Abstract:
A brake tensioning system and method are described herein for use on vehicles. The system includes a tool, and the method includes the use of the tool to effectuate tensioning of a brake system conveniently, accurately, and repeatably.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) of the filing date of U.S. provisional patent Application No. 61/638,334, filed Apr. 25, 2012, entitled “APPARATUS, SYSTEM AND METHOD FOR TENSIONING AN EMERGENCY BRAKE SYSTEM”, and of U.S. provisional patent Application No. 61/738,225, filed Dec. 17, 2012, entitled “APPARATUS, SYSTEM AND METHOD FOR TENSIONING AN EMERGENCY BRAKE SYSTEM”, both of which are hereby incorporated by reference as if fully disclosed herein. 
         [0002]    This application also incorporates by reference U.S. Pat. No. 7,819,042, filed Jul. 31, 2008, and entitled “System and Method for Tensioning an Emergency Brake System;” and U.S. Pat. No. 8,051,745, and entitled “Method and Apparatus for Tensioning an Emergency Brake System on a Vehicle,” both of which are incorporated by reference as if fully disclosed herein. 
     
    
     FIELD 
       [0003]    This disclosure relates to an apparatus, system and methods associated with the tensioning of an emergency brake system on a vehicle, and more particularly to a tool having an internal tensioning structure that includes a stationary load measuring structure and a movable nut retention assembly, which together act with a nut and cable components and an associated method to tension the brake system to the desired tension level. 
       BACKGROUND 
       [0004]    Conventional apparatus used in the assembly of emergency brake cable systems often require more than one person and more than one station on an assembly line for adequate installation and tensioning. Once the emergency brake cable system is initially installed, one assembly worker typically first tensions the system to the desired level, at which the voids are removed from the cable and the conduits through which the cable runs. At a second assembly position, a second assembly worker then typically reduces the tension in the system in a variety of ways so that the emergency brake cable system is not causing the brakes to be engaged. The existing systems require more than one assembly worker and more than one station, and thus are a relatively expensive endeavor. 
         [0005]    A further limitation of the existing brake cable system installation technology is that the tension in the cable system is typically measured by indirect methods, such as strain gauges and other types of transducers. This means that the actual tension in the brake cable system, which is important to the proper functioning of the emergency brake, is at best characterized and not directly known during the assembly process. This indirect tension measurement has limited measurement accuracy, and thus causes there to be a relatively wide variation in the ultimate tension at which the emergency brake cable system is assembled in a vehicle. This creates unwanted variations in the emergency brake cable system operation on the finished vehicle. 
         [0006]    Some other emergency brake tensioning systems have reduced the human element involved in the process by use of automated mechanisms. However, these systems use hydraulics or pneumatics as part of the process, which may lead to maintenance problems, cleanliness issues, tension measurement inaccuracies, and generally to a more complicated and inconvenient system. 
         [0007]    What is needed is an emergency brake cable tensioning method and apparatus that overcomes the above issues, and allows fewer resources to be used in tensioning the cable system, thus saving money in the assembly process and ultimately allowing automobiles to be manufactured more efficiently. In addition, what is needed is an emergency brake cable tensioning method and apparatus that allows the direct measurement of the tension of the brake cable system with relatively few moving parts, particularly in the load measurement structure, during brake cable assembly to allow the accurate tensioning of the emergency brake cable system for proper performance in the finished vehicle. These and other advantages provided by examples of the present disclosure will be recognized from the following description. 
       SUMMARY 
       [0008]    In overcoming the shortcomings noted above, an inventive tensioning tool and associated method are described herein that, among other things, selectively create a mechanical column coupling to allow for the accurate measurement of the tension developed in an emergency brake tensioning system. 
         [0009]    In one example, a tensioning tool for use in tensioning an emergency brake cable system for a vehicle is provided, the apparatus being driven by a rotational driver, and the brake system including a rotatable cable end. The apparatus includes a body, a rotating assembly positioned in the body for engaging the cable end, an engagement member at least partially external to the body and movable between a first position and a second position to secure and release the cable end, the rotating assembly stationarily positioned in the body and forming a load measurement column, wherein insertion of the cable end into rotating assembly and movement of the engagement member from the first position to the second position causes the cable end to be secured in the rotating assembly. Tensioning is performed and tension load measured without substantial axial movement of the load sensor. 
         [0010]    In another example, a tensioning tool for use in tensioning an emergency brake cable system for a vehicle is provided, the tool being driven by a rotational driver, and the brake system including a rotatable cable end. The tool includes a body; a first portion rotatably positioned in the body for engaging the cable end, the first portion including a locking mechanism for receiving the cable end, the locking mechanism movable between at least a first locked position and a second unlocked position; and a second portion movably positioned relative to the body and at least partially external to the body and operably engaging the locking mechanism. Upon insertion of a nut into the first portion, movement of the second portion to the second locked position secures the nut in the first portion. 
         [0011]    The first portion may be fixed in axial position relative to the body. The first portion may include an input shaft that rotates relative to the body. The first portion may be an elongated shaft having a front portion and a rear portion, the front portion of the shaft including the locking mechanism and defining a recess, the rear portion of the shaft extending through a load cell configured to remain substantially stationary relative to the body and operably bear upon a portion of the body when the shaft is engaged with the cable end. The rear portion of the shaft may extend through a bearing that allows rotation of the shaft relative to the body. The tool may include a gear operably engaged with a source of rotational movement and non-rotatably engaged with the shaft; and a thrust bearing operably engaging the gear and the load cell for allowing rotation of the gear while creating a compressive load on the load cell. The second portion may include an elongated actuator at least partially movable through the body; an engagement actuator operably engaged with the elongated actuator, the engagement actuator operable to actuate the locking mechanism between the locked and unlocked position, the engagement actuator movable relative to the input shaft. The elongated actuator may include an engagement tab that extends through a slot in the body and engages the engagement actuator. The engagement actuator may be a sleeve positioned at least partially interior of the body and at least partially surrounds at least a front portion of the first portion. 
         [0012]    In another example, a tensioning tool for use in tensioning an emergency brake cable system for a vehicle is provided, the tool being driven by a rotational driver, and the brake system including a rotatable cable end. The tool includes a front portion having a first axis and a shaft, the front portion configured to selectively secure and release the cable end, the shaft configured to rotate the cable end; a rear portion having a second axis, the rear portion including a gear train for rotating the shaft about a shaft centerline; the front and rear portions positioned offset from one another such that the first axis and the second axis are parallel to and spaced apart from one another, each of the first axis and the second axis are parallel to the shaft centerline. 
         [0013]    In another example, a tensioning tool for use in tensioning an emergency brake cable system for a vehicle is provided, the tool being driven by a rotational driver. The tool includes a rotatable shaft, a sleeve at least partially surrounding at least a portion of the shaft and slidable relative to the shaft, and an actuator rod laterally offset from the shaft and movable relative to the shaft, the actuator rod coupled to the sleeve and operable to slide the sleeve relative to the shaft. The tensioning tool may include a first gear meshingly engaged with a portion of the shaft. The tensioning tool may include a second gear operably engaged by the rotational driver, wherein the actuator rod extends laterally between the shaft and the second gear. The actuator rod may extend through an aperture formed in the first gear. A length of the actuator rod may overlap with a length of the shaft. The shaft may define a shoulder, and the tensioning tool may include a load cell at least partially surrounding at least a portion of the shaft axially between the shoulder and the sleeve. 
         [0014]    In another example, a method for engaging a tensioning tool with an emergency brake cable system for a vehicle is provided, the brake system including a rotatable cable end movable relative to a cable. The method includes receiving the cable end in the tool; moving an external portion of the tool to a first position to axially secure the cable end in the tool; tensioning the cable system by moving the cable end relative to the cable; and moving the external portion of the tool to a second position to axially release the cable end from the tool. 
         [0015]    In another example, a method for tensioning an emergency brake cable system for a vehicle is provided, the brake system including a rotatable cable end movable relative to a cable. The method includes securing the cable end in a recess formed in a tool; rotating a portion of the tool to rotate the cable end relative to the cable; measuring tension in the cable system by a sensor stationarily positioned within the tool; and releasing the cable end from the recess formed in the tool. 
         [0016]    In another example, a method for measuring and determining the apparent stiffness of a park brake cable system and adjusting tensioning force applied to the system based upon such determination in real time is provided. The method includes operably engaging a tensioning apparatus with a park brake cable of a park brake cable system, the tensioning apparatus including a housing that contains a load cell and attached to a programmable drive, the brake cable system including an equalizer adapted to balance tensions in at least two lengths of cable, wherein a nut is operably associated with a threaded rod, the nut including a surface for operably engaging the equalizer; securing the nut within the apparatus; positioning the surface of the nut away from the equalizer a specified distance; driving the nut with the tensioning apparatus to tension the park brake cable to a first tension level sufficient to remove voids from the cable system; measuring the first tension level using the load cell; relieving the tension in the park brake cable to a second level approaching zero by driving the tensioning apparatus in reverse; tensioning the cable to a third tension level with the tensioning apparatus, the third tension level being higher than the second tension level; measuring the third tension level with the load cell; tensioning the cable to a fourth tension level with the tensioning apparatus, the fourth tension level being higher than the third tension level; measuring the fourth tension level with the load cell; based on the speed of rotation of the drive and time elapsed, or using total angle of rotation, determining the actual distance traveled by the nut between the third and fourth tension levels; based on the distance traveled, formulating an algorithm that represents the slope of the tension travel relationship or characteristic stiffness of the cable system; based on a desired final residual tension in the cable system, determining the number of reverse revolutions of the nut to achieve the desired final residual tension; driving the nut in reverse the required number of reverse revolutions with the tensioning apparatus; and operably disengaging the tensioning apparatus from the end of the park brake cable, wherein the nut returns to the equalizer and substantially maintains the desired residual tension in the park brake cable system. 
         [0017]    In another example, a method of obtaining a desired residual level of tension in a park brake cable system is provided. The method includes determining a tension/travel curve between a lower first tension and a higher second tension by moving a nut along a threaded rod; and using the tension/travel curve to determine a distance to move the nut along the threaded rod to a desired residual level of tension. 
         [0018]    While multiple examples are disclosed herein, still other examples will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative examples of the disclosure. As will be realized by those of ordinary skill in the art upon reading the following disclosure, the disclosed examples are capable of modifications in various aspects, all without departing from the spirit and scope of the claimed invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
         [0019]    This summary of the disclosure is given to aid understanding, and one of skill in the art will understand that each of the various aspects and features of the disclosure may advantageously be used separately in some instances, or in combination with other aspects and features of the disclosure in other instances. Accordingly, while the disclosure is presented in terms of examples, it should be appreciated that individual aspects of any example can be claimed separately or in combination with aspects and features of that example or any other example. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  shows a diagram of an example emergency brake cable system to be tensioned by any of the example tensioning tools and associated methods described herein. 
           [0021]      FIG. 2  is a perspective view of an example tensioning tool, prior to mounting a nut in the end effector. 
           [0022]      FIG. 3  is a side view of the tensioning tool of  FIG. 2 . 
           [0023]      FIG. 4  is an end view of the tensioning tool of  FIG. 3 . 
           [0024]      FIG. 5  is a section view taken along line  5 - 5  of  FIG. 4 , showing the tensioning tool of  FIG. 2  prior to receiving a nut in the end effector, and with the input shaft and piston assembly in their forward-most position. 
           [0025]      FIG. 6  is a section view similar to that of  FIG. 5 , but after the nut has been inserted into the end effector, and prior to moving the input shaft and piston assembly rearwardly relative to the barrel and housing. 
           [0026]      FIG. 7  is a section view similar to that of  FIG. 6 , but after the input shaft and piston assembly have been moved rearwardly into the barrel and housing, causing the release ring to move forward and actuate the locking mechanism to form a rigid mechanical column structure. 
           [0027]      FIG. 8  is a section view similar to that of  FIG. 7 , but after the nut runner has been actuated to rotate the input shaft to turn the nut up the threaded rod and tension the associated cable system. 
           [0028]      FIGS. 9   a  and  9   b  are an exploded view of the tensioning tool of  FIG. 2  showing the components associated therewith as described with respect to various figures listed above. 
           [0029]      FIG. 10  shows a section view similar to that of  FIG. 5 , for another example tensioning tool, where the release ring has a different structure for engaging the barrel in its forward-most position. 
           [0030]      FIG. 11  shows a section view similar to that of  FIG. 8 , for the tensioning tool shown in  FIG. 10 , with the nut positioned in the end effector and having been run up the threaded rod to tension the associated emergency brake cable system. 
           [0031]      FIG. 12  shows a front perspective view of a tensioning tool of another example. 
           [0032]      FIG. 13  is a rear perspective view of the tensioning tool of  FIG. 12 . 
           [0033]      FIG. 14  shows a portion of the housing of the tensioning tool of  FIG. 12 . 
           [0034]      FIG. 15  shows a rear portion of the housing of the tensioning tool of  FIG. 12 . 
           [0035]      FIG. 16  shows a side elevation view of  FIG. 14 . 
           [0036]      FIG. 17  shows an enlarged front perspective view of the release fork of the tensioning tool of  FIG. 12 . 
           [0037]      FIG. 18  shows an enlarged rear perspective view of the release fork of  FIG. 17 . 
           [0038]      FIG. 19  shows an enlarged high-angle perspective view of the release fork of  FIG. 17 . 
           [0039]      FIG. 20  shows a section view taken along lines  20 - 20  of  FIG. 12 . 
           [0040]      FIG. 21  shows a section similar to  FIG. 20 , with a nut positioned in the end effector, and the tool engaged with the equalizer. 
           [0041]      FIG. 22  shows a section similar to  FIG. 21 , with the nut retracted into the input shaft and being tensioned. 
           [0042]      FIG. 23  shows a front perspective view of another example of the brake cable tensioning tool. 
           [0043]      FIG. 24  shows a rear perspective view of the tensioning tool of  FIG. 23 . 
           [0044]      FIG. 25  shows an enlarged rear perspective view of the tensioning tool of  FIG. 23 . 
           [0045]      FIG. 26  shows a section view taken along line  26 - 26  of  FIG. 23 . 
           [0046]      FIG. 27  shows an enlarged section similar to portions of  FIG. 26 , showing the end effector of the input shaft. 
           [0047]      FIG. 28  shows an enlarged section similar to portions of  FIG. 26 , showing the input shaft, load cell column, and anchor against the housing, and the gear train and release rod. 
           [0048]      FIG. 29  shows an enlarged section similar to portions of  FIG. 26 , showing the rear portion including the gear train and release rod. 
           [0049]      FIG. 30  is a section similar to  FIG. 26 , showing a nut positioned in the end effector. 
           [0050]      FIG. 31  is a section similar to  FIG. 30 , showing a nut secured in the end effector by a float sleeve at its forward position. 
           [0051]      FIG. 32  is a section similar to  FIG. 31 , showing the nut threaded onto the rod by the rotation of the input shaft, the nut positioned at a location to create a high level of tension. 
           [0052]      FIG. 33  is a section similar to  FIG. 32 , showing the nut moved toward the end of the threaded rod to lessen the tension in the cable system. 
           [0053]      FIG. 34  is a section similar to  FIG. 33 , showing the nut released from the end effector and engaging the equalizer after being tensioned. 
           [0054]      FIG. 35  is a section similar to  FIG. 34 , showing the nut removed from the end effector. 
           [0055]      FIGS. 36 and 37  are output graphs that each show an output of a brake cable system during the tensioning steps, and in particular show the forward tension time between tension levels T 3  to T 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0056]    The instant disclosure generally provides a tensioning apparatus attachment to a drive tool, such as a ratchet, nut runner, or other type of wrench, used for tensioning the park brake cable system of an automobile during assembly.  FIG. 1  illustrates a schematic of a system utilizing an example attachment. In particular,  FIG. 1  illustrates a side pull park brake system  100 . The park brake system  100  includes a front cable  102 , a rear right cable  104 , and a rear left cable  106 . The front cable  102  is attached to a pull handle  108  at its first end and a connector clip  110  at its second end. The connector clip  110  attaches to the front end of the rear right cable  104 , which extends towards and attaches to the brake assembly  112  on the rear right wheel. The rear left cable  106  is attached to the front cable  102  through a reactive conduit system  114  as is well-known in the art. The front end of the rear left cable  106  is attached to one end of an equalizer bracket  116 , which is in turn attached to and part of the reactive conduit system  114 . The rear end of the rear left cable  106  is attached to the rear left brake assembly  118 . The front cable  102  and the rear right cable  104  may be one continuous cable; however, it may be more convenient for the front and rear cables  102 ,  104  to be separate from one another for ease of manufacturing. 
         [0057]    The operation of a reactive conduit side pull park brake system  100  is well-known. The problem solved by the present disclosure is that the tensioning of the system during assembly is made significantly more convenient by use of a tensioning apparatus in combination with a drive means, which results in an accurately tensioned cable system. In addition, the use of a tensioning apparatus may reduce overall costs of building the park brake system into a vehicle during assembly, improve quality, and reduce labor costs. While described in connection with a side pull park brake system, the tensioning apparatus may be utilized on a center pull park brake system or other brake systems. 
         [0058]    The front end of the rear left cable  106  includes a threaded rod  124  of approximately one-half inch to four inches long. The free end of the threaded rod is positioned through an aperture in the end of the equalizer bracket  116  and a nut  126  is positioned on the free end of the threaded rod  124  in order to hold the threaded rod in attachment with the equalizer bracket. The tensioning apparatus  120  and the drive means  122  are used to tension the entire park brake cable system to remove voids and stretch from the various park brake cables so that the park brake cable system  100  functions appropriately during the use of the vehicle, and to lessen slackening or loosening. The particular tensioning apparatus  120  by itself, or in combination with the drive means  122  (collectively referred to as the “park brake tensioning system”), may be used together to tension the park brake system. 
         [0059]    One of the brake system assembly benefits provided by the park brake tensioning system involves the utilization of a relief distance. The relief distance is the distance that the end of the cable being used to tension the system is allowed to relax after the tensioning of the system has been performed. Relaxation of the tension releases the engaged brakes from the drums, or the calipers from the disk (for disk brakes), just enough to allow the wheel to turn freely while keeping a sufficient level of tension in the park brake system in order to easily engage the parking brake. 
         [0060]    Note that the tensioning method and apparatus of the present invention can be implemented at any place in a park brake cable system where there is an action/reaction point, such as where the park brake handle attaches to the front cable, where the rear cable is attached to the brake assemblies, where the front cable and rear right cable attach together, or other locations. 
         [0061]    Referring still to  FIG. 1 , the tensioning apparatus  120 , including the nut runner  122 , is interfaced with a control system  128  to monitor and control the operation of the tensioning apparatus  120 . The control system  128  works to measure tension in the system and control the operation of the nut runner  122  to increase, decrease, or maintain tension. The system in which the tool is utilized includes (in a non-limiting way) the tool  120 , the nut runner  122 , and the control system  128 . The control system  128  is in operable communication with a load cell (described below), or other load or tension measurement device or component associated with the tensioning apparatus  120 , to receive and/or send signals there from and thereto. The control system  128  is also in operable communication with the nut runner  122  to receive and/or send signals there from and thereto. The control system  128  may include software, CPU, memory, inputs and outputs, digital or analog components, displays and data outputs, and programmable logic units to facilitate controlling and feedback instructions and data collection and analysis from the system for operation of the tensioning tool  120 . The control system  128  may include the ability to receive from and output to a data and/or display signal and/or to a wired or wireless network for observing and operating of the control system. Alternatively, the nut runner  122  may be controlled manually. 
         [0062]    As shown in  FIGS. 2 ,  3  and  4 , the tensioning tool  120  includes a main body  130  having a barrel  132  operably associated with a housing  134 . The tensioning tool  120  includes a release ring  136  movable relative to the housing  134  and the barrel  132 , and in this embodiment is externally disposed relative to the housing. The release ring  136  may be internal to or a combination of internal and external to the housing. The release ring  136  allows the relative motion of internal portions of the barrel  132  and housing  134  with respect to the barrel and housing. 
         [0063]    The nut  126 , or cable end, is attached to the threaded rod  124  as part of the cable assembly in an emergency park brake system. The threaded rod  124  extends through the equalizer bracket  116 , with the nut  126  keeping the rod  124  (and cable  106  to which it is attached) from being pulled back through the bracket  116  by the tension in the cable. The equalizer bracket  116 , as explained above, is attached to the reactive conduit of the emergency brake system, or it may be attached directly to the frame of a vehicle, depending on the design of the emergency braking system. 
         [0064]    In general, the nut  126  is first threaded on the rod  124 . The nut  126  is then positioned into the end effector  138  in the barrel  132  of the tensioning tool  120 . The nut  126  is then pushed into the end effector  138  to push the end effector and the nut further into the barrel  132 . This causes the structure internal to the barrel  132  to move rearwardly (described in more detail below), freeing the release ring  136  to move forwardly and lock the nut  126  in the end effector  138  and a portion of the internal structure in engagement with the barrel  132  and the housing  134 . This locking mechanism causes the internal structure, housing and barrel to form a rigid, mechanical structure or column against which to tension the emergency brake system. This mechanical structure is effectively a column oriented along the length of the cable, which will provide a very incompressible system against which to measure the tension. Because generally in this example the system does not rely on any pneumatic or hydraulic components to maintain its incompressibility, it may be simpler, more reliable, and have less associated support equipment and related maintenance than those that do. 
         [0065]    With the end of the barrel  132  resting on the equalizer bracket  116 , tensioning of the cable system can then begin by actuating the nut runner  122 , which in turn rotates the end effector  138  and runs the nut  126  up the threaded rod  124 . When the desired tension is reached, the release ring  136  is manually pulled rearwardly relative to the housing  134 , which unlocks the internal structure and allows the end effector  138  and the nut  126  to move toward the equalizer bracket  116  and release the nut  126  from the end effector  138 . 
         [0066]    In general, with reference to  FIGS. 5-9 , an example tensioning tool and operating method is shown. The housing  134  is generally cylindrical in shape, with portions having various dimensions, and defining an internal cavity  140 . A front portion  142  of the housing  134  has a reduced external and internal dimension and receives the release ring  136 , as well as a rear end  144  of the barrel  132 . A shoulder  148  is formed between the rear portion  146  and the front portion  142  of the housing  134  where the internal and external diameters transition. The release ring  136  is mounted circumferentially around the front portion  142 , and is axially slidable relative to the housing  134 . The front portion  142  of the housing  134  includes at least one aperture  150  formed therein. If more than one aperture is formed, they are formed annularly around the front portion  142 . Each aperture  150  receives a locking ball  152 , which moves radially through the aperture based on the relative positioning of the locking ring  126  and piston assembly  154 , as is described in more detail below. The rear end  144  of the barrel  132  is threadedly engaged with an externally threaded terminal end of the front portion  142 . An external shoulder  156  on the front portion  142  engages an internal shoulder  158  on the rear end  144  of the barrel  132  to seat the two together. The rear portion  146  of the housing  134 , as noted above, includes a slot  160  formed in its sidewall for allowing axial motion of certain components that are positioned in the housing and extend through the slot to outside the housing. An aperture  162  is also formed to allow the nut runner to be inserted into the housing to actuate the internal components. 
         [0067]    Still referring to  FIG. 5 , the barrel  132  is shown engaged at its rear end  144  with the front portion  142  of the housing  134 . The barrel  132  has an elongated cylindrical shape, and includes a front end  164  opposite its rear end  144 . The barrel  132  also defines an internal cavity  166  extending from one end to the other. The barrel  132  is lined by a sheath including two collar lengths positioned end to end. Each collar length has a first end and a second end. The front collar length  168  has a first end  170  adjacent the front end  164  of the barrel  132 , and a second end  172  adjacent the first end  174  of the rear collar length  176 . The first end  170  of the front collar length  168  has a first larger interior diameter  178 , transitioning by a nut-engagement shoulder  180  or cam surface to a second smaller interior diameter. This internal region formed by the first larger interior diameter  178  is utilized for grasping the nut  126  using a series of nut engagement balls  182 , as described later. 
         [0068]    The rear collar length  176  has a first end  174  adjacent the second end  172  of the front collar length  168 , and a second end  184  adjacent the threaded engagement between the rear end  144  of the barrel  132  and the front portion  142  of the housing  134 . The second end  184  of the rear collar length  176  has an outwardly extending flange  186  to allow it to be seated against a shoulder  188  formed adjacent the rear end  144  of the barrel  132  by the terminal end of the front portion  142  of the housing  134  when the barrel  132  and the housing  134  are engaged together as shown in  FIG. 5 . The rear terminal end of the barrel  132  forms a substantially annular axial extending lip  190  that has a larger internal diameter than the front  142  of the housing  134 , and is spaced away there from to form an annular space. The axial lip  190  extends rearwardly over the front portion  142  of the housing, and rearwardly from the threaded engagement between the barrel  132  and the housing  134 . A washer  192  may be positioned between the first end  170  of the front collar length  168  and the front end  164  of the barrel  132 . 
         [0069]    Still referring to  FIGS. 5-9 , the housing  134  forms an anchor structure relative to which some of the internal components move in one condition, and to which some of the internal components are locked in another condition. The internal components include an input shaft  194 , a piston  196 , a locking structure  198 , a tension measurement structure  200 , and a nut runner engagement portion  202 . The input shaft  194  is positioned in the barrel  132 , inside the sheath, and is rotatable and axially movable relative thereto. The front end  204  of the input shaft  194  includes an end effector  138 , which receives the nut  126  and threaded rod  124  (see  FIGS. 6 ,  7 ,  8 , and  9 ). The end effector  138  has at least one aperture  206  formed therein to receive a corresponding nut engagement ball  182  and allow the ball to move radially in and out of the aperture in conjunction with the relative position of the input shaft  194  along the length of the barrel  132 . The end effector  138  acts with the nut engagement balls  182  and the nut engagement cam  180  to securely trap (both axially and rotationally) the nut in the end effector when desired, and is described in greater detail below. 
         [0070]    The input shaft  194  extends from a front end  204  adjacent the front end  164  of the barrel  132  along the length of the barrel and through the housing  134  to a rear end  208  in operable engagement with the nut runner  122 . The rear end  208  of the input shaft  194  is operably associated with the nut runner  122 , which acts to selectively rotate the input shaft  194  clockwise or counter clockwise, or to stop rotation, depending on the controls received from the control system  128 . This rear end  208  of the input shaft  194  may move relative to the nut runner  122 , and may move into and out of operable engagement therewith, or may move relative to the nut runner  122  and stay in operable engagement therewith through the entirety of the movement. 
         [0071]    Along a central section of the input shaft  194 , near the rear end  144  of the barrel, prior to entering the front portion  142  of the housing  134 , the input shaft  194  forms a circumferential shoulder  210  where the outer diameter of the input shaft  194  is reduced. The input shaft  194  rotates along its longitudinal axis relative to the housing  134  and the barrel  132 , under the control of the nut runner  122 . 
         [0072]    The piston  196  is received over the input shaft  194 , and is positioned inside the first  142  and second  146  portions of the housing  134 . The piston  196  may be fixed in its position relative to the length of the input shaft, but the input shaft  194  and the piston  196  may rotate relative to one another. The piston  196  has a front portion  212  and a rear portion  214 . The front portion  212  is generally coextensive with the front portion  142  of the housing and also fits closely around the external surface of the input shaft  194 . The rear portion  214  is spaced away from the external surface of the input shaft  194 , and the circumferential piston walls  216  fit closely with the internal wall of the rear portion  146  of the housing  134 , forming an annular space therein. Corresponding internal and external shoulders  218  are formed where the piston transitions from the front  212  to the rear  214  piston portion. 
         [0073]    The front end of the front portion  212  of the piston  196  engages a spacer sleeve  220  positioned on the outside of the input shaft  194 . One end of the spacer sleeve  220  engages the shoulder  210  on the outside of the input shaft  194 , and the other, rear end of the spacer sleeve  220  abuts the front portion  212  of the piston  196 . The front portion  212  of the piston  196 , on its external circumference, forms an annular recess  222 . The rear end of the annular recess forms an annular shoulder  224  to work in conjunction with the locking balls  152  to fix the piston  196  and input shaft  194  relative to the housing  134 , as is explained in more detail below. 
         [0074]    Referring still to  FIGS. 5-10 , and particularly  FIG. 6 , various components are positioned within the annular space between the walls  216  of the rear portion of the piston  196  and the input shaft  194 , referred to above as the piston assembly  154 . A load cell  200  is received on a bearing on the input shaft  194  in order to allow the input shaft to rotate relative to the load cell, and the load cell abuts on its front side the internal shoulder  218  of the piston  196 . The internal shoulder  218  of the piston  196  is the surface against which the load cell is compressed to measure the tension in the cable system. In one embodiment the load cell is concentrically positioned around the input shaft  194 , and because of this annular orientation around the input shaft  194 , the load cell  200  measures the load in-line with the application of the load by the input shaft, and generally in-line with the terminal end of the cable system to which the input shaft  194  is attached. 
         [0075]    An assembly of items that generally combine together to apply a load responsive of the cable tension to the load cell  200 , called the compressive component  225 , are described hereafter. In one example described herein, an axial collar  226  abuts the rear surface of the load cell  200  and extends along the walls  216  of the second portion  214  of the piston  196 . Structure associated with the piston assembly  154  external to the housing  134  may be attached to the collar  226 , such as by a screw  228 , and extend through the slot  160  in the housing  134 . This external structure thus may move along with the piston  196 . This structure may include the input/output communication cable  230  for the load cell  200 , among other items. A radial collar  232  is positioned about the input shaft  194  inside the rear end of the axial collar  226 . The front face of the radial collar  232  engages a facial bearing  234 . The radial collar  232  may rotate with the input shaft  194  while in engagement with the facial bearing  234 . The facial bearing  234  helps isolate the rotation of the radial collar  232  with the input shaft  194  from the load cell  200 . The facial bearing  234  is supported by a mount  236 , which may itself be mounted on a bearing on the input shaft  194 . The front surface  237  of the mount  236  may engage the rear surface of the load cell. A retaining collar  238  is mounted on the input shaft  194  and is held in axial position against the radial collar  232  by a retainer  240  and snap ring washer  242 . This compressive component  225 , made up of elements described herein that apply a load to the load cell, acts to transmit the load applied to the input shaft to the load cell. 
         [0076]    The compression applied to the load cell  200  is derived, in one embodiment, from the cable pulling on the input shaft  194  as the cable system is tensioned. As the input shaft is pulled to the left (in the orientation of  FIG. 6 ), the compressive component  225  applies a load to the load cell  200 . In more detail of this particular example, the snap ring washer and retainer  240  apply a force in that direction to the retaining collar  238 , which in turn applies a load in that direction to the radial collar  232 , which in turn applies a load in that direction to the facial bearing  234  and mount  236 , which in turn apply the load in that direction to the load cell  200 . The load cell abuts on its front surface the shoulder structure  218  of the piston  196 , and is thus compressed between the load applied as described above and the shoulder structure  218 . The piston  196 , being locked to the housing by the structure described herein, provides a solid base against which the load cell may be compressed. The load cell creates a signal indicative of the load (cable tension) and transmits that signal along line  230  to the control system  128  for storage, display, analysis and/or possible control of the nut runner and tensioning tool. 
         [0077]    Various other structures may be employed to create the compressive component  225  to apply a load to the load cell  200  and allow the input shaft  194  to rotate. For instance, and in a non-limiting manner, the retaining collar  238  may be circumferentially mounted on the input shaft, similar to the radial collar  232 . It may turn with the input shaft or be rotationally independent of the input shaft. It may extend all or partially through the input shaft, as shown, acting in part as a pin, as a manner of mounting on the input shaft. The radial collar  232 , facial seal  234 , and/or other components may also not be included. Also, the axial collar  226  may be axially movable relative to the piston walls and be operably associated with the retaining collar  240  and snap ring  242  and be loaded thereby (ultimately by the tension load on the input shaft as described above) and in turn apply a load, along with or separate from the mount  236 , to the load cell  200 . The axial collar may also be cup-shaped and rotatably mounted on the input shaft, and axially movable with respect to the piston walls, with the mount  236 , facial bearing  234  and radial collar  232  mounted relatively within the cup. When the load is applied through the retaining collar to the radial collar, the facial bearing and to the cup-shaped axial collar, the bottom of the cup-shaped axial collar may apply the compressive load to the load cell  200 . Further, all of the structure described above may not be required to create the resulting load on the load cell. Additionally, other structure may be added if desired. 
         [0078]    The compressive component  225  may also include, in another example, the radial collar  232 , mount  236  and any additional structure retained on the input shaft in an axial location by a pin positioned through the input shaft. When the tension is applied to the input shaft, the pin holds the compressive component  225  in axial position on the input shaft in order to apply the tension load to the load cell. The compressive component  225  that engage the load cell  200  may be positioned annularly around the input shaft to engage the load cell  200  about its annular shape. The portions of the compressive component that are inside the axial collar  226  may rotate with the input shaft, or may not rotate with the input shaft. 
         [0079]    As can be appreciated from the above description, the structure of the compressive component  225  associated with the piston assembly and input shaft  194  may have many forms different than that described above to perform the same or similar function of allowing the input shaft to rotate relative to the piston, and apply a load to a load cell for measuring the tension in the cable system during the tensioning process. Further, the load cell  200  may be positioned in the main body, and operably associated with the main body or piston  196  in other orientations to measure the load. The load cell may also be replaced with another type of load sensor that works to measure load in either compression, tension, lateral deflection or the like. 
         [0080]    The rear end  208  of the input shaft  194 , as mentioned above, is arranged to engage the drive end of the nut runner  122 , and may axially slide there along as needed when the input shaft  194  is moved axially, as explained below. The particular engagement arrangement of the nut runner  122  and the input shaft is not critical to the nature of the invention described herein. 
         [0081]    Continuing to refer to  FIG. 6 , a return spring  244  is positioned in the second portion  146  of the housing  134  to urge the piston  196  forwardly in the housing  134 . In this instance the spring  244  is positioned between a portion of the nut runner  122  fixed by a snap washer  245  to the rear of the housing  134 , and the axial collar  226 . The return spring  244  compresses as the input shaft  194  and piston  196  are moved axially rearwardly, and continually biases the piston  196  and input shaft  194  forwardly. This forward biasing force will be described in more detail hereafter. 
         [0082]    Referring still generally to  FIGS. 5-8 , and particularly to  FIG. 7  for clarity, the release ring  136  is positioned around the front portion  142  of the housing  134  and moves axially on the along the front portion  142 . The release ring  136  includes an annular inner lip  246  and an annular outer lip  248  extending forwardly, with a gap  250  formed there between (See  FIG. 6 ). The gap  250  receives the rear lip  190  formed on the barrel  132 . An annular recess  252  is formed facing rearwardly to receive and seat the front end of the release spring  254 . The rear end of the release spring  254  engages the outer shoulder  148  of the housing  134 . A rear portion of the release ring  136  extends over and moves relative to the second portion  146  of the housing  134  to help contain the release spring  254 . The radially inward surface  256  of the inner lip  246  acts to retain the locking ball  152  in the aperture  150  in the first portion  142  of the housing  134 . A cam or shoulder surface  258  is formed around the base of the inner lip  246  to encourage the locking ball  152  to move radially inwardly through the aperture  150  as the release ring  136  is moved forward relative to the housing  134 , as is described below. 
         [0083]    The release mechanism, in this instance a release ring  136 , may move from a forward position to a rearward position along the front portion  142  of the housing  134 . The release spring  254  biases the release ring  136  towards the forward position. In the forward-most position, the release ring abuts the annular lip  190  on the barrel  132 . (See  FIG. 7 ). The release ring  136  may also take the form of a lever or other structure not in the form of a ring or circle. 
         [0084]    The input shaft  194  is operably engaged with the piston  196  to move the piston rearwardly when the input shaft  194  moves rearwardly (toward the nut runner  122 ). The input shaft  194  may be operably engaged with the piston  196  to move the piston forwardly upon forward movement of the input shaft  194 . 
         [0085]    The operation of the tensioning apparatus  120  is now described with respect to  FIGS. 5-8 . After the nut  126  is threaded onto the end of the threaded rod  124  as described above, the nut  126  is positioned in the end effector  138  and is engaged with the input shaft  194  to be turned by the input shaft as the input shaft is turned by the nut runner  122 . Prior to insertion of the nut  126 , the tensioning apparatus appears in the ready state shown in  FIG. 5 . In the ready state, the input shaft  194  is positioned forwardly in the barrel  132  with the end effector  138  positioned and ready for insertion of the nut  126 . In this forward position, the piston  196  is in its forwardmost position with the outer shoulder  218  engaging the inner shoulder  148  of the housing  134 . The release ring  136  is in its rearward most position, with the locking balls  152  moved by the outer surface of the first portion of the piston  196  to their radially-outermost positions in the respective apertures  150  in the first portion  142  of the housing  134  and bounded by the inner-lip  246  of the release ring  136 . The release ring  136  may not move any more forwardly because of the locking balls  152 , which engage the cam surface  258  of the release ring  136 . Since the locking balls  152  are held in position by the walls of their respective apertures  150 , the locking balls  152  keep the release ring  136  from moving forward under the force of the release spring  254 . The return spring  244  in the housing  134  is in the extended position. In this embodiment, the rear end of the input shaft  194  is in engagement with the nut runner  122 . 
         [0086]      FIG. 6  shows the tensioning tool  120  positioned over the nut  126 , and specifically the nut  126  being received in the end effector  138 . This is performed manually, or may be performed automatically with the appropriate automated equipment. In this position the tensioning tool  120  stays in the ready state. Note that the nut  126 , in this embodiment, defines a circumferential groove  260  for receiving the nut engaging balls  182  in the end effector  138 . When positioned in the end effector  138 , the groove  260  in the nut  126  is radially aligned with the nut engaging balls  182 . The arrow  262  represents the movement of the tensioning tool  120  towards the bracket  116 , which may occur at this time. 
         [0087]      FIG. 7  shows the nut  126  and the end effector  138  having been pushed into the barrel  132 . This movement is performed manually by an operator grasping the threaded rod  124  and pushing the threaded nut  126  into the tensioning tool  120  a certain amount. It may be performed automatically, also, with the appropriate automation device. Moving the nut  126  further into the tensioning device  120  has at least two purposes. First, it causes the end effector  138  to engage the nut  126  in the input shaft  194  and retain it there both axially and rotationally (the end effector  138  has a recess having a complementary shape to the shape of the nut  126 ). Second, the rearward movement of the input shaft  194  actuates the locking device  198  to firmly engage the piston  196  in the retracted position with the barrel  132  and housing  134 , forming the rigid structure against which the tension of the system, created by the cable pulling on the input shaft  194 , is measured during the tensioning step. Also, by moving the nut  126  away from the equalizer bracket  116 , the tension load measured is substantially isolated from the normal forces on the face of the nut that would affect that measurement if the nut  126  was in engagement with the equalizer bracket  116 . 
         [0088]    Referring still to  FIG. 7 , the nut  126  is withheld by the end effector  138  by at least one nut engagement ball  182  that is held in engagement with a groove  260  in the nut  126 . As the nut  126  is moved rearwardly, the nut engagement ball  182  moves through the aperture  206  in the front end of the input shaft  194 . As the ball  182  and the input shaft  194  move rearwardly relative to the barrel  132  and housing  134 , the cam surface  180  on the front collar length  168  helps urge the ball  182  radially inwardly through the apertures  206  and into the groove  260  in the nut  126 . The ball  182  is held in this engaged position with the nut  126  by the internal surface of the front collar length  168  of the barrel  132 . In this way, when the input shaft  194  is moved rearwardly into the barrel  132 , the nut  126  is releasably engaged with the end effector  138  and the nut  126  then moves axially and rotationally with the input shaft  194 . The distance the nut  126  must be moved into the end effector  138  to cause engagement is generally the relief distance. The relief distance may be that distance which the nut  126  must travel, after the brake system has been tensioned, in order for the brakes shoes or calipers to release from the drums or discs (respectively) to allow the wheels to turn freely. Alternatively, the control system  128  may instruct the nut runner to lessen the tension by appropriately rotating the nut along the threaded shaft  124 . 
         [0089]    Still referring to  FIG. 7 , the rearward movement of the input shaft also causes the piston  196  (and piston assembly  154 ) to move rearwardly in the tensioning tool  120 . The input shaft  194  causes the spacer collar  220  to move, which in turn causes the piston  196  to move rearwardly. The piston  196  moves rearwardly in the housing  134 , compressing the return spring  244 . The rearward movement of the piston  196  also moves the front portion  212  of the piston  196  rearwardly relative to the locking ball  152  held in the release ring  136 . As the front portion  212  moves rearwardly, the recess  222  formed therein moves under the locking ball  152  (or balls). The locking ball  152 , while positioned in the recess  222  and engaging the outer surface of the front portion  212  of the piston  196  and the shoulder  224  of the recess  222 , moves from engaging the cam  258  on the release ring  136 , which was keeping it in its rearward most position. As the locking ball moves radially inwardly, encouraged by the angular force applied by the cam  258  on the locking ring  136 , the locking ball  152  moves through the aperture  150  into the groove  222  on the front portion of the piston, and out of interfering engagement with the release ring  136 . The release spring  254  then biases the release ring  136  forwardly on the front portion  142  of the housing  134  to the release ring&#39;s forward-most position. In this forward-most position, the axial lip  190  on the rear of the barrel  132  is received in the annular recess  250  between the radially inner  246  and outer lips  248  at the front end of the release ring  136 , thus prohibiting the release ring  136  from any further forward motion. This brings the inner retaining wall  270  of the release ring  136  into engagement with the locking ball  152 , which then holds the locking ball  152  against the piston  196 . At this location, the piston  196  is biased forward, so the shoulder  224  at the border of the recess  222  is pushed into engagement with the portion of the locking ball  152  extending radially inwardly from the aperture  150 , thus keeping the piston  196  from moving any further forwardly. The piston  196  thus may not move any further forwardly relative to the barrel  132  or housing  134 , and is fixed axially relative to the input shaft  194 . The piston walls  216 , at this position, are sized to engage in physical interference at or near the end of the housing, but may not be required to. In this embodiment, the interference is caused by a snap ring  245  positioned in the inner wall of the housing  134  at the appropriate location, used to hold a portion of the drive means  122  in location in the housing  134 . Note, at this position, if the piston walls  216  were of shorter length, the input shaft  194  and piston  196  may be pushed further into the barrel and housing if desired, but need not be. 
         [0090]    The release ring  136 , forward portion of the housing  142 , locking balls  152  and the forward portion  212  of the piston  196  combine to create a mechanical locking system  198 . This mechanical locking system  198  converts the relative movement between the barrel  132  and housing  134  with the piston  196  into a rigid column. This mechanical locking system  198  works automatically under the spring bias of the release spring  254  primarily in operative association with the release ring  136 . Once the input shaft  194  and piston  196  are pushed far enough rearwardly into the barrel  132  and housing  134 , the locking mechanism  198  engages to automatically to form the rigid column between the housing  134 , barrel  132  and piston  196 . The rigid column allows the tension of the cable system to be measured directly through a rigid mechanical structure by the load cell with no reliance on an incompressible fluid system, such as hydraulics, or high-pressure pneumatics, and the associated support equipment and maintenance. The arrow  272  in  FIG. 7  shows the relative motion of the input shaft  194  and piston assembly  154 . The arrow  274  shows the relative motion of the release ring. 
         [0091]    In this locked mechanical column system shown in  FIG. 7 , the load on the cable system is measured by the load cell  200  positioned between the now anchored inner shoulder  218  of the piston  196  and the compressive component  225 , including in one embodiment the collar  238  mounted near the inner end of the input shaft  194 . As the system is tensioned (as explained below), the cable  106  pulls the nut  126 , which pulls the end effector  138 , which pulls the input shaft  194 , which pulls the collar  238  (and the elements of the compressive component  225 ) to effectively compress the load cell  200 . The compression of the load cell  200  is communicated to the control system  128  and translated to a tension load, which data is used by the control system  128  for display and to control the nut runner  122  and possibly other equipment. 
         [0092]    The cable system, as described above regarding  FIG. 7 , may now be tensioned with the tensioning tool  120 . At this position, the control system  128  may send control signals to the nut runner  122 , which rotates the input shaft  194 , and thus rotates the nut  126  on the threaded rod  124 . As the input shaft  194  is rotated, the piston  196  may not be rotated. In the embodiment described herein, the collar  238  in engagement with the facial seal rotates with the input shaft  194 . As the threaded rod  124  is pulled through the nut  126 , the tension increases in the brake cable system. As the tension increases, the load cell  200  senses the load by being compressed by the compressive component and transmits signals to the controls system  128  to monitor the load (tension) in the brake cable system. Once the appropriate tension load is achieved, and the tensioning act is completed (more than one series of tensioning can be accomplished at this stage by controlling the nut runner  122  to increase and decrease tension as desired), the nut runner  122  may be deactivated. During tensioning, the tensioning tool may engage the bracket  116 , such as at its front end as shown in  FIG. 7 , against which to react during the tensioning step. The tensioning tool  120  may be engaged against another fixed or anchor surface whether or not directly in contact with the bracket  116 . 
         [0093]    After tensioning is complete, the tensioning tool  120  may be released from the nut  126 . This is shown in  FIG. 8 . To release the nut  126  from the tensioning tool  120 , the release ring  136  is slid rearwardly (arrow  276 ) on the first portion  142  of the housing  134 . This disengages the inner retaining wall  270  of the release ring  136  from the locking ball  152 , and allows the locking ball  152  to move radially outwardly, being urged radially outwardly by the cam surface  224  on the forward portion  212  of the piston. As the locking ball  152  moves radially outwardly, it disengages from the cam surface  224  on the piston  196 , and thus allows the piston  196  to move further forwardly in the tool  120 , along with the input shaft  194 . The piston  196  moves forwardly far enough to cause the outer shoulder  218  of the piston  196  to engage the inner shoulder  148  of the housing  134 . This forward movement of the piston  196 , if not caused by the tension in the cable system pulling the nut  126  and the input shaft  194  towards the equalizer  116  (typically the tensioning step is performed with the end of the barrel of the tool in engagement with the equalizer), is effected by the return spring  244  pushing the piston  196  forwardly in the housing  134 . 
         [0094]    As the piston  196  moves forwardly in the housing  134 , it pushes the input shaft  194  forwardly also. The input shaft  194  is pushed forwardly far enough to allow the nut engagement balls  182  to release from engagement with the nut  126  (by being forced radially outwardly through the apertures  206  in the forward end of the input shaft  194  by the cam surface at the border of the groove  260  on the nut), thus allowing the nut  126  to be removed from the end effector  138 . This is shown in  FIG. 8 . In the position shown in  FIG. 8 , once the nut  126  is removed, it is the initialized state as shown in  FIG. 5 . The tool  120  is ready to be attached to another brake system for the tensioning operation. The arrow  278  in  FIG. 8  shows the relative motion of the piston  196 , input shaft  194 , and piston assembly  154  upon activation of the release ring  136 , all relative to the housing  134  and barrel  132 . 
         [0095]    The method in which the tool  120  is used includes the acts of engaging the nut  126  in the tool  120 , causing the nut  126  to be rotationally engaged with the tool  120 , causing the tool  120  to be in an orientation facilitating tensioning the brake cable system with a mechanically rigid structure formed by the tool  120  (these last two acts may occur simultaneously, as described herein, or may occur non-simultaneously with one occurring before the other); causing the tool  120  to tension the brake cable system, and causing the tool  120  to release the nut  126  from the tool  120 . The nut  126  may be positioned manually in the tool or by an automated machine. The release ring  136  may be operated manually or by an automated machine. 
         [0096]      FIGS. 9   a  and  9   b  are an exploded view of the brake tensioner shown in  FIGS. 5-8 .  FIG. 9   a , with reference to the descriptions of  FIGS. 5-8 , shows the barrel  132 , washer  192 , front collar length  168 , release ring  136 , input shaft  194 , rear collar length  176 , spacer collar  220 , release spring  254 , and housing  134 .  FIG. 9   b , as a continuation of  FIG. 9   a , shows the piston  196 , load cell  200 , radial collar  232 , axial collar  226 , return spring  244 , snap ring  245 , and nut runner  122  with components. 
         [0097]      FIGS. 10 and 11  show another example of the tensioning tool  120  earlier described, prior to engagement with the nut ( FIG. 10 ) and after the tensioning step, but before disengagement from the nut ( FIG. 11 ). The tool  120  works in much the same way as that described with respect to  FIGS. 5-8  above. The barrel  132  and body  134  are rigidly attached together, and the input shaft  194  and piston  196 , with its accompanying structure (load cell  200 , washers, etc.) are situated in the barrel  132  and housing  134  in order to move relative thereto. The release ring  136  acts to cause the mechanical locking mechanism  198  to actuate, and releases the mechanical locking mechanism  198  similarly to the previous embodiment. The release ring  136 , in this example however, does not have a forwardly extending lip, nor does the barrel  132  have a rearwardly extending lip, as the previous embodiment does. Instead, the front edge  280  of the release ring  136  is relatively flat and abuts a flange  282  on the rearward end of the barrel  132  to denote the forward-most extent of the release ring&#39;s movement. The engagement of the nut, formation of the rigid column, tensioning, and disengagement of the nut, are all similarly accomplished in this example. 
         [0098]    In other examples, the housing of the tool encloses a tensioning assembly that does not move axially relative to the housing, and instead is axially stationary therein during connection with the cable system, tensioning the cable system, and releasing the cable system. The tensioning assembly moves in a rotational manner about the longitudinal axis of the tool. Two examples of such a tool are described below. The examples of these tools work with the control system as described above as with the previous examples, and may be utilized with a threaded rod, nut, and equalizer structure, also all as described above. 
         [0099]      FIGS. 12-22  show different aspects of another example of a tensioning tool  320 .  FIGS. 12-13  show the tool  320  having a housing  322  with a front portion  324  and a rear portion  326 . The front portion  324  encloses a load measuring structure and a nut engagement feature to secure the end of the threaded rod  124  to the front end of the front portion  324 . The rear portion  326  extends downwardly from the rear of the front portion  324 , and encompasses a gear structure for engagement with the nut runner  122  to drive the rotational movement of the load measuring structure within the front portion  324 . An actuator button  328  on the rear of the rear portion  326  allows a user to secure and release the threaded rod  124  from the tool  320  as explained below. 
         [0100]    With specific reference to  FIG. 12 , the front portion  324  defines a front aperture  330 , through which the nut  126  and an end of the threaded rod  124  are inserted to be secured in the tool  320 . A sub-housing  332  extends down from the front portion  324  and defines another aperture  334 . This aperture  334  receives a fastener  398 , such as a screw, to secure the sub-housing  332  with the end of an actuator or push rod  397  (see  FIGS. 20-22 ). The other end of the push rod  397  is attached to the actuator button  328 . The triangular housing  332  moves when the push rod  397  is moved, and causes the engagement and release of the nut  126  within the aperture  330  of the front portion  324 , as described in greater details below. The aperture  336  shown in the downwardly extending rear portion  326  may receive a portion of the nut runner  122  when attached to the tool  320 . 
         [0101]      FIG. 13  shows a rear perspective view of the tensioning tool  320 , which shows a rear aperture  338  to receive an end of the threaded rod  124  in the event the nut  126  is threaded down sufficiently on the rod  124  to require the free end of the threaded rod  124  to extend there through. The actuator button  328  is also shown, which when depressed forwardly (in  FIG. 16 , into the page in the axial direction of the front portion), the actuator button  328  moves the triangular sub component  332  in the same direction. 
         [0102]      FIG. 14  shows a load cell component  340  that makes up part of the front housing  324  and downwardly descending rear housing  326 . The top portion  342  of the load cell component  340  is circular in cross section, and defines a central aperture  344  for rotatingly receiving an input shaft  380  (see  FIGS. 20-22 ) that rotates to turn the nut  126  on the free end of the threaded rod  124 . The slot  346  that extends around a portion of the forwardly-extending cylindrical rim  348  associated with the top portion  342  facilitates the axial movement of the triangular sub-housing  332  as it moves fore and aft. The intermediate aperture  344  receives the push rod  397  attached to the actuator button  328  to move the triangular sub housing  332 . The lower aperture  336  is the same aperture  336  as shown in  FIG. 12 . 
         [0103]    Referring at least to  FIG. 14  and  FIG. 20 , the top portion  342  of the load cell component  340  includes a central portion or wall  347  and an annular rim  348  extending from the perimeter of the central portion  347 . The central portion  347  defines the aperture  344 , and the annular rim  348  defines a recess  350  for receiving other components as described below. In this example, the central portion  347  is configured to integrally include an annular load cell  352 . In other examples, the central portion  347  may be hollow or otherwise configured to receive a separate load cell component that would fit into a region of the central portion  347 . 
         [0104]      FIG. 15  shows a rear view of the load cell component  340 . Recesses  352   a - 352   c  are formed in a downwardly-extending leg  354  of the load cell component  340  and receive gear assemblies that engage the nut runner tool  122  and drive the rotational motion of the input shaft  380  to tension the cables  106 . The recesses  352   a - 352   c  are substantially vertically aligned with one another in overlapping relationship so that the recesses  352   a - 352   c  are open to one another. In this configuration, when inserted into the recesses  352   a - 352   c , the gear assemblies mesh with one another to transfer rotational torque from the nut runner  122  to the input shaft  380 , and ultimately to the nut  126 . A boss or sleeve  356  may be positioned centrally around the aperture  344  within the intermediate recess  352   b  to positively locate a gear assembly within the recess  352   b  and/or to radially separate the respective gear component from the push rod  397  (see  FIGS. 20-22 ). Although not depicted, a boss or sleeve  356  may be included within the recess  352   a .  FIG. 16  shows a side view of the load cell component  340  of the tool  320 . 
         [0105]      FIG. 17-19  are various views of the triangular sub-component  332  (also referred to as a release fork) of the front portion  324 . The triangular sub-component  332  includes a concave outer wall  358  that generally corresponds in shape to the cylindrical rim  348  of the load cell component  340 . A flange  360 , which may be substantially U-shaped, extends inwardly from the concave wall  358 . A described in some detail below, the sub-component  332  (which may be triangular or other suitable shapes) is actuated to move forwardly and rearwardly with the push rod  397 . The flange  360  is effectively a key tab, which is received in a slot  362  in a floating sleeve  364  (see below). A key tab is a structure that fits into or with a second structure, and may cause the second structure to move under the influence of the key tab. The floating sleeve  364  is used to engage and disengage the nut  126  mounted on the free end of the threaded rod  124  from the tool  320 . The substantially U-shaped flange  360  is positioned forwardly of a vertically-extending mid-line, front to back, of the triangular sub-component  332 . 
         [0106]      FIGS. 20-22  are cross sectional views of the tool  320  of  FIGS. 12 and 13 . The front housing  324  includes the top portion  342  of the load cell component  340  and a nose portion  366  having a central aperture  368  that is fitted to the front of the load cell component  340 . The nose portion  366  includes a collar  370  extending outwardly and around to define the central aperture  368 , and to form an outer rim  372  against which the equalizer  116  is positioned during use. A flange  374  extends inwardly of the nose portion  366  to be received inside the outer rim  348  of the front end of the load cell component  340 . The flange  374  and rim  348  are secured together, such as by being press fit, threaded, glued, welded, or otherwise assembled. Such assembly may be in a manner allowing the nose portion  366  to be removed if desired. A back cover  376  is attached to the rear of the front and rear portions to cover the recesses  352   a - 352   c  in which the gear mechanisms  378  are positioned to drive the input shaft  380 . The back cover  376  includes an aperture  382  aligned with the central aperture  344  of the front portion  342 . The back cover  376  may be removable. 
         [0107]    Referring still to  FIG. 20 , the input shaft  380  is rotatably received through the central aperture  344  of the housing for the load cell  384 , as well as through the load cell component  340 . While the load cell component  340  includes an integrally-formed load cell  384  for sensing the compression caused by tension in the cable  106 , as noted above, a separate load cell may be positioned in this central region (shown in dash) and have the same or similar performance. Communication lines  386  (such as wires) extend from the load cell  384  through the slot to the control system  128  for the communication of signals, etc. The input shaft  380  has a radially extending shoulder  386  at or near its rear end. The peripheral edge  378   c  of the shoulder  386  of the input shaft  380  engages the gear mechanism  378   a ,  378   b  driven by the nut runner  122 . The nut runner  122  thus actuates the gear mechanism  378 , which in turn actuates the input shaft  380  to rotate about its longitudinal axis in the central aperture  344 . 
         [0108]    A thrust bearing  388  is positioned between the shoulder  386  and the rear surface of the central portion  347  of the load cell component  340 , and is loaded against the bearing  388  in a compressive manner when under tension from the cable system during use. The input shaft  380  in this example does not move axially inside the housing  322 , and is instead axially secured to not move appreciably during use, as described below. 
         [0109]    Still referring to  FIG. 20 , the forward end of the input shaft  380  defines the nut engagement chamber  390  having the retention ball bearings  392  as described above, and having faceted internal sidewalls to mate with the sidewalls of the nut  126 . A generally annular-shaped float sleeve  364  is positioned around the cylindrical outer circumference of the input shaft  380 , positioned between a front face of the central portion of the load cell  384  and the rim of the rear flange  374  of the nose member  366 . The float sleeve  364  defines a circumferential slot  362  on its outer perimeter. The upwardly-extending, substantially U-shaped flange  360  on the triangular sub-component  332  is received in the slot  362 . A front section of the inner diameter of the float sleeve  364  has a larger diameter, and the rear section of the inner diameter of the float sleeve has a smaller diameter, with a sloped cam-face  394  extending between the two diameters. The float sleeve  364  does not rotate with the input shaft  380 . The float sleeve  364  may move axially relative to the input shaft  380 . 
         [0110]    The cam-face  394  on the float sleeve  380  is sloped forwardly and outwardly to act as a ramp. When the float sleeve  364  is moved forwardly in the cavity  396  between the front face of the central portion  347  of the load cell component  340  and the rim of the rear flange  374  of the nose  366 , the ramp  394  pushes the ball bearing engagement structures  392  inwardly to fit into the groove on the nut  126  and securely receive the nut  126  in the end of the input shaft  380 . This is described below with respect to  FIG. 22 . 
         [0111]    A push rod (release rod)  397  is received in the aperture  344  formed in the downwardly extending rear portion  354  of the tool  320 . The push rod  397 , at its rear end, is mounted with an actuator button  328  that the user may push or pull. The free end of the push rod  397  is mounted to the triangular sub component  332  by a fastener  398 . The push rod  397  has a length that is sufficient to allow the actuator button  328  to be pushed forwardly to the second position (generally in the direction of the front portion of the tool) which in turn pushes the triangular sub component  332  in that direction and for the same distance also. The movement triangular sub component  332  causes the float sleeve  364  to move accordingly (due the key tab  360  engagement in the slot  362  of the float sleeve  364 ) within the cavity  396  in the front portion of the tool  320 . The key tab  360  extends through a slot  346  formed in the housing  322 . This, as explained with respect to  FIG. 22 , locks the nut  126  in the input shaft  380 . 
         [0112]    When the push rod  397  is positioned in the first position, the actuator button  328  is spaced away from the back cover  376  of the tool  320 , and the triangular sub-component  332  is positioned so that the key tab  360  has pulled the float sleeve  364  rearwardly on the input shaft  380  to release the nut  126 . 
         [0113]    Referring now to  FIG. 21 , the nut  126  is received in the end of the input shaft  380 , and the float sleeve  364  and push rod  397  are in the first position with the nut  126  not secured in the input shaft  380 . This represents the first step of the method of tensioning the park brake system utilizing this example of the tool  320 . The nut  126 , threaded on the end of the threaded rod  124  with the threaded rod  124  positioned through the equalizer  116 , is placed into the end of the tool  320  and into the nut-receiving chamber  390  of the input shaft  380 . This may be done manually by an operator, or automatically. The rim  372  of the collar  370  on the nose portion  366  is then engaged with the equalizer  116  to bear against the equalizer  116  as the tensioning steps are performed. The distance between the outer end of the nut  126  and the equalizer surface  116  against which the tool  320  rests is the relief distance  399 . 
         [0114]      FIG. 22  shows another step of the method of using the tool  320  in tightening the cables  106  of the brake system. The actuator button  328  is pushed from the first position to the second position, which moves the triangular sub component  332  forward the same amount, which in turn moves the float sleeve  364  (by way of the key tab  360  engagement within the slot  362  of the float sleeve  364 ). The float sleeve  364  is moved from a rear position in the cavity  396  to a forward position in the cavity  396 , which in turn causes the ramp  394  to engage the ball bearings  392  and push the ball bearings  392  radially inwardly to engage the nut  126 . The ball bearings  392  are held in place by the inner radius of the rear portion of the float sleeve  364  while the actuator button  328  is in the second position. The nut  126  is rotationally fixed to the input shaft  380  due to the mating faceted surfaces of the nut receiving chamber  390  engaging the corresponding faceted outer surface of the nut  126 . 
         [0115]    As explained in more detail above and below, at this point the control system  128  operates the nut runner  122  to perform the tensioning method suitable for appropriately tensioning the brake system cables  106 . In this tool  320  example, the load cell  384  is compressed between the shoulder  386  of the input shaft  380  and the rear face of the central portion  357  of the load cell component  340 . The load cell component  340  is a portion of the housing  322  of the tool  320 , which through the nose member  366 , engages the equalizer  116  to anchor the load bearing system to a fixed position against which to measure. This structure is a solid column against which the load cell  384  is compressed, and provides superior stability and repeatability in the measurements of the tensioning load applied to the cables  106  during the tensioning operation. The load cell  384  is not moved axially during this process, for instance to secure the nut  126 . Instead just the floating sleeve  364  is moved relative to the housing  322 , load cell  384 , bearings  392 , nose  366 , and nut  126  to lock the nut  126  into input shaft  380 . No hydraulics or pneumatics are required to actuate the tool  320 , simply the manual (or automatic) actuation of the push rod  397  to engage the nut  126 , and the control system&#39;s  128  actuation of the nut runner  122  to perform the tensioning steps. 
         [0116]    Another example of a tool  420  is shown in  FIGS. 23 through 35 . In this different example, the tool  420  has a substantially similar structure to the example shown in  FIGS. 12 through 22 , and operates in a similar manner. As shown in  FIGS. 23 ,  24  and  25 , the tool  420  includes a body or housing  422  having a front housing or portion  424 , a rear housing or portion  426 , and a sub-housing  430 . The housing  422  receives the operating parts necessary, as discussed above regarding the previous example, for engaging the threaded rod  124  and nut  126 , actuating an engagement structure, and rotating the nut  126  relative to the rod  124  to tension the cable system to the desired level. 
         [0117]    The rear portion  426  and the front portion  424  are generally cylindrical in shape. As shown in  FIG. 23-25 , the front and rear portions  424 ,  426  are configured to engage one another adjacent respective ends, and are offset from each other so as to have parallel axes that are spaced apart from one another. The offset of the front portion  424  relative to the rear portion  426  is beneficial in reducing the overall length of the tool  420  (since some parts may be overlapped, such as the gear drive), which enhances maneuverability and the ability to position the tool  420  in a more direct alignment with the axial extension of the cable end during use. The shape of the tool  420  (offset front and rear portions  424 ,  426 ) along with the length together are helpful to require less clearance respective of other components during use, and also aids alignment with the cable end. 
         [0118]    A release rod  428  extends through the rear portion  426  and through the sub-housing  430  to engage a release tab  432 . An actuator button  434  is attached at the opposite end of the release rod  428  relative to the release tab  432  to aid in actuating the release rod  428  and release tab  432 . The rear portion  426  receives the nut driver or runner  122  through an opening or recess  436  (best seen in  FIG. 25 ) for actuating the input shaft  438 , which is positioned in the front housing  424 . The front housing  424  includes an aperture  440  at a distal end for receiving the threaded rod  124  and nut  126  combination as noted above. A slot  442  is formed in the front case or casing  428  adjacent or near the location of the load cell  444  to accommodate a load cell communication line. A collar  446  extends through the slot  442 , and receives or guides the communication lines to and from the load cell  444  positioned in the front case  428  as defined below. The slot  442  has larger dimensions, both axially and radially, than the collar  446  to facilitate possible movement of the collar  446  with respect to the front case  448 . 
         [0119]      FIG. 26  is a cross section of the tool  420  of this example, showing the tool  420  adjacent a portion of an emergency brake cable system, which includes an equalizer  116  receiving the threaded rod  124  end of a cable  106 , and a nut  126  partially threaded onto the end of the rod  124 . 
         [0120]    Referring still to  FIG. 26 , the front housing  424  includes a sleeve or nose portion  448  attached at its rear end to the front casing  430 , in turn attached to a back cover  450 . The rear portion  426  includes a mounting cylinder  452  with a mounting cover  454  positioned at its rear end. The front case  430  extends away from the front housing  424  to encompass the front end of the back portion  426 , and the back cover  450  of the front housing  424  extends away from the front housing  424  and generally coextensive with the front case  430  to serve as an internal frame structure of the rear portion  426 . For instance, the back cover  450  defines an aperture through which the release rod  428  extends. 
         [0121]    With reference to  FIGS. 26 and 27 , the nut engagement end  452  of the input shaft  438  is shown and described, and is also referenced herein as the end effector. The input shaft  438  is positioned in the nose portion  448  of the front housing  424 , and has a front section  438   a  having a front end, and a rear section  438   b  having a rear end. The front section  438   a  defines a central bore  454  with a nut receiving engagement cavity  456  at its terminal front end. The front section  438   a , adjacent the nut engagement cavity  456 , is rotatably supported by a bearing  458 . The nut engagement cavity  456  is not engaged with the nut  126  in  FIG. 26 , and in  FIG. 27  the nut engagement cavity  456  has received the nut  126 , but the nut  126  is not secured within the cavity  456 . As shown in  FIG. 26 , the nose portion  448  includes a float sleeve  460  which moves axially under the control of the release rod  428  and tab  432 . The float sleeve  460 , when moved axially towards the front end of the input shaft  438  causes ball bearings  462  to move axially inwardly, similar to that described above, to engage the annular groove  464  formed in the nut  126 . This locks the nut  126  in the engagement end  452 . The nut  126  has facets formed on its outer perimeter for mating engagement in the engagement end  452 . Thus, once locked into the engagement end  452 , the nut  126  turns with the input shaft  438  to cause the nut  126  to move along the threads of the threaded rod  124 . The input shaft  438  may be solid, hollow, or a combination, and the outer surface may take the form of a complete cylinder where it is hollow, or a partial cylinder with a discontinuous outer surface (slots, braids, holes, continuous, spiral strips, etc.). 
         [0122]    Referring to  FIGS. 26 and 28 , the input shaft  438  has a front hollow section  438   a  and a rear solid section  438   b . The rear section  438   b  forms a solid rod, and has an outer dimension reduced in diameter from the front section  438   a . A shoulder  438   c  is formed where the front section  438   a  transitions to the rear section  438   b  and the outer dimension is reduced in size. The input shaft  438  is received in the front nose  448  of the front housing  424 , and extends through the front housing  424 . The front wall  466  of the front case  430  includes a collar  468  extending axially there from, coaxial with the input shaft  438  rotational axis. The collar  468  forms a cylindrical recess, which receives a rotational bearing  470 . The rear section  438   b  passes through the rotational bearing  470 , and an aperture formed in a front wall  466  of the front case  430 , at the center of the base wall of the collar  468 . The shoulder  438   c  of the input shaft  438  engages an end of the bearing  470 , which in turn engages the base wall of the collar  468  (front face of the front wall  466 ). This forms a solid structure against which the rear section  438   b  of the input shaft  438  is loaded, as explained in more detail below. 
         [0123]    An output gear  472  is mounted on the rear end of the rear section  438   b  of the input shaft  438  to engage with the gear drive of the nut runner  122 . Positioned on the rear section  438   b  of the input shaft  438  between the rear face of the front wall  466  and the output gear  472  are: the load cell  444 , with a front rim engaging and bearing against the back side of the front wall  466  of the front case  468 ; a compression washer  474 , which bears against the back rim of the load cell  444 ; a thrust bearing  476  positioned between the washer  474  and the output gear  472 . The load cell  444 , compression washer  474 , thrust bearing  476 , and output gear  472  all rotate with the input shaft  438 . The mounting of the output gear  472  on the rear end of the rear section  438   b  of the input shaft  438  may retain the thrust bearing  476 , compression washer  474 , and load cell  444  on the rear portion  438   b  of the input shaft  438  between the rear face of the front wall  466  of the front case  468  and the output gear  472 . The shoulder  438   c  on the input shaft  438  butts up against the front rim of the shaft bearing  470 , and provides the anchor against which the fastener  478  of the output gear  472  applies a force. As explained in more detail below, when the input shaft  438  is under load from the tensioning process, the output gear  472  axially (along the centerline of the input shaft  438 ) compresses the thrust bearing  476  against the compression washer  474 , which in turn compresses the load cell  444  against the rear face of the front wall  466 , which provides the direct measurement of the tension in the cable  106  during the tensioning process. The load may be designed to not be axial and along the centerline, but instead may be axial and parallel to but spaced away from the centerline of the input shaft  438 . 
         [0124]    As with some of the previous examples, the load cell  444  surrounds the input shaft  438 , and in one example is concentric to the input shaft  438 . In this way the load cell  444  is concentric to the axis of the tension load caused by the tensioning of the cable system, and the tension load is axially aligned with the centerline of the input shaft  438 . As noted elsewhere, the load cell  444  is stationary relative to the external body or housing  422  during the tensioning operation. The load cell  444  may also be axially stationary relative to the input shaft  438 , which rotates relative to the load cell  444 . 
         [0125]    The rear portion  426  of the tool  420  is shown and described with respect to  FIGS. 26 and 29 . The rear portion  426  is formed from a portion of the front casing or plate  430  extending above the front portion  424  (in  FIG. 26  and  FIG. 29 ), a portion of the back cover  450  also extending upwardly from the front portion  424  and spaced rearwardly from the front casing or plate  430  to form a cavity there between, a mounting cylinder  452  extending generally rearwardly from the back cover  450  and defining a second cavity  480  for receiving the nut runner  122 , and a mounting cover  454  forming the rear wall of the mounting cylinder  452 . 
         [0126]    The release rod  428  extends through an aperture formed in said rear portion  426 , which aperture extends through said mounting cover  454 , back cover  450 , and front case  430 . The release rod  428  defines a rear end having a button  434  attached thereto, and a front end having a release tab  432  attached thereto and extending generally radially there from. A pair of grooves or indentations  482  is formed adjacent the rear end of the release rod  428  to interact with a spring-loaded ball  484  to form a detent structure for positioning the release rod  428  in a forward (actuated) position or a rearward (un-actuated). Each detent structure acts to movably secure the particular axial position of the release rod  428  in the housing, and indicates that the release rod  428 , and thus the release tab  432 , is positioned in either the forward position to actuate the engagement end  452  of the input shaft  438 , or the rearward position to de-actuate the engagement end  452  of the input shaft  438 . When in actuated or forward position, the release tab  432  pushes the floating sleeve  460  towards the nose  448 , which in turn pushes the ball bearings  462  radially inwardly to engage the nut  126 . When in the rearward, or de-actuated, position, the release tab  432  pulls the float sleeve  460  rearwardly to disengage from the ball bearings  462 , and release the nut  126 . The detent ball  484  engages the grooves or dents  482  of the release rod  428  under the biasing force of a spring  486  and selectively maintains the release rod  428  in the particular selected position. The release rod  428  may be moved from this position by axially loading the release rod  428  to overcome the spring  486  bias force holding the ball  484  in the dent or groove  482 . Other structures are contemplated for releasably securing the release rod  428  in the forward position, or in other positions. The floating sleeve  460  defines an annular groove  488  adjacent its rear end, the annular groove  488  receiving the tip of the release tab  432  (see  FIG. 26 ). The release tab  432 , when positioned in the groove  488 , thus causes the float sleeve  460  to move, or stay stationary, in conjunction with it. For example, the release tab  432  moves the float sleeve  460  forwardly when the release rod  428  is moved forwardly, and moves the float sleeve  460  rearwardly when the release rod  428  is moved rearwardly. The release tab  432  may be received in a slot  489  formed in the outer housing  490  of the front portion  424 . The edges of the slot  489  define the maximum extension and retraction of the release rod  428 , with the detents  482  described above positioned accordingly at the limits or elsewhere along the extension distance as desired. 
         [0127]    Continuing to refer primarily to  FIG. 29 , as well as others of  FIGS. 26-35 , the release rod  428 , release tab  432 , and float sleeve  460  create a manual actuator for the engagement end  452  of the input shaft  438 . The manual actuator moves, such as by a human operator pushing or pulling the button  434 , relative to the tool body or housing  422 . The manual engagement is effectuated by axial movement of a member (release rod  428 ) in operable engagement (release tab  432  engaging with the float sleeve  460 ) with the engagement end  452  of the input shaft  438 . The movement of the member  428  relative to the body or housing  422  causes the engagement end  452  to secure the nut  126  for actuation by the input shaft  438 . The manual engagement is contemplated to be automatically actuated by a solenoid or other switch controlled by an operator or a logic controller. The actuation of the manual actuator moves the float sleeve  460  to cause retention of the nut  126  in the input shaft  438 . During engagement with the nut  126 , tensioning of the cable system, and disengagement with the nut  126 , the load cell column, as defined above, is not in this example axially moved relative to the body or housing  422 , or the input shaft  438 , and thus remains substantially stationary. The member  428  allows for external actuation of the input shaft  438  to engage the nut  126 , in this example by use of the release rod  428 . The release rod  428 , engagement tab  432 , and float sleeve  460  move collectively relative to the load cell  444 . The term “external” as used herein may include by a mechanism not entirely received within the body or housing  422 . 
         [0128]    This structure provides a sound, well anchored, and simplified load cell-based tensioning and measuring system. The load cell  444  in this and the previous example shown in  FIGS. 12-22 , is rigidly mounted in a column-like structure, and when under tension load from the cable system, is anchored and compressed against the front case  430  of the body or housing  422 , which in turn is abutted against a rigid structure, such as the equalizer  116  or other such item. This provides a solid foundation for the column structure of the load cell  444  to be compressed against to register or directly measure the tension in the cable system along the axial line of extension of the cable  106 . The load cell measurement mechanism described herein need not be assembled into nor disassembled from the cable system itself. Instead it is attached to the end of the cable system, which provides ease of access and accurate measurement, along with a minimal time requirement to tension and measure the brake cable system during assembly, repair or maintenance. 
         [0129]    In continuing reference to  FIGS. 26 and 29 , the cavity  480  formed between the back cover  454  and the front case  430  receives the gear train  492 . The gear train  492  includes an input gear  493  in rotary engagement with an idler gear  494 , which is in rotary engagement with the output gear  472 . The output gear  472  is in rotary engagement with the input shaft  438  as described above. The input gear  493  includes a connector structure, such as a receiving aperture  495 , to receive a nut runner  122  having a head portion positioned in the second cavity  480  (see  FIG. 25 ). The nut runner  122  is rotated under electric, pneumatic, or hydraulic power to rotate the input gear  493 , which in turn actuates idler gear  494 , which in turn rotates the output gear  472 . The rotation of the output gear  472  causes the input shaft  438  to rotate, which in turn rotates the nut  126  secured in the engagement end  452  of the input shaft  438  to rotate relative to the threaded rod  124  and cable  106 . More or fewer gears are contemplated for use in the gear train  492 . 
         [0130]    The operation of the tool as described above is now described with reference to the structure and function described above, and with respect to the method steps or acts referred to below, and with respect to FIGS.  26  and  30 - 35 . 
         [0131]    The pre-install step includes the threaded rod  124  as shown in  FIG. 26  extending through the aperture formed in the equalizer  116  and secured with the nut  126 . The nut  126  is minimally attached to the threaded rod  124 , engaging with optionally only a few threads to hold it in place on the rod  124  before or after the vehicle arrives at the tensioning station. 
         [0132]    As shown in  FIG. 30 , in a following step, the nut  126  and threaded rod  124  are pushed and/or pulled into the nose  448  of the end effecter  452  of the input shaft  438 . This action positions the nut  126  inside the engagement end  452  of the input shaft  438 , where the nut  126  is received and oriented in the end effector  452  to be positioned with groove  464  of the nut  126  adjacent to the balls  462  in the end effector  452 . 
         [0133]    In a following step, shown in  FIG. 31 , the operator pushes on the engagement button  434  which moves the release rod  428  and float sleeve  460  forward relative to the tool body or housing  422 . The ramp  498  in the forward portion of the float sleeve  460  forces the balls  462  positioned in the engagement end  452  radially inward to be positioned in the groove  464  on the nut  126 , which locks the nut  126  in place. The tension in the cable system at this point may be considered a first tension level. 
         [0134]    In a following step, show in  FIG. 32 , the operator insures that the nut runner  122  is engaged with the tool  420 , and that the nose end  448  of the tool  420  is resting against, or close to resting against, and engaging the equalizer  116 . Note the relief distance  499  between the end of the nut  126  nearest the equalizer  116  and the equalizer  116 . This relief distance  499  is the distance which the nut  126  moves after being disengaged from the tool  420 . Moving through the relief distance  499  reduces the tension in the cable system. The relief distance  499  may be defined in a fixed value by the extension of the nose end  448  of the tool  420  past the end of the nut  126 . The relief distance  499  may also be adjustably defined, such as by a selectively movable collar threadedly attached to the nose end  448  of the tool  420 . Other adjustable attachment structures are contemplated. The relief distance  499  may be in the range of 0.00 inches to approximately 1 inch, and is beneficially approximately 0.25 inches. In the examples shown in  FIGS. 12-35 , the nut  126  may be moved away from the equalizer  116  without having to transition or move the load cell  444  or the input shaft  438  within the body or housing  422 . Only the float sleeve  460  moves, which is intended to simply provide a mechanism to push the ball bearings  462  into the groove  464  of the nut  126 , and retain the ball bearings  462  therein until it is desired to release the nut  126  from the end effector  452 . 
         [0135]    Continuing with  FIG. 32 , the operator actuates the nut runner drive  122 , which through the gear train  492  causes the input shaft  438  to rotate and turn the nut  126 . The nut  126  is thereby run up the threaded rod  124  (moved along the threaded rod  124  away from its terminal end) to create tension in the cable system. This tension level is referred to as the first higher tension level. In this step as shown in  FIG. 32 , the rod  124  is shown in a position to represent the higher tension level, which may be a maximum tension level. The tension in the cable system is measured by the load cell  444  positioned in the tool  420  to effectively react against the input shaft  438  and the fixed body or housing  422 . The load cell  444  is in communication with the control system  128 , and sends signals indicative of the load under which the load cell  444  is subjected during use. This is the “pre stretch” or higher tension level required to remove voids from the system. Once achieving this level the nut runner  122  may stop, be inactive for a time period allow the system to relax, and then continue to increase or decrease tension slowly until a stable tension is established or no longer drifts below a specified level. This tension level is referred to as a “stable tension” level. In this position, the nut  126  may be turned either way by the input shaft  438  to increase or decrease tension as desired. The nut runner  122  is controlled by a control system  128 , such as that shown in  FIG. 1  and as described above with reference to  FIG. 1 , and may include a smart phone, tablet, wired or wireless connection to a server or the internet for control, recording, analysis, or maintenance assessment. 
         [0136]    Referring to  FIG. 33 , in a following step, before further tensioning or de-tensioning the cable system and releasing and returning the nut  126  to the equalizer  116 , it is often necessary to relieve a specified amount of tension so that when the nut  126  is fully released the amount of residual or final tension is higher than a determined limit (which for instance, would leave the brakes engaged). It is therefore often necessary to run the nut  126  in reverse a select number of rotations or angle of rotation to relieve the tension before final release. This may be achieved by slowly running the nut  126  in reverse to a pre-defined tension lower than the maximum pre stretch level. Any number of tensioning and de-tensioning steps may be performed before releasing the nut  126 , depending on the desired effect on the cable tensioning system. 
         [0137]    Referring to  FIG. 34 , in a following step, the operator then moves the engagement button  434  to the disengaged position, causing the release rod  428  to move rearwardly, in turn causing the float sleeve  460  to slide rearwardly and release the balls  462  from the groove  464  of the nut  126 . The nut  126  is released the final relief distance  499  to contact, engage, and react directly against the equalizer  116 . A desired final tension is achieved at this point. 
         [0138]    Referring to  FIG. 35 , in a following step, the tensioning tool  420  may be removed from the system and prepared for use on the next vehicle. 
         [0139]    In a typical automotive parking brake system the brake pedal or hand lever is connected to a cable  106  which passes through an equalizer  116 . The equalizer  116  typically divides the tension force so it is evenly distributed between two cables connected to the rear brakes. The cable system typically operates independently of the hydraulic system. The cable  106  is attached to the braking brake mechanism through an actuator lever attached to parking brake mechanism. Typically in a park brake system there is a return spring which keeps the actuator lever in the fully released position when the brake pedal or hand lever is released. 
         [0140]    In many processes used to adjust the parking brake in an automobile, one of the desired outcomes is to achieve a consistent rate of resistance experienced by the driver when the driver actuates the pedal or hand lever for any given model of vehicle. It is additionally desirable to ensure that there is just enough residual tension in the cable system to allow the hand lever or pedal to return fully to the un-actuated position when the brake is released. A significant challenge in this endeavor is to achieve this desired consistency at very low tension levels or at the very beginning of the actuation cycle and, conversely, at the end of the release cycle. At this level, tension in the cable system is caused by compression of a return spring reacting against the actuator lever that is attached to the cable and by compression in the cable conduit thereby causing a small amount of desired residual tension in the overall system and allowing the hand lever or pedal to return fully to the initial position when the driver releases the parking brake. 
         [0141]    Adjusting the park brake system so that it is capable of consistently achieving high levels of clamping force when fully actuated is typically a primary goal of the adjustment process. To achieve this high level of tension consistently it may be helpful to utilize a process that mostly or fully stretches the cable and compresses the conduit so that voids in the system are mostly or entirely removed over the long term. It is a further desire, however, to ensure that there is a remaining low level of residual cable tension so that the hand lever or brake pedal returns consistently to its initial position when the system is dis-engaged. This is particularly challenging in that each brake has different initial travel losses due to manufacturing tolerances. This variation in travel losses are compounded with variable ratio levers, variation in return springs, conduit compressibility, and other factors which may result in systems that appear to have different characteristic stiffness. The challenge to tensioning a system with significant apparent stiffness variation is knowing how far to release the system from a high tension level that results in the residual tension being sufficient to return the hand lever or brake pedal to the fully released position without over tensioning the system. 
         [0142]    The process or method described herein, whether implemented on the structure described herein or other structure for tensioning an emergency brake cable system, describes how to achieve a final or terminal low level residual tension in the system that addresses and overcomes the inconsistencies associated with the variation in apparent system stiffness. This process could occur supplemental to, integral with, or as a second or final stage of an overall adjustment process. 
         [0143]      FIGS. 36 and 37  are output graphs that each show tension measurement output of a brake cable system during the tensioning steps, and in particular show the forward tension time between tension levels T 3  to T 4 . The time it took the tool to run-up the nut  126  on the threaded rod  124  in  FIG. 36  from tension T 3  to tension T 4  was approximately 6 seconds (however it could be longer or shorter). 
         [0144]    In the final adjustment of the emergency brake system, the nut  126 , while held in a position a specified distance (return distance) away from the equalizer  116  and not reacting against the equalizer  116 , is slowly run-up the threaded rod  124  to a predetermined target tension level which is consistent with the brake being applied at a low level T 4 . During this run-up, the distance traveled can be determined based on the rotational speed of the tool used to rotate the nut  126  and the time required to go between a low tension level (T 3 ) and a higher target tension level (T 4 ). Based on the speed of the nut runner  122 , the pitch of the thread on the threaded rod  124 , and the time interval from tension level T 3  to tension level T 4 , the distance traveled may be determined. The distance traveled from tension level T 3  to tension level T 4  is used to define the tension/travel relationship. Once the tension/travel relationship is defined for a particular cable system, the desired residual tension may be obtained by translating the nut  126  (with the nut runner  122 , for example) toward a free end of the threaded rod  124  as desired. While there is an assumption in this example that the tension/travel relationship is generally linear in the range of the curve being addressed (low tension region), non-linear characteristics of the curve may be determined by taking more data points along the tension curve between T 3  and T 4 , which in turn may be configured into an algorithm used to set the desired residual tension level and to obtain it by reversing the nut  126  on the threaded rod  124 . 
         [0145]    Additionally or alternately, a servo motor may be used to determine a distance traveled by the nut  126  along the threaded rod  124  by counting the total angle needed to go from tension level T 3  to tension level T 4 . The servo motor may have a sensor monitoring total angle of rotation, and with the pitch information of the threaded rod  124 , the distance traveled by the nut  126  along the threaded rod  124  corresponding to the tension in the cable system increasing from tension level T 3  to tension level T 4  may be determined. With the distance traveled information, the tension/travel curve may be determined, which is used to accurately estimate the distance the nut  126  needs to be reversed along the threaded rod  124  toward a free end of the rod  124  to obtain the desired residual tension level.  FIGS. 36 and 37  are output graphs that each show an output of a brake cable system during the tensioning steps, and in particular show the forward tension time between tension levels T 3  to T 4 . The residual tension level may be greater than, less than, or the same as tension level T 3 . Other types of measurements may be utilized to determine the distance traveled by the nut  126  corresponding to the load cell  444  and thus the cable system tension increasing from tension T 3  to tension T 4 , such as by optical sensors, electric eye monitoring, or resistive techniques. 
         [0146]    At these low tension levels, the distance traveled and the tension time will often vary from brake to brake. In determining the distance traveled going between tension T 3  and tension T 4 , the apparent stiffness of the system (which varies due to variations in the return spring, loss travel, variable ratio levers, conduit compressibility, environmental and other factors) is determined. Based on this apparent system stiffness and target force level (T 3 ), the number of reverse revolutions of the nut  126  towards a free end of the threaded rod  124  needed to move the nut  126  along the threaded rod  124  a desired or calculated distance and achieve a desired residual tension in the cable system is determined. 
         [0147]    This improved method utilizes a performance path whereby tension and travel are adjusted as a result of real time inputs received during the cable adjustment process and adjusts each cable system according to the apparent stiffness of each cable system. Other methods known in the prior art are prescriptive in that they employ a predefined set of travel and tension targets that are applied to each and every cable system. These predefined targets are typically based upon a statistical analysis to define the characteristics of a typical cable system for a particular vehicle. 
         [0148]    All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are only used for identification purposes to aid the reader&#39;s understanding of the examples of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention unless specifically set forth in the claims. Joinder references (e.g., attached, coupled, connected, joined, and the like) are to be construed broadly and may include intermediate members between a connection of elements and relative movement between elements. As such, joinder references do not necessarily infer that two elements are directly connected and in fixed relation to each other. 
         [0149]    In some instances, components are described with reference to “ends” having a particular characteristic and/or being connected with another part. However, those skilled in the art will recognize that the present invention is not limited to components which terminate immediately beyond their points of connection with other parts. Thus, the term “end” should be interpreted broadly, in a manner that includes areas adjacent, rearward, forward of, or otherwise near the terminus of a particular element, link, component, part, member or the like. 
         [0150]    In methodologies directly or indirectly set forth herein, various steps and operations are described in one possible order of operation, but those skilled in the art will recognize that steps and operations may be rearranged, replaced, or eliminated without necessarily departing from the spirit and scope of the present invention. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims. Accordingly the matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting.