Patent Publication Number: US-11662202-B2

Title: Length adjustable level

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a continuation U.S. application Ser. No. 16/293,356, filed Mar. 5, 2019, which is a continuation of International Application No. PCT/US2019/019587, filed on Feb. 26, 2019, which claims priority from U.S. Provisional Application No. 62/635,922, filed Feb. 27, 2018, the contents of which are incorporated herein in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to the field of tools. The present invention relates specifically to a tool, such as a level or a spirit level, that is extendable such that its length may be adjusted as needed by a user. Levels, such as spirit levels, are used to determine the levelness of a structure, surface or workpiece. In use, the level is placed on or in contact with a surface to be measured, and the user views the location of a bubble within a vial (or other levelness indicator) relative to markings that indicate the levelness of the structure, surface or workpiece. 
     SUMMARY OF THE INVENTION 
     One embodiment of the invention relates to a level configured to have an adjustable longitudinal length. The level includes a fixed outer body member coupled at a fixed position to an inner body member and a slidable outer body member slidably coupled to the inner body member and opposing the fixed outer body member. The level includes a locking mechanism moveable between a locked position in which the slidable outer body member is locked relative to the inner body member and an unlocked position in which the slidable outer body member is allowed to move relative to the inner body member. 
     In various embodiments, the locking mechanism includes a user operated control. The user operated control is configured such that translational movement (or non-rotational movement) of the control moves the locking mechanism between locked and unlocked positions. In a specific embodiment, the translational movement is parallel to one or more working surfaces of the level. 
     In various embodiments, when viewed in longitudinal cross-section, the slidable outer body member has a vertically extending central wall, an upper wall defining an upper working surface located at an upper end of the central wall, and a lower wall structure extending from a lower end of the central wall defining a longitudinally extending cavity. The inner body member is received within the longitudinally extending cavity. In specific embodiments, the lower wall structure completely surrounds the inner body member when viewed in longitudinal cross-section, at at least some cross-sectional locations. The locking mechanism is supported by the slidable outer body member within an aperture extending through the central wall. In various embodiments, the locking mechanism is accessible from both left and right side surfaces of the level when the level is in a fully collapsed (e.g., minimum length) position. 
     In one embodiment the level comprises an inner body member that extends along a longitudinal axis, a first body portion coupled to the inner body member, a second body portion slidably coupled to the inner body member, a level sensing device, and a locking mechanism coupled to the second body portion. The first body portion comprises a first planar base surface and a first top surface opposing the base surface. The second body portion comprises a second planar base surface coplanar with the first planar base surface and a second top surface coplanar with the first top surface. The first and second base surfaces collectively define a working base surface and the first and second top surfaces collectively defines a working top surface. The locking mechanism comprises a user actuated control, wherein the user actuated control is configured such that translational movement of the user actuated control moves the locking mechanism between a locked position and an unlocked position. Relative positions of the first body portion and the second body portion define a fully retracted position and a fully extended position, the fully retracted position defining a shortest working length of the level along the longitudinal axis and the fully extended position defining a longest working length of the level along the longitudinal axis. 
     In another embodiment a level comprises a fixed body member, an extended body member that extends along a longitudinal axis, a slidable body member slidably coupled to a second end of the extended body member, an orientation measuring component, and a locking mechanism. The fixed body member is coupled to a first end of the extended body member and comprises a first planar base surface and a first top surface opposing the base surface. The slidable body member comprises a second planar base surface coplanar with the first planar base surface, the first and second base surfaces collectively defining a working base surface, and a second top surface coplanar with the first top surface, the first and second top surfaces collectively defining a working top surface. The locking mechanism comprises a user actuated control, wherein the user actuated control is configured such that movement of the user actuated control moves the locking mechanism between a locked position and an unlocked position. Relative positions of the fixed body member and the slidable body member define a fully retracted position and a fully extended position, the fully retracted position comprising a shortest working length of the level along the longitudinal axis and the fully extended position comprising a longest working length of the level along the longitudinal axis. The user actuated control of the locking mechanism is accessible to a user when the level is in the fully retracted position. 
     In another embodiment a level comprises an inner body member that extends along a longitudinal axis, a first body portion coupled to the inner body member, a second body portion slidably coupled to the inner body member, a level sensing device supported by the second body member, and a locking mechanism. The first body portion comprises a first planar base surface and a first top surface opposing the base surface. The second body portion comprises a second planar base surface coplanar with the first planar base surface, the first and second base surfaces collectively defining a working base surface, a second top surface coplanar with the first top surface, the first and second top surfaces collectively defining a working top surface, a central wall, an upper wall that defines to the second top surface coupled to an upper end of the central wall, and a box structure coupled to a lower end of the central wall and defining a channel that receives the inner body member. The user actuated control is coupled to the central wall of the second body member and configured such that movement of the user actuated control moves the locking mechanism between a locked position and an unlocked position. Relative positions of the first body portion and the second body portion define a fully retracted position and a fully extended position, the fully retracted position comprising a shortest working length of the level along the longitudinal axis and the fully extended position comprising a longest working length of the level along the longitudinal axis. 
     In various embodiments, the level includes an adjustable friction mechanism supported by the slidable outer body member that applies an adjustable amount of friction against the inner body member. 
     Additional features and advantages will be set forth in the detailed description which follows, and, in part, will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are exemplary. 
     The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments and together with the description serve to explain principles and operation of the various embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of a level, according to an exemplary embodiment. 
         FIG.  2 A  is a cross-sectional side view of the level of  FIG.  1    showing a locking mechanism, according to an exemplary embodiment. 
         FIG.  2 B  is a perspective view of the locking mechanism of  FIG.  2 A  with a locking mechanism frame removed, according to an exemplary embodiment. 
         FIG.  3    is a longitudinal cross-section view of the level of  FIG.  1   , according to an exemplary embodiment. 
         FIG.  4    is a longitudinal cross-section view of a level outer body portion, according to another exemplary embodiment. 
         FIG.  5    is a cross-sectional side view of a level and a locking mechanism in the unlocked position, according to another exemplary embodiment. 
         FIG.  6    is a cross-sectional side view of the level and the locking mechanism of  FIG.  5    in the locked position, according to another exemplary embodiment. 
         FIG.  7    is a cross-sectional side view of a level and a locking mechanism in the unlocked position, according to another exemplary embodiment. 
         FIG.  8    is a cross-sectional side view of the level and the locking mechanism of  FIG.  7    in the locked position, according to another exemplary embodiment. 
         FIG.  9    is a longitudinal cross-section view of a level outer body portion, according to another exemplary embodiment. 
         FIG.  10 A  is a longitudinal cross-sectional view of a level and locking mechanism in the unlocked position within the body portion of  FIG.  9   , according to an exemplary embodiment. 
         FIG.  10 B  is a side view of the level and locking mechanism of  FIG.  10 A , according to an exemplary embodiment 
         FIG.  11 A  is a longitudinal cross-sectional view of the level and locking mechanism of  FIG.  10 A  in the locked position within the body portion of  FIG.  9   , according to an exemplary embodiment. 
         FIG.  11 B  is a side view of the level and locking mechanism of  FIG.  11 A , according to an exemplary embodiment 
         FIG.  12    is a longitudinal cross-section view of a level outer body portion, according to another exemplary embodiment. 
         FIG.  13 A  is a longitudinal cross-sectional view of a level and locking mechanism in the unlocked position within the body portion of  FIG.  12   , according to an exemplary embodiment. 
         FIG.  13 B  is a side view of the level and locking mechanism of  FIG.  13 A , according to an exemplary embodiment 
         FIG.  14 A  is a longitudinal cross-sectional view of the level and locking mechanism of  FIG.  13 A  in the locked position, according to an exemplary embodiment. 
         FIG.  14 B  is a side view of the level and locking mechanism of  FIG.  14 A , according to an exemplary embodiment 
         FIG.  15    is a detailed perspective view of a friction member for an extendable level, according to an exemplary embodiment. 
         FIG.  16    is a perspective view of a locking mechanism and a friction element for an extendable level, according to another exemplary embodiment. 
         FIG.  17    is a side view of the locking mechanism of  FIG.  16   , according to an exemplary embodiment. 
         FIG.  18    is a cross-sectional view of the friction element of  FIG.  16   , according to an exemplary embodiment. 
         FIG.  19    is a perspective view of an inner body and a rear bushing for an extendable level, according to an exemplary embodiment. 
         FIG.  20    is a cross-sectional view of the inner body and rear bushing of  FIG.  19    located within an outer body of an extending level, according to an exemplary embodiment. 
         FIG.  21    is a perspective view of an inner body and a front bushing for an extendable level, according to an exemplary embodiment. 
         FIG.  22    is an exploded view of the front bushing of  FIG.  21   , according to an exemplary embodiment. 
         FIG.  23    is a perspective view of an outer body of an extendable level including a front bushing, according to another exemplary embodiment. 
         FIG.  24    is a perspective view of the front bushing of  FIG.  23   , according to an exemplary embodiment. 
         FIG.  25    is a perspective view of a standoff for an extendable level, according to an exemplary embodiment. 
         FIG.  26    is a side view of the standoff of  FIG.  25    mounted to a fixed body portion of an extendable level, according to an exemplary embodiment. 
         FIG.  27    is a side view of the standoff of  FIG.  26    prior to mounting to or after removal from a fixed body portion of an extendable level, according to an exemplary embodiment. 
         FIG.  28    is an exploded perspective view of a level vial assembly for an extendable level, according to an exemplary embodiment. 
         FIG.  29    is an exploded perspective view of a double level vial assembly for an extendable level, according to an exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring generally to the figures, various embodiments of a level, such as a spirit level, are shown. In general, levels have one or more precision surfaces used for engagement with a workpiece during leveling. The level discussed herein is designed such that the level&#39;s length can be adjusted by the user as needed for various leveling applications. As will be discussed in more detail below Applicant has developed a locking system that allows the user to lock the level at the desired length that Applicant believes provides more effective and robust locking than conventional expanding levels. 
     For example, Applicant&#39;s locking mechanism provides for a large engagement surface that engages an inner body portion when the level is locked at the desired length. Applicant has found that by using a locking mechanism with a large engagement surface, the locking force is evenly distributed over a large area which limits the potential of distorting or misaligning the precision measuring surfaces when the locking force is applied. In addition, in specific embodiments, the locking mechanism is designed such that translational movement of the user actuated control (as opposed to rotational motion) is used to move the locking mechanism into the locked position. Applicant believes that, in contrast to rotational or lever-type lock controls, the translational movement is easy to operate and facilitates the even application and distribution of locking force. 
     Further, in various embodiments, the locking mechanism includes additional design aspects that Applicant believes improves function of the extendable level discussed herein. For example, the outer level body profile and the user actuated control for the locking mechanism are designed such that the user actuated control for the locking mechanism is always accessible to the user, and specifically is accessible both when the level is in the fully retracted position, when the level is in the fully extended position and at any position in between. Specifically, by providing user access to the locking mechanism control when the level is in the fully collapsed position, the locking mechanism discussed herein allows the level to be placed into the locked position when the level is in the fully retracted position. 
     Further, in various embodiments, the control for the locking mechanism is placed along the level body spaced from the gap or separation created between opposing portions of the outer level body when the level is in an extended position. Thus, this design does not require the user&#39;s fingers to be placed in this gap to actuate the locking mechanism which reduces the chance that the user&#39;s fingers get pinched between the outer level body sections. 
     Further, in various embodiments, the outer level body includes an upper portion having an I-beam cross-sectional profile, and a lower section defining a hollow region within which the inner body member is located. This body shape provides for easy gripping/handling along the upper I-beam wall that extends the entire length of the level, while also providing an internally received telescoping inner body member. Applicant believes that conventional extending levels do not provide this combination of design features. Further, this outer body design allows for the user actuated control for the locking mechanism to be positioned through the vertical wall of the I-beam structure such that it is accessible from either side of the level when the level is in both fully retracted and expanded positions. 
     In various embodiments, the locking mechanism includes a friction member that ensures that some level of friction is provided between the locking mechanism and the inner body member even when the locking mechanism is in the unlocked position. This friction acts to control movement of the inner body member as it slides into or out of the outer body member when the locking mechanism is in the unlocked position. In specific embodiments, the amount of friction provided by the friction member is adjustable by the user which allows the user to select how easily the outer body member is permitted to slide relative to the inner body member. This friction mechanism prevents/limits fast and/or unintended sliding between the two level components when the locking mechanism is unlocked, and assists the locking mechanism in restricting movement when the locking mechanism is in the locked position. 
     Referring to  FIG.  1   , an extendable, expandable or length adjustable level, such as level  10 , is shown according to an exemplary embodiment. In general, level  10  is extendable in that its length is reversibly adjustable allowing the user to increase and decrease the length of level  10  as may be needed for various uses. 
     In general, level  10  includes an outer body  12  that includes a base surface  14  and an opposing top surface  16 . Base surface  14  and top surface  16  are flat, planar surfaces that can be used to engage a surface of a workpiece to be measured using level  10 . In some specific embodiments, base surface  14  and/or top surface  16  are machined to have a flat, flush or planar surface following formation of outer body  12  (e.g., following extrusion of a metal forming outer body  12 ), and in some embodiments, this machined surface may be anodized. Surfaces  14  and  16  may be referred to as working surfaces of level  10 . Surfaces  14  and  16  are planar surfaces that are parallel to each other and are also parallel to a longitudinal axis  18  of level  10 . 
     Outer body  12  includes a first body portion, shown as fixed portion  20 , also referred to as fixed body member  20 , and a second body portion, shown as slidable portion  22 , also referred to as slidable body member  22 . In general, fixed portion  20  is rigidly and/or permanently coupled to inner body  24  at a first end  21  of level  10 , and slidable portion  22  slidably engages inner body  24 . Slidable portion  22  defines a second end  23  of level  10  located at the end of slidable body member  22  opposite from fixed portion  20 . In general, to expand level  10 , slidable portion  22  is moved along inner body  24 , also referred to as extended body member  24 , away from fixed portion  20  along longitudinal axis  18 , and to retract/collapse level  10 , slidable portion  22  is moved along inner body  24  toward fixed portion  20 . 
     In some embodiments, inner body  24  is sized such that its entire length fits within slidable portion  22 . Thus, when level  10  is moved to the fully retracted or collapsed position, an inward facing edge  28  of fixed portion  20  abuts an inward facing edge  26  of slidable portion  22 . In this completely collapsed position, fixed portion  20  and slidable portion  22  come together completely covering inner body  24 . 
     Referring to  FIG.  1   , level  10  includes a plurality of bores formed in slidable body portion  22 . As shown in  FIG.  1   , level  10  includes a first vial opening  30 , a second vial opening  32  and a handhold opening  36  formed through slidable portion  22  of outer body  12 . Openings  30  and  32  each receive a level sensing device, shown as level vial  34  (e.g., bubble vials, spirit vials, etc.) which are supported by slidable body portion  22  in the appropriate orientation relative to surfaces  14  and/or  16  in order for the vials to indicate the angle, levelness, degree of plumb, etc. of the corresponding surface of a workpiece, as needed for a particular level design or level type. It should be understood, that level  10  may include less than two level vials or more than two level vials as may be desired for a particular level design. Further, level  10  may be equipped with other orientation measuring components, level sensing and indicating devices other than spirit level vials. For example, level  10  may be equipped with digital/electronic level sensors and display(s) instead of or in addition to level vials  34 . 
     To allow level  10  to provide planar working surfaces at different lengths, the upper and lower surfaces of fixed portion  20  and of slidable portion  22  are coplanar with each other. Specifically, fixed portion  20  includes an upper surface  40  and a lower surface  42 , and slidable portion  22  includes an upper surface  44  and a lower surface  46 . Upper surface  40  is coplanar with upper surface  44 , and/or lower surface  42  is coplanar with lower surface  46 . In this arrangement, upper surface  40  and upper surface  44  operate together providing top working surface  16  of level  10  at all adjustable lengths of level  10 , from fully extended to fully retracted. 
     Similarly, lower surface  42  and lower surface  46  operate together providing base surface  14  of level  10  at all adjustable lengths of level  10 , from a fully extended position to a fully retracted position, wherein the fully retracted position comprises the shortest working length of the level along the longitudinal axis and the fully extended position comprises the longest working length of the level along the longitudinal axis. Unlike a standard fixed length level with a single integral body that defines the working surfaces, one difficulty with expandable levels is the ability to maintain the coplanar nature of the working surfaces on opposing outer body portions, while at the same time providing a robust and easy to use locking mechanism. As will be discussed in more detail below, the locking mechanisms and/or frame designs discussed here are believed to address both of these potential design issues. 
     Referring to  FIGS.  1 - 3   , in addition to the bores for the vials and handholds, level  10  includes an opening  38  formed through slidable portion  22  that receives locking mechanism  50 . Locking mechanism  50  includes a user actuated control, shown as slide  52 , and a locking mechanism frame  54 . In general, slide  52  is the control mechanism that the user operates to move the locking mechanism between locked and unlocked positions. In the locked position, an engagement structure engages inner body member  24 , fixing slidable body portion  22  in place onto inner body member  24 , which also fixes sliding body member  22  in place relative to fixed body member  20 . Through this mechanism, the user is able to set the longitudinal length of level  10  as desired. In various embodiments slide  52  is at least partially disposed within opening  38 . 
     As shown in  FIG.  3   , locking mechanism frame  54  includes left and right portions  56  and  58  that are coupled to slidable body portion  22  and that supports the various components of locking mechanism  50  relative to slidable body portion  22 . In this arrangement, left and right portions  56  and  58  are attached to the outer side surfaces of slidable body portion  22  and support the components of locking mechanism  50  in place within opening  38 . 
     In contrast to at least some expanding level designs that utilize lever-based locking mechanisms, locking mechanism  50  is configured such that translational or linear movement of slide  52  cause locking mechanism  50  to move between the locked and unlocked positions. In the arrangement of locking mechanism  50  shown in  FIGS.  2 A and  2 B , translational movement of slide  52  in a direction parallel to at least one of working surfaces  14  and  16  causes engagement/disengagement of locking mechanism  50 . 
     Referring to  FIGS.  2 A and  2 B , the structure and operation of locking mechanism  50  are shown in more detail. Locking mechanism  50  includes a brake structure  60 , also referred to as braking structure  60 . Brake structure  60  includes a lower engagement surface  62  and an angled upper surface  64 . Lower engagement surface  62  provides frictional engagement (either directly or indirectly) to the upper surface of inner body member  24 , when in the locked position. This frictional engagement holds slidable body member  22  in place relative to inner body member  24 , when locking mechanism  50  is in the locked position. 
     Locking mechanism  50  includes an opposing ramp structure  66  that is coupled to slide  52  and that engages brake structure  60  along angled upper surface  64 . Through the interaction of the angle of ramp structure  66  and angled upper surface  64  of brake structure  60 , horizontal movement of slide  52  is translated into vertical movement of brake structure  60  relative to inner body member  24 . Thus, when slide  52  is moved in a first direction (e.g., translated horizontally away from fixed outer body portion  20 ), brake structure  60  is pulled upward away from inner body portion  24  to the unlocked position. In the unlocked position, this movement causes brake engagement surface  62  to disengage from inner body portion  24 , and slidable body portion  22  is allowed to slide along inner body portion  24 . When slide  52  is moved in a second direction (e.g., translated horizontally toward fixed outer body portion  20 ), brake structure  60  is pushed downward toward inner body portion  24  to the locked position. In the locked position, brake engagement surface  62  is pressed into frictional engagement with inner body portion  24  such that slidable body portion  22  is fixed in place relative to inner body portion  24 . 
     As will be understood, application of locking force by locking mechanism  50  in a consistent manner allows for consistent coplanar alignment of the working surfaces of body portions  20  and  22  when in the locked position. In comparison to other locking mechanisms of prior expandable level designs that utilize screw type or lever type locking mechanisms, Applicant believes that the design locking mechanism  50  provides for an improved leveling accuracy when in the locked position. In particular, brake engagement surface  62  is relatively large such that the requisite frictional locking force is distributed over a large area, which in turn limits the deformation of working surfaces of level  10  which may otherwise occur in other locking member designs. 
     As shown best in  FIG.  2 A , engagement surface  62  has a length, L 1 , that is relatively large, particularly as compared to the longitudinal length of level  10 . In various embodiments, L 1  is between 30 mm and 300 mm, specifically is between 50 mm and 150 mm, and more specifically is between 70 mm and 90 mm, and even more specifically is between 80 mm and 85 mm, and even more specifically is 82.7 mm. In various other embodiments L 1  is at least 30 mm, at least 50 mm, or at least 70 mm. In specific embodiments, the ratio of L 1  to the minimum length (i.e., fully retracted length) of level  10  is between 1:10 and 1:30, and more specifically is between 1:15 and 1:30, and more specifically is 14.74:1 or 23.96:1. In specific embodiments the ratio of L 1  to the maximum length (i.e., fully extended length) of level  10  is between 1:15 and 1:50, and more specifically between 1:20 and 1:40, and more specifically 1:23.96 or 1:44.23. Applicant believes that the size of L 1  and the L 1  ratio discussed above represents a large engagement contact area which results in less deformation, particularly when compared to other locking mechanisms such as lever-type clamping mechanisms that have small contact surfaces. 
     The relatively large size of engagement surface  62  can also be expressed in terms of the area of engagement surface  62 . In various embodiments, the area of engagement surface  62  is between 500 mm 2  and 3000 mm 2 , specifically between 800 mm 2  and 1500 mm 2  and more specifically between 1000 mm 2  and 1400 mm 2  and more specifically is between 1200 mm 2  and 1400 mm 2  and more specifically is 1348 mm 2 . In various other embodiments the area of engagement surface  62  is at least 500 mm 2 , at least 800 mm 2 , or at least 1000 mm 2 . Applicant believes that by increasing the size, and particularly the length of engagement surface  62 , the potential for bending of inner body member  24  around the contact point with the brake engagement surface is decreased by holding inner body member  24  in a cantilevered fashion from the lock engagement area. 
     Referring to  FIG.  3   , the design of the level body, particularly of body portions  20  and  22 , of level  10  is shown. As shown in  FIG.  3   , a longitudinal cross-sectional view of slidable body portion  22  is shown according to an exemplary embodiment. In general, slidable body portion  22  includes an upper portion that is similar to an I-beam level and a lower portion that defines a channel that receives inner body portion  24 . 
     Specifically, slidable body portion  22  includes an upper wall  70  that defines top working surface  16  located at the upper end of a generally vertical wall or web, shown as wall  72 . Applicant believes that upper wall  70  provides an easy to hold structure located along the entire upper end of level  10 . 
     A box structure  74  is located at the lower end of wall  72  and includes an inner surface defining channel  76  and a lower wall defining base surface  14 . In this arrangement, the wall  78  that defines box structure  74  is a closed, contiguous wall (at least at some places on the length of level  10 ) that surrounds and defines channel  76 . As can be seen in  FIGS.  2 A and  3   , channel  76  slidably receives inner body member  24 , allowing slidable body member  22  to be moved along inner body member  24  during length adjustment. Applicant believes that by surrounding inner body member  24  with box structure  74  to provide the telescoping engagement of the level, a robust connection between inner body member  24  and slidable body member  22  is provided (at least compared to the partial engagement of rail type structures present in some prior designs). It should be noted that, in at least some embodiments, fixed level body portion  20  has the same frame shape as slidable body member  22  discussed above. 
     Further, in contrast to some conventional expanding level designs, this frame shape allows for positioning and easy accessibility to slide  52  (e.g., the locking mechanism control). As shown in  FIGS.  1  and  3   , opening  38  extends through vertical wall  72 , and slide  52  is positioned within and extends through opening  38 . In this arrangement, because slide  52  is not located within a cavity of the level body, slide  52  is accessible to the user at any extended or collapsed position (including at the fully retracted position). Further, in this arrangement, slide  52  is accessible from either side of level  10 , allowing the user to conveniently move between locked and unlocked positions from either side of level  10 . 
     As shown in  FIGS.  2 A and  2 B , in various embodiments, level  10  includes a friction element, shown as adjustable friction element  80 . In general, friction element  80  is positioned to contact inner body member  24  to provide a constant but relatively low level of friction to control the sliding of slidable body member  22  relative to inner body member  24  when locking mechanism  50  is in the unlocked position. By providing a low level of friction, friction element  80  increases the amount of force that must be applied in order to slide slidable body member  22  along inner body member  24 . This constant friction decreases the chance of unintended movement of slidable body member  22 . In specific embodiments, friction element  80  is adjustable via an adjustment control (e.g., via a screw  82  or other mechanism) which allows the user to adjust the amount of friction applied by friction element  80 , which in turn allows the user to adjust how free slidable body member  22  is to slide relative to inner body member  24 . In various embodiments friction element  80  includes an engagement surface  84 , and the position of engagement surface  84  relative to an opposing surface of inner body member  24  is adjusted via screw  82 . Operation of screw  82  moves engagement surface  84  toward inner body member  24  to increase friction and away from inner body member  24  to decrease friction. 
     In the embodiment shown, friction element  80  is supported from locking mechanism frame  54  adjacent to brake structure  60 . In one specific embodiment, friction element  80  is separate from locking mechanism  50  (e.g., is separate and separately adjustable from brake member  60 ) and is located between locking mechanism  50  and the central level vial  34 . 
     Referring to  FIG.  4   , a slidable level body  100  is shown according to another exemplary embodiment. Slidable level body  100  is substantially the same as slidable level body portion  22  discussed above, except for the differences discussed herein. Level body  100  includes a pair of opposing internal arms  102  that are located within channel  76 . In this embodiment, the lower surface of inner body member  24  engages arms  102 . In some such embodiments, arms  102  prevent direct engagement between inner body member  24  and the lower wall that defines base surface  14 . In at least some embodiments, this arrangement may decrease/limit the potential for deformation of base surface  14  when force is applied during locking of the locking mechanism. 
     In addition, level body  100  includes a pair of angled walls  104  that extend from central wall  72  to join upper wall  70 . In this manner, upper cavities  106  are defined between walls  104 , central wall  72  and upper wall  70  at the upper end of central wall  72 . Because of the structural support provided by angled walls  104 , this arrangement may allow for the overall thickness and amount of metal used for upper wall  70  to be decreased. 
     Referring to  FIGS.  5  and  6   , a locking mechanism  110  for an extendable level, such as level  10 , is shown according to another exemplary embodiment. Locking mechanism  110  is substantially the same as locking mechanism  50  discussed above, except for the differences discussed herein.  FIG.  5    shows locking mechanism  110  in the unlocked position, and  FIG.  6    shows locking mechanism  110  in the locked position. Locking mechanism  110  includes an adjustable friction element  112  that extends through brake element  60 . Adjustable friction element  112  operates the same as friction element  80  discussed above. As shown, adjustment screw  114  that changes the amount of friction applied by friction element  112  is located and accessible within aperture  116  defined within slide  52 . In addition, friction element  112  is coupled to slide  52  such that friction element  112  moves with slide  52  as locking mechanism  110  is moved between locked and unlocked positions. 
     Referring to  FIGS.  7  and  8   , a locking mechanism  120  for an extendable level, such as level  10 , is shown according to another exemplary embodiment. Locking mechanism  120  is substantially the same as locking mechanism  50  discussed above, except for the differences discussed herein.  FIG.  7    shows locking mechanism  120  in the unlocked position, and  FIG.  8    shows locking mechanism  120  in the locked position. Locking mechanism  120  includes a plurality of brake elements, shown as pivoting cams  122 . As slide  52  is moved from the unlocked position to the locked position, pivoting cams  122  pivot into engagement with the upper surface of inner body member  24  causing sliding body member  22  to be locked into place relative to inner body member  24 . Similar to locking mechanism  110 , locking mechanism  120  includes adjustable friction element  112  coupled to slide  52  and accessible through aperture  116 . 
     Referring to  FIGS.  9 - 11   , a locking mechanism  130  and an associated slidable body member  132  are shown according to exemplary embodiments. Slidable body member  132  is substantially the same as slidable level body portion  22  discussed above, except for the differences discussed herein. Locking mechanism  130  is substantially the same as locking mechanism  50  discussed above, except for the differences discussed herein. 
     Slidable body member  132  is a box-type level body having a single contiguous wall structure  134  defining an internal cavity  136  that houses both inner body member  24  and locking mechanism  130 . Wall structure  134  defines a plurality of outwardly extending sections  138 . As shown in  FIGS.  10  and  11   , outwardly extending sections  138  provide non-vertical surfaces that act as rails for support of locking mechanism  130  and for the guiding inner body member  24  within slidable body member  132 . 
       FIGS.  10 A and  10 B  show locking mechanism  130  in the unlocked position, and  FIGS.  11 A and  11 B  show locking mechanism  130  in the locked position. In general, locking mechanism  130  includes a brake structure  140  that has angled engagement surfaces  142 , and in this embodiment, inner body member  24  includes a channel structure having opposing, upwardly and laterally inwardly facing, angled surfaces  144 . Locking mechanism  130  is configured such that movement of slide  52  pushes engagement surfaces  142  of brake structure  140  laterally outward and into engagement with the angled surfaces  144  of inner body member  24  when moved to the locked position. In this embodiment, the locking force applied by locking mechanism  130  is directed completely or partially in the horizontal direction coplanar with base surface  14  toward the vertical side walls of level body  132 , which may decrease the likelihood that the working surfaces  14  and/or  16  of level  10  are deformed/misaligned during application of locking force. 
     Referring to  FIGS.  12 - 14   , a locking mechanism  150  and an associated slidable body member  152  are shown according to exemplary embodiments. Slidable body member  152  is substantially the same as slidable body member  22  discussed above, except for the differences discussed herein. Locking mechanism  150  is substantially the same as locking mechanism  50  discussed above, except for the differences discussed herein. 
     Slidable body member  152  is a box-type level body having a single contiguous wall structure  154  defining an internal cavity  156  that houses both inner body member  24  and locking mechanism  150 . Wall structure  154  is shaped such that internal cavity  156  has a generally rectangular cross-sectional shape. 
       FIGS.  13 A and  13 B  show locking mechanism  150  in the unlocked position, and  FIGS.  14 A and  14 B  show locking mechanism  150  in the locked position. In general, locking mechanism  150  includes a brake structure  160  that has angled engagement surfaces  162 , and in this embodiment, inner body member  24  includes a tapered upper end having opposing, upwardly and laterally outwardly facing, angled surfaces  164 . Locking mechanism  150  is configured such that movement of slide  52  pulls engagement surfaces  162  of brake structure  160  laterally inward and into engagement with the angled surfaces  164  of inner body member  24  when moved to the locked position. Similar to locking mechanism  130 , the locking force applied by locking mechanism  150  is directed completely or partially in the horizontal direction, which may decrease the likelihood that the working surfaces  14  and/or  16  of level  10  are deformed/misaligned during application of locking force. 
     As shown in  FIG.  15   , locking mechanism  150  includes an adjustable friction element  170  that is positioned adjacent to locking mechanism  150 . Adjustable friction element  170  operates the same as friction element  80  discussed above. As shown, friction element  170  includes an adjustment control, shown as adjustment screw  172 , that changes the amount of friction applied by friction element  112 . As shown best in  FIGS.  13 B and  14 B , adjustment screw  172  is accessible from gap  174  between body portions  22  and  20  (shown in  FIG.  1   ) when the level is in an extended position. 
     In specific embodiments, the level body components (such as fixed body portion  20 , slidable body portion  22  and inner body portion  24 ) discussed herein are each formed from a hollow piece of material, such as hollow pieces of metal material (e.g., hollow pieces of extruded aluminum). Further, it should be understood that the terms vertical and horizontal used herein refer to reference axes where horizontal is a plane that lies parallel to the working surfaces of the level and vertical is a plane that lies perpendicular to the working surfaces of the level. 
     Referring to  FIGS.  16 - 18   , a locking mechanism  200  is shown according to an exemplary embodiment. In general, locking mechanism  200  is the same as locking mechanism  50 , except for the differences discussed herein. Locking mechanism  200  includes a user actuated control, shown as slide  202 , supported by locking mechanism frame  54 . Locking mechanism  200  includes a brake structure  204 . Brake structure  204  includes a pair of angled channels  206  and a lower engagement surface  208 . Like lower engagement surface  62 , lower engagement surface  208  provides frictional engagement (either directly or indirectly) to the upper surface of inner body member  24 , when in the locked position. This frictional engagement holds slidable body member  22  in place relative to inner body member  24 , when locking mechanism  50  is in the locked position. 
     Locking mechanism  200  includes angled channels  206  that are coupled to slide  202  via slide posts  210 . As shown in  FIG.  17   , slide posts  210  extend horizontally away from the inner surface of slide  202  such that the slide posts  210  are received in the angled channels  206 . Through the interaction of slide posts  210  and angled channels  206  of brake structure  204 , horizontal movement of slide  202  is translated into vertical movement of brake structure  204  relative to inner body member  24 . Thus, when slide  202  is moved in a first direction (e.g., translated horizontally away from fixed outer body portion  20 , shown in  FIG.  16   ), brake  204  is pulled upward away from inner body portion  24  to the unlocked position. In the unlocked position, this movement causes brake engagement surface  208  to disengage from inner body portion  24 , and slidable body portion  22  is allowed to slide along inner body portion  24 . When slide  202  is moved in a second direction (e.g., translated horizontally toward fixed outer body portion  20 ), brake  204  is pushed downward toward inner body portion  24  to the locked position. In the locked position, brake engagement surface  208  is pressed into frictional engagement with inner body portion  24  such that slidable body portion  22  is fixed in place relative to inner body portion  24 . 
     Referring to  FIG.  17   , an expanded open section  212  is located at the upper end of each angled channel  206 , and includes angled lower surface  213  and depression  215  within angled lower surface  213 . As can be seen in  FIG.  17   , a maximum height of open section  212  is greater than a maximum height of channel  206 . In this arrangement, open section  212  allows slide posts  210  to shift downward a small distance when brake structure  204  reaches the locked position. This movement provides a tactile and/or auditory indication of reaching the locked position as posts  210  snap into the expanded open sections  212 . 
     In various embodiments the materials for brake structure  60  and/or brake structure  204  are selected to provide for a high friction engagement to the upper surface of inner body member  24 . In particular embodiments, a lower portion of the brake structure defining the engagement surface may be made from a compressible and/or lower durometer material than the rest of the brake structure which facilitates high friction engagement with inner body member  24  upon locking. 
     Further referring to  FIGS.  16 - 18   , a friction element, shown as adjustable friction element  220 , is shown according to an exemplary embodiment. In general, adjustable friction element  220  is the same as adjustable friction element  80 , except for the differences discussed herein. Like friction element  80 , friction element  220  is adjustable via an adjustment control (e.g., via a screw  82  or other mechanism) which allows the user to adjust the amount of friction applied by friction element  220 , which in turn allows the user to adjust how free slidable body member  22  is to slide relative to inner body member  24 . 
     As shown best in  FIG.  18   , friction element  220  includes two body portions, shown as left body portion  222  and right body portion  224 . Body portions  222  and  224  have opposing and contacting vertical angled surfaces  226  and  228 . In a specific embodiment, angled surfaces  226  and  228  form a 60 degree angle relative to the horizontal plane in the orientation of  FIG.  18   . By operation of screw  82 , body portions  222  and  224  are pulled/pushed relative to each causing the lower engagement surface  84  to move vertically relative to the upper surface of inner body member  24 , and this in turn adjusts the amount of the constant friction applied by friction element  220 . 
     In specific embodiments, body portions  222  and  224  are formed from a low wear, relatively low friction and/or durable polymer material, such as a polyoxymethylene polymer material, like Delrin available from DuPont. Further to facilitate fine adjustment of the amount of friction applied by adjustable friction element  220 , screw  82  may have low pitch threading such that each rotation of screw  82  translates to a small adjustment in the vertical position change of body portions  222  and  224 . 
     Referring to  FIGS.  19 - 22   , the expanding levels discussed herein may include one or more bushing structures located between inner body member  24  and the inner surface of slidable body member  22  that defines channel  76  (see e.g.  FIG.  4   ). In such embodiments, the bushing structures may provide for improved sliding via controlled friction and/or wear resistance as compared to an arrangement in which the outer surface of body member  24  directly engages the inner surface of slidable body member  22 . 
     In the specific embodiments, front and rear bushing structures may be located around inner body member  24  toward each end of slidable body member  22 . In particular,  FIGS.  19  and  20    show a rear bushing  230  which is located near one end of inner body  24  within channel  76 , adjacent end vial opening  32  and level body end  23  (see  FIG.  1   ). Further,  FIGS.  21  and  22    show a front bushing  260  which is located at the other end of inner body  24  within channel  76  adjacent/below locking mechanism  50  (see  FIG.  1   ). 
     As shown in  FIGS.  19  and  20   , rear bushing  230  includes an upper component  232  that is located outside of an upper wall  234  of inner body member  24  and a lower component  236  that is located outside of lower wall  238  of inner body member  24 . In general, components  232  and  236  are formed from a low friction, low wear polymer material providing bushing functionality between inner body member  24  and slidable body member  22 . 
     As shown best in  FIG.  20   , an upper sleeve or collar  240  is coupled to and extends downward from upper bushing component  232 , and a lower sleeve or collar  242  is coupled to and extends upward from lower bushing component  236 . Collars  240  and  242  each include a sidewall structure, shown as cylindrical sidewalls  246  that define a cavity  248  or recess  248 . As shown in  FIG.  20   , cylindrical sidewalls  246  extend through openings in walls  234  and  238  of inner body member  24 , and a biasing element, shown as spring  250 , is located between collars  240  and  242 . Spring  250  applies a force between upper bushing component  232  and lower bushing component  236  to provide a high level of bushing contact to the inner surfaces of slidable body member  22 . 
     In addition to providing a high level of bushing contact, Applicant has found that the design of rear bushing  230  provides a robust and failure resistant arrangement particularly well suited for a tool regularly used in a construction environment. In particular, the upper and lower ends of spring  250  are each received within the open central cavities  248  defined by collars  240  and  242 . In this arrangement, the relatively large support contact area between spring  250  and collars  240  and  242  is less likely to fail, particularly in strain, as compared to pin-type mounting arrangements. 
     Further, in this arrangement, the ends of spring  250  are surrounded by and captured within collars  240 , and the ends of springs  250  extend in the vertical direction through both walls  234  and  238  of inner body member  24 , respectively, to engage with bushing components  232  and  236 , respectively. Applicant believes that this arrangement provides a robust bushing structure (at least compared to a bushing structure in which spring  250  is received over a pin structure). In particular, even in the event of breakage or crack formation between collars  240  or  242  and the associated bushing component  232  or  236 , respectively, the capture of spring  250  within the collar, the capture of the collar within the opening extending through inner body member and the biasing force of the spring  250  will tend to hold bushing  230  together and in the proper position, despite crack formation. 
     Referring to  FIGS.  21  and  22   , front bushing  260  is shown in detail. As shown best in  FIG.  21   , front bushing  260  is coupled to slidable body member  22  and around inner body member  24  below locking mechanism  50 . In general, front bushing  260  includes a low friction, low wear polymer material providing bushing functionality between inner body member  24  and slidable body member  22 , facilitating sliding of inner body member  24  relative to slidable body member  22 . 
     In various embodiments, front bushing  260  is formed from two separate pieces shown as first segment  262  and second segment  264 . Upper portions of first segment  262  and second segment  264  meet at an angled interface  266  defining a gap  268 . This angled interface  266  and gap  268  allow for flexion/compression during assembly, which allows front bushing  260  to be inserted into slidable body member  22 , and the resilience of the bushing material and/or outward bias of front bushing  260  provides for a high level of contact between the outer surfaces of front bushing  260  and the inner surface of slidable body member  22  that defines channel  76 . 
     Front bushing  260  includes one or more posts, shown as hex pegs  270 . In this embodiment, hex pegs  270  are received through openings  272  formed through the sidewall of slidable body member  22 . In this manner, front bushing  260  is fixed in place relative to slidable body member  22 , and inner body member  24  to slide relative to front bushing  260  during extension and retraction of the expanding level. 
     Referring to  FIGS.  23  and  24   , a front bushing  280  is shown according to an exemplary embodiment. Front bushing  280  is substantially the same as front bushing  260  except for the differences discussed herein. Front bushing  280  includes a flexible and outwardly biased arm  282  formed in each sidewall  284  of front bushing  280 . Hex pegs  270  are located on arms  282 , and the outward bias of arms  282  facilitate the snap fitting and retention of front bushing  280  in outer body member  22 . In addition, this outward bias also acts to securely retain hex pegs  270  engaged within openings  272 . 
     Referring to  FIGS.  25 - 27   , in various embodiments, level  10  may include a pair of standoffs  300  that can be removably attached at opposing ends of level body  12 . In general, standoffs  300  define a pair of aligned and height-extended leveling surfaces  302 . In use, standoffs  300  can be mounted to level body  12  in order to use level  10  to level two surfaces that have an obstruction located in between. 
     To mount standoffs  300  to level body  12 , fastener  304  is mounted and retained within standoff  300 . In the embodiment shown in  FIG.  25   , fastener  304  is a threaded fastener that is threaded into an opposing threaded opening located in level body  12 . As shown in  FIG.  25   , fastener  304  is retained within standoff  300  (e.g., via a lip that captures fastener within standoff  300 ) such that fastener  304  does not separate from standoff  300 , when standoff  300  is disconnected from level  10 . In some embodiments, level body  12  may include one or more alignment pins  306  that facilitate alignment of fastener  304  with the receiving hole within the level body. As can be seen best in  FIG.  27   , level  10  does not include an additional, projecting standoff mounting structure along upper surface  40 , such that surface  40  remains level following removal of standoff  300 . 
     In addition, standoff  300  includes a projection or hook  310 . In general hook  310  provides a structure that grips an edge or corner of a workpiece, allowing the user to pull and extend level  10  while the end, with the standoff, is held in place via engagement of the workpiece by the hook  310 . As shown best in  FIGS.  26  and  27   , hook  310  is a projection that extends outward away from surface  302  and in a direction toward slidable body member  22 . In this manner the upper half of standoff  300  is asymmetrical about a vertical axis as shown in  FIGS.  26  and  27   . Further, hook  310  defines a width dimension that is greater than the width dimension of surface  302  but is also less than the width dimension at the lower end of standoff  300 . 
     Referring to  FIG.  28   , a vial assembly  320  for holding/positioning a level vial  34  within wall  72  is shown according to an exemplary embodiment. In general, vial assembly  320  includes a rear frame  322 , a front frame  324 , a front face plate  326  and a plurality of fasteners, shown as screws  328 . In general, vial opening  32  is located within wall  72 , and level vial  34  is located within vial opening  32 . Rear frame  322  is positioned to surround both vial opening  32  and level vial  34  along the rear face of wall  72 , and front frame  324  is positioned to surround both vial opening  32  and level vial  34  along the front face of wall  72 . In this arrangement, inward facing surfaces of rear frame  322  and of front frame  324  engage level vial  34  trapping level vial  34  within vial opening  32 . 
     Vial assembly  320  includes screws  328 . Screws  328  pass through screw holes  330  in front frame  324  and are received within threaded screw channels  332  within rear frame  322 . As screws  328  are tightened, level vial  34  is clamped between rear frame  322  and front frame  324  which fixes level vial  34  in place relative to wall  72 . In conventional assemblies in which a level vial is mounted within a vertical wall or web in a typical I-beam-style level frame, glue or adhesive is typically used to fix the level vial and associated frame components in place. However, Applicant has found that such vial assemblies are susceptible to being pushed out of the vial opening due to relative weakness of such adhesives. In contrast, the mechanical, clamping force type mounting provided by screws  328  and frames  322  and  324  eliminate/reduce the risk of vial  34  being pushed from vial opening  32 . 
     Vial assembly  320  includes front face plate  326  that is mounted over front frame  324  and over screws  328 . Front face plate  326  provides a face that is uninterrupted by screw heads, screw holes or other fasteners. In specific embodiments, front face plate  326  is glued in place over front frame  324 . 
     Referring to  FIG.  29   , in some embodiments, level  10  may include a double vial assembly  340  located near one of the ends of level body  12 . As shown in  FIG.  29   , double vial assembly is located adjacent to end  23 , located at the end of level  10  opposite fixed body portion  20 . In general, double vial assembly  340  includes a pair of level vials  34 , one oriented horizontally and one oriented vertically, that are received within a pair of adjacent vial openings  32 . Locating the pair of vials  34 , adjacent end  23  allows the user to easily view level vials oriented in both vertical and horizontal directions, particularly when level  10  is in the extended position. 
     Like vial assembly  320 , double vial assembly  340  includes a rear frame  342 , a front frame  344  and a front face plate  346 . Double vial assembly  340  is assembled like assembly  320  except that it supports two level vials  34  instead of one. 
     It should be understood that the figures illustrate the exemplary embodiments in detail, and it should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting. 
     Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only. The construction and arrangements, shown in the various exemplary embodiments, are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Some elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process, logical algorithm, or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present invention. 
     Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein the article “a” is intended to include one or more components or elements, and is not intended to be construed as meaning only one. 
     Various embodiments of the invention relate to any combination of any of the features, and any such combination of features may be claimed in this or future applications. Any of the features, elements, or components of any of the exemplary embodiments discussed above may be utilized alone or in combination with any of the features, elements, or components of any of the other embodiments discussed above. 
     In various exemplary embodiments, the relative dimensions, including angles, lengths and radii, as shown in the Figures are to scale. Actual measurements of the Figures will disclose relative dimensions, angles and proportions of the various exemplary embodiments. Various exemplary embodiments extend to various ranges around the absolute and relative dimensions, angles and proportions that may be determined from the Figures. Various exemplary embodiments include any combination of one or more relative dimensions or angles that may be determined from the Figures. Further, actual dimensions not expressly set out in this description can be determined by using the ratios of dimensions measured in the Figures in combination with the express dimensions set out in this description. In addition, in various embodiments, the present disclosure extends to a variety of ranges (e.g., plus or minus 30%, 20%, or 10%) around any of the absolute or relative dimensions disclosed herein or determinable from the Figures.