Abstract:
A floor or road saw ( 20 ) that includes a multi-speed transmission ( 24 ) that includes a neutral position. The transmission does not require the use of belts, polychains, or clutches that require regular maintenance and/or replacement. Moreover, the transmission ( 24 ) of the saw ( 20 ) may be shifted when the transmission is engaged and shifted through a set of gears ( 62 ) in a sequential manner. Further, the transmission is well suited for use on saws where power source or prime mover ( 22 ) is disposed parallel to the longitudinal axis of the saw ( 20 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention applies to road or floor saws and more specifically to self-propelled operator-guided or steerable saws supported on a frame with wheels. 
         [0003]    2. Description of the Related Art 
         [0004]    In the concrete industry, when building bridges, buildings, roads and the like, it is often necessary to pour large horizontal slabs of concrete. Once poured, it is usually necessary to machine the slab. Such machining may include cutting seams completely through the slab (to form expansion joints and to allow for foundation shifting), cutting notches partially into the slab (to create stress cracks along which the slab will split), cutting multiple grooves into the slab to create a high friction surface such as for bridges, grinding the surface of the slab and the like. Concrete saws are also used in the demolition or removal of concrete, such as during the sawing and replacement of bridge decks. Various types of concrete saws may be utilized to carry out these machining and demolition tasks. In larger industrial applications, large self-propelled saws are used that are powered in a variety of manners, such as by gasoline, diesel, electric, propane and natural gas engines mounted on the saw. While performing a cut, the operator controls the direction, cutting speed, cutting depth and the like. 
         [0005]    Recently designed concrete saws may include an engine that is mounted with its longitudinal axis in line with the longitudinal axis of the saw. This is in contrast to traditional transverse mounting arrangements. This new arrangement allows the saw to be moved through doorways and other passages that were previously not passable. Even with such an improvement, modern saws lack flexibility in other areas. Transmissions presently in use comprise a number of belts that are subject to wear and breakage, and belts require regular re-tensioning. These belt-driven transmissions do not provide a “neutral” configuration where the transmission is engaged, but the saw blade is not being driven except by means of a conventional clutch that is subject to wear. Often these transmissions operate at only a single speed, and if a multiple speed transmission is provided, it does not afford sequential shifting which avoids over-speeding a blade by accidentally shifting to a very high gear. Also, the prior art transmissions do not provide the convenience of being able to shift gears during the cutting operation (i.e., “on the fly”). 
         [0006]    Therefore, there exists a need in the art for an improved road or floor saw which includes a transmission with more operational flexibility. Moreover, there exists a need in the art for a concrete saw that is low maintenance that provides a multi-speed transmission. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention provides an improvement over the prior art by providing a floor or road saw that includes a multi-speed transmission that includes a neutral position. The transmission of the present invention does not require the use of belts, polychains or clutches that require regular maintenance and/or replacement. Moreover, the transmission of the saw may be shifted when the transmission is engaged and shifted through a set of gears in a sequential manner. Further, the transmission is well suited for use on saws where power source or prime mover is disposed parallel to the longitudinal axis of the saw. 
         [0008]    In one embodiment the invention provides a concrete saw having a generally rectangular frame having a front end and a rear end, a prime mover or power source supported by the frame and including a rotational output shaft aligned generally with the length of the frame, a gear drive driven by the prime mover rotational output shaft, the gear drive having a transfer gear shaft in rotational communication with a transmission main shaft, wherein the transfer gear shaft is oriented transverse to the prime mover rotational output shaft, and a beltless transmission including the transmission main shaft and an outlet shaft wherein the outlet shaft is in rotational communication with a saw blade. 
         [0009]    In another embodiment, the saw includes a dampening mechanism that interrupts direct rotational communication between the prime mover and the saw blade when the saw blade encounters a predetermined degree of rotational resistance. In one such embodiment the dampening mechanism is a resettable disengagement device that completely interrupts communication between the prime mover and the saw blade. In another embodiment the beltless transmission is multi-speed and it includes a selectable full rotational neutral position. In another embodiment, the multi-speed beltless transmission provides sequential shifting, and it is capable of being shifted during cutting operations. 
         [0010]    The foregoing and other features of the invention are hereinafter more fully described and particularly pointed out in the claims, the following descriptions setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the present invention may be employed. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0011]      FIG. 1  is a perspective view of a mobile saw of the present invention; 
           [0012]      FIG. 2  is a detailed perspective view of the engine, transmission and saw blade of the present invention; 
           [0013]      FIG. 3  is a broken away perspective view of the transmission; 
           [0014]      FIG. 4  is a perspective view of the transmission and saw blade, particularly showing an exploded view of the resettable clutch; 
           [0015]      FIG. 4A  is a cross-sectional schematic view of an electric clutch suitable for use in the present invention; 
           [0016]      FIG. 4B  is a cross-sectional schematic view of a conventional friction clutch suitable for use in the present invention; 
           [0017]      FIG. 4C  is a perspective schematic view of a flexible rubber coupling suitable for use in the present invention; 
           [0018]      FIG. 5  is a schematic representation of a first embodiment of the invention; 
           [0019]      FIG. 6  is a schematic representation of a second embodiment of the invention; 
           [0020]      FIG. 7  is a schematic representation of a third embodiment of the invention; 
           [0021]      FIG. 8  is a schematic representation of a fourth embodiment of the invention; 
           [0022]      FIG. 9  is a schematic representation of a fifth embodiment of the invention; 
           [0023]      FIG. 10  is a schematic representation of a sixth embodiment of the invention; 
           [0024]      FIG. 11  is a schematic representation of a seventh embodiment of the invention; 
           [0025]      FIG. 12  is an exploded view of a gear and engagement dog upon a shaft; and a portion of the main shaft of  FIG. 3 ; and 
           [0026]      FIG. 13  is a view of a portion of the transmission of  FIG. 3  with the left gear sets separated and pulled away. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Referring to the drawings, a mobile road or floor saw  20  according to the present invention is illustrated. The saw  20  includes an engine  22  that is used to drive a transmission  24  that in turn drives a saw blade  26 . The saw  20  is used to cut seams, notches and/or grooves into or through asphalt, concrete, stone or other similar surfaces. 
         [0028]    Referring to  FIGS. 1-3 , the engine or prime mover  22  of the saw  20  has a generally rectangular shape and is supported upon a generally rectangular frame  28 . The frame  28  has a front end  30  and a rear end  32 . The engine  22  is of a type generally known in the art and is oriented with a driven output shaft  34  parallel to an axis “A-A” defined by the length of the rectangular frame  28 . The engine  22  includes means for cooling, such as a fan  36  and radiator  38 , at an end opposite the output shaft  34  and adjacent to the rear end  32  of the frame  28 . It will be appreciated that prime mover  22  may comprise a gasoline, diesel or propane (internal combustion) engine, or an electrical motor. 
         [0029]    The output shaft  34  of the engine  22  is in rotational communication with a transmission  24 . The entire saw blade drive system, including the transmission  24  is beltless, thus, it does not rely on the use of belts or polychains and pulleys. Additionally, the blade drive system does not require the use of a conventional clutch. The transmission  24  is contained within a housing  42 . The housing  42  comprises a face shell  44 , a back shell  46  and first and second oblong end plates  48  and  50 . The face shell  44  is supported between the first and second oblong end plates  48  and  50 . In combination, the first and second end plates  48  and  50 , face shell  44  and back shell  46  define the transmission housing  42 . The prime mover  22  is attached to frame  28  by support plates  49  and transmission housing  42  is attached to the frame  28  by support legs  51 . 
         [0030]    Referring specifically to  FIG. 3 , the transmission  24  includes a transverse gear pairing (gear drive)  52 , a main shaft  54  that supports driving gears  56  and engagement dogs  58 , a counter shaft  60  that supports driven gears  62  and an outlet shaft  64  as described in more detail below. 
         [0031]    The output shaft  34  of the engine  22  is coupled to a flywheel  66 , which is in turn coupled to a first gear  70  of the transverse gear pairing  52 . Gear teeth upon the first gear  70  of the transverse gear pairing  52  mesh with gear teeth of the second gear  72  in the transverse gear pairing  52 . Each of the first gear  70  and second gear  72  include teeth in a spiral bevel configuration. The second gear  72  is supported upon a transfer gear shaft  74  at the end of shaft  74 . The transfer gear shaft  74 , at a distal end  78 , is supported upon the transmission housing  42 . A transfer gear  80  is affixed to the transfer gear shaft  74  at the distal end  78 . The transfer gear  80  includes teeth that mesh with a main shaft transfer gear  82  upon a main shaft  54  of the transmission  24 . 
         [0032]    The main shaft  54  of the transmission  24  is oriented parallel to the transfer gear shaft  74  and supports four driving gears  56  and associated engagement dogs  58  as well as the main shaft transfer gear  82  previously mentioned. The main shaft  54  is oriented transverse to the output shaft  34  of the engine  22  and placed beneath the second gear  72  of the transverse gear pairing  52 . Referring to  FIGS. 3 ,  4 ,  12  and  13 , the main shaft  54  includes sleeves  84  having unsplined (i.e. smooth outer surface)  85  and splined sections  86 . Sleeves  84  are driven by and in engagement with main shaft  54 . 
         [0033]    The four driving speed gears  56  are located at an end of the main shaft  54  opposite the transfer gear  82  and are selectively engageable with the main shaft  54 . Each driving speed gear  56  includes a set of peripheral teeth  90  and a set of receptors  92 . The peripheral teeth  90  are upon the outer radial surface  94  of the gear  56  while the receptors  92  are upon the axial surface  96  of the gear  56 . Referring to  FIGS. 12 and 13 , the driving gears  56  are supported and freely rotate on unsplined sections  85  of the sleeves  84 . The engagement dogs  58  are supported upon and are axially slidable along splined sections  86  of the sleeves  84 . Two engagement dogs  58  are located between the gear most proximate to the main shaft transfer gear  82  and an adjacent gear. Two further engagement dogs  58  are located between a gear most distant to the main shaft transfer gear  82  and an adjacent gear. The engagement dogs  58  include protruding ribs  93  and the dogs are slidingly engageable with the driving speed gears  56 . More particularly, when a dog is slid into engagement, the ribs  93  of the dog engage the receptors  92  of the driving gear  56 , thereby driving gear  56 . The dogs  58  are moved by shift forks  98 . The shift forks  98  are supported by a post  100  affixed to the transmission housing  42  and their movement is controlled by a conventional cable-type lever  102 . It will be appreciated that other conventional means may be used to manipulate the position of dogs such as electric and hydraulic actuators. 
         [0034]    A counter shaft  60  is located below and oriented parallel to the main shaft  54  and supports four driven gears  62  and an output gear  104 . The counter shaft  60  has a length generally equivalent to the main shaft  54  and is supported by the transmission housing  42 . The counter shaft  60  is driven by the main shaft  54 . The driven gears  62  on the main shaft  54  are aligned with and continuously engaged with the counter shaft  60 . The driven gears  62  are in constant engagement with the counter shaft  60 . The driven speed gears  62  include teeth  106  upon outer radial surfaces  108 . The counter shaft  60  also supports the output gear  104  at an end opposite that of the driven gears  62 . 
         [0035]    An idler gear  110  is supported on a stub shaft  112  adjacent to and below the counter shaft  60 . The stub shaft  112  is oriented parallel to the counter shaft  60  and is supported by the transmission housing  42 . 
         [0036]    The transmission outlet shaft  64  is supported by the transmission housing  42  adjacent to and below the stub shaft  112  and supports an outlet gear  114 . The transmission outlet shaft  64  is oriented parallel to the main shaft  54  and countershaft  60  of the transmission  24  and extends outside of the transmission housing  42  on both ends. The outlet gear  114  is continuously engaged with the idler gear  110  supported on the stub shaft  112 . 
         [0037]    The blade drive system includes the resettable overload clutch  130  that is located between the engine output shaft  34  and the transverse gear pairing  52 . 
         [0038]    Support bearings  116  are affixed to the exterior of the transmission housing  42  adjacent to the outlet shaft  64 . The support bearings  116  abut the housing  42  and support the outlet shaft  64 . 
         [0039]    Referring to  FIG. 2 , a saw blade  26  is affixed to one end of the transmission outlet shaft  64 . A radial axis defined by the saw blade  26  is parallel to an axis A-A defined by the length of the saw frame  28 . The saw  20  also includes operational systems that are known or conventional in the art. These systems include a locomotion system that drives wheels  124  supporting the saw frame  28  at a desired speed. A lift system  126  is also included that is able to tilt the saw frame  28 . When tilted the saw blade  26  may be taken out of contact with the substrate being cut. The saw  20  includes an engine mounting system that minimizes vibration within the frame. The saw  20  also includes a conventional speed selection lever  128  for controlling the speed of advancement of the saw. 
         [0040]    The engine  22  is mounted upon the saw frame  28 . The transmission housing  42  is affixed to the engine  22  such that the output shaft  34  of the engine  22  enters the transmission housing  42 . The transmission housing  42  is also supported on supports  51 . The configuration of the transmission  24 , as previously described, changes the direction of an axis “A-A” representing rotational motion and torque generated by the engine  22  about ninety degrees. Additionally, the vertical position of the rotational axis is moved downward to an axis “B-B”. 
         [0041]    The engine  22  drives the transmission and indirectly, the saw blade  26 . The output shaft  34  of the engine  22  is in rotational communication with the first gear  70  of the transverse gear  52  pairing via the engine&#39;s flywheel  66 . The transverse gear pairing  52  changes the axis of the rotational motion provided by the engine  22  ninety degrees. The second gear  72  of the transverse gear pairing  52  is rotated by the first gear  70 . The transfer gear  80  on the shaft  74  supporting the second gear  72  of the transverse gear pairing  52  drives a main shaft transfer gear  82  of the transmission  24 . The main shaft  54  and the driving gears  56  thereon work in conjunction with the countershaft  60  to vary the speed of the outlet shaft  64  of the transmission  24 . 
         [0042]    The driving speed gears  56  on the main shaft  54  are continuously engaged with the driven speed gears  62  on the counter shaft  60 . However, the driving speed gears  56  slip upon the sleeves  84  unless the engagement dogs  58 , that are splined to the splined portion of the sleeves  84 , are slid into engagement with the driving gears  56 . Only one engagement dog  58  is engaged at a time. To which gear the engagement dog  58  is engaged determines the speed of the counter shaft  60  with respect to the main shaft  54 . The engagement dogs  58  are moved into and out of engagement by the shift forks  98 . The transmission  24  provides multiple output speeds. 
         [0043]    The engagement of the dogs  58  with the driving gears  56  is performed sequentially. For example, a gear numbered three must be accessed after a gear numbered two. The progression continues through the entire driving gear set  56 . The transmission  24  includes a neutral state when none of the engagement dogs  58  are engaged with a driving gear  56 . The gear progression is as follows: neutral (when no dogs are in engagement with a driving gear), first gear, second gear, third gear, fourth gear. 
         [0044]    Shifting from a first gear to a second gear is performed while the transmission main shaft  54  is in rotational communication with the engine output shaft  34  and the transmission main shaft  54  is in rotational communication with the counter shaft  60 . This is referred to as on-the-fly shifting. 
         [0045]    Preferably, saw  20  includes some type of dampening mechanism that interrupts direct communication between the engine  22  and saw blade  26  when the blade encounters significant predetermined resistance. Referring to  FIG. 4 , there is shown a resettable clutch  130  that is in continuous engagement under normal operating conditions. However, when the saw blade  26  encounters rotational resistance beyond a desired level, the clutch  130  actuates and totally interrupts rotational communication between the engine output shaft  34  and the first gear  70 , thus, interrupting rotational communication between the saw blade  26  and the transmission  24 . It is possible to place the clutch  130  in a different location, for example on counter shaft  60 , however, it is preferable to locate clutch  130  as shown in order to maintain the same torque for different output speeds. 
         [0046]    Resettable clutch  130  is commercially available from various sources including American Autogard Corp. of Rockford, Ill., and Cabat Inc. of Racine, Wis. Such a clutch  130  is disclosed in U.S. Pat. No. 3,893,553 which is hereby incorporated by reference. Generally, such clutch  130  includes a plurality of springs  132  that load balls  134  in an engaged position relative to end caps  135 . A torque overload, of predetermined load, causes the balls  134  to retract into the rotor  136 , allowing the rotor to rotate relative to housing  138 . With about 15° of rotation, the drive key  140  escapes into the recess  142  in the housing, allowing the hub  144  to rotate freely without ratcheting the balls  134 . Re-engagement is accomplished by reversing the relative rotation. Specifically, the clutch  130  is re-engaged by rotating the saw blade  26  in a reverse direction for less than one full revolution. Some resettable clutches employ resetting functions that are independent of the connection and the present invention contemplates the use of such devices. 
         [0047]    It will be appreciated that a resettable clutch may also be incorporated into a conventional saw that employs belts or polychains such as in the saw shown in U.S. Pat. No. 6,318,353 the disclosure of which is incorporated herein by reference. In the saw of the &#39;353 patent a resettable overload clutch  130  could be incorporated between the engine output shaft and the drive sprockets. 
         [0048]    As shown in  FIG. 4A  the dampening mechanism may comprise a conventional electric clutch  300  mounted between the engine output shaft  34  and the first gear  70 . A sensor  331  would be provided on engine  22  such that when the saw blade  26  encounters rotational resistance beyond a desired level and the engine slows at a predetermined rate, stationary field coil  333  is de-energized thus allowing armature assembly  335  which is in rotational communication with first gear  70  to move freely from the rotor assembly  337  which is in rotational communication with engine output shaft  34 . Re-engagement is accomplished by an operator simply re-establishing the electric field on coil  333  thereby bringing rotor  337  and armature  335  back into direct communication. 
         [0049]    As shown in  FIG. 4B  the dampening mechanism may comprise a conventional friction clutch  340  mounted between the engine output shaft  34  and the first gear  70 . Like electric clutch  300 , friction clutch  340  would be automatically disengaged by a sensor  331  that detects a sudden predetermined drop in engine  22  speed. Throw-out bearing assembly  343  may be moved so as to bring clutch plate  344  in and out of engagement by any one of a number of conventional means such as by using a hydraulic or pneumatic activator  345  that is actuated by sensor  331 , so as to disengage and engage rotational communication between the clutch flywheel  350  connected to output shaft  34  on engine  22  and the clutch shaft  352  connected to first gear  70 . 
         [0050]    As shown in  FIG. 4C  the dampening mechanism may also comprise a flexible rubber coupling  360  comprising an outer wheel  363  which is rotationally attached to first gear  70  and an inner hub  365  that is attached to engine  22  output shaft  34 . Connecting hub  365  to wheel  363  is a flexible rubber disk  368  that is capable of absorbing tremendous energy when the saw blade  26  encounters unexpected rotational resistance, thereby protecting the blade  26  and transmission  24  from possible damage due to a sudden high load being placed on the saw. In an extreme loading situation it may be possible for disk  368  to slip relative to the teeth  370  formed in wheel  363  thus allowing hub  365  to move slightly independent of wheel  363 . Flexible rubber couplings suitable for use in the present invention are available from the Ringfeder Corporation of Westwood, N.J., under the trade name ARCUSAFLEX™. 
         [0051]    It will be appreciated that the gear types upon the main shaft  54  and counter shaft  60  may be reversed. That is, the counter shaft  60  may include driven  62  gears that are selectively engaged with the counter shaft  60  via engagement dogs  58  while the main shaft driving gears  56  are in continuous engagement with the main shaft  54 . 
         [0052]    The components described above may be arranged in a number of functional permutations as shown in  FIGS. 5-11 . 
         [0053]    Specifically,  FIG. 5  schematically illustrates a saw including an engine  22 ′, a transverse gear pairing  52 ′, a transmission  24 ′ that is beltless and a saw blade  26 ′. In this embodiment, transmission  24 ′ merely provides a single speed with no neutral.  FIG. 6  shows a saw including an engine  22 ′, a transverse gear pairing  52 ′, a transmission  24 ′ and a saw blade  26 ′. Transmission  24 ′ provides a single speed and a dampening mechanism  130 ′ is provided. Dampening mechanism  130 ′ may comprise a resettable overload clutch, a friction clutch, an electric clutch or flexible rubber coupling.  FIG. 7  shows a saw including an engine  22 ′, a transverse gear pairing, a transmission  24  that is beltless and includes a neutral gear or position, and a saw blade  26 ′.  FIG. 8  shows a saw including an engine  22 ′, a transmission  24 ′ that is beltless and a variable speed type with neutral, and a saw blade  26 ′. In the saw of  FIG. 8  there is no transverse gear pairing and thus the major axis of the engine is transverse to the cutting planes of the blade  26 ′.  FIG. 9  shows a saw including an engine  22 ′, a transmission  24 ′, a resettable clutch  130 ′ and a saw blade  26 ′. The saw of  FIG. 9  would be configured like the saw of  FIG. 8 , the major axis of the engine being transverse to the cutting plane of the blade  26 ′.  FIG. 10  shows a saw configured like the saw of  FIG. 8  including an engine  22 ′, a transmission  24 ′ that is a variable speed type, and a saw blade  26 ′.  FIG. 11  shows a saw configured like the saw of  FIG. 8  including an engine  22 ′, a transmission that is beltless and includes a neutral gear, and a saw blade. 
         [0054]    The saw of the present invention does not rely upon belt and pulley drives, wherein the belts must be replaced and/or re-tensioned regularly. The transmission of the saw may be shifted sequentially while the saw is in operation, without the use of a clutch. The transmission of the saw of the present invention also includes a neutral setting or position wherein the saw may be propelled (i.e., for safe maneuvering out of the cut) without the saw blade turning. It will be appreciated that in addition to the walk-behind saw shown in  FIG. 1 , the principles of the present invention may be readily applied to a riding saw as shown in U.S. Pat. No. 5,724,956 the disclosure of which is incorporated herein by reference. 
         [0055]    While the invention has been shown and described with respect to a specific embodiment thereof, this is for the purpose of illustration rather than limitation, and other variations and modifications of the specific device herein shown and described will be apparent to those skilled in the art all within the intended spirit and scope of the invention. Accordingly, the patent is not to be limited in scope and effect to the specific embodiments herein shown and described, or in any other way that is inconsistent with the extent to which the progress in the art has been advanced by the invention.