied and/or evacuated to of from the strut device. In particular, coupling a pneumatic gas source to the pneumatic connection of the inlet of said internal reservoir allows for filling of said internal reservoir with a supply of pneumatic gas.

A further preferred embodiment of the strut device according to the invention is characterised in that the pneumatic connections comprise a co-axial pneumatic connection. The co-axial pneumatic connection allows for having a single pneumatic connection leading to or coming from different destinations. Accordingly, pneumatic gas can be exchanged with said different destinations within the strut via a single pneumatic connection.

A preferred embodiment of the strut device according to the invention is characterised in that the valve device is at least partially upstream of one or more of the pneumatic connections. This allows for a flow of pneumatic gas via one or more of the pneumatic connections to be controlled upstream of the connections. In particular, a preferred 5 embodiment of the strut device according to the invention is characterised in that the valve device is at least partially accommodated in a self-contained module coupled with one or more of the pneumatic connections. This allows for flow control of the pneumatic gas externally of the tool housing. The strut device can be rendered pneumatically operable by merely coupling the module with the one or more pneumatic connections that are present on the tool housing. The tool itself, accordingly, needs only little modification to accommodate said internal reservoir.

A preferred embodiment of the strut according to the invention is characterised in that the valve device is at least partially accommodated in a self-contained module and in that the module is detachable attached. With the module being removably coupled, the module can be detached to ensure that there is no possible flow connection between the pressure chamber and said internal reservoir. This prevents the possibility of an unintended pressurizing of the pressure chamber and, accordingly, an accidental extension of the strut device. Thus, by removing the module the strut device can be safely stored with said internal reservoir filled without a risk of the strut device accidentally extending. Furthermore, removing the module renders the device manually operable. This is especially beneficial in emergency situations where pneumatic operable strut devices are not allowed to be used or personnel is not sufficiently skilled to operate the valve device. However, should it later on be required to again have the strut device pneumatically operable the module can be coupled again. in particular, a further preferred embodiment of the strut according to the invention is characterised in that the module is detachably coupled to one or more pneumatic connections that are provided to said housing. This way the external module may be coupled removably to one or more pneumatic connections that are provided externally to the housing and communicate with said internal reservoir and/or pressure chamber.

The connection between said internal reservoir and the pressure chamber may be broken by detaching the module from the pneumatic connections to make sure that the device is not accidentally energized. With the pneumatic connections in place the device may still conveniently be used traditionally with an external supply of pressurized gas. in order to render the strut device completely self-sustainable, a further preferred embodiment of the strut device according to the invention is characterised in that the valve device is electronically controllable, and that the valve device comprises an electronic power source, in particular a rechargeable battery, and a control device. The strut device comprising its own power source and control unit enable complete operation of the valve device that drives the strut device.

A further preferred embodiment of the strut device according to the invention is characterised in that the valve device comprises a receiver for wireless control. The wireless control enables a user to control the valve device and, accordingly, operate the strut device entirely remotely from a distance. Accordingly, a user can operate the strut device within a safe distance from a load to be stabilised.

A further preferred embodiment of the strut device according to the invention is characterised in that the valve device comprises downstream of said internal reservoir a reduction valve, from which the pneumatic gas is offered at a reduced operating pressure. Accordingly gas can be stored in said internal reservoir at a higher pressure than an operating pressure needed on the site. The reduction valve allows for release of pneumatic gas at a reduced pressure as would be required.

The invention will now be further elucidated on the basis of an exemplary embodiment and accompanying drawings. In the drawings:

Figure 1A shows a front perspective view of a strut device according to the invention;

Figure 18 shows a sectional side view of the strut device of figure 1A;

Figure 2 shows a sectional side view of a second embodiment of the strut device according to the invention;

Figure 3 shows a self-contained module that is shown in figures 1A and 18;

Figure 4 shows an exploded view of the self-contained module and the strut device that is shown figures 1A to 3; figure 5 shows a front perspective view of an extension body according to the invention;

Figure 6 shows a sectional side view of the strut device according to the invention comprising the extension body of figure 5; and

Figures 7A -7D shows schematic illustrations of a valve device according to the invention. it is noted that the drawings are purely schematic and not drawn to scale. Some dimensions in particular may be exaggerated to greater or lesser extent for the sake of clarity. Corresponding parts are designated in the figures with the same reference numeral.

With reference to figures 1A and 1B, an extendable strut device is generally indicated with reference numeral 1. The strut 1 comprises and elongate tool member 2 which has a first part 3 and a second part 4. The first and second parts 3, 4 are each an elongate tube made from a high load bearing material, for example, steel. The second part 4 has an outer diameter smaller that an inner diameter of the inner part 3, allowing the second part 4 to be co-axially received in the first part 3. The first 3 and second parts 4 are axially extendable relative to each other between a compact first position and an extended second position.

An interior space is left between a top region of the second part 4 and a top region of the first part 3 which defines a pressure chamber 5 between the first part 3 and the second part 4. The pressure chamber 5 is operatively coupled with an inlet 6 for a pneumatic gas. Pneumatic gas entering the pressure chamber 5 allows for the second part 4 to be driven from the first part 3, accordingly adjusting the first and second parts 3, 4 to an extended position.

The tool member 2 has an internal reservoir 7 in which a supply of compressed pneumatic gas is held. The pneumatic gas may, in particular, be stored in said internal reservoir 7 at a considerably higher pressure than what is required to operate the strut 1. For example, pneumatic gas may be held at a pressure exceeding tens or hundreds

Bar. In this example the pneumatic gas is typically loaded in said reservoir 7 at a pressure of the order of 300 Bar to provide for several operating cycles. Said internal reservoir 7 extends in the tool member 2 co-axially with the first and second parts 3, 4.

Said internal reservoir 7 comprises an air tight enclosure. In the embodiments shown in figures 1B and 2, a shaft 10 extends in the second part 4. A first embodiment of said internal reservoir 7 is shown in figure 1B wherein an open space surrounds the shaft 10.

Said internal reservoir 7 extends in the open space surrounding the shaft 10. In a second embodiment of said internal reservoir shown in figure 2, the shaft 10 has a wider diameter than that shown in figure 1B to allow said internal reservoir 7 to be within the shaft 10. A tube {not shown) may be positioned over the shaft 10 to seal said internal reservoir 7 air tight. Said internal reservoir 7 has an inlet and/or outlet 71 for pneumatic gas.

Blocking means 9 are provided between the first part 3 and second part 4. The blocking means 9 comprises a number of balls 91 which are located in six parallel ring-shaped grooves 92 at top an end region of the second part 4. The grooves 92 each gradually increase in a depth thereof. A maximum depth of the grooves 6 correspond to a diameter of the balls 91. With the balls 91 positioned at the deepest area of the grooves 92 the balls 91 are spaced from an inner surface of the first part 3. This allows the first tube 3 and second tube 4 to be freely axially extendable with respect to each other.

With the balls 91 at a shallower part of the grooves 92, the balls 91 are clamped between the first and second parts 3, 4 to block the first and second parts 3, 4 in an extended position. To release the blocking means 9, the balls 91 are moved to the maximum depth parts of the grooves. To enable this, a biassing member 12 comprising a spring is connected between an end of the shaft 10 and an end of the blocking means 9. By pushing the shaft 10 towards the blocking means 9, the biassing member 12 forces the balls 91 to the maximum depth areas of the grooves 91, unblocking the blocking means 9. Pushing of the shaft 10 is controlled with a de-blocking actuator 13 which may be pneumatically controlled. The pneumatic gas inlet 6 is also operatively coupled to the de-blocking actuator 13.

Said internal reservoir 7 is connected to the pressure chamber 5 and to the actuator 13 by means of valve devices 8 which are electronically controllable. Each valve device 8 comprises a valve 81, in particular, a solenoid valve, which is connected to an energy source 83 and a control means 82. The energy source 83 is a rechargeable battery. The control means 82 has a wireless receiver allowing for wireless control of the control means 82. Working of the valve device 8 will be further described further below.

An extension body 15, shown in figure 5, having an extension body 15 is functionally connectable to an end of the strut device 1, as shown in figure 6. The extension body 15 has a cylindrical body 151 in which a body cavity 152 extends longitudinally. The body cavity 152 has an internal reservoir 7' with an internal reservoir inlet 7'. A valve device 8, of the type described above, is connectable to said internal reservoir 7' to control pneumatic gas flow to and from said internal reservoir 7'. Said internal reservoir 7' may be operatively coupled to a further pneumatic device, for example, a lifting cushion.

Said internal reservoir inlet 71 and the inlet 6 is each a pneumatic connection.

Pneumatic connection 6 is a co-axial connection operatively coupled to both the pressure chamber 5 and the actuator 13. The pneumatic connections 6, 71 extend parallel from an exterior of a housing 21 of the tool member 2.

A self-contained module 14 is detachable connected to the pneumatic connections 6, 71. The module 14 has a substantially box-shaped casing with two pneumatic connections 141, 142 extending from a connection side thereof. The pneumatic connections 141, 142 corresponds to the pneumatic connections 6, 71 and are receptively clipped over the pneumatic connections 6, 71 in a disconnectable manner.

Release buttons 143 are provided at opposing sides of the module 14. Pressing of these buttons 143 allow for disconnecting the pneumatic connections 141, 142 from the pneumatic connections 6, 71 whereby the module can be removed from the tool member 2. The module 14 has an opening 145 through which said internal reservoir 7 can be filled or through which gas can be released from the module 14. in the case of the module 14 being connected to the extension body 15, as shown in figure 5, the module 14 may only need one pneumatic connection 142 which is connectable to the pneumatic connection 71 of said internal reservoir 7'. To connect a further pneumatic operable device to the module 14, the module 14 has in this case two pneumatic connections 144 accessible from outside of the casing of the module 14.

Figures 7A to 7D show schematic diagrams of pneumatic gas flow in the strut device.

The figures each show said internal reservoir pneumatic connection 71 and co-axial pneumatic connection 6, which is operatively coupled to the chamber 5 and the actuator 13. A first flow path A operatively couples a pneumatic gas supply source to said internal reservoir pneumatic connection 71. Flow path A includes a shut-off valve 81 and a three-way valve 81 located between the shut-off-valve 81 and internal reservoir pneumatic connection 71. A second flow path B extends from three-way valve 81 towards the co-axial pneumatic connection 6. Flow path B splits into two flow paths

B’ and B’, which are each connected to the pneumatic connection 6. Flow path B’ has a two-way valve 81 and flow path B’* has a three-way valve 81. A third flow path C extends from flow path B and meets flow path A between the shut-off valve 81 and the three-way valve 81.

Figure 7A shows filling of said internal reservoir 7 wherein both the shut-off valve 81 and the three-way valve 81 are open to allow flow in flow path A. Pneumatic gas flows in flow path A through pneumatic connection 71 and to said internal reservoir 7.

To extend the tool member 2, shown in figure 78, the three-way valve 81 in flow path A is opened towards flow path B. The two-way valve 81 to flow-path B’ is closed and the three-way valve in flow path B is opened towards flow path B’. Gas flows from said internal reservoir 7, through the three-way valve 81, into flow path B and into flow path

B”. Gas in flow path B” flows through the pneumatic connection 6 and to the chamber 5.

To de-block the tool member 2, shown in figure 7C, the three-way valve 81 in flow path

A is opened towards flow path B and the three-way valve towards flow path B’ is closed. The two-way valve in flow path B’ is open. Gas flow from said internal reservoir 7, through the three-way valve 81, into flow path B and into flow path B’. Gas in flow path B’ flows through the pneumatic connection 6 and to the actuator 13

To release gas from the chamber 5, shown in figure 7D, the three-way valve 81 in flow path B” is opened towards flow path C. The stop-valve 81 in flow path A is also open.

Gas flow from the chamber 5, through the pneumatic connection 6, along flow path C and exit past the stop-valve 81.

A reduction valve 84 is provided downstream of said internal reservoir 7. The reduction valve 84 allows for a reduction of a pressure of pneumatic gas coming from said internal reservoir 7 to a workable pressure. Accordingly, pneumatic gas in said internal reservoir 7 may be held at a higher pressure than what would be required to operate the strut 1 whilst pneumatic gas is released through said reduction valve 84 at a workable pressure. For example, said internal reservoir may be filled up to 300 Bar whilst a maximum of 12 Bar would be required to operate the strut device 1.

In use, the self-contained module 14 is connected to the tool member 2 by clipping the pneumatic connections 141, 142 onto the pneumatic connections 6, 71. A pneumatic gas supply source is operatively connected to opening 145 of the module 14 through which said internal reservoir 7 is filled. Once filled the pneumatic gas supply source is disconnected from the module 14. The further internal reservoir 7' of the extension 15 can be filled in a similar manner. The strut 1 and extension 15 with the filled internal reservoirs 7, 7' can now be stored for later use.

To stabilise a load at an emergency site one side of the strut 1 is placed on a support, for example, a steel plate. The tool member is then manually extended to allow an opposing end to be placed under the load. To force the opposing end against the load and thus stabilise the load, a user can control the valve device 8 by means of remote control to open the required valves 81. This allows the chamber 5 to be filled. Therewith the tool member 2 extends by means op pneumatic force to a required length, allowing the strut 1 to stabilise the load. The blocking means 9 prevent the tool 2 from retracting from such extended state.

Once the strut 1 is no longer required for stabilising the load, a user can remote control the valve device 8 to allow gas to pneumatically de-block the blocking means.

Thereafter, pneumatic gas in the chamber 5 is released. A user can thus adjust the strut 1 to a compact state.

Should the strut 1 not have a sufficient length for supporting the load, the extension body 15 can be connected to the end of the strut 1 to increase a length of the strut 1.

Said internal reservoir 7' may be operatively coupled to pneumatic equipment, for example, a lifting cushion, via the pneumatic connections 144 to supply such equipment with compressed pneumatic gas stored in the extension body. This allows for operation of the equipment. It is also envisaged that two or more extension bodies may be connected to each other. it is envisaged that the invention herein described is desirable to use since the invention alleviates the need to have separate gas cylinders and supply lines in order to operate the strut device. Accordingly, space can be cleared up in both an emergency vehicle and on an emergency site. Furthermore, without the need to connect the gas cylinder to the strut, set-up time can be saved. Having the module removeable from the strut allows for conveniently changing the strut between a manual operable tool and a pneumatic operable tool. This allows for one strut to be used in both situations.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, for example, instead of a co-axial pneumatic connection multiple pneumatic connections may be provided in parallel to direct pneumatic gas to different areas of the strut.

The module may also be internally provided inside the housing instead of externally thereto.

Particularly, the following embodiments are envisaged within the spirit and scope of the appended claims:

1. An extendable strut device, comprising a tool housing and an extendable tool member having a first part and a second part which are axially displaceable relative to each other between a compact first state and an extended second state of the tool member, wherein between the first part and the second part a pressure chamber is operatively coupled with an inlet for a pressurized pneumatic gas capable and configured to drive the first and second part apart from within the pressure chamber, characterised in that an internal reservoir is provided therein, having an inlet and/or an outlet and being configured to contain a supply of compressed pneumatic gas at an elevated pressure, in that said internal reservoir is coupled to the pressure chamber by means of a valve device, comprising one or more valve members, and in that control means are provided to enable a user to operate said valve device. 2. A strut device according to embodiment 1, characterised in that the first part and the second part are co-axially engaged and extendable relative to each other, and that said internal reservoir extends within the tool member co-axially with the first part and the second part. 3. A strut device according to embodiment 2, characterised in that an elongate shaft extends within at least one of the first part and the second part, and that said internal reservoir is provided within the shaft.

4. A strut device according to embodiment 2 or 3, characterised in that an elongate shaft extends within at least one of the first and second parts, and that said internal reservoir is provided around the shaft.

5. A strut device according to any one of the preceding embodiments, characterised in that de-activateable blocking means are provided between the first part and the second part which resist retraction of the first and the second part from an at least partially extended state, that pneumatically operable de-blocking means are provided which, when energised, disable the blocking means, and that said internal reservoir is coupled to the de-blocking means by means of the valve device. 6. A strut device comprising a cylindrical extension body in which a body cavity extends longitudinally, which extension body is functionally connectable to an end of a further strut device to provide an extension thereto, characterised in that the body cavity comprises an internal reservoir having an inlet and/or an outlet, in that said internal reservoir is configured to contain a supply of compressed pneumatic gas at an elevated pressure, in that a valve device is connected to the inlet and/or outlet of said internal reservoir, and in that control means are provided to enable a user to operate the valve device.

7. A strut device according to any one of the preceding embodiments, characterised in that one or more pneumatic connections are provided externally to said housing, comprising a pneumatic connection to the inlet and/or outlet of said internal reservoir.

8. A strut device according to embodiment 7, characterised in that the pneumatic connections comprise a co-axial pneumatic connection. 9. A strut device according to embodiment 7 or 8, characterised in that the valve device is at least partially upstream of one or more of the pneumatic connections.

10. A strut device according to any one of the preceding embodiments, characterised in that the valve device is at least partially accommodated in a self-contained module and in that the module is detachably attached.

11. A strut device according to embodiment 10, characterised in that the module is detachably coupled with one or more pneumatic connections that are provided externally to said housing.

12. A strut device according to any one of the preceding embodiments,

characterised in that the valve device is electronically controllable, the valve device comprising an electronic power source, in particular a rechargeable battery, and a control device.

13. A strut device according to embodiment 12, characterised in that the valve device comprises a receiver for wireless control.

14. A strut device according to any one of the preceding embodiments, characterised in that the valve device comprises downstream of said internal reservoir a reduction valve, from which the pneumatic gas is offered at a reduced operating pressure.

Claims

Conclusions:

1. An extendable prop device comprising a housing and an extendable working member having a first part and a second part which are axially adjustable relative to each other between a compact first state and a deferred second state of the working member, wherein between the first part and the second part a pressure chamber is operatively coupled with an inlet for a pneumatic pressure gas which is capable and arranged to drive the first and second parts apart through the intermediary of the pressure chamber, characterised in that an internal reservoir is provided therein with an inlet and/or an outlet, in which a compressed supply of pneumatic gas can be maintained under increased pressure, that the outlet is coupled to the pressure chamber between the internal reservoir and the valve device through a valve device, which valve device comprises one or more valve members and that operating means are provided which enable a user to operate the valve device.

2. A prop assembly as claimed in claim 1, characterised in that the first part and the second part are coaxially interlocking and extendable relative to each other, and in that the internal reservoir extends coaxially with the first part and the second part within the working member.

3. A prop arrangement as claimed in claim 2, characterised in that an elongate shaft extends within at least one of the first and second parts, and in that the internal reservoir is provided within the shaft.

4. A prop arrangement according to claim 2 or 3, characterised in that an elongated shaft extends within at least one of the first and second parts, and in that the internal reservoir is provided around the shaft.

5. A support device according to one or more of the preceding claims, characterised in that releasable blocking means are provided between the first part and the second part which prevent the first and second part from resetting from an at least partially suspended state, that pneumatically actuated release means are provided which, when actuated, release the blocking means, and that the internal reservoir is coupled to the release means by means of the valve device.

6. A prop device comprising a cylindrical extension body in which a body cavity extends longitudinally, which extension body is operatively coupleable to an end of a further prop device to provide an extension thereto, characterised in that the body cavity comprises an internal reservoir with an inlet and/or an outlet in which a compressed supply of pneumatic gas can be maintained under increased pressure, that a valve device is connected to the inlet and/or the outlet of the internal reservoir, and that operating means are provided which enable a user to operate the valve device.

7. A support device according to one or more of the preceding claims, characterised in that one or more pneumatic connections are provided externally on the housing, comprising a pneumatic connection to the inlet and/or the outlet of the internal reservoir.

8. A prop device according to claim 7, characterised in that the pneumatic connections comprise a co-axial pneumatic connection.

9. A support device according to claim 7 or 8, characterised in that the valve device is arranged at least partly upstream of one or more of the pneumatic connections.

10. A support device according to claim one or more of the preceding claims, characterised in that the valve device is at least partly housed in an independent module which is detachably mounted.

11. A prop device according to claim 10, characterised in that the module is detachably coupled to one or more pneumatic connections provided externally on the housing.

12. A prop device according to one or more of the preceding claims, characterised in that the valve device is electronically controllable and that the valve device comprises an electronic power source, in particular a rechargeable battery, and a control device.

13. A prop device according to claim 12, characterized in that the valve device comprises a receiver device for wireless control.

14. A prop device according to one or more of the preceding claims, characterised in that the valve device comprises a pressure reducing valve downstream of the internal reservoir, from which the pneumatic gas can be removed under a reduced working pressure.