Abstract:
A power tool for tightening and loosening a bolt connected with a nut and a washer arranged so that the nut banks with one of its sides onto one of washer faces, the power tool comprising a housing, drive means accommodated in the housing, and at least two coaxial connecting means including a first connecting means provided for engaging and turning the nut and subjected to a turning force in one direction, and a second connecting means subjected to a turning force in an opposite direction, the coaxial connecting means being formed so that one of the coaxial connecting means is being turned while the other of the two coaxial connecting means stand still depending on a turning friction encountered as a result of one being connected with the washer while the other one is connected with the nut, or the result of one being connected with the bolt and the other one is connected with the nut, or as a result of one being connected with a reaction arm adapted to abut against an adjacent stationary object while the other one is connected with the nut.

Description:
BACKGROUND OF THE INVENTION 
     The present relates to power tools for tightening and loosening threaded connectors, such as bolts provided with nuts and washers. 
     It is known that most pneumatic, hydraulic or manually operated torque tools have a smaller operating radius than the nut placed on for tightening. It is also known that the industry is trying to build smaller equipment despite higher pressures and bigger loads. 
     U.S. Pat. No. 5,318,393 discloses a nut which is composed of two sleeves surrounding the bolt. Its diameter can not be reduced relative to the nut it replaces. A tensioning bolt disclosed in my U.S. patent application Ser. No. 091033,790 filed on Mar. 3, 1998 makes feasible to reduce the outside diameter of the nut below 1.5 times the bolt diameter. This allows the manufacturer to put the bolts closer together so as to obtain a better compression flow on the flange or casing. By placing the bolts closer together, more and thus smaller bolts can be applied to obtain the desired compression, especially since the preset, desired residual load can be obtained very accurately. 
     For tensioning of a bolt, a turning action force is applied by a power tool, and at the same time a reaction force must be applied which counteracts the turning action force. It is desirable to provide possibilities to apply the reaction force on various parts of the threaded fasteners, such as bolts provided with nuts and washers. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of present invention to provide a power tool which is a further improvement of the existing power tools for tightening or loosening bolts provided with washers and nuts. 
     In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a power tool for tightening and loosening a bolt having a nut and a washer arranged so that the nut banks with one of its sides onto one of washer faces, the power tool comprising A power tool for tightening and loosening a bolt connected with a nut and a washer arranged so that the nut banks with one of its sides onto one of washer faces, the power tool comprising a housing, drive means accommodated in the housing, and at least two coaxial connecting means including a first connecting means provided for engaging and turning the nut and subjected to a turning force in one direction, and a second connecting means subjected to a turning force in an opposite direction, the coaxial connecting means being formed so that one of the coaxial connecting means is being turned while the other of the two coaxial connecting means stand still depending on a turning friction encountered as a result of one being connected with the washer while the other one is connected with the nut, or the result of one being connected with the bolt and the other one is connected with the nut, or as a result of one being connected with a reaction arm adapted to abut against an adjacent stationary object while the other one is connected with the nut. 
     When the power tool is designed in accordance with the present invention, then during tightening or loosening a threaded connector an active turning force is applied to the nut of the bolt, while a reaction force can be applied by the tool directly to the bolt so that the action force, turns around it, or it can be indirectly applied to the bolt through the washer which is connected to the bolt so that the action force turns inside the applied reaction force or the reaction force can be applied as a result of a connection to a reaction arm that abuts against an adjacent stationary object. 
     The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1 and 2 are views showing a lever-type power tool in accordance with the present invention, which is provided for tightening or loosening a bolt having a washer and a nut, with application of a reaction force to the washer in FIG.  1  and to the bolt in FIG. 2; 
     FIGS. 3 and 4 are views showing a rotary motor-type power tool for tightening and loosening a bolt provided with a washer and a nut, with application of a reaction force to the washer in FIG.  3  and to the bolt in FIG. 4; and 
     FIG. 5 is a view showing a power tool for tightening and loosening a bolt, which is provided with a reaction arm adapted to abut against an adjacent stationary object to produce a reaction force. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A power tool shown in FIG. 1 is a lever-type power tool. It has drive means formed for example as a well known hydraulic drive which during a displacement of a piston in a hydraulic cylinder turns a drive plate  2 , which in turn turns a ratchet  3  through a pawl-ratchet mechanism. The tool further has a housing extending perpendicular to the axis of the drive unit  1  and to an axis of the bolt. The housing is identified with reference numeral  4  and accommodates the hydraulic drive  1  and the drive plate  2  with the ratchet  3 . 
     The power tool is used for tightening or loosening a threaded connector which includes a bolt  5  extending through, for example, two parts P1 and P2. The bolt  5  has a main portion  5 ′ extending through the parts P1 and P2, a threaded portion  5 ″, and an intermediate portion  5 ′″ which can have a polygonal outer surface. The threaded connector further has a polygonal washer which is identified with reference numeral  6 . The polygonal washer has an inner polygonal opening which it is fitted on the polygonal portion  5 ′″ of the bolt  5 , and an outer polygonal surface. The threaded connector finally has a nut  7  which is formed as a conventional hexagonal nut having an inner threaded opening for screwing on an outer threaded surface of the portion  5 ″ of the bolt  5 , and also having an outer hexagonal surface. 
     The power tool further has first connecting means  8  for connecting the drive unit  1  with the nut  7 . The first connecting means  8  can be formed by a plurality of splines provided on an inner surface of the ratchet  3  and coaxial with an axis of the bolt  5 . First transmitting means is provided for transmitting a rotation of the ratchet  3  to the nut  7 . The first transmitting means include a stepped shaft  9  which has a first portion  9 ′ provided with a plurality of splines engaging with the splines of the first connecting means  8 , and a second square portion  9 ″ connected with a drive socket  10 . The drive socket  10  has a square opening with which it is fitted on the square portion  9 ″ of the shaft  9 , and a tubular portion provided with an inner hexagonal opening with which the socket  10  can be fitted on the outer hexagonal surface of the nut  7 . 
     The power tool further has second connecting means. The second connecting means include two selectively actuatable means. One of the selectively actuatable means is identified with reference numeral  11  and formed for example by a plurality of inner splines which are coaxial with the axis of the bolt. The inner splines  11  are located at one side of the housing as considered in an axial direction of the bolt. In particular, as can be seen from FIGS. 1 and 2, the inner splines  11  are located in the lower part of the housing  4 . The second connecting means further includes another selectively actuatable means which is identified with reference numeral  12  and formed for example by a plurality of inner splines which are coaxial to the axis of the bolt and located at an opposite side of the housing as considered in direction of the axis of the bolt, or in the upper part of the housing. The first connecting means  8  and the second connecting means  11 ,  12  are coaxial with one another. 
     As can be seen from FIG. 1, a transmitting means formed as a reaction socket  13  non-rotatably connect the selectively actuatable means  11  to the washer  6 . The transmitting means is formed as a reaction socket which has a portion  13 ′ provided with outer splines engaging with the inner splines of the selectively actuatable means  11 , and a portion  13 ″ having a hexagonal inner surface fitted on the hexagonal outer surface of the washer  6 . 
     As can be seen from FIG. 2, another transmitting member  14  non-rotatably connects the selectively actuatable means  12  with the bolt  5 . The transmitting member  14  is formed as a shaft having one portion  14 ′ provided with outer splines engaging with the inner splines of the selectively actuatable means  12  , and a portion  14 ″ provided with outer splines and engaging with inner splines formed in an end opening of the bolt  5 . 
     The lever-type power tool in accordance with the present invention operates in the following manner: 
     In the lever-type tool, such as for example a hydraulic wrench, with the tool housing perpendicular to the axis of the drive unit and the bolt axis, the tool housing can not turn around the bolt without hitting obstacles on the side of the application. Therefore, the tool housing has to remain stationary at all times. When it is desirable to apply an active turning force to the nut  7  and to apply a reaction force to the washer  6 , the embodiment shown in FIG. 1 is utilized. The drive unit  1  is activated and turns the drive plate  2 , the ratchet  3  is turned by the drive plate  2  and through the first connecting means  8  it turns the shaft  9  so that the drive socket  10  is turned, and the nut  7  engaged by the drive socket is turned. The reaction socket  13  is non rotatably connected to one side of the housing, in particular to the selectively actuatable means  11  of the second connecting means on the one hand, and non rotatably connected to the washer  6  on the other hand. The washer  6 , in turn, is non rotatably connected with the bolt  5  through the portion  5 ′″. As a result, a reaction force is applied to the bolt, while the active force is applied to the nut, the nut is turned, and the bolt is tensioned or relaxed in the parts P1 and P2, torsion-and side-load free. 
     When it is necessary to apply a reaction force directly to the bolt  5 , the embodiment of FIG. 2 is utilized. Here also, the nut  7  is turned by the drive socket  10  which is non-rotatably connected to the first connecting means  8  provided in the ratchet  3  which is turned in the drive plate  2  by the drive unit  1 . However, in contrast to the embodiments shown in FIG. 2, the shaft  14  which is non-rotatably connected with the selectively actuatable means  12  of the second connecting means provided on the opposite side of the housing  4  is directly non-rotatably connected by its portion  14 ″ with the bolt  5 . Therefore, during the operation of the tool only the nut turns, but the bolt does not turn and instead is tensioned or relaxed in the parts P1 and P2, torsion and side-load free. 
     FIGS. 3 and 4 show a rotary motor-type power tool with a housing  24  which has at least a part arranged coaxially with a drive axis. The tool is used also for tightening or loosening a bolt  5  having a washer  6  with an inner polygonal opening and an outer polygonal surface, and a standard hexagonal nut  7  with an inner thread and an outer polygonal surface. 
     The power tool is provided with first connecting means for connecting a not shown drive unit with the nut  7 . The first connecting means is identified with reference numeral  18  and formed as a polygonal projection connected with a turnable shaft or the like of the not shown drive unit. A first transferring member  20  which is formed as a drive socket has one portion provided with an inner polygonal opening engaging with the polygonal projection  18 , and another portion provided with an inner hexagonal opening engaging with the hexagonal outer surface of the nut  7 . 
     The tool further has second connecting means for non-rotatably connecting the housing  24  with the washer  6 . The second connecting means include one selectively actuatable means which is formed for example as a polygonal projection  21  of the housing  24 . transmitting member non-rotatably connects the selectively actuatable means with the washer  6 . It is formed as a reaction socket  23  having one portion provided with an inner polygonal opening for engaging the polygonal projection  21  of the housing, and another portion provided with a polygonal opening for engaging an outer polygonal surface of the washer  6 , as shown in FIG.  3 . 
     The second connecting means of the power tool shown in FIGS. 3 and 4 also has another selectively actuatable means  22  which is formed for example as a non-rotatable square projection connected to a non-rotatable part of the housing or the drive. A transmitting member  25  non-rotatably connects the selectively actuatable means  22  with the bolt  5 . The transmitting member  25  has one portion  25 ′ which is provided with an inner square opening for receiving the square projection of the selectively actuatable means  22 , and another polygonal portion  25 ′ which non-rotatably engages in a polygonal opening at an end of the bolt  5 . 
     The rotary motor-type power tool shown in FIGS. 3 and 4 operates in the following manner. When the drive unit of the tool is activated, it turns the polygonal projection  18  which forms the first connecting means and the drive socket  20 , which in turn turns the nut  7 . In the situation shown in FIG. 3, the reaction socket  23  non-rotatably connects the selectively actuatable means  21  with the washer  6 , which in turn is non-rotatably connected with the bolt  5 , so as to provide a reaction force indirectly through the washer  6 . As a result, the nut  7  is turned and the bolt  5  is tensioned or relaxed in the parts P1, P2, torsion and side-load free. If it is desirable to react on the bolt directly, the embodiment of FIG. 4 is utilized. Here the drive socket  20  connects the first connecting means  18  with the nut  7 , while the shaft  25  connects the selectively actuatable means  22  non-rotatably directly with the bolt  5  to provide a reaction force. As a result, the nut  7  is turned and the bolt is tensioned or relaxed in the parts P1, P2, torsion-and side-load free. 
     FIG. 5 shows a further embodiment of the tool in accordance with the present invention. The tool here is provided with a reaction arm  33 . The reaction arm  33  has one portion  33 ′ which is non-rotatably connectable, for example with the selectively actuatable means  11  of the second connecting means. It further has another portion  33 ″ which is adapted to abut against an adjacent stationary object. 
     The power tool shown in FIG. 5 operates in the following manner: 
     The drive unit  1  is activated and turns the drive plate  2 , the ratchet  3  is turned by the drive plate  2  and through the first connecting means  8  turns the shaft  9  so that the drive socket  10  is turned, and the nut  7  engaged by the drive socket is turned. The reaction arm  33  abuts against an adjacent stationary object, for example against a neighboring nut or the bolt. As a result, the reaction force is applied to the housing of the tool, while the active force is applied to the nut, the nut is turned and then bolt is tensioned or relaxed in the parts P1 and P2, torsion and side-load free. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as embodied in a power tool, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. 
     What is claimed as new and desired to be protected by letters patent is set forth in the appended claims: