FIELD OF INVENTION

This invention relates to a clamp for retaining elongate rigid materials such as tubes, pipes, rods or bars. More precisely, this is a clamp that is particularly suited to the safe and effective lifting, lowering and maneuvering of scaffold tubes.

BACKGROUND OF INVENTION

Construction sites commonly employ scaffolding tubes, where a temporary framework is needed to access to heights and areas that would be otherwise hard or unsafe to reach. Scaffolding, also called scaffold or staging, is used to support workers and construction-related materials, thus assisting in working safely at height: repairing, constructing or maintaining human-made structures like buildings, bridges, or similar structures. Additional applications of scaffolding include forming concert stages or ramps.

Commonly, the scaffolding components constitute a system comprising a load-bearing base plate, standard horizontal and vertical tubes, diagonal elements for more stable construction and load bearing, and connector joints, couplers or other mounting means. Such systems are assembled and disassembled as required.

Although scaffolding remains widely recognised as an irreplaceable part of a modern-day construction site, it has the potential to result in death or severe injury, as the customary process of assembling and disassembling the scaffolds is hazardous.

The most common procedure of lifting the scaffold tube from the ground to the assembly personnel in a certain height is to tie up the tubes with one end of a rope and raise the tubes by pulling the rope. The rope may be pulled manually or by employing one or more pulleys or by any lifting force-generating machinery, a traction sheave, or similar mechanisms.

It is clear, that such processes are inherently hazardous owing to their reliance on a manually tied knot whose integrity may vary according to the skill of the person tying it. Further contributors to hazard are the low-friction and dull surface of the tube, and the lack of fastening points on the tubes and the significant weight of the load. Safety statistics record that occasionally the tubes slip out of the knot during lifting or lowering and fall, resulting in damage and serious and occasionally fatal injuries, as the tied load of tubes is a significant weight.

There have been several attempts to provide a safer way of lifting scaffold tubes, preventing tubes from slipping out and falling during the ascent and descent. These include a scaffold tube clamp for lifting scaffold pipes, described in a British patent No. GB2478965, published on 28-09-2011. This patent application describes a scaffold tube clamp for raising and lowering scaffold tubes. The clamp includes a clamping means for holding a scaffold tube, a releasable catch which may include a pin and strap or maybe a cam and lever quick-release catch. The clamp also includes a lifting eye or aperture which may be positioned in several orientations. The clamp may be used when erecting or dismantling scaffolding to reduce the risk of falling tubes and make the process safer.

Another similar device - a pipe clamp and scaffold hanger is described in a Japanese patent No. JP2000230315, published on 22-08-2000. This invention aims to provide a pipe clamp capable of being suitably used for a hanging scaffold and a scaffold hanger capable of promoting work efficiency and safety when the hanging scaffold is dismantled. A scaffold hanger is equipped with a hook provided to at least the first end of a chain, the chain wound on a scaffold bearing section in a building or the like and a pipe clamp is providing a connection means on a main clamp body grasping the main pipe constituting a scaffold. Then, the chain is wrapped around the scaffold bearing section, the hook of the first end of the chain is connected to a middle part of the chain from the second end side to the scaffold bearing section, the chain is mounted to the scaffold bearing section, at the same time, a joint device of the pipe clamp is connected to the second end side of the chain, the main clamp body of the pipe clamp is fixed to the main pipe, and the scaffold is borne through the chain and pipe clamp in a state to hang to the scaffold bearing section.

Another scaffold lifting device is described in a British patent No. GB2267530, published on 08-12-1993. It describes flanks or boards, preferably of standardised dimensions of width and height (thickness) are secured to an assembly of scaffold struts or poles by cable devices having spring hooks at each end thereof. A plank is placed transversely of at least two parallel poles, and attachment means are applied to the poles at opposite sides of the plank. A cable device is secured about the first plank with the cable between the attachment means, and the operation is repeated using further cable devices which are fastened at an intermediate point on the first cable device to fasten the planks together to form a platform.

Another Japanese patent No. JP2008038390, published on 21 -02-2008, describes a mounting fitting for rope. This invention aims to provide a mounting fitting for a rope having an excellent function for facilitating mounting work of the rope on a pipe when assembling a pipe scaffold. Hook parts of two hook plate parts are provided with a circular arc part for holding the pipe, respectively. An elastic plate part piece is held by two hook parts, and the mounting fitting is fixed on an outer peripheral part of the pipe through the circular arc parts by giving pressing force for pressing the outer peripheral part in the peripheral direction of the pipe held by the circular arc parts in these hook parts against the circular arc parts in the hook parts to the pipe. This mounting fitting for the rope is provided with a means for releasing fixation of the mounting fitting through the circular arc parts by the outer peripheral parts of the pipe by releasing pressing force given to the pipe. A rope holding part is provided with a rope stretching structure for holding or connecting the pipe on which the mounting fitting for the rope is fixed on/with the other member through the mounting fitting.

The inventions mentioned above are relevant to scaffold tube clamping applications and furthermore for scaffold tube lifting applications. Patent No. GB2478965 provides an entirely radial scaffold clamp, denying the operator a firm grip on the device. Moreover, it relies on a toggle clamp which has no fail-safe feature and, therefore, the lifted or lowered workpiece can be released from the clamp if the toggleo accidentally opened by a contact to an obstacle during the lift, for example, a looped plastic sheeting widely used in scaffolding constructions. Furthermore, the most convenient operation of this clamp appears to be 3-handed, by meaning the 1 -st hand to hold a tube, 2-nd hand to close the clasp and 3-rd hand to toggle the clamp. A Patent No. JP2000230315 provides a somewhat clumsy chain mechanism, wherein the chain goes through the clamp, and the fixation of the tube is cumbersome. Patent No. GB2267530 provides two conjugated elements, where the elements are to be used with an assembly of cables and planks, thus making the process complex. Finally, patent No. JP2008038390 provides a device, which requires both time and energy to mount it on a pipe, as it is a two hook parts system, and the operator has to fix in on a tube with difficulty. Moreover, it provides no fail- safe feature to prevent an accidental ejection of the tube from the clamp.

SUMMARY

This invention eliminates the drawbacks indicated above by providing a clamp (1 ) for lifting and lowering scaffolding tubes. The clamp (1 ) comprises a first arm (2), a second arm (3), means for conjugating the arms (4), an opening (5) for the rope to be tied to the clamp (1 ) and locking means (8).

The clamp (1 ) provides a unique locking solution having a fail-safe feature and ensuring that the unlocking of the clamp can not occur without a manual intervention (2, 3) to a standard scaffolding tube entirely while being able to provide a comfortable grip for the user and secure locking means, thus offering a simple, safe and swift scaffolding lifting and lowering solution. The user ties the rope through the opening (5) of the clamp or by connecting a rated swaged connection of the rope by means of a carabiner. The user operates the clamp (1 ) by opening the locking means (8), opening the arms (2, 3), clamping a scaffolding tube with the arms (2, 3), closing the arms (2, 3) and locking the arms (2, 3) with locking means (8).

DESCRIPTION OF DRAWINGS

Flere the drawings are provided only for the sake of clarity and should be referred only as a possible implementation of the invention and should not limit the scope of the invention by any means. Exemplary drawings of the clamp. Fig. 1 is a schematic representation of the most preferred embodiment of a clamp (1 ) in an unlocked state. The clamp (1 ) comprises a first arm (2) and a second arm (3). Both arms (2, 3) have concave parts (6) shaped to fit the tube for a firm grip on a scaffolding tube and elongated parts for a smooth operation. A nut passes through both arms (2, 3), conjugating arms (2, 3), and also acting as an axis of rotation. Threaded parts (7) provide a secure fixation for the locking mechanism (8). The locking mechanism (8) is a lock nut. The user unlocks the clamp (1 ) by unthreading the locking nut (8) from the-lower set of threads (73) and further threading the locking nut (8) up to the upper- set of threads (71 ) completely, unclasping both arms (2, 3). Isometric projection view.

Fig. 2 is a schematic representation of the most preferred embodiment of a clamp (1 ) in a locked state. The clamp (1 ) comprises a first arm (2) and a second arm (3). Both arms (2, 3) have concave parts (6) shaped to fit the tube for a firm grip on a scaffolding tube and elongated parts for a smooth operation. The user locks the clamp (1 ) by twisting the lock nut (8) clockwise, clasping both arms (2, 3). Threaded parts (7) provide a secure fixation for the locking mechanism (8). Isometric projection view.

Fig. 3 is a schematic representation of the most preferred embodiment of a clamp (1 ) in an opened state. The clamp (1 ) comprises a first arm (2) and a second arm (3). Both arms (2, 3) have concave parts (6) shaped to fit the tube for a firm grip on a scaffolding tube and elongated parts for a smooth operation. The arms (2, 3) rotate around the conjunction point (4). Isometric projection view.

Fig. 4 is a schematic representation of another embodiment of a clamp (1 ) in an opened state. The clamp (1 ) comprises a first arm (2) and a second arm (3). Both arms (2, 3) have concave parts (6) shaped to fit the tube for a firm grip on a scaffolding tube and elongated parts for a smooth operation. A nut passes through both arms (2, 3), conjugating arms (2, 3), and also acting as an axis of rotation. The second arm (3) comprises locking mechanism (8) which is a semi-hooked clasp. Isometric projection view.

Fig. 5 is a schematic representation of another embodiment of a clamp (1 ) in a locked state. The clamp (1 ) comprises a first arm (2) and a second arm (3). Both arms (2, 3) have concave parts (6) shaped to fit the tube for a firm grip on a scaffolding tube and elongated parts for a smooth operation. A nut passes through both arms (2, 3), conjugating arms (2, 3), and also acting as an axis of rotation. The semi-hooked clasp (8) secures the clamp (1 ) in a locked state. Isometric projection view.

Fig. 6 is a schematic representation of another embodiment of a clamp (1 ) in an opened state. The clamp (1 ) comprises a first arm (2) and a second arm (3). Both arms (2, 3) have concave parts (6) shaped to fit the tube for a firm grip on a scaffolding tube and elongated parts for a smooth operation. A nut passes through both arms (2, 3), conjugating arms (2, 3), and also acting as an axis of rotation. The second arm (3) comprises locking mechanism (8) which is a slidable locking mechanism. The user locks the clasp (1 ) by sliding the locking mechanism (8) downwards. Isometric projection view.

Fig. 7 is a schematic representation of another embodiment of a clamp (1 ) in an opened state. The clamp (1 ) comprises locking mechanism (8) which is a ring-lock mechanism, which is a simple ring without threads. The user locks the clasp (1 ) by sliding the locking mechanism (8) downwards. Isometric projection view.

Fig. 8 is a schematic representation of another embodiment of a clamp (1 ) in a closed state. The clamp (1 ) comprises locking mechanism (8) which is a ring-lock mechanism. The user unlocks the clasp (1 ) by sliding the locking mechanism (8) upwards. Isometric projection view. Fig. 9 is a schematic representation of another embodiment of a clamp (1 ) in an opened state. The clamp (1 ) comprises locking mechanism (8) which is a spring loaded latch. Isometric projection view.

Fig. 10 is a schematic representation of another embodiment of a clamp (1 ) in a closed state. The clamp (1 ) comprises locking mechanism (8) which is a spring loaded latch. Isometric projection view.

Fig. 11 is a schematic representation of system (21 ) and application for safe lifting, lowering or manoeuvring of scaffold tubes, the system comprises the clamp (1 ) for scaffold tube clamping.

Fig. 12 a-c is a representation of the manual operation steps of the clamp.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

This invention comprises a clamp (1 ) for lifting and lowering elongate rigid materials, such as scaffolding tubes. This device aims to provide means for increasing safety level while assembling and disassembling scaffolds, thus reducing work-related injuries and mishaps. The user raises the pipe by using the clamp (1 ) instead of tying a rope to the tube, and furthermore, the locking means of the clamp has built-in redundancy making it impossible for the clamp to open accidentaly. The clamp (1 ) provides a unique locking solution having a fail-safe feature and ensuring that the unlocking of the clamp can not occur without a manual intervention (2, 3) to a standard scaffolding tube entirely while being able to provide safe locking means, thus offering a secure scaffolding lifting solution.

In the most preferred embodiment, the user operates the clamp (1 ) by opening the locking means (8), opening the arms (2, 3), fitting a scaffolding tube (6), closing the arms (2, 3) and locking the arms with locking means (8). The user attaches the clamp (1 ) to the rope (23) through the opening by tying a knot (as in Fig. 12 a-c) or connects a rated swaged connection of the rope by means of a carabiner (24, Fig. 11 ). In the most preferred embodiment the clamp (1 ) comprises first arm (2), second arm (3), means for conjugating the arms (4), an opening (5) for the rope to be tied to the clamp (1 ) and locking means (8) (see Fig. 1 ).

In the most preferred embodiment, the first arm (2) comprises a cavity for conjunction means (4), concave parts (6) shaped to fit the tube to clasping a standard scaffold tube, an elongating part with threads (7) and an opening (5) at the end of the arm (2) (see Fig. 2). It should be clear for the person skilled in the art, that this invention should not be limited by the threads (7), as the threads (7) are integrated into the first arm (2) only as a corresponding part for the locking means (8).

In the most preferred embodiment, the second arm (3) comprises a cavity for conjunction means (4), a concave part (6) to clasp a standard scaffold tube and an elongating part with threads (7). The shape of the second arm (3) is corresponding to the form of the first arm (2) so that the second part (3) enfolds the first part (2) partly when closed (see Fig. 2). It should be apparent to a person skilled in the art that the shape of the clasp (1 ) can vary, especially length of the elongating parts of both arms (2, 3). Also, it should be clear for the person skilled in the art, that this invention should not be limited by the threads (7), as the threads (7) are integrated into the second arm (3) only as a corresponding part for the locking means (8).

In the most preferred embodiment, the conjunction means (4) comprise a nut, mounted through cavities of both arms (2, 3) (see Fig. 1 ). The holes have predetermined size, corresponding to the size of the nut (4). The length of the nut (4) is such that it entirely takes up the space of both cavities of the arms (2, 3). The holes are at the bottom of the arms (2, 3). The nut (4) can be covered with covering means to achieve a more aesthetic result. It should be apparent to a person skilled in the art that the conjunction means (4) can be other than described above and should not limit the scope of the invention. Other conjunction means (4) may be but are not limited to: shafts, rods, bolts, pins, pintles and gudgeons. It should also be apparent for a person skilled in the art that a hinge being produced by strap is also within the scope of the invention. Such straps may be, but are not limited to leather, braided steel band or nylon webbing.

In the most preferred embodiment, the concave parts (6) of both arms (2, 3) are circular parts, which fully abut to a standard scaffold tube, thus providing a firm grip on it. When the clasp (1 ) is locked, the concave parts (6) secures the scaffold tube, limiting any unpredictable movements of the tube during the lifting process. Abut areas of both concave parts (6) to the tube are at a sufficient distance from each other. Sufficient extent is such so that the torque, generated by the tube, would be compensated by the support reaction force generated torques, occurring in the abutting areas. It should be apparent to a person skilled in the art that the shape of the concave parts (6) can differ slightly, and it should not limit the scope of the invention. Also, other concave clasping means, such as belts, should also be considered as the scope of this invention.

Due to concave parts (6), this invention has the effect of clamping the tube through cantilevering forces. These forces are neutral when the clamp (1 ) is centred in the tube (the mass centre of the tube is within the area of the clamp (1 )), but the clamping forces increase as the tilt angle of the system increases. This effect arises because when the mass centre of the tube is located in either side of the system, (as is the scaffold industry guideline on lifting and lowering tubes) the gravitational forces affect the inner area of the concave parts (6) unevenly (Fig. 11 ), the mechanical pressure is distributed onto a smaller inner area, thus increasing the reaction of support forces, consequently increasing the friction, especially, if the clamp is fabricated from a harder alloy or material than the tube is. So if for any reasons the tube began to slip (for instance, due to variation in the tube diameter), the clamp’s (1 ) clamping force would increase and reduce the risk for the tube to slide of the system.

In the most preferred embodiment, the opening (5) is a slip loop, coupled to the first arm (2) of the clamp (1 ). Slip loop (5) has a sufficient size to tie a rope onto and to confine the locking mechanism (8) from dismounting (see Fig. 1 ). It should be apparent to a person skilled in the art that the opening (5) can be other than described above, as long as it provides secure tying means, and should not limit the scope of the invention. Another opening (5) shapes may be but are not limited to: a circle with a prong, a hook, a carabiner, U-shaped bolt, and various rope clamps.

In the most preferred embodiment, the locking means (8) is a lock nut (8), which comprises inner threads, corresponding to the threads (7) of the clamp (1 ). The user operates the lock nut (8) by twisting the nut (8) clockwise or counter-clockwise onto the threads (7). The lock nut (8) secures both arms (2, 3) in a simple, intuitive and cost-effective manner. A lock nut (8) is easy to use and can be operated by one person with no additional tools or assistance. This locking mechanism (7, 8) should be considered as a fail-safe, as it can only provide two states - opened or closed - whereas an unsafe mechanism would have a third state - nearly opened or not fully closed. Therefore, a special unthreaded gap (72) is designed in the threads (7) thereby dividing them into the upper set of threads (71 ) and lower set of threads (73, 74). In order to open the locking means (8), the user must manually twist the lock nut (8) from the lower threads (7, 73, 74), located on both the first and the second arms (2, 3) (see Fig. 2), then slide the nut (8) upwards along the unthreaded gap (72) and twist the nut (8) once again onto the upper threads (7, 71 ), located on the first arm (2) (see Fig. 1 ). Only then can the user open the clamp (1 ). The closing procedure is reverse - the user must twist the lock nut (8) from the upper threads (7, 71 ), located on the first arm (2), then slide the nut (8) downwards and twist the nut (8) once again onto the lower threads (7, 73, 74), located on both the first and the second arms (2, 3). So, if during operation the nut (8) would disengage from the lower threads (7, 73, 74) and the upper threads (7, 71 ), the nut (8) would sustain the clamp (1 ) in the closed state, thus making this locking mechanism (7, 8) fail-safe. Flowever, it should be clear for a person skilled in the art that the scope of this invention comprises all sorts of locking mechanisms, which are capable of providing a fail-safe locked and unlocked state of the clamp (1 ). Other locking mechanisms can be but are not limited to: elongated fixating parts, rings, nuts, slidable locking mechanisms, spring loaded locking mechanisms, locked tongue based locking mechanisms, etc. In the most preferred embodiment, the material of the clamp (1 ) is a steel alloy, but it should be apparent to a person skilled in the art that there are numerous materials and combinations of materials which could be used to manufacture the clamp (1 ). Other materials may be but are not limited to polymers, composites, steel, aluminium, titanium, etc.

In another embodiment, the first (2) and the second (3) arms do not comprise threads (7), as the locking mechanism (8) is different. In this embodiment, the first arm (2) includes a cavity for conjunction means (4), a concave part (6) to clasp a standard scaffold tube, an elongating part and an opening (5) at the end of the arm (2). The second arm (3) comprises a cavity for conjunction means (4), a concave part (6) to clasp a standard scaffold tube and a locking mechanism (8), which is a semi- hooked clasp. The shape of the second arm (3) is corresponding to the form of the first arm (2) so that the second part (3) enfolds the first part (2) partly when closed (see Fig. 4)

In this embodiment, the user operates the clamp (1 ) by opening the locking means (8), opening the arms (2, 3), fitting a scaffolding tube into a concave part (6), closing the arms (2, 3) and locking the arms with locking means (8). The user ties the rope through the opening (5) of the clamp (1 ) by tying a knot or by deploying a carabiner. The user locks the arms by pressing the arms (2, 3) together with force, fastening the barb of the semi-hooked clasp onto the first arm (2) (see Fig. 5). The user unlocks the clamp (1 ) by pushing the clasp as mentioned above outwards, detaching the barb from the first arm (2).

Yet in another embodiment, the first (2) and the second (3) arms do not comprise threads (7), as the locking mechanism (8) is different. In this embodiment, the first arm (2) comprises a cavity for conjunction means (4), a concave part (6) to clasp a standard scaffold tube, an elongating part, an opening (5) at the end of the arm (2) and a cavity for the locking mechanism to fixate. The second arm (3) comprises a cavity for conjunction means (4), a concave part (6) to clasp a standard scaffold tube and a locking mechanism (8), which is a slidable locking mechanism (see Fig. 6). The shape of the second arm (3) is corresponding to the shape of the first arm (2) so that the second part (3) enfolds the first part (2) partly when closed.

In this embodiment, the user operates the clamp (1 ) by opening the locking means (8), opening the arms (2, 3), fitting a scaffolding tube into a concave part (6), closing the arms (2, 3) and locking the arms with locking means (8). The user ties the rope through the opening (5) of the clamp (1 ) by connecting a swaged looped end or rated knot of the rope to a carabiner. The user locks the arms by sliding the locking mechanism (8) upwards, fastening the tongue of the mechanism (8) to the first arm (2). The user unlocks the clamp (1 ) by pushing the clasp as mentioned above downwards, releasing the tongue from the locking position.

It should be apparent to a person skilled in the art that there are numerous variations of locking mechanisms (8) and it can be other than described above, as long as it provides secure locking, and should not limit the scope of the invention. Furhermore, the system and a typical application (21 ) of a workpiece or a scaffold tube (25) safe lifting, lowering or manoeuvring by means of the clamp (1 ) is depicted in Fig. 11. The system (21 ) comprises at least:

• an upper point (22) such as a lifting-lowering winch, pulley, gin wheel, locking gin wheel or a steady hanger point,

• a flexible connector (23) such as a rope or chain or a lifting sling, arranged from the fixed upper point (22) down and connected to the clamping apparatus,

• a clamp apparatus,

• a workpiece or a scaffold tube (25) being lifted, lowered and maneuvered. Additionally, an optional carabiner (24) may be used in between the flexible connector having a rated connection or a rope with a swaged end-loop (23) and the clamp (1 ).

The clamping apparatus is the clamp (1 , Fig. 1 -10) having a rigid construction described previously in this chapter. The construction is special by that the elongated parts of the clamp arms (2), (3) functionally are the levers (32), (33) of manually operating the clamp and cantilevering the workpiece (Fig. 11 ) during the lift. It means, that it is substantially easier and more convenient for the scaffolding operator to operate manually the clamp and tube by using these levers (32), (33), moreover, there are no any additional tools required.

Further, the locking means of the clamp (1 , Fig. 1 -3) comprises:

• The upper set of threads (71 ) and the lower set of threads (73, Fig. 1 , 2, 3) on the first lever (32) and the lower set of threads (74, Fig. 1 , 3) on the second lever (33), wherein both lower sets of threads (73) and (74) are together complementary to common threaded nut when both levers alligned in parallel one to another in the closed position.

• A locking nut (8, Fig. 1 -3) with its inner threads matching the upper and lower sets of threads (7, 71 , 73, 74) of the levers (32), (33), said locking nut (8) threaded at least onto the upper set of threads (71 , Fig. 2) of the first lever (32) whereby the clamp is in the unlocked state (Fig. 1 , 3), and the further threading of the locking nut (8) down to the lower sets of threads of both levers (73, 74, Fig. 2) transfers the clamp (1 ) to at least the closed-locked state (Fig. 2) with the locking nut (8) fully threaded onto the lower set of threads (73, 74, Fig. 2) of both levers, wherein the locked and unlocked states may be manually operated without the need for any tools.

This special construction of the locking means allows safe fixing of the scaffolding tube (25) in the clamp (1 ). The upper set of threads (71 ) and the lower set of threads (73) have an unthreaded gap (72) in between, the gap (72) being wider than the height of the locking nut (8), whereby the locking nut (8) hangs freely but still keeps the levers (32) and (33) in the locked state. This feature acts as the fail-safe state of the locking means, i. e., an accidental unlocking is impossible without manual manipulation of the locking nut (8), threading it fully to the upper set of threads (71 ) thereby permiting the second (shorter) arm (2) to open the clamp. The second benefit is that the position of the locking nut (8) on the upper threads (71 ) or the unthreaded gap (72) or the lower threads (73, 740) serve as a clear visual indicator of the clamp locking state to the site personnel.

Furthermore, the levers (32), (33) assist the clamp to grip the scaffold tube (25) better during the lifting, lowering or manoeuvring process, which is especially beneficial in that a single hand around both open levers (32), (33) permits a levered grasp over the workpiece, thus permitting an overall convenient two-hand operation (Fig. 12 a-c). A better grip is implied by bending forces Fi and F ₂ in the clamp (1 ) which are combined with tensile forces F _T and gravity forces F _G , as depicted in Fig 11. Because of the bending moments, the tube receives abutment from the top and bottom concave parts (6) of the clamp (1 ). This abutment provides an additional grip to the workpiece or the scaffold tube (25) being lifted, lowered or maneuvered. It is the enhanced grip by the clamp.

The clamp (1 ) can have different constructions of the locking means (Fig. 1 to 10). The clamp in Fig. 1 -3 comprises the locking means without the lower threads (7, Fig. 1 and 3) on both levers (32) and (33). The clamp in Fig. 7-8 comprises the locking means without threads on both levers (32) and (33). The clamp in Fig . 9-10 has the same construction as the clamp in Fig. 7-8, but further comprising a loaded spring between the locking nut (8) and the opening (5). The locking means of the clamp (1 , Fig. 4-5) is a semi-hooked clasp (8, Fig. 4 and 5), embedded into the second lever (33), comprising a barb, capable of affixing to the first lever (23). The locking means of the clamp (1 , Fig. 6) is a spring-loaded slidable locking mechanism (8, Fig. 6), embedded into the second lever (33, Fig. 6), comprising a tongue, capable of affixing to the first lever (32). Nevertheless, any embodiment of the clamp (1 ) still provides the same levers (32), (33) for manual convenient operation of the clamp and the enhanced gripping of the tube during the lifting, lowering or manouevring process.

The operation of the clamp (1 ) is based on a method comprising typical steps:

• the clamp is operated to the open state,

• the clamp is applied to clasp the scaffold tube (25),

• the clamp is operated from the open to the closed-unlocked state,

• the clamp is operated from the closed-unlocked state to the closed-locked state,

• the clamp is operated from the closed-locked to the closed-unlocked state,

• the clamp is returned to the open state to permit the scaffold tube (25) removal from the clamp.

Flowever, due to the special construction of the present clamp (1 ), several steps are special and more convenient for the scaffolding operator, i. e. :

• the clamp (1 ) can be applied to clasp the scaffold tube (25) at any position of its length whereby the scaffold tube (25) is held by the clamp (1 ),

• the clamp (1 , Fig. 1 -3) is operated from the open state (Fig. 3) to the closed-unlocked state (Fig. 1 ) by manually enfolding the levers (32) and (32) together,

• the clamp (1 ) is locked, by manually threading the locking nut (8) down from the closed-unlocked state over the upper set of threads, passing over an unthreaded portion of the levers, and fully onto the lower set of threads (Fig. 2),

• the clamp (1 ) is unlocked by manually threading the locking nut (8) up from the closed-locked state over the lower set of threads (7), passing over the unthreaded portion of the levers, and fully onto the upper set of threads (Fig. 1 ),

• the clamp (1 ) is operated from the closed-unlocked state (Fig. 1 ) to the open state (Fig. 3) by manually opening the levers (32), (32) for the scaffold tube (25) to be removed. For the clamp with the semi-hooked clasp (1 , Fig. 4-5), the locking and unlocking steps are different and specified as follows:

• the clamp (1 ) is unlocked by pushing the semi-hooked clasp (8, Fig. 4-5) outwards, and detaching the barb of the semi-hooked clasp (8, Fig. 4-5) from the first lever (32),

• the clamp (1 ) is locked by pressing the levers (32 and 33, Fig. 4-5) together with force, and fastening the barb of the semi-hooked clasp (8, Fig. 4-5) onto the first lever (32) in a secure manner,

For the clamp with the sliding the locking mechanism (1 , Fig. 6), the locking and unlocking steps are are different and specified as follows:

• is unlocked by sliding the locking mechanism (8, Fig. 6) downwards and dismounting the tongue of the mechanism (8, Fig. 6) from the first lever (32),

• is locked by sliding the locking mechanism (8, Fig.6) upwards and fastening the tongue of the mechanism to the first lever (32).