Abstract:
A mechanical bracket is provided for providing enhanced quick release for attaching and detaching of a tank such as a air tank with respect thereto usually by emergency workers such as firemen and the like. The tank includes a secure clamping mechanism for firmly and fixedly and yet detachably securing a tank preferably vertically relative to a wall wherein two driveshafts are rotatable between a closed position holding the tank and an open position releasing the tank. A uniquely designed guide boss configuration is fixedly secured to the frame immediately behind each driveshaft to prevent lateral flexing thereof which normally occurs when a tank is firmly clamped therebetween. Each guide boss preferably includes at least one profile guide surface partially encircling the adjacent driveshaft to minimize flexing thereof and is spaced therefrom at approximately five to ten thousandths of an inch for controlling such flexing.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to brackets or other holding or supporting mechanisms preferably capable of being detachably secured with respect to a cylindrical air tank or cylinder of the type that is carried on the back of a firefighter or rescue squad member or other similar emergency worker. 
   Devices of this type are widespread in usage especially among emergency workers and normally are held in vertical position against the walls of firehouses or are kept in containers stored in truck compartments or in the rescue squad buildings or firehouses. Organized orderly storage of such tanks is very important in view of the fact that each one is assigned to an individual emergency worker. As such, such tanks need to be mounted vertically in firehouses, in fire trucks and in other places where emergency equipment is stored. In this manner a swift and convenient access to cylinders of this type is made possible. 
   The present invention more particularly relates to a device for preventing the flexing of vertically extending rotatable driveshafts which cause movement of the tank gripping means between the open position releasing the tank and the closed position holding the tank. In the closed position a great amount of force is placed laterally on these driveshafts and to prevent them from flexing the present invention provides a unique advancement over the prior art by the positioning of specifically designed generally arcuate guide bosses immediately adjacent each driveshaft to prevent outward lateral flexing thereof away from the tank storage zone. 
   2. Description of the Prior Art 
   Many patents have been granted on mechanical holding brackets for cylindrical tanks such as air tanks with various configurations for detachably securing the tanks to a vertical surface such as wall. Some of the most relevant prior art is shown in the following patents. See U.S. Pat. No. 2,109,821 patented Mar. 1, 1938 to R. W. Dunica on a “Fire Extinguisher Holder”; and U.S. Pat. No. 2,431,698 patented Dec. 2, 1947 to H. Lombard on a “Removable Mounting Installation; and U.S. Pat. No. 3,194,529 patented Jul. 13, 1965 to G. R. Brock and assigned to Sterling Precision Corporation on a “Bracket For Holding Fire Extinguishers”; and U.S. Pat. No. 3,547,391 patented Dec. 15, 1970 to Donald E. Johnson on a “Quick Release Support For Rescue; and U.S. Pat. No. 3,603,550 patented Sep. 7, 1971 to Clarence D. Byrd and assigned to Lacy J. Miller Machine Company, Inc. on a “Quick Release Support; and U.S. Pat. No. 3,737,133 patented Jun. 5, 1973 to Allan J. Boecker and assigned to Akron Brass Company on a “Quick-Release Article Holder; and U.S. Pat. No. 3,765,635 patented Oct. 16, 1973 to Wayne R. Burrell et al and assigned to Burrell Bros., Inc. on a “Bracket For Gas Containers And Similar Tanks; and U.S. Pat. No. 3,780,972 patented Dec. 25, 1973 to John C. Brodersen on a “Mounting Apparatus For Gas Containers”; and U.S. Pat. No. 3,823,907 patented Jul. 16, 1974 to Theodore Ziaylek, Jr. on a “Positive Locking Device”; and U.S. Pat. No. 3,921,950 patented Nov. 25, 1975 to Victor Edward Sentinella on “Extinguisher Mountings”; and U.S. Design Pat. Des. No. 244,392 patented May 17, 1977 to Roger Jay Montambo and assigned to The Ansul Company on a “Combined Fire Extinguisher And Bracket; and U.S. Pat. No. 4,023,761 patented May 17, 1977 to John Molis on an “Adjustable Bracket To Stabilize Upright Compressed Gas Containers Against Displacement On Mobile Vehicles And Ship-Board Installations And Maintenance Shops”; and U.S. Design Pat. Des. No. 245,929 patented Sep. 27, 1977 to Roger Jay Montambo and assigned to The Ansul Company on a “Fire Extinguisher Bracket”; and U.S. Pat. No. 4,213,592 patented Jul. 22, 1980 to Daniel J. Lingenfelser and assigned to Caterpillar Tractor Co. on a “Bracket Assembly For Mounting Fire Extinguishers Thereon”; and U.S. Pat. No. 4,304,383 patented Dec. 8, 1981 to Paul O. Huston on a “Bracket For Holding A Tank”; and U.S. Design Pat. Des. No. 267,227 patented Dec. 14, 1982 to Theodore Ziaylek, Jr. and assigned to Ziamatic Corporation on a “Support Bracket For A Gas Cylinder”; and U.S. Pat. No. 4,555,083 patented Nov. 26, 1985 to Frank D. Carter on a “Scuba Tank Positioner”; and U.S. Pat. No. 4,586,687 patented May 6, 1986 to T. Ziaylek, Jr. on an “Air Tank Support Of The Quick Release Type; and U.S. Pat. No. 4,821,990 patented Apr. 18, 1989 to Toney L. Porter et al on a “Flashlight Holder”; and U.S. Pat. No. 4,979,659 patented Dec. 25, 1990 to Kenneth B. Boyd on an “Air Bottle Support Harness”; and U.S. Pat. No. 5,025,935 patented Jun. 25, 1991 to Josh L. Hadachek on a “Portable Upright Scuba Cylinder Retention Rack”; and U.S. Pat. No. 5,318,266 patented Jun. 7, 1994 to Hui-Long Liu on a “Drink Holder”; and U.S. Design Pat. No. Des. 347,735 patented Jun. 14, 1994 to Theodore Ziaylek, Jr. et al on a “Quick Release Support Tank Bracket”; and U.S. Pat. No. 5,522,530 patented Jun. 4, 1996 to Carl A. Boettcher on a “Hand Truck Sentry System”; and U.S. Pat. No. 5,533,701 patented Jul. 9, 1996 to Robert D. Trank on a “Foldable Stabilizing Bracket For Compressed Air Tanks”; and U.S. Pat. No. 5,354,029 patented Oct. 11, 1994 to Theodore Ziaylek, Jr. et al on a “Quick Release Tank Support Bracket With Positive Locking Engagement Means”; and U.S. Design Pat. No. Des. 394,381 patented May 19, 1998 to Theodore Ziaylek, Jr. et al on a “Tank Bracket”; and U.S. Pat. No. 6,124,796 patented Sep. 26, 2000 to William Hincher on a “Fire Equipment Bracket Having Integral Locating Beacon”; and U.S. Pat. No. 6,220,557 patented Apr. 24, 2001 to Michael P. Ziaylek et al and assigned to Michael P. Ziaylek, Theodore Ziaylek, Jr. and Theodore P. Ziaylek on a “Mounting Bracket Means For Detachably Supporting A Generally Cylindrically-Shaped Member Upon A Wall Surface”; and U.S. Pat. No. 6,318,568 patented Nov. 20, 2001 to Anthony Mc Cord and assigned to L&#39;Air Liquide, Societe Anonyme pour l&#39;Etude et l&#39;Exploitation des Procedes on an “Installation For Storing And Holding Gas Cylinders”; and U.S. Pat. No. 6,520,123 patented Feb. 18, 2003 to Philip A. Parker et al on an “Expansion Cage”; and U.S. Pat. No. 6,543,736 patented Apr. 8, 2003 to Bradley J. Field and assigned to Pacific Safety Products Inc. on a “Quick Release Supporting Apparatus For A Canister”; and European Patent EP0272494 B1 patented Mar. 27, 1991 to Helmut Gerhard and assigned to Westerwalder Eisenwerk Gerhard GmbH on a “Temperature-controlled Tank Container”; and European Patent No. EP0284884 B1 patented Nov. 13, 1991 to Helmut Gerhard and assigned to Westerwalder Eisenwerk Gerhard GmbH on a “Tank Container”; and European Patent No. EP0312285 B1 patented Apr. 3, 1991 to Robin Ernest Fossey on a “Container Design Limited”; and European Patent Application No. EP0334265 A1 filed Mar. 20, 1989 to Helmut Gerhard and assigned to Westerwalder Eisenwerk Gerhard GmbH on a “Tank Container”; and European Patent No. EP0629391 B1 patented Aug. 27, 1997 to Michael M. Locarno and assigned to Bel-Art Products, Inc. on an “Oxygen Tank Holder For Use With Wheelchairs”; and European Patent Application No. JP11105704 A filed Oct. 6, 1997 to Shigeyoshi Asari and assigned to Hino Motors Ltd on an “Air Tank Fixing Structure of Vehicle”. 
   SUMMARY OF THE INVENTION 
   The present invention provides an improved mechanical bracket which can quickly open or close for detachably securing a tank such as a cylindrical air tank therewithin. The bracket will preferably include a frame made of aluminum which extends generally vertically. This frame will preferably include an upper flange extending outwardly therefrom as well as a lower flange extending outwardly therefrom. Preferably there will be a significant spacing between the upper flange and the lower flange to define the tank holding zone vertically therebetween. In the preferred configuration disclosed herein the upper flange is positioned adjacent to the upper end of the frame and the lower flange is positioned near the lower end of the frame. 
   A securement mechanism is also included preferably for the purpose of facilitating mounting of the frame with respect to environmental structure such as walls, doors or seat-backs. This securement apparatus preferably includes an upper securement mechanism such as a bolt and hole design positioned adjacent the upper flange as well as a lower securement mechanism similarly configured positioned adjacent to the lower flange to facilitate fixed securement of the frame relative to environmental structure. An intermediate securement mechanism may also be included at an intermediate position below the upper securement mechanism and above the lower securement mechanism. These three separate securement devices will be operative to facilitate firm and fixed mounting of the frame with respect to environmental structure as needed. 
   The bracket further includes a first driveshaft made of steel preferably and rotatably mounted within the upper flange and rotatably mounted within the lower flange and extending therebetween adjacent to the tank holding zone. 
   The mechanical bracket preferably will also include a second driveshaft which is also preferably made of steel which is rotatably mounted within the upper flange at a position laterally spatially disposed from the first driveshaft. This second driveshaft is preferably rotatably mounted within the lower flange at a position spatially disposed laterally from the first driveshaft also. In this manner the second driveshaft can extend vertically between the upper and lower flanges at a position laterally displaced from the first driveshaft. The second driveshaft and the first driveshaft will preferably extend vertically approximately parallel with respect to one another in order to further define the tank holding zone therebetween. 
   A tank clamping mechanism is also preferably secured to the first driveshaft means and the second driveshaft means and is movable therewith between a closed position retaining a tank in the tank holding zone and an open position allowing release of the tank for removal thereof from the tank holding zone. 
   The tank clamping means preferably includes at least two clamping members. First included is an upper tank clamping member which includes a first upper clamping arm and a second upper clamping arm. The first upper clamping arm is secured to the driveshaft at a position thereon closer to the upper flange than the lower flange and the second upper clamping arm is secured to the second driveshaft at a position thereon closer to the upper flange than to the lower flange. 
   The tank clamping mechanism preferably also includes a lower tank clamping member including a first lower clamping arm and a second lower clamping arm. The first lower clamping arm is secured to the first driveshaft at a position thereon closer to the lower flange than to the upper flange and the second lower clamping arm is secured to the second driveshaft at a position thereon closer to the lower flange than the upper flange. 
   A first guide boss is preferably included which is made in the preferred configuration of aluminum and is formed integrally with the frame below the upper flange and above the lower flange. As such, the first guide boss is preferably located at a position intermediate between the upper and lower flanges and immediately adjacent to the first driveshaft in order to facilitate maintaining of structural integrity of the frame and minimize lateral deflecting of the first driveshaft. The first guide boss preferably defines a first profiled guide surface which is preferably of an arcuate shape and is at least partially positioned encircling the first driveshaft and is positioned thereadjacent for controlling lateral deflection. The first profiled guide surface of the first guide boss is positioned adjacent to the first driveshaft diametrically opposite from the location of the tank holding zone in order to restrict lateral flexing of the first driveshaft away from the tank holding zone. The first profiled guide surface of the first guide boss is preferably laterally spaced from the first driveshaft at a distance of approximately five thousandths of an inch to ten thousandths of an inch. The first profiled guide surface of the first guide boss preferably extends through an arc of approximately 120 degrees to further limit this lateral deflecting of the first driveshaft. The first guide boss is preferably also located at an intermediate position adjacent to the first driveshaft below the first upper clamping arm and above the first lower clamping arm in order to minimize lateral deflecting of the driveshaft furthermore. The first guide boss is preferably positioned at a location halfway between the upper flange thereabove and the lower flange therebelow. In the preferred configuration the first profiled guide surface includes a first upper guide edge and a first lower guide edge. These two guide edges are spaced apart from one another. The first upper guide edge and the first lower guide edge preferably cooperate to further facilitate limiting of the deflecting of the first driveshaft laterally. 
   A second guide boss is preferably included which is in this preferred embodiment made of aluminum and also is formed integrally with respect to the frame below the upper flange and above the lower flange at a position approximately halfway therebetween. The second guide boss is preferably positioned immediately adjacent the intermediate securement mechanism in order to facilitate maintaining of structural integrity of the frame thereadjacent and for minimizing lateral deflecting of the second driveshaft. This second guide boss preferably defines a second profile guide surface which is arcuate and at least partially encircled the second driveshaft. It is positioned thereadjacent for the purpose of preventing lateral deflection. The second profiled guide surface of the second guide boss is preferably located at a position adjacent the second driveshaft diametrically opposite from the tank holding zone thereadjacent in order to restrict lateral flexing of the second driveshaft away from the tank holding zone when firming securing a tank in place. The second profiled guide surface of the second guide boss is preferably laterally spaced from the second driveshaft at a distance of between five and ten thousandths of an inch. The second profiled guide surface of the guide boss is arcuate and extends through an arc of approximately 120 degrees to further limit this lateral flexing. The second profiled guide surface of the second guide boss preferably includes a second upper guide edge and a second lower guide edge. Preferably they are spaced apart from one another and cooperate together to further minimize deflecting of the second driveshaft. 
   An interengagement mechanism is also included which is operatively attached with respect to the first driveshaft mechanism and the second driveshaft mechanism for rotating both simultaneously. This interengagement mechanism is operative to rotate the first driveshaft counterclockwise and the second driveshaft clockwise simultaneously to move the first clamping means and the second clamping means toward the closed position for retaining of a tank within the tank holding zone. The interengagement means is operative to rotate the first driveshaft clockwise and the second driveshaft counterclockwise on the other hand simultaneously to move the first and second clamping devices toward the opened position to facilitate release of a tank from the tank holding zone. 
   In the preferred configuration of the present invention the first driveshaft is formed with a hexagonal cross-sectional shape such that it defines first flat zones with first protruding corner edges positioned therebetween. In this manner keying of the driveshaft with respect to the clamping arms is significantly enhanced to facilitate simultaneous rotation thereof. Similarly the second driveshaft is preferably formed with a hexagonal cross-sectional shape such that it defines second flat zones and second protruding corner edges positioned therebetween to facilitate keying of the second driveshaft relative to the clamping arms to enhance simultaneous rotation therebetween. In the configuration of the present invention the first protruding corner edges and the second protruding corner edges will be spaced from the arcuate surface of the first and second guide bosses at a distance of between five and ten thousandths of an inch to minimize lateral flexing thereof. Damage to the driveshafts will be minimized in view of the fact that they are preferably made of steel whereas the guide surfaces are made of aluminum which is a significantly softer and will disfigure rather than marring the steel driveshafts themselves which need to be maintained in good working condition at all times. 
   It is an object of the present invention to provide an improved quick release mechanical bracket for detachably retaining a tank therewithin which is particularly usable with cylindrical air tanks which has a minimum number of moving parts. 
   It is an object of the present invention to provide an improved quick release mechanical bracket for detachably retaining a tank therewithin which is particularly usable with cylindrical air tanks which can firmly secure a tank when held and easily and quickly release same for use. 
   It is an object of the present invention to provide an improved quick release mechanical bracket for detachably retaining a tank therewithin which is particularly usable with cylindrical air tanks which has minimal initial capital cost outlay. 
   It is an object of the present invention to provide an improved quick release mechanical bracket for detachably retaining a tank therewithin which is particularly usable with cylindrical air tanks which limits lateral flexing of the driveshafts powering the clamping arms which contact, abut and grip the tanks positioned therewithin within the tank holding zone. 
   It is an object of the present invention to provide an improved quick release mechanical bracket for detachably retaining a tank therewithin which is particularly usable with cylindrical air tanks which can include bosses positioned intermediate between the upper and lower flanges thereof which bosses include at least on profiled guide surface thereon for limiting lateral flexing of two vertically extending generally parallel oriented driveshafts. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     While the invention is particularly pointed out and distinctly claimed in the concluding portions herein, a preferred embodiment is set forth in the following detailed description which may be best understood when read in connection with the accompanying drawings, in which: 
       FIG. 1  is a front plan view of an embodiment of the improved quick release mechanical bracket of the present invention; 
       FIG. 2  is a side plan view of the embodiment shown in  FIG. 1  taken from the left; 
       FIG. 3  is a bottom plan view of the embodiment shown in  FIG. 1 ; 
       FIG. 4  is a front perspective illustration of the embodiment shown in  FIG. 1 ; 
       FIG. 5  is an exploded side plan view showing the cooperative interaction between the second guide boss and the second driveshaft; and 
       FIG. 6  is a top plan view of  FIG. 1  taken along lines  6 — 6 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present invention provides a unique design for a quick release mechanical bracket configured for the purpose of detachably holding a tank  10  and preferably a cylindrical tank relative thereto detachably. This improved quick release mechanical bracket includes a frame  12  which is preferably made of cast aluminum. Frame  12  preferably includes an upper flange  14  extending outwardly therefrom near the upper portion of the frame  12  and a lower flange  16  extending outwardly therefrom near the lower portion of the frame  12 . In this manner the upper flange  14  and the lower flange  16  define therebetween a tank holding zone  18  designed for detachably receiving and selectively retaining the cylindrical tank  10  therewithin as desired. 
   A securement apparatus  20  is preferably included for detachably affixing the frame  12  with respect to the surrounding environmental structure such as walls or the like. The securement apparatus  20  preferably comprises a plurality of holes defined in the frame  11  through which screws, bolts or lag bolts can extend to fixedly secure the frame  12  with respect to an environmental structure. Preferably an upper securement means  22  will be included which can comprise two threaded engagement bolts and two holes positioned near the upper flange  14 . Also a lower securement means  24  can be included comprising holes defined in the frame  12  adjacent to the lower flange  16 . Furthermore an intermediate securement mechanism  26  can be defined by the frame  12  below the upper securement means  22  and above the lower securement means  24  in such a manner as to fixedly secure the intermediate portion of the frame  12  with respect to the adjacently positioned environmental structure such as a wall or seat-back. 
   A first driveshaft  28  is included which is rotatably movable relative to the frame  12 . First driveshaft  28  is preferably rotatably mounted within the upper flange  14  of frame  12  and is also rotatably mounted within the lower flange  16  of frame  12  and extends vertically therebetween. The first driveshaft  28  preferably is of hexagonal cross-section and defines a plurality of first flat zones  70  with a plurality of first protruding corner edges  72  positioned therebetween. Preferably the first driveshaft  28  will include six such first flat zones  70  since it is preferably hexagonal in cross-section and will include six first protruding corner edges  72  located therebetween. 
   A second driveshaft  30  is also included in this embodiment which is rotatably mounted with respect to the upper flange  14  and the lower flange  16  at a position laterally displaced from the point of movable securement of the first driveshaft  28  with respect thereto. The second driveshaft  30  as such will be rotatably movable within the upper and lower flanges  14  and  16  and will extend therebetween vertically in a direction extending approximately parallel to and laterally displaced from the first driveshaft means. The first driveshaft  28  and the second driveshaft  30  will define the tank holding zone  18  thereadjacent. 
   The second driveshaft  30  will also preferably assume a hexagonal cross-section with six second flat zones  74  defined about the outer periphery therearound with six second protruding corner edges  76  positioned between adjacent second flat zones  74 . A tank clamping means  32  is preferably secured to the two driveshafts  28  and  30  and is movable between a closed position  34  for clamping and holding of a tank  10  within the tank holding zone  18  and an opened position  36  for allowing release of the tank therefrom. 
   In the preferred embodiment shown herein an upper tank clamping member  38  is included as well as a lower tank clamping member  44 . The upper tank clamping member  38  includes a first upper clamping arm  40  fixedly secured to the first driveshaft  28  to be rotatable therewith. A second upper clamping arm  42  is secured to the second driveshaft  30  at a position immediately adjacent to the first upper clamping arm  40 . In this manner first and second upper clamping arms  40  and  42  will cooperate and move simultaneously between the opened position  36  and the closed position  34 . The lower tank clamping member  44  will also include a first lower clamping arm  46  as well as a second lower clamping arm  48 . The first lower clamping arm  46  will be secured to the first driveshaft  28  to be rotatable therewith and the second lower clamping arm  48  will be secured to the second driveshaft  30  to be rotatably movable therewith. In this manner with coordinated movement between the first and second driveshafts  28  and  30  coordinated movement will be achieved between the first lower clamping arm  46  and the second lower clamping arm  48  causing simultaneous movement of both arms between the closed position  34  and the opened position  36  simultaneously. 
   An interengagement means  68  will be operatively secured with respect to the first driveshaft  28  and the second driveshaft  30  to cause simultaneous operation of each in the opposite direction. In this manner the first and second driveshaft members  28  and  30  will simultaneously move toward the closed position  34  and will simultaneously be moved toward the opened position  36  with the respective upper tank clamping member  38  and lower tank clamping member  44  fixedly secured to each. The configuration of the interengagement means can comprise many different designs only one of which is shown in this embodiment. The design shown in this embodiment works similar to that shown in U.S. Pat. No. 4,586,687 which is incorporated herein by reference and was invented and patented on May 6, 1986 by one of the inventors herein. That design is a predecessor design of the present invention and the means of operation of that interengagement means is hereby incorporated herewith for the purposes of illustration. However, it should be appreciated that any mechanism or interengagement means which causes simultaneous rotation of the first driveshaft and the second driveshaft such as to move them simultaneously between the closed position  34  and the opened position  36  would be operable with respect to the present invention. 
   It should be appreciated that a significant amount of force can be exerted against the tank  10  of the present invention by the upper tank clamping member  38  and the lower tank clamping member  44  and in particular the individual clamping arms thereof. These arms need to very firmly secure the tank  10  in position within the tank holding zone  18 . This is important in order to prevent accidental falling of the tank from position secured to the mechanical bracket of the present invention. The type of quick release mechanical bracket utilizing the present invention is often utilized in emergency vehicles and such vehicles often experience significant amounts of lurching and vibration while driving quickly to an emergency situation such as a fire. As such, the forces needed to hold the tank  10  in place need to be extremely strong. As shown in the present invention rubber bumpers  86  can be included such that they can be compressed such that when a tank  10  is in the tank holding zone  18  and is firmly grasped therewithin by movement of the upper tank clamping member  38  and the lower tank clamping member  44  to the closed position  34  it will cause compression of these bumpers thereby providing a significant amount of force in multiple directions to aid in retaining of the cylindrical tank  10  firmly within the zone  18 . 
   The significant amount of pressure that needs to be exerted in order to maintain such cylindrical tanks  10  firmly in securement tends to laterally flex the first driveshaft  28  and the second driveshaft  30  in a direction away from the tank holding zone. The present invention provides a unique improvement by defining guide bosses immediately thereadjacent for restricting this lateral flexing. For this purpose a first guide boss  50  is shown which prevents a first profiled guide surface  52  for limiting flexing of the first driveshaft  28  laterally away from the tank holding zone  18 . The forces and operation of this system is best shown in FIG.  6 . There the hexagonal cross-section of the first driveshaft  28  is clearly shown. Also the first profiled guide surface  52  which is generally arcuate of the boss guide boss  50  is clearly shown. The first profiled guide surface  52  is separated from the first drive shaft  28  by approximately 0.005 to 0.010 inches. In this manner flexing is greatly minimized so that the first driveshaft  28  will be maintained in a vertically standing direction parallel to the second driveshaft  30  even when fully clamped in position holding a tank  10  within the tank holding zone  18 . It is preferable that the positioning of the first guide boss  50  be adjacent to the intermediate securement means  26  for facilitating stability in the overall structural integrity thereof. Also with this configuration it is preferable to form the driveshaft out of steel while the frame  12  and the guide boss  50  are formed of aluminum. In this manner damage to the first driveshaft  28  is eliminated if lateral flexing causes abutment thereof and in particular abutment of the first protruding corner edges  72  thereof with respect to the first profiled guide surface  52  which is formed preferably of cast aluminum. As shown further in  FIG. 1 , it is preferable that the first profiled guide surface  52  actually comprise two separate guide edges. That is, first guide boss  50  should include a first upper guide edge  54  and a first lower guide edge  56 . These two guide edges will provide two points of abutment of the first guide boss  50  with respect to the first driveshaft  28  and in this manner further restrict lateral flexing thereof away from the tank holding zone  18 . 
   A similar construction is preferably included by defining of a second guide boss  60  immediately adjacent to the second driveshaft  30 . Second guide boss  60  preferably includes a second profiled guide surface  62  of aluminum which is spaced from the second driveshaft means  30  by a distance of between 0.005 and 0.010 inches in order to limit lateral flexing of driveshaft  30 . The second guide boss  60  will preferably define a second profiled guide surface  62  and preferably two specific guide edges, namely, the second upper guide edge  64  and the second lower guide edge  66  as best shown in  FIGS. 6 and 1  which will be adapted to abut the second driveshaft  38  if it flexes away from the tank holding zone  18 . 
   Preferably the contour of the first profiled guide surface  52  and the second profiled guide surface  62  will extend through an arc of approximately 120 degrees as shown as first 120 degree arc  58  and second 120 degree arc  67  shown in FIG.  6 . The hexagonal arc of approximately 120 degrees will allow the profiled guide surfaces  52  and  62  to contact three of the first protruding corner edges  72  and second protruding corner edges  76  responsive to lateral flexing of either the first driveshaft  28  or the second driveshaft  30  away from the tank holding zone  18 . By the defining of the restricting profiles to approximately 120 degrees the rotational orientation of the driveshafts  28  and  30  will not have any impact on the ability of the profiled guide surfaces  52  and  62  to limit flexing of the adjacent driveshaft because at all times the profiled guiding surfaces will be capable of contacting at least two and as many as three of the protruding edges of the adjacently positioned driveshafts when configured with hexagonal cross-sections. 
   The arrow  82  in  FIG. 6  shows the vector or the direction of the flexing force of the first driveshaft  28  which needs to be restricted by positioning of the first guide boss  50  appropriately. In a similar manner arrow  84  shows the vector of direction of the lateral flexing force exerted against the second driveshaft  30  which needs to be restricted by accurate and careful positioning of the second guide boss  60 . Also in this figure, arrows  78  show the limited lateral clearance or spacing distance between the first protruding edges  72  of the first driveshaft  28  and the first profiled guide surface  52  of figure guide boss  50 . In a similar manner arrows  80  show the second spacing distance which is also preferably 0.005 to 0.010 inches between the second protruding corner edges  76  of the second driveshaft  30  and the immediately adjacently positioned second profiled guide surface  62  of second guide boss  60 . Choice of materials is another important consideration of the present invention. By choosing the frame  12  and the preferably integrally formed first and second guide bosses  50  and  60  to be made of cast aluminum will allow them to be softer than the adjacently located driveshaft which is preferably made of steel. In this manner damage to either the first driveshaft  28  or the second drive shaft  30  by contacting thereof with respect to the first guide boss  50  or the second guide boss  60  will be prevented. 
   As such, the present invention provides a unique guiding means for maintaining the integrity of the two vertically extending driveshafts  28  and  30 . It is important that these rotatable parts be maintained in parallel relationship with respect to one another and not become flexed to a position such that they are no longer aligned in order to maintain full efficiency of operation thereof. 
   While particular embodiments of this invention have been shown in the drawings and described above, it will be apparent, that many changes may be made in the form, arrangement and positioning of the various elements of the combination. In consideration thereof it should be understood that preferred embodiments of this invention disclosed herein are intended to be illustrative only and not intended to limit the scope of the invention.