Drawing board fitment
United States Patent 11 1 Bruneau 1 DRAWING BOARD FITMENT [76] Inventor: Andre Bruneau, 25-Mont par.  
 Montferrand-le-Chateau. France [22] Filed: July 24, i972 [21] Appl. No; 274,791  
 1 Apr. 22, 1975 Primary E.\&#39;uminerHarry N. Haroian Assistant Examiner1ohn W. Shepperd Attorney, Agent. or Firm-Robert E. Burns; Emmanuel J. Lobato; Bruce L. Adams [57] ABSTRACT A drawing board includes at least one arm having a longitudinal channel like track defined between a pair of spaced apart parallel rails and a third rail parallel to and facing said pair of rails, the rails being disposed in the configuration of an acute angled triangle. A car riage. carrying either a second arm, or carrying a drawing head, adapted to roll along said track includes two pairs of first rollers spaced along the carriage. the rollers of each pair being eccentric and adjustable by rotation to come into operative rolling contact with one of said pair of rails and said third rail respectively. At least one third roller which may also be adjustable by means of an eccentric mounting is mounted on the carriage, preferably between the two pairs of first rollers, so as to roll on the other of said pair of rails, whereby loads on the carriages are distributed on the three rails by the triangular configuration.  
 ll Claims, 9 Drawing Figures DRAWING BOARD FITMENT The invention relates to drawing boards and is particularly concerned with drawing board fitments for movably supporting a drawing head or instrument guide. for example. over the drawing board surface.  
  Such fitments may include a horizontal arm. secured to the drawing board. along which a carriage is movably mounted. said carriage carrying a second arm. perpendicular to the first. a drawing head&#34; being slidably movable along the second arm. In a known drawing board, the horizontal arm includes a longitudinally dis posed channel-like guide rail in which a plurality of rollers of the carriage are mounted. However. whilst these rollers occupy a relatively large volume. they have not been found to provide an extremely precise guiding. and adjustment of the rollers to take up any play is either not provided for or is a relatively difficult and delicate operation.  
  It is an object of the invention to provide a drawing board fitment of the mentioned type. the mounting of which is simple and rapid and with which the rollers can be simply and accurately adjusted to take up any unwanted play.  
  According to the invention. a drawing board fitment comprises carriage means including a carriage movably mounted along at least one elongate rectilinear arm. said arm including a longitudinal channeHike track defined between a pair of rails extending in parallel spaced-apart relationship and a third rail parallel to and in spaced-apart facing relationship to said pair of rails. said carriage including two pairs offirst rollers. the first rollers of each pair being axially spaced apart and rotatably mounted about parallel spaced-apart axes on spin dles secured on a common carrying axle rotatably mounted on the carriage. said spindles being parallel to their carrying axle with at least one of said spindles eccentric to the carrying axle. the carrying axles of said two pairs of first rollers being disposed parallel to one another and spaced apart along said carriage. said carrying axles each being adjustable by rotation relative to the carriage to an operative position in which one of each pair of first rollers is in rolling contact with said one of said pair of rails and the other of each pair of first rollers is in rolling contact with said third rail, and at least one second roller rotatably mounted on the carriage about an axis parallel to or substantially parallel to the carrying axles and spindles of said pairs of first rollers. said second roller being adapted when said pairs of first rollers are in said operative position to be in rolling contact with the other of said pair of rails.  
  Embodiments of the invention will now be particularly described. by way of example, with reference to the accompanying drawings. in which:  
  FIG. 1 is a schematic plan view of a drawing board incorporating a fitment according to the invention;  
  FIGS. 2 and 3 are enlarged scale schematic plan views of the two carriages of said fitment fitted in their respective arms;  
  FIG. 4 is a cross-section taken along any of lines IVIV of FIG. 2 or of FIG. 3;  
  FIG. 5 is a cross-section taken along any of lines V-V of FIG. 2 or of FIG. 3;  
 FIG. 6 is a view similar to FIG. 4 ofa varied embodiment;  
  FIG. 7 is a schematic underneath view of one of the carriages of this varied embodiment;  
 FIG. 8 is a schematic view ofa detail of FIG. 7; and  
  FIG. 9 is a schematic view taken in cross-section through a varied type of rail-forming section.  
  With reference to FIG. 1. a drawing board I carries on its upper horizontal edge a horizontal guide arm 2 including a longitudinal channel-like track along which a carriage 3 is movably mounted.  
  Carriage 3 in integral with a second arm 4. disposed perpendicular to arm 2, and which also includes a longitudinal channel-like track along which a carriage 5 is movably mounted. Carriage 5, which carries an L- square I I pivotally mounted about a conventional head 10. is connected to a counterweight 7 by an endless cable 6, 60 passing about a pulley 8 on carriage 3 and a pulley 9 at the lower free end of arm 4.  
  The guiding of carriages 3 and 5 along their respective tracks of arms 2 and 4 is provided according to the same principle. which will be explained with reference to FIGS. 4 and 5.  
  Guide arm 4 is composed of a section including two longitudinally extending housings l2 and 13 separated by a common vertical wall l2a. Housing 12. of generally rectangular or square cross-section. receives the counterweight 7 which is of similar cross-sectional shape. Housing 13 is of generally U-shaped crosssection. formed by a base part I30 coplanar with the adjacent wall 121; of housing 12. and two arms of unequal length. the longer arm being formed by wall 12a. and the shorter arm by an overhanging outer wall 13b. Housing I3 has an oblique opening 14 through which a support plate 45 of the corresponding carriage extends. Housing 13 includes three longitudinally extending rails. namely a pair of spaced apart parallel rails 18 and 19 on wall l2u. and a third rail 20 on wall 13b. rail 20 being parallel to and in spaced-apart facing relationship to rails 18 and 19.  
  Arm 2 is of identical construction to arm 4. or at least includes an identical housing 13 with three rails l8. l9 and 20.  
  With reference to FIGS. 2, 3 and 4, each of carriages 3 and 5 includes two pairs of rollers l5/l6 spaced apart along the carriages. said rollers being adapted in the operative position shown in FIG. 4 to be in rolling contact with rails I8 an 20 respectively.  
  Each pair of rollers 15. I6 is rotatably mounted by means of ball bearings 22, 220 about parallel spacedapart spindles 25, 26 respectively. which spindles are secured on either side of a common carrying axle 23 having a bearing surface 24 rotatably mounted in a bearing 45a of support plate 45. Spindle 26 of roller [6 is concentric to the axis of the axle 23, whereas spindle 25 is eccentric to this axis. The outer ends of spindles 25 and 26 are threaded and receive nuts 29 and 27 respectively which hold ball bearings 22, 22a and rollers l5, 16 in place. Axle 23 includes a flange 28 which bears against the upper surface of support 45 so that. together with the action of ball bearing 22 via a washer on the lower surface of support 45. any axial movement of axle 23 relative to plate 45 is prevented.  
  However. axle 23 can be rotated in bearing 45a and locked in a chosen position by tightening nut 29. It is thus possible to adjust the pressure of rollers l5. 16 against rails 18, 20 whereby rollers l5 and 16 can be accurately set for rolling contact with their respective rails.  
  Rollers I5 and 16 include. on their facing edges. side flanges 52, 53 respectively, said flanges coming to bear against upper and lower edges of their respective rails l8 and 20 so as to immobilize the carrying axles 23. and hence the carriage, in the axial direction of axles 23.  
  With reference to FIG. 5, roller 17 is adapted. when rollers and 16 are in the operative position shown in FIG 4. to come into rolling contact with rail 19. Roller 17 is rotatably mounted. by means of a ball bearing 47, on a spindle 46 eccentric to the axis 50 of a carrying axle 44 with a cylindrical bearing surface 43 by means of which it is rotatably mounted in a bearing 45b of plate 45. Ball bearing 47 and roller 17 are secured on spindle 46 by means of a nut 49, whilst the axle 44 is rotatably secured in bearing 45b of plate 45 by means ofa nut 48. a flange 28&#39; of axle 44 preventing any axial movement thereof.  
  The bearing pressure of roller 17 on rail I9 can thus be adjusted by turning axle 44 in its bearing 45b. and securing it in a desired position by tightening nut 48.  
  Carriages 3 and 5 each include two pairs of longitudinally spaced-apart pair of rollers 15, I6 between which are placed two rollers 17 for carriage 3 and one roller 17 for carriage 5, the carying axles 23 and 44 of these rollers are being disposed parallel to one another. Each roller 17 together with a pair of rollers l5, 16, provides a distribution of the frictional and bearing forces ofthe rollers on their rails in a triangular configuration, which enabies the respective carriage to be held without play in relation to its arm.  
  FIG. 6 shows a varied embodiment of the housings l2, l3 ofan arm 4, and a corresponding varied embodiment of the pair of rollers. donoted by l5, 16&#39;, which include a generally V- or channel shaped peripheral profile adapted to engage over rails 18. 20&#39; of corresponding shape and which provide a reaction on the rollers according to arrows 30.  
  FIGS. 7 and 8 schematically show a carriage 5 adapted to cooperate with an arm 4 of the type shown in FIG. 6. Carriage 5 is connected by two parts 6 and 6a of a cable joined to a counterweight 7 (not shown), as schematically indicated in FIG. I. The end of part 6a is secured to a fixed stud, whilst part 6 has at its end a ball-like member 34 which is housed in a recess in a drum 3] about which the cable winds. Drum 31 is integral with a toothed wheel 32 controlled by an endless screw 33 provided with a driving profile 35 accessible from the under side of carriage S to enable adjustment of the tension of cable 6, 6a. A support roller 17&#39;, shown in dotted lines in FIG. 7, is disposed intermediate of the pairs of rollers l5&#39;/l6&#39; along carriage 5 and is adapted to bear against a flat rail 19&#39; formed on wall 12a (FIG. 6).  
  The profile of arm 4 (FIG. 6) is designed to envelop all ofthe moving parts (i.e. rollers and cables, with the exception, of course, of the carriage body), and includes: housings l2 and 13; a passage-way 36 between arms 13a and 13b for a remmote remote locking device for carriage 3; a trapezoidal groove 37 outside the vertical outer wall 12c of housing 12 and a trapezoidal groove 38 below the lower wall 12a of housing 12. These grooves 37, 38 which are generally perpendicular to one another, serve for housing support bars for rigidly connecting arm 4 to carriage 3. At its outer end, i.e., opposed from carriage 3, groove 38 can have a support roller fitted therein, for easing the movement of arm 4 over board 1. Special grooves 39 and 40 respectively at the lower edge of groove 37 and adjacent passage-way 36 are provided for fitting end-caps so as to close the ends of arm 4.  
  The described profile of arm 4 can be extruded in indefinite lengths. and cut to the required dimensions of a drawing board.  
  FIG. 9 is a cross-section through a varied form of profile of arm 4, schematically showing the positions occupied by a set of rollers l5&#34;. l6&#34;. 17&#34; which, in this example. are carried on a common axle, the axes of rol&#39; lers l5&#34; and 17&#34; coinciding with the axis about which the carrying axle is pivoted. and the axis of roller 16&#34; being eccentric thereto. Two, or possibly more, of such sets of rollers would be spaced along each carriage. The median lines of rails l8, l9 and 20 are disposed in the configuration of an isosceles triangle, which distributes the loads acting on the carriage during rolling.  
  It can be seen from the FIGS. 4 and 5, FIG. 6 and FIG. 9 that the three rails can have various relative dispositions. although the median lines of the rolling tracks of the rails are disposed in the general configuration of an acute angled triangle. In FIGS. 4 and 5 (and in FIG. 6) rail 19 (19) is spaced apart from rail 20 (20&#39;) along a direction generally perpendicular to the facing rails by a greater distance than is rail 18 (18); also. a part of rail 19 (19&#39;) is perpendicularly in face with a part of rail 20 (20&#39;).  
 What is claimed is:  
  l. Drawing board fitment comprising at least one elongated rectilinear arm. said arm including a pair of rails extending in parallel spaced apart relationship and a third rail parallel to and in spaced-apart facing rela tionship to said pair of rails defining a longitudinal channel-like track therebetween, a carriage movably mounted along said arm including two pairs of first rollers, means rotatably mounting the rollers of each pair in an axially spaced-apart relationship about parallel spaced-apart axes including a common carrying axle rotatably mounted on the carriage and spindles mounted parallel to the carrying axle with at least one of said spindles eccentric with respect to the carrying axle, wherein the carrying axles of said two pairs of first rollers are disposed parallel to one another and spacedapart along said carriage and each being adjustable by rotation relative to the carriage to an operative position in which one roller of each pair of first rollers is in rolling contact with one rail of said pair of rails and the other roller of each pair of first rollers is in rolling contact with said third rail, at least one second roller and means rotatably mounting same on the carriage about an axis substantially parallel to the carrying axles and spindles of said pairs of first rollers, and wherein said second roller is operative when said pairs of first rollers are in said operative position to be in rolling contact with the other rail of said pair of rails.  
  2. Drawing board fitment according to claim I, in which said means mounting said second roller comprises a carrying axle rotatably mounted on the carriage and a spindle secured eccentrically on same.  
  3. Drawing board fitment according to claim 2, in which the longitudinal axes of the rolling tracks of said three rails are disposed in the configuration of an acute angled triangle.  
  4. Drawing board fitment according to claim I, in which the three rails have flat outer surfaces disposed parallel to one another and said other rail of said pair of rails is spaced apart from said third rail along a direction generally perpendicular to the surfaces thereof by a greater distance than the distance between said other rail and said one rail of said pair of rails.  
  5. Drawing board fitment according to claim 4, in which a part of the surface of said third rail opposes a part of said other rail of said pair of rails.  
  6. Drawing board fitment according to claim 1, in which one of the spindles of each pair of first rollers is concentric to its carrying axle. the roller of said one spindle being adapted to be in rolling contact with said one of said pair of rails.  
  7. Drawing board fitment according to claim 1, in which said first rollers each include at least one side flange. said side flanges of each pair of first rollers being disposed on their respective rails so as to prevent movement of the carrying axles in the axial direction thereof.  
  8. Drawing board fitment according to claim l, in which said first rollers each have a generally channel shaped peripheral profile adapted to engage over rolling tracks of complementary shape of said one of said pair of rails and said third rail.  
  9. Drawing board fitment according to claim I, in which said rails are moulded in one piece inside a generally U-shaped elongate rectilinear section of said arm. one of the arms of the U being longer than the other, said longer arm carrying said pair of rails and the shorter arm carrying said third rail.  
  10. Drawing board fitment according to claim 9. comprising first and second rectilinear arms respectively having first and second carriages slidably mounted therealong. said first arm being secured to a drawing board, said first carriage including two second rollers placed symmetrically between the two pairs of first rollers thereof. said first carriage carrying said second arm disposed at right angles to said first arm, and said second carriage including one second roller placed equidistantly between the two pairs of first rollers thereof.  
  ll. Drawing board fitment according to claim 10, in which one of said first and second arms is adapted to remain horizontal, and the other arm is adapted to lie in an inclined plane, said other arm including a hollow rectangular section adjacent and in one piece with said generally U-shaped section. said longer arm of the U- shaped section forming one of the walls of said rectangular section. and the base of said U-shaped section being substantially coplanar with another of the walls of said rectangular section. said hollow rectangular section housing a counterweight movable therealong. said counterweight being connected to the carriage of said other arm by a cable passing about a pulley on the carriage of said one arm.