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This application is a continuation of Ser. No. 09/411,001, filed Oct. 1, 1999, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to floor stripping devices, and more particularly concerns improvements in the driving and blade support means for same. 
     U.S. Pat. No. 3,376,071 discloses a floor stripping machine of the type in which the present invention is usable to great advantage. Such machine incorporates a cutting blade carried by a head pivotally mounted to a frame. Problems with machines as disclosed in that patent include failure of rapidly oscillating head driving connecting rods and associated parts and bearings; insufficient lubricating of such rods, parts and bearings, undue wear of the oscillating head at its pivots; unwarranted high cost of repair and replacement of such elements; and difficulty with clamping a blade to the bottom side of the head. 
     U.S. Pat. Nos. 4,512,611, 4,504,093, 4,483,566, 4,452,492, 4,365,843 and 4,365,842 and 4,512,611 disclose improvements over said U.S. Pat. No. 3,376,071. 
     SUMMARY OF THE INVENTION 
     It is a major object of the invention to provide an additional solution to the above described problems and disadvantages. Basically, the invention is embodied in improved floor stripping apparatus having a floor stripping blade, a head, and a drive, and includes: 
     a) a connecting element having a first tubular part and a second tubular part, said parts having spaced, parallel axes, said second tubular part pivotally connected to the head, 
     b) a drive shaft extending within the first tubular part, said shaft operatively connectible to the drive to be rotated thereby, 
     c) said drive shaft carrying two axially spaced eccentrics to be rotated by the shaft, there being a lubricant receiving space located directly between said eccentrics, 
     d) two annular bearings respectively carried by and within said first tubular part, said bearings respectively receiving said spaced eccentrics to oscillate said first tubular part, said head and said blade as said eccentrics are rotated by the shaft. 
     e) there being spiral grooves sunk in the external surfaces of said eccentrics to communicate with said lubricant receiving space to receive lubricant for distribution along said eccentrics to the annular bearings. 
    
    
     These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which: 
     DRAWING DESCRIPTION 
     FIG. 1 is a side elevation showing a floor stripping machine incorporating the invention; 
     FIG. 2 is a top plan view of the FIG. 1 machine; 
     FIG. 3 is an enlarged elevation taken on lines  3 — 3  of FIG. 4; 
     FIG. 4 is a section taken on lines  4 — 4  of FIG. 3; 
     FIG. 5 is a section taken on lines  5 — 5  of FIG. 3; 
     FIG. 6 is an enlarged section taken through connecting structure seen in FIG. 4; 
     FIG. 7 is an end elevation view of the FIG. 6 connecting structure; 
     FIG. 8 is a side elevation; 
     FIG. 9 is a perspective view; 
     FIG. 10 is a fragmentary front elevation, showing the head of FIG. 8; 
     FIG. 11 is a fragmentary plan view on lines  11 — 11  of FIG. 8, and FIG. 11 a  is a view like FIG. 11; 
     FIG. 12 is a view like FIG. 10, but showing a modification; 
     FIG. 13 is an elevation showing details of an improved version; 
     FIGS. 14 and 15 are sections on lines  14 — 14  and  15 — 15  of FIG. 13; 
     FIG. 16 is a section on lines  16 — 16  of FIG. 15; 
     FIG. 17 is an enlarged view of shaft eccentrics at opposite ends of a lubricant receiving space; 
     FIG. 18 is an elevation taken on lines  18 — 18  of FIG. 17; 
     FIG. 19 is a top plan view taken on lines  19 — 19  of FIG. 18; 
     FIG. 20 is an end view taken on lines  20 — 20  of FIG. 18; and 
     FIG. 21 is an end view taken on lines  21 — 21  of FIG.  18 . 
     FIG. 22 is a section taken on lines  22 — 22  of FIG. 17, to show groove configuration. 
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings and initially, to FIGS. 1 and 2, inclusive, for this purpose, it will be seen that one type of machine in which the invention may be incorporated has been designated in its entirety by reference number  10 . Mounted on the machine  10  are a pair of rubber tires  12  which permit the machine  10  to be easily transported and maneuvered. The wheels  12  are carried by an axle  14  which in turn passes through the rear portions of the base frame  16 . Mounted on the frame  16  is an electrical motor  18 . The machine  10  may alternately be powered by an internal combustion engine. The motor  18  is held in place by four mounting bolts  19  which pass through slots  20  in the frame  16 . When the bolts  19  are loosened the motor can be moved forward or backward on the frame  16  by reason of the slots  20  to adjust the tension in the drive belt  21 . Covering the motor  18  and attached to the frame  16  is a cover shroud  22 . The shroud  22  slides over the side walls  23  of the frame and is held in place by bolts  24  as can be seen in FIG.  1 . Positioned on the front of the frame  16  is a nose weight  25 . The weight is held in place by means of a releasable wire clip  26  which fastens the forward edge of the shroud  22  with the weight  25 . The weight provides the necessary weight on the cutting edge  28  which will later be described. 
     The handle bar  29  comprises a pair of elongated tubular members  30  which are attached at their lower ends to the shroud  22 , and at their upper ends are joined by tubular cross members  31  and  32 . Hand grips  33  are used to handle and maneuver the machine  10 . 
     FIGS. 3 through 5 show the cutter head subassembly  36  in detail. The frame  16  previously mentioned is substantially U-shaped with a horizontal web portion  34  and a pair of vertical flanges  35  as can best be seen in FIG.  5 . At the forward end of the frame  16  positioned between the flanges  35  is the cutting head  38 . The head  38  is formed with a web  40  and a pair of flanges  42 . The cutting head is pivotally mounted at the upper end to the frame  16  by a pin  44  which passes through both pairs of flanges  35  and  42 . Passing through the pair of flanges  35  and journalled thereto is a rotatably mounted drive shaft  46  which is shown in FIGS. 4 and 6. The shaft  46  is journalled at its outer ends in a pair of roller bearings  48  which are in turn bolted to the frame flanges  35  by means of bolts  50 . Retaining the cam shaft in the bearings  48  are pair of locking sleeves  52  which are mounted on the shaft  46  immediately outward of the bearings  48 . Keyed to one end of the shaft  46  is a sheave  54  adapted to carry a V-belt. Mounted on the shaft  56  of the motor  18  is a similar sheave  58  which lies in the same plane of rotation as sheave  54 . The two sheaves  54  and  58  are connected by means of a rubber V-belt  21 . The tension in the V-belt  21  may be adjusted as previously discussed. 
     The shaft  46  extends within a first tubular part  90  of a connecting element  91 , the latter also incorporating a second and smaller diameter tubular part  92 . Those tubular parts comprise steel interconnected by a steel plate  93  welded to outer side portions of the sections, as at  94  and  95 . See FIG.  7 . 
     Shaft  46  carries two axially spaced eccentrics  96  and  97 . See in FIG. 7 the axis  96   c  of eccentric  96  offset from the axis  46   a  of shaft  46 . Each eccentric is cylindrical to rotate within a bearing, such as a bushing, the two bushings indicated at  98  and  99  and received in counterbores  98   a  and  99   a  in the pipe section, and against step shoulders  98   b  and  99   b . The large space  100  thus provided between the eccentrics provides a lubricant (grease) reservoir, for long lasting lubrication of the two bearings, as the shaft rotates and as the eccentrics oscillate the part  90 , and the element  91  back and forth, as will be described. Shaft section  46   b  extends between and interconnects the two eccentrics. 
     Note that the eccentrics have oppositely facing end portions or faces  96   a  and  97   a , which, due to their flaring eccentricity, tend to positively displace the grease as the eccentrics rotate. This serves to urge grease radially outwardly, and to feed toward the bushings and the bearing surfaces of the eccentrics and bushings, for enhancement of lubrication as will be referred to. Note that faces  96   a  and  97   a  intersect the outer surfaces of the eccentrics in planes  96   b  and  97   b  that are at angles α relative to the shaft axis, angles α being less than 90°. Grease is introduced to space  100  via a grease fitting  101  in part  90 , as shown. 
     Annular elastomeric seals  102  and  103  are located at opposite ends of the bushings, and pressed into the shaft counterbores  102   a  and  103   a , as shown. Those seals exert pressure on the shaft eccentrics to prevent escape of grease. 
     At the opposite end of element  91  is a bearing shaft  68  journaled via bushings  66  to the pipe section  92 . Shaft  68  is in turn mounted to cutting head  38 . When shaft  56  is rotated, element  91  is oscillated back and forth to cause head  38  to move back and forth about the axis of pipe  44 , as indicated by arrows in FIG.  3 . 
     At the lower extremities of the cutting head  38  the flanges  42  become wider to accommodate the cutting blade shoe  70 . The shoe  70  is adjustably held against the cutting head by two pairs of bolts  72  and  74 . The bolts  72  pass through openings  75  in the rear of the blade shoe  70  and are threaded into  42  as seen in FIG.  3 . The bolts  74  pass through openings  76  and are threaded into the ends of shaft  77 . The purpose of the blade shoe  70  is to rigidly hold the cutting blade  78  in its cutting position. Located on the back edge of the blade shoe  70  are a pair of adjusting bolts  80  and locking nuts  81  which allow for adjustment of the position of the blade stop  82  which in turn adjusts the amount of blade edge exposure. The front edge  83  of the blade shoe  70  is tapered to provide a maximum amount of rigidity to the cutting blade and yet permit a shallow angle of slope between the cutting blade  78  and the flooring surface being stripped. 
     FIGS. 8,  10  and  11  show a modified head  138  consisting of lightweight metal such as aluminum, or aluminum alloys, or magnesium, or magnesium alloys. The head has two elongated flanges  142  interconnected by a web  140 . The flanges are locally thickened near upper ends of the flanges to define two widened lugs  242  that form widened bearings openings  150  for a pivot shaft  144 . The latter is connected to the frame flanges  135  (corresponding to flanges  35  in FIG.  5 ). The bearing openings (and the lugs) have lengths “l” in access of ¾ inch, and preferably are between ¾ an 1½ inches in length. As a result, destructive wear of the head metal surrounding the openings  150  is eliminated, and in particular or heavy duty operation where stripping forces are extensive. 
     The openings are sized to closely receive the pivot shaft  144 , and define a common axis  144   a . FIG. 11 a  shows modification, with a steel tube  344  received in openings  150 , and in turn receiving the shaft  144 . Tube  344  helps distribute loading to insure against destructive wear of the lightweight metal lugs  242 . 
     FIGS. 8 and 9 also show the use of the modified blade holder plate  170  attached to the head  138  at its bottom side  138   a . Blade  178  is clamped against that side, by the plate. Two shafts,  177  and  168  extend parallel to the web  140  and through flanges  142  to provide shaft projections  177   a  and  168   a  at the exterior side of each flange. Two pairs of fasteners  200  and  201  extend in parallel relation through suitable openings in the holder plate and in the blade, at opposite ends of the shafts, respectively. The fasteners have heads  200   a  and  201   a  that clamp split washers  202  and  203  against the bottom of the holder plate. Also, the fasteners have threaded shanks  200   b  and  201   b  received in threaded engagement with threaded openings  177   b  and  168   b  in the shaft projections  177   a  and  168   a . Accordingly, tightening of the blade in position as shown in FIG. 9 may be accomplished using one hand  210  only, i.e. by manipulation of the wrench  204  in grip engagement with the fastener heads, and the blade may be held and positioned by the other hand  211 . 
     The operation of the stripping machine  10  varies with the type of floor being removed. The steeper the angle of the blade  78  with the floor the deeper the blade will dig. The angle can be varied by lifting the wheels  12  off the floor. The angle can also be varied by extending the blade  78  further past the edge of the shoe  70 . When removing a plywood or particle board floor an extra long blade which extends an additional four inches or more past the edge of the shoe  70  has proven very useful. The longer the blade  78  is extended out of the shoe the less the angle between the cutting blade and floor. The amount of Weight applied to the cutting edge  28  is also variable depending upon the flooring being removed. The weight can be varied by the amount of pressure applied by the hands to the handle bar  29 . Generally, the machine best operates when the handle bar  29  is lifted up until the wheels are one-half-inch off the floor. When an exceptionally tough flooring is being removed, a blade with teeth formed on the cutting edge has been found to be very effective. 
     FIG. 12 is a view like FIG. 10, with corresponding elements having the same identifying numbers. It differs from FIG. 10 in the provision of bushings  280  and  281  fitted and retained in bores  282  and  283  in lugs  242 . The bushings may endwise fit against stop shoulders  284  and  285  in the lugs. The bushings may advantageously be self-lubricated, as provided by annular material  280   a  and  281   a  carried in metallic (as for example bronze) sleeves  280   b  and  281   b  press-fitted in bores  282  and  283 . Material  280   a  and  281   a  may for example consist of molybdenum disulfide. One example of such bushings are known “OILITE” bushings. 
     Pivot shaft  144  (typically steel) is received in, and has low friction running fit in, the bores of the annuli  280   a  and  281   a , for long lasting, low wear operation. 
     FIGS. 13-16 show an improved form of the head  338  and connector  391 . (Elements corresponding to those of FIGS. 1-11 have the same numbers, with “3” preceding each number). 
     Connector  391  is a casting made of lightweight metal such as zinc or aluminum, and has first and second tubular parts  390  and  392 , the outer diameter of part  390  for example being about 1⅝ inches, and that of part  392  being about 1¼ inches. Self lubricated bushings or bearings  398  and  399  are press fitted into bores  398   a  and  399   a  of part  390 . Shaft  346  is as described before, and as shown in FIG. 6, where it bears number  46 . 
     The connector  391  also includes two legs  400  and  401  which extend substantially parallel between tubular parts  390  and  392  and merge therewith, at the opposite ends of the legs, at locations spaced from the opposite ends of the tubular parts  390  and  392 . The legs have first webs  401   a  and  401   b  which define planes  402  normal to parallel axis  403  and  404  defined by parts  390  and  392 . Those planes also intersect the enlarged, heavy duty lugs  442  integral with head  338 , for maximum strength. 
     The legs also have second webs  401   c  and  401   d  defining planes  405  normal to planes  402 , and parallel to spaced parallel axis  403  and  404 . Second webs  401   c  and  401   d  merge with the tubular parts or elements  390  and  392  along the sides thereof facing one another, as shown. Webs  401   a  and  401   b  intersect webs  401   c  and  401   d  at mid-region  406  (see FIG.  16 ), and all four webs taper outwardly, away from that region, as shown to form a cross. Accordingly, a high strength, low weight, connection of parts  390  and  391  is formed, utilizing a light-weight, unitary metal casting. Mid-region  406  is enlarged, for added strength, and webs  401   a - 401   d  maximally resist relative bending of parts  390  and  392 . 
     The flanges  342  have widths “w” that increase in dimension in direction toward the plate  370  and blade  378 , as shown in FIG. 15, and the tubular part  392  is confined between those flanges, with the webs  401   a - 401   d  merging with part  392  between the flanges of increased width near plate  370 . 
     Self-lubricated bushings are employed at  380  and  381 , in the two lugs  342 , to receive tubular shaft  344 . “OILITE” bushings may be used for this purpose. 
     The head  338  may also consist of the same lightweight metal as connector  390 , whereby a very lightweight assembly is provided for minimum vibration transmission to the user. 
     Referring to FIGS. 17-22, they show preferred forms of the shaft  46  and eccentrics  96  and  97  in greater detail. Grooves are sunk in the outer surfaces  200  and  201  of the eccentrics, the grooves indicated at  202  and  203 . Each groove spirals along and about the length of the eccentric, and typically about 360° around and along the eccentric body. The grooves have grease entrance ends  202   a  and  203   a  at axially spaced locations closest to the center of  100 , in communication with outer portions of the lubricant receiving space  100 , at its opposite ends. Each groove typically extends from its entrance end at one end wall of the eccentric to the opposite end at the opposite end wall of the eccentric. A single spiral, or about such a single spiral, from end to end of the eccentric maximizes grease exposure to different areas of the bearings, while minimizing groove length. 
     Grease is urged, under centrifugal pressure, into and along the spiral length of the groove, for distribution to the bearing cylindrical surfaces that extend about the outer surfaces of the two eccentrics, for assured optimum lubrication. Each groove typically has width “w” which is about 0.125 inch, and depth “d”, which is about 0.015, as indicated in FIG.  22 . Seals  102  and  103  at the ends of the eccentric block leakage of grease from the lubricated spaces between the eccentrics and bearing bushings, to which lubricant such as grease is pressure fed via the spiraling grooves. The eccentric shaft end portions are indicated at  46   b - 46   c.    
     The spiraling grooving extends eccentrically relative to the shaft axis of rotation; and rotation of the grooving about the shaft axis effects pulsing centrifugal force application to the eccentrically rotating lubricant in the groove and outward vibration or pulsing of the lubricant in the grooving toward the surrounding surface of the bearing, enhancing the lubrication distribution effect and effectiveness. 
     As shown in FIG. 13, the two planes  402 , as referred to above, also intersect the two eccentrics  96  and  97 , the lubricant receiving space being centered between the eccentric oppositely facing flaring ends.

Summary:
Apparatus usable in power-operated floor stripping apparatus that includes a frame, a drive carried on the frame, wheels supporting the frame, a handle to guide the frame, and a cutting blade carried by a head which is pivotally mounted to the frame, the apparatus comprising a lightweight rugged connecting element having a first tubular part and a second tubular part, those parts having spaced, parallel axis, the second tubular part pivotally connected to the head. There are two axially spaced eccentrics on the drive shaft, which rotate within two annular bearings carried by the first tubular part. Spiral grooves are sunk in the external surfaces of said eccentrics to communicate with said lubricant receiving space to receive lubricant for distribution along said eccentrics to the annular bearings.