DE69226536T2 - HAND TOOL FOR ATTACHING ENDINGS TO SECURITY CABLES - Google Patents

Description

Background of the invention:

The present invention relates to a hand tool for attachment of press rings to securing strands, which prevent accidental loosening of such connections when passed through a large number of screw connections.

In rotating machines with small tolerances between rotating and fixed components, such as turbines, it is essential that all parts, no matter how small, are protected from contact with rotating components of the machine. The presence of any foreign object can have catastrophic consequences for the entire rotating machine.

Machines of this type are inherently complex and require many screws, nuts, bolts and other screw connections to assemble all of their components. Since very high speeds are reached during the operation of such machines, which lead to vibrations in the machine parts, it is essential to to protect against accidental loosening of the numerous screw connections.

The use of safety wires to prevent the accidental loosening of screw connections is already known. As a rule, the safety wire is passed through cross holes in at least two screw connections and twisted alternately clockwise and anti-clockwise between the screw connections. This process is repeated until every screw connection in the structure is secured with wire. After the required tightening and twisting, the wire is cut off and bent into a specific position.

Although the well-known technique of securing wires has produced satisfactory results, its application is time-consuming and cumbersome. The results of such securing are often unsatisfactory due to differences in the length and tightness as well as the tension of the fastening wires. It is estimated that annual losses of approximately 10 million US dollars are caused solely by loosening screw connections that are inadequately secured with securing wires.

US-A-4 966 600, to which the preamble of claim 1 refers, describes a clamping device as a hand tool for attaching a compression ring to surgical wires.

EP-A-0 385 667 describes a locking device on a manual crimping tool to prevent the crimping mandrel from springing back until the final crimping position sition is reached.

A cutting device can be removed from EP-A-0 390 760 to carry out a cutting process after twisting the wire.

The present invention provides an apparatus for applying a press ring to a strand member, e.g. B. a wire or a cable, with a tool body, a means connected thereto for positioning the press ring, which receives a strand element pulled through this press ring, with a strand tensioning means for gripping a strand element and for applying a desired tension to this strand element, which is drawn into a press ring positioned on the tool body and secured against longitudinal movements, with a means contained in the tool body for pressing on press rings and with a manual actuating means with rotatably mounted handles which are operatively connected to the means for pressing on the press ring in order to move the means for pressing on the press ring between a retracted position and a pressing position in which it grips and presses on a press ring applied to the means for positioning contained in the tool body, characterized by: a means which is operatively connected to the manual actuating means to prevent the means for pressing on the press ring from sliding back into the retracted position before it moves into Direction of the pressing position has reached its final pressing position, by a separating device for severing a tensioned strand element which is pulled through a pressing ring which is positioned in the tool body during its pressing operation, the separating device comprising an elongated Hole for receiving the press ring as part of the means for positioning the press ring and extending partially through the tool body with the larger dimension of the hole in the direction of movement of the means for positioning the press ring, through an opening for guiding the strand element in the tool body, which faces one side of the hole for receiving the press ring and penetrates its bottom, in order to insert the strand element through a press ring provided in the hole and to guide it through the opening for guiding the strand element in the tool body, wherein the means for pressing on the press ring is mounted in such a way that it enables relative movements between a press ring in the hole and the strand element guided in the opening during the pressing on of a press ring, and through a shearing edge associated with the opening for severing a strand element by the relative movement between the press ring and the opening for guiding the strand element during the pressing on process of the press ring.

Short description of the figures

Show it:

Fig. 1 is a plan view of a safety wire installed according to the prior art;

Fig. 2 is a plan view of a safety wire fitted with the device according to the invention;

Fig. 3 is a plan view of the hand tool according to the invention;

Fig. 4 is a longitudinal cross-section along the line IV-IV in Fig. 3;

Fig. 5A-5C are schematic representations of the function of the press ring holder to position a press ring during the insertion of a locking wire into the press ring and the hand tool;

Fig. 6A, 6B side views of the press ring holder to illustrate the storage and removal of a press ring from the holder;

Fig. 7 shows a partial cross-section of a press ring applied to a safety wire and inserted into the tool, ready for pressing on;

Fig. 8 is an exploded view of the clamping mechanism according to the invention;

Fig. 9 is a rear view of the clutch plate in the direction of arrow IX in Fig. 8;

Fig. 10 is a partial cross-section along X-X in Fig. 9;

Fig. 11 is a front view of the clamping element in the direction of arrow XI in Fig. 8;

Fig. 12 is a front view of the tension adjustment screw in the direction of arrow XII in Fig. 8;

Fig. 13 a cross section of the locking mechanism of the device according to the invention and

Fig. 14A-14C are schematic representations of the successive movements of the locking mechanism to illustrate the positions of the pawl.

Detailed description of a preferred version

Fig. 1 shows a safety wire 18 attached according to the prior art to three screw connections 10, 12 and 14 in an area 16 of a rotary machine (not shown). The safety wire 18 comprises two partial strands 18a and 18b, which are twisted or separated at one end in such a way that a strand 18a is guided through a transverse opening in the connecting element 10 and a strand 18b is guided around the outside of the connecting element 10. The strands are twisted on the opposite side of the fastening element 10; in the same way, one strand passes through a transverse opening in the fastening element 12, while the other strand is laid around the fastening element 12. The safety wire 18 is continued to the last connecting element 14, through whose transverse opening one strand is pushed through, while the other strand is guided around the outside of the fastening element. The strands are twisted on the opposite side of the fastening element 14.

Fig. 2 shows a cable securing system fitted with the device according to the invention. Again, the screw connections 10, 12 and 14 are connected to the area 16 of a rotary machine. The safety cable 20 consists of a multi-core cable with a compression ring 22 attached to the cable end 20a. The safety cable 20 is passed through the transverse openings in the screw connections 10, 12 and 14, the compression ring 22 pressing against one side of the connecting element 10. At this point, the compression ring 24 is placed on one end of the cable 20 on the side of the fastening element 14; a tension is applied to the safety cable 20 and the compression ring 24 is pressed onto the safety cable so that it presses against the side of the connecting element 14. The safety cable 20 is then automatically tensioned. The predetermined tension in the safety cable 20 is caused by the pressure of the compression rings 22 and 24 on the sides of the respective screw connections 10 and 14.

As can be seen from Fig. 3 and 4, the manual crimping tool according to the invention contains two mutually pivotable handles 26, 28, which are fixed to a bearing pin 30 and can be pivoted towards and away from each other about the longitudinal axis of the pin 30 (arrows 31 in Fig. 4). The respective handles 26 and 28 can have padded or wrapped areas 26a and 28a and can have fork-shaped sections at the front with generally parallel extended sections 26b and 26c (see Fig. 3). Of course, the handle 28 can be constructed in a similar fork-shaped manner, but the forked sections must be closer together so that the front sections of the handle 28a fit between the sections 26b and 26c near the bearing pin 30.

One end of a connecting piece 32 is mounted on the handle 26 via a pin 34, the axis of the pin 34 being substantially parallel to the axis of the bearing pin 30. The other end of the connecting piece 32 is rotatably attached to a projection 36 via a pin 38.

In a similar manner, one end of a connector 40 is mounted on the handle 28 via a pin 42, while the other end is mounted on the sleeve link 36 via a pin 44. The axis of the pin 42 may also be parallel to the axis of the bearing pin 30.

The proximal end 46a of an elongated housing 46 is secured to the boss 36 by brazing or the like. As shown in Fig. 4, the elongated housing 46 also has an outer end 46b with an at least partially triangular hole 48. The elongated housing 46 has a longitudinal central opening which slidably receives a mandrel 50. One end 50a of the mandrel 50 is secured to the handles 26 and 28 via the bearing journal 30. As described in more detail below, the press mandrel 50 can be moved back and forth between a retracted position in which its opposite end 50b does not extend significantly into the hole 48 and a pressing position in which its end 50b extends far enough into the hole 48 that it presses against a press ring positioned in the hole 48 in order to press the latter onto a safety cable passed through it.

To use the hand tool according to the invention, the safety cable must first be pulled through both the press ring and the hole in the elongated housing of the tool; a predetermined tension must be applied to the safety cable and the press ring must be permanently pressed onto the safety cable.

The first part of this operation can be carried out with the aid of a press ring holder 52 as shown in Figs. 5A to 5C, 6A and 6B. The press ring holder 52 can be equipped with a storage 54 whose storage space 56 accommodates a plurality of press rings 24. In Figs. 5A and 6A, four press rings 24a, 24b, 24c and 24d are shown, although of course a plurality of such press rings can also be accommodated in the storage 56. The press ring holder 52 also has an insertion chamber 58 delimited by the edge pieces 58a and 58b. As can be seen from Figs. 5A and 6A, a spring 64 bears against a portion of the accumulator 54 and against the uppermost pressing ring (in this case pressing ring 24d) in the accumulator, so that the stacked pressing rings are pressed by the accumulator 56 toward the insertion chamber 58.

Extending from the compression ring holder 52 are resilient lips 60 and 62 which are attached to the compression ring holder 52 to frictionally engage surfaces 46c and 46d on opposite sides of the elongated housing 46. Once the resilient lips 60 and 62 have releasably secured the compression ring holder 52 to the elongated housing 46, the insertion chamber 58 is aligned with the hole 48.

The press ring holder 52 may also have collar-like projections 66 and 68 on opposite sides. Each of these projections defines an opening which is aligned with the opening of the press ring 24a in the insertion chamber 48. The opening of the projection 66 may be beveled at the edge to form a conical inlet in order to facilitate the threading of the Safety cable, into the press ring holder 52.

As can be seen from Fig. 5A, the safety cable 20 is automatically guided through the opening of the compression ring 24a and through the opening of the projection 68 when inserted into the opening of the projection 66. The cable end 20 is then passed through the hole 48 of the elongated housing 46 and through a smaller, substantially cylindrical opening 70 which connects the hole 48 to the opposite side of the elongated housing 46 as shown in Fig. 7.

Once a desired length of the safety cable 20 has been pulled through the screw connection 14, the compression ring 24a and the elongated housing 46, the compression ring holder 52 is moved in the direction of arrow 72 in Fig. 5B to release from the elongated housing 46. As can be seen from Fig. 6A, the compression ring holder 52 has wall areas 74, 76 with reduced wall thickness, which are located substantially on opposite sides of the insertion chamber 58. As shown in Fig. 6B, these areas 74, 76 enable the lower two halves of the compression ring holder, which are divided by a gap 59 and delimit the insertion chamber 48, to pivot out as soon as it is pushed upward in the direction of arrow 78 in Fig. 5C. The movement in the direction of arrow 78 allows the press ring 24a, which is placed on a safety cable 20, to exit the press ring holder 52 in the insertion chamber 50. As soon as the press ring 24a has exited the press ring holder 52 through the edge pieces 58a and 58b, its lower part springs back into the position shown in Fig. 6A due to its elasticity in order to prevent further press rings from exiting. The spring 64 then pushes the stack of press rings downwards so that the Press ring 24b is located in the insertion chamber.

After releasing the press ring holder 52 from the elongated housing 46, the latter is moved in the direction of arrow 80 in Fig. 5C to insert a press ring 24a, as shown in Fig. 7, into the hole 48.

At this point, it is necessary to apply a predetermined tension to the safety cable 20 before the compression ring 24a is permanently pressed onto the cable. This is accomplished by attaching the end of the safety cable 20 to a tensioning device 82 shown in Figs. 3 and 8. The tensioning device according to the invention is illustrated in Figs. 8 to 12. The tensioning device is inserted into a unidirectionally rotatable device 84, as is known from commercial devices. A strand gripper 86 is inserted through the unidirectionally rotatable device 84 so that the front part 86a of the strand gripper is on one side of the rotatable device 84, while the part 86b of the strand gripper for clamping the safety cable protrudes from the opposite side of the rotatable device 84. This end 86b of the strand gripper may have a slot 88 with an enlarged inner portion 88a so that the end of the safety cable 20 may be inserted into the slot 88 and displaced into the enlarged portion 88a and then no longer aligned with the slot 88. An annular groove 89 may receive a C-clamp (not shown) to secure the strand gripper 86 to the unidirectional rotatable device 84. The strand gripper 86 also has a longitudinal central opening with a threaded bore.

At least one driver 92 is attached to the front side 90 of the front part 86a of the strand gripper. The drivers 92 can be spherical and rotatably attached to the strand gripper or can be permanently attached to the top side 90 of the front part 86a of the strand gripper, projecting above it. Although only four such drivers are shown in Fig. 11, more or fewer can of course be used without departing from the scope of the invention.

A clutch plate 94 is attached to a clamping knob 96 in a recess by means of any permanent fastening, such as a screw connection. The end face 98 of the clutch plate 94 has, as shown in Figs. 9 and 10, at least one drive recess 100 with inclined ramps 102. The recesses 100 are designed so that the drivers 92 engage them. The number of drive recesses is the same as the number of drivers.

A retaining pin 104, the function of which is explained in more detail below, is fastened between the clamping knob 96 and the coupling plate 94. As shown in Fig. 8, the projection 104a of a retaining pin 104 is inserted into the recess 96a of the clamping knob 96 and into a bevel 94a of the coupling plate 94. The fastening between these parts is designed in such a way that when the clamping knob 96 and consequently the coupling plate 94 are rotated about the axis 106, the retaining pin 104 is not rotated about this axis, but any axial movement of the clamping knob 96 along its axis of rotation 106 guides the retaining pin 104 axially in the same direction.

A screw 108 for adjusting the tension has a head 108a and a shaft 108b which extends through the tension knob 96 and the coupling plate 94 and which is screwed into the longitudinal central opening of the strand gripper 86. One or more wave-shaped disc springs 110 may be inserted between the head 108a of the screw 108 and the tension knob 96 for adjusting the tension. The face 108c of the screw head has a groove 108d to facilitate turning the screw for adjusting the tension with a screwdriver or the like.

An adjusting screw 109 can be screwed into the opposite end of the longitudinal central opening of the strand gripper 86 so that it presses against the shaft end 108b of the tension adjusting screw 108. This holds the screw 108 in its desired position and prevents inadvertent rotation of the tensioning screw 108.

The tensioning device works as follows: After the end of the safety cable 20 is inserted into the slot 88 and its enlarged cavity 88a, the tensioning knob 96 is manually rotated about the axis 106. Due to the unidirectional rotation of the device 84, the strand gripper 86 and consequently also the tensioning knob 96 only rotate in one direction. The preload force of the disc springs 110 presses the tensioning knob 96 as well as the coupling plate 94 along the axis 106 against the strand gripper 86 so that the drivers 92 engage in the recesses 100. In this way, the rotation of the tensioning knob 96 causes the strand gripper 86 to rotate via the coupling plate 94.

Such a rotation causes a pressure ring drawn and secured against longitudinal movement safety cable 20 is wound around the end 86b of the strand gripper 86, thereby increasing the tension in the safety cable 20. As soon as this tension reaches its predetermined value, the rotational force acting on the strand gripper 86 via the engagement of the drivers 92 in the driver recesses 100 becomes smaller than the restoring force on the strand gripper 86 caused by the safety cable 20. This prevents the strand gripper 86 from rotating and causes the drivers 92 to slide along the inclined ramps 102 when the clamping knob is rotated. The sliding of the drivers 92 along the inclined ramps 102 in turn leads to an axial movement of the clamping knob 96 along the axis 106 away from the strand gripper 86. As soon as the drivers 92 have been released from the driver recesses 100, no further rotation of the strand gripper 86 can take place via the clamping knob 96. The rotation of the strand gripper 86 in the opposite direction is prevented by the device 84, which can only rotate in one direction.

The amount of tension at which the dogs 92 slide along the inclined ramps 102 can be adjusted by turning the screw 108. Rotation in one direction increases the preload force to the right (as shown in Fig. 8) on the tension knob 96 and forces it against the strand gripper 86. This places a higher tension on the safety cable 20 before the dogs 92 disengage from the recesses 100. Similarly, rotation of the screw 108 in the other direction to adjust the tension decreases the tension applied to the safety cable 20 at which the dogs 92 disengage from the recesses 100.

Once the desired tension is applied to the safety cable 20, the compression ring 24a can be pressed onto the safety cable. This is accomplished by manually squeezing the handles 26 and 28 together. As shown in Fig. 4, such movement of the handles 26 and 28 causes the pins 34 and 42 to move about the axis of the journal 30. This movement causes relative movement between the elongate housing 46 and the compression mandrel 50 which is attached to the journal 30. As can be seen in Fig. 7, the movement of the handles 26 and 28 toward each other causes the elongate housing 46 to move to the right with respect to the compression mandrel 50. The movement of the mandrel along the generally triangular hole 48 deforms the compression ring 24a such that it is compressed and permanently secured to the safety cable 20. The relative movement between the elongated housing 46 and the compression ring 24a causes a shearing of the safety cable 20 between the inner edge of the opening 70 and the adjacent edge of the compression ring 24a. The edges move in different directions so that a shearing movement is exerted on the safety cable 20 which severs the cable after the compression ring 24a is compressed.

In order to prevent the movement of the handles 26 and 28 away from each other until the press ring 24a is permanently attached to the safety cable 20, a locking device 112 is provided. As can be seen from Fig. 4 and 13, the locking device 112 has a locking body 114 attached to the handle 26 via a pin 116. It also has a support body 118 attached to the handle 28 via a pin 120. This support body 118 has a lateral opening 122 in which the device 84 of the clamping device, which can only be rotated in one direction, is arranged. A locking member 124 is fixed to the support body 118 by means of a screw thread. The locking member 124 also extends over the locking body 114 and has a plurality of saw teeth 128 within a region of length "1". In addition, the locking member 124 has a groove 130 for locking in at each end of the region of the saw teeth 128. As illustrated in Fig. 13, the depth of this groove 130 is greater than that of the saw teeth 128.

A pawl 132 is mounted on the locking body 114 via a pin 134. Elastic preloading means 136a and 136b are attached to the opposite sides of the pawl 132, which exert a preloading force on the pawl 132 in order to force it into the central position, as shown in Fig. 13. A compression spring 138 is inserted between the locking body 114 and the support body 118 in order to press these components apart.

The operation of the locking device is illustrated in Fig. 14A-14C. The movement of the handles 26 and 28 towards each other also leads to a movement of the locking body 114 and the support body 118 towards each other. Consequently, the locking body 114 moves in the direction of arrow 138 in Fig. 14A relative to the locking member 124. As soon as the locking body 114 is displaced against the support body 118, a locking tip 140 of the locking pawl 132 engages the saw teeth 128. The movement of the locking body 114 causes the locking pawl 132 to pivot about the pin 134, whereby the elastic preloading means 136a is compressed. This compression increases the force which pushes the locking pawl 132 into its However, the depth of the saw teeth 128 is too small to allow the pawl to return to its center position.

Consequently, once the locking tip 114 has engaged the saw teeth 128, movement of the locking body 114 in any direction other than that indicated by arrow 138 in Fig. 14A is not possible. This prevents the handles 26 and 28 from moving away from each other as long as the pawl 132 engages the saw teeth 128.

If the handles 26 and 28 have been moved towards each other so far that the press mandrel 50 has pressed the press ring 24a completely onto the safety cable 20, the locking body 114 and the support body 118 are in the position shown in Fig. 14B. In this position, the locking tip 140 of the locking pawl 132 engages in the lower locking groove 130, the depth of which is sufficient to align the locking pawl 132 in its central position due to the pre-tensioning force of the elastic pre-tensioning means 136a.

As soon as the locking tip 140 engages in the locking groove 130, the locking body 114 and the support body 118 can move away from each other, as shown in Fig. 14C. The relative movement of the locking body 114 with respect to the support body 118 in the direction of arrow 142 brings the locking tip back into contact with the saw teeth 128. The depth of the saw teeth 128 causes the locking pawl 132 to pivot about the pin 134 so that the elastic preloading means 136b is compressed. The depth of the saw teeth 128 is, however, not sufficient to allow the locking pawl 132 to align in its central position. This prevents the locking body 114 from moving in any direction other than the direction shown by arrow 142. As soon as the locking body 114 has reached the position shown in Fig. 13, the upper locking groove 130 allows the pawl 132 to return to its central position by the spring forces of the elastic preloading means 136a and 136b.

The invention additionally includes a locking device to actively prevent movement of the handles 26 and 28 relative to one another until the predetermined tension is applied to the safety cable 20. This is achieved with the aid of a locking member 144 which can be screwed into the locking body 114 and slides into the support body 118. The locking member 144 has a circumferential recess 146 for locking which is aligned with the opening 148 running transversely through the support body 118 as soon as the handles 26 and 28 are in their fully open position and the locking body 114 is in the position shown in Fig. 13 (in which the locking tip 140 engages the locking groove 130). When the clamping device 82 is assembled and the device 84, which can only be rotated in one direction, is inserted into the opening 122 of the support body 118, the retaining pin 104 attached to the clamping knob 96 extends into the opening 148. The length of the retaining pin 104 is selected such that it extends into the opening 148 and into the recess 146 for locking as long as the clamping knob 96 is operatively connected to the clamping element 86 (i.e. as long as the drivers 92 engage in the driver recesses 100). This prevents any movement of the locking member 144 along its longitudinal axis, so that the handles 26 and 28 are prevented from moving towards one another.

As already mentioned, the sliding of the drivers 92 along the inclined ramps 102 leads to a movement of the Tension knob 96 and coupling plate 94 along the rotation axis 106 as soon as the cable has the desired tension. This axial movement pulls the pin 104 out of the connection with the circumferential recess 146 for locking, whereby the locking body and the support body together with the handles 26 and 28 can be moved towards each other again.

The foregoing description is for illustrative purposes only and should in no way be construed as a limitation on the invention, the scope of which is determined solely by the appended claims.

Claims (12)

1. Device for attaching a press ring to a strand element (20), e.g. B. a wire or a cable, with a tool body (26, 28), a means (48) connected thereto for positioning the press ring, which receives a strand element pulled through this press ring, with a strand tensioning device (82) for gripping a strand element and applying a desired tension to this strand element, which is drawn into a press ring positioned on the tool body and secured against longitudinal movements, with a means (50) contained in the tool body for pressing on press rings and with a manual actuating means with pivotally mounted handles (26a, 28a) which are operatively connected to the means for pressing on the press ring in order to move the means for pressing on the press ring between a retracted position and a pressing position in which it grips and presses on a press ring positioned on the means contained in the tool body, characterized by a means (112) which is operatively connected to the manual actuating means in order to prevent the Means for pressing the pressing ring slides back into the retracted position before it has reached its final pressing position when moving towards the pressing position, by a separating device for severing a tensioned strand element which is pulled through a pressing ring which is positioned in the tool body during the pressing process, the separating device having an elongated hole (48) for receiving the pressing ring as part of the means for positioning the pressing ring and extending partially through the tool body with the larger dimension of the hole in the direction of movement of the means for positioning the pressing ring, by an opening (70) for guiding the strand element in the tool body, which opening faces one side of the hole (48) and passes through the bottom thereof in order to guide the strand element through a pressing ring provided in the hole (48) and through the opening (70) for guiding the strand element in the tool body, the means (50) for pressing the pressing ring being arranged such that it Relative movements between a press ring in the hole (48) and the strand element guided in the opening (70) are made possible during the pressing on of a press ring, and by a shearing edge associated with the opening (70) for severing a strand element by the relative movement between the press ring and the opening (70) for guiding the strand element during the pressing on process of the press ring. 2. Device according to claim 1, characterized in that the means for pressing on a press ring is equipped with a press mandrel (50), the end piece (50b) of which is inserted into the immediately adjacent Hole for receiving the press ring is retractable, that the hole for receiving the press ring has a side wall for pressing on the press ring, against which a positioned press ring can be pressed, and that the opening for guiding the strand element passes through the hole for receiving the press ring at a point on the hole bottom which is closer to the end piece of the press mandrel than the side wall of the hole for pressing on the press ring. 3. Device according to one of the preceding claims, characterized in that a locking device (82) is attached to the means for tensioning strand elements and to the manual actuating means, with the aid of which the press mandrel is prevented from being moved into the pressing position before a predetermined tension acts on the strand element. 4. Device according to one of the preceding claims, characterized in that the means which prevents the means for pressing on a press ring from reaching the retracted position before it has reached its pressing position has a sawtooth-shaped ratchet mechanism (128, 132) which is operatively connected to the manual actuating means, the manual actuating means comprising the two handles (26a, 28a) and the means (30) which connects the two handles so that they can be moved towards and away from each other, that the ratchet mechanism has a latching body (114) which is arranged on one of the two handles, while a support body (118) is arranged on which a latching member (124) is arranged, into which the latching body (114) engages, wherein the locking member (124) has a plurality of saw teeth (128, 130) so that a pawl (132) which is operatively connected to the locking body can be latched into the saw teeth of the latch mechanism during the relative movement between the latch mechanism and the locking body when the handles move towards and away from each other. 5. Device according to claim 4, characterized in that the locking pawl (132) has a locking tip (140), that a means (134) for supporting the locking pawl (132) on the locking body (114) and a pre-tensioning means (136a, 126b) for aligning the locking pawl in the central position are provided, that the saw teeth of the locking mechanism contain a plurality of first saw teeth (128) of a small depth which is not sufficient to enable the locking pawl to align in its central position as soon as it engages in these saw teeth, and that the saw teeth of the locking mechanism have at least one groove (130) for engaging the locking pawl (132), the depth of which is sufficient to enable the locking pawl to align in its central position when it is engaged in this groove. 6. Device according to claim 3, characterized in that the locking device has a locking device with a locking member (144) which is operatively connected to one (26a) of the two handles, that the locking member has a recess (146) for latching, that a retaining pin (104) operatively connected to the other of the two handles (28a) is provided, and means (92, 100) for moving the retaining pin between an engagement position in which it engages in the recess in a locking manner to prevent relative movements of the two handles, and an unlocked position in which it is disengaged from the recess to enable relative movements of the two handles. 7. Device according to claim 1 or 2, characterized in that the tensioning device for the strand elements has a rotatable means (82) attached to the tool body for winding the strand elements, which comprises a strand gripper (86, 88) for gripping and winding a strand element pulled through a press ring positioned in the tool body, that a tension knob (96) is provided for rotating the strand gripper via a releasable coupling (92, 100) which operatively connects the strand gripper and the tension knob, so that the tension knob is released from the strand gripper as soon as the tension knob exerts a predetermined tension on the strand element. 8. Device according to claim 7, characterized in that the coupling has at least one driving recess (100) with an inclined ramp (102) for the operative connection of the strand gripper with the clamping knob, that at least one driver (92) is attached to the corresponding part of the strand gripper or on the clamping knob in such a way as to engage in the at least one driving recess, that a pre-tensioning device (110) is provided for the flexible displacement of the driver into the at least one recess, so that the at least one driver enters into a drive connection with the at least one driving recess until the tension in a position gripped by the strand gripper opened and wound strand element, which is secured against longitudinal movements, reaches the predetermined tension in order to guide the at least one driver along the inclined ramp of the at least one recess and out of engagement with the at least one recess. 9. Device according to claim 8, characterized in that the pre-tensioning device has a tension regulating device (108) connected to the tensioning knob. 10. Device according to one of the preceding claims, characterized in that the means for positioning a press ring additionally has a storage (54) for receiving a plurality of press rings, and that means are provided for releasably securing the press ring holder to the tool body, wherein at least one press ring (24a) close to the tool body is in a position for pressing onto the strand element. 11. Device according to claim 10, characterized in that the storage (54) for press rings is elongated and has a side (52) adapted for connection to the tool body, as well as a means (64) for urging the stored press rings against this side of the holder. 12. Device according to claim 1, characterized in that the manual actuating means comprises a bearing pin (30) on which the two handles are mounted so as to be movable relative to and from each other, that the means for positioning a press ring comprises a long elongated housing (46) with a proximal end (46a) and an outer end (46b) in which the means for positioning the press ring is located in the form of a hole (48) suitable for receiving and positioning a press ring and into which the outer end (50b) of the press mandrel (50) projects, the press mandrel being located inside the elongated housing so that the outer end of the press mandrel in its pressing position projects into the hole at the outer end of the elongated housing, and that a means moves the press mandrel at least in the direction of the pressing position when the handles are operated.