US2429132A - Counterweighted parallel motion arm - Google Patents

Description

ocf.14,1947. @Hmm Em 2,429,132]

COUNTERWEIGHTED PARALLEL MOTION ARM FiledvSept. 22', 1944 5 Sheets-Sheet 1 Oct. 14, 1947.

c. H. LITTLE Er Al.

COUNTERWEIGHTED PARALLEL MOTION ARM Filed sept'. 22, 1944 s sheets-sheet 2 l 74 75 75 u. iw. mmm. uw m m m a W Z AH, BW M W Oct. 14, 1947. .c. LITTLE Er AL. l 2,429,132

COUNTERWEIGHTED PARALLEL MOTION ARM A Trae/vs ys Patented ct. 14, 1947 COUNTERWEIGHTJDBARALLEL MOTION- R Charles Henry Little, Cleveland Heights, and Charles Hubbard Little,-Cleveland, Ohio Application september 22, 1944, serialNo. 555,217'0 (c1. seais) 12 Claims.

The present invention relates to drafting machines and similar devices comprising a parallel motion mechanism or arm, one end of which is secured to or is adapted to be secured to a table, drafting board or like device, affording a Working surface over which the free end of the arm provided with some suitable instrument is adapted to be moved and the instrument carried thereby maintained parallel in successive positions.

Where the working surface is inclined, the parallel motion arm, which usually comprises tWo relatively movable sections, will not remain in any predetermined position without being heldA therein by the operator. In an attempt to overcome this difculty, various counterpoise mechanisms employing Weights as the counterpoise vforce producing means have been proposed but none of the counterpoise mechanisms heretofore employed have been entirely satisfactory for various reasons, such as', that they give the machine a bulky and ungainly appearance, impose limitations upon the otherwise normal range of movement of the parallel motion arm, etc,

One of the principal objects of the present invention is the provision of a novel and improved drafting machine or similar device, including a parallel motion arm and weight-actuated counterpoise mechanism, which machine is so constructed and arranged that it Will not have the A appearance of being bulky and ungainly, and the counterpoise mechanism vvvill not interfere With the otherwise normal range of movement of the parallel motion arm.

Another object of the invention is the provision of a novel and improved drafting machine or similar device comprising'a Wheel and band type parallel motion arm and counterpoise mechanism therefor including a gravity-actuated Weight located underneath the Working su'rface or drafting board.

Another object of the invention is the provision of a novel and improved drafting machine or like device comprising a wheel and band type parallel motion arm and Weight-operated counterpoise mechanism therefor effective to balance the parallel motion arm at allV board angles from zero to ninety degrees.-

Another object of the invention is the provision of a novel and improved drafting machine or like device comprising a parallel motion arm and counterpoise mechanism therefor, which counterpoise mechanism is automatically operable for 4diierent board angles.

Another object of the invention is the provision of a novel and improved drafting machine or similar device comprising' a Wheel and band type parallel motion arm andcounterpoise mechanism therefor including a Weight adapted to be located at the side of the'draiting board or Working surface opposite to said' arm and operatively connected to said arm by means permitting adjustment of said WeightV angularly with respect to the arm.

The invention resides in certain constructions and combinations and arrangements of parts and further objects andadvantages will be apparent to those skilled in the art to which it relates from the following description of the preferred embodiment withv reference to the accompanying drawings forming a part or this speciiication in which similar reference characters designate corre- Spending parts., andin which Fria 1,- is a front View of, a drafting machine embodying the presentinvention attached to a vertical draftingA board;

Fig. 2 is a fragmentary sectiona1 View, With portions in .ematicaV voli-th devie Shown in Fial, approximately on the line 2-2 of Fig. 1, with both Sections 0f ihepaallel motonrmlvsltimed at right angles @the uppersdggof the drawing board: and Fig. 3 is a fragmentaryA rear View of the device shown in Fig. ,1, with the various parts in the Positions Shown .in Fg- 2f Y The drafting machine ShOWrl comprises a jointed two-,section parallel vmotion mechanism or arm of the wheel and band type having an instrument or protractor head A at one end and the other end rlxedly secured, as by wood screws l0,

to a verticaldrafting board B. The instrument,

head A is adapted tov be moved about the Workinefsurfeeof the .drawing board B and the rulersor other instruments `forming a part thereof.; A maintained parallel by the parallel motion mech-y." anism in` successive positions to which they are moved- The parallel motion mechanism or arm shown, which is the preferred construction, comprises tvvo angularly movable sections, each comprising a pair of wheels of equal diameterencircled by a exiblebandand 'lfielrlv in spaced relation with the band under tension by a strut so constructed as toenclose the band. and wheels. The upper or anchor section of the parallel motion mechanism or arm comprisesthevvheels ll and I2 encircled by an endless band I3 andheld in spaced relation by a strut C comprising yokes or yoke mem.- bers |.4'and I 5 kconnected by tubular side members I6 and Il. The upper yoke I4 is pivotally connected to -the vanchor assembly D, of which the 3 upper wheel H is a part and through the medium of which the parallel motion arm is connected to the drawing board B by being ilxedly secured to the front or left-hand end of an elongated bolt or spindle I8 rotatably supported in the anchor bracket by anti-friction bearings 20 and 2|, 22 and 23 adjacent to A the front, intermediate and rear parts thereof, respectively. The anchor bracket D is made in two parts 24, 25 to facilitate assembly of the various bearings and` other parts. The endless band [3 is separable with the ends thereof detaohably connected together to facilitate assembly and replacement thereof. The tubular side members of the strut C are preferably similar to those disclosed'and claimed in our copending application Serial No.

631,334, led November 28, 1945, andare sepa rable intermediate their ends with the adjacent portions thereof connected together by tubelike nut members 2S rotatable in one direction to expand the strut and tense theband and in the opposite direction to release the'same so that they can be moved along the side members to expose a portion or portions of the band.V

' The protractor section of the parallel motion arm'is of similar construction and comprises equal diameter wheels 30 and 3l encircled by an endless band 32 and held in spaced relation by a strut comprising yoke members 33', 34 connected by tubular'side members 35, 36` including tubular nut members similar to the tubular nut members previously referred to. rIhe wheels l2 and 35 at the elbow of the arm are preferably formed integral and are operatively connected to the respective struts by antifriction bearings 31, 38, respectively. The wheel 3l located at the free end of the parallel motion arm forms a part'of the instrument head A. The construction of the protractor strut is such that it fencloses the wheels and band of the protracto section. y

The instrument or protractor head proper, designated generally as A is similar in construction tothatdisclosed and claimed*v in our copending application Serial No. 555,268,1iled September 22, 1944, entitled Drafting machine, and is not herein shown and described in detail. Reference is made to the aforesaid application for a complete disclosure thereof. Suffice it to say that the instrument head A comprises a 'ruler assembly F including a normally rotatable member 40 forming one element of the protractor proper and one or more rulers 4l detachably secured to a ruler or chuck arm 42. In addition, the instrument head comprises a normally stationary protractor element 43 which cooperates with the rotatable protractor element 4 0 to indicate the angular position of the ruler or rulers, index mechanism including the thumb piece 44, a protractor clamp 45, and a ruler assembly clamp 46.

The counterpoise mechanism shown comprises a pair of counterpoise weights or weight members 50,51 located at the side of the `drawing board B opposite the parallel motion arm and formed integral with pulley wheels 52, 53 rotatably supported by anti-friction bearings 54, 55 upon a, bolt 56 fixed in a bracket 51 secured by wood screws 58 to the rear of underside of the drawing board B adjacent to the middle thereof so as not to unduly affect the balance of the board. The pulley wheels 52, 53 are operatively connected to pulley wheels 6061 by flexible members or cables 62, 33 comprising turnbuckles G4 of which there is one in each of the two reaches in each cable for tensioning the same.r

The rear or lower pulley or wheel 6B which forms a part of the counterpoise mechanism for the anchor section of the parallel motion arm is keyed or otherwise non-rotatably fixed to the bolt I8 adjacent to its rear end and the pulley or wheel 6| which forms a part of the counterpoise mechanism for the protractor or instrument section of the parallel motion arm is rotatably supported on the bolt I8 by an anti-friction bearing 10.

The pulley I is operatively connected to the strut of the instrument or lower section of the arm by an internal gear 1l iixed to the front face or side of the pulley E I. The gear and pulley are concentric with the bolt 18 and the gear is continuously in mesh with a pinion 12 fixed to the lower end of a shaft 13 rotatably supported in the bracket D by anti-friction bearings 14, 15. The upper or left-hand end of the shaft 13 is provided with a pinion 1S continuously in mesh with an internal gear 11 fixed to the lower or right-hand side of a pulley 18 rotatably supported on the upper member 25 of the bracket D by an anti-friction bearing 80. The pulley 18 is operatively connected to an equal diameter pulley 8l formed integral with or attached tothe upper side of the yoke member 33 of the instrument strut by a flexible member or cable 82 extending around both pulleys and provided with a turnbuckle 83 for tensioning the same. Any rotation of the instrument section of the parallel motion arm relative to the drafting board or any force tending to rotate the same is transmitted by the cable 82, pulley 18, etc., to the ,pulley 6I and from thepulley 5l to the weight 5I by the flexible member 63.

-The effective weight of the counterpoise weight members 5G, 5l may be adjusted, if desired, in any suitable manner. As shown, the weight members 5D, 5| include supplemental members 84, 85, slidable upon rods 8S, 81 fixed to the members 55, 5 l, respectively. The supplemental members 84, 85 are adapted to be secured to the rods 86, 81 in any adjusted position by set screws or the like. If desired, a supplemental bracket or base 88 may be connected to the lower or rear side of the Aanchor bracket D and to the lower or rear end of the bolt` 56 for the purpose of relieving the drafting board B of some, if not al1, of the strain produced therein by the tension of the cables 62, 63. l

The flexible members'or cables 62, 63, as shown, encircle the pulley wheels 52, 68 and 53, 6|, respectively, and are preferably connected to the wheels by screws 89. This construction reduces the amount of tension which would otherwise be required to prevent the wheels from slipping with respect to the cables.` If more rotation is desired than that permitted by the con-struction shown, it will be obvious that the cables may be looped about the pulleys a greater number of times or the connection 89 therebetween and the pulleys omitted.

The two turnbuckles employed in each of the cables 62, 63 are for the purpose of tensioning the cables and permitting the weights to be angularly adjusted slightly with respect to the sections of the parallel motion arm with which they are associated. It will be apparent that if only one turnbucklewasemployed, the angular relationship between the weights and the arm would be disturbedeverytime that the cables were tightened. Alternatively, other means may be employed for adjusting the angularity of the weights with respect to the arm, for example, provision lmay be made for adjusting the weights Vrelative 1to the pulleys 52, 53, the pulley 6U relative to the spindle le, er the. puller el relative te the pill: lex 18..

it is believed that the. egeiratieii ef the .eleviee will. be. apparent. frein the feregeirie. deserpten. tnerecrlrieilv, when trie parallel. metten. arm le petitioned at rient angles. tc the ripper ed'ee 0f tlie. drawing. beard, the center. et gravity f the ccnnterpclee weights is directly between the belts le, te., ariel. the weights. cle riet tend te retate the Parallel greifen eirrri de the. errri. 0r either Setticn thereef` ie moved clit 0f the aforesaid reel-r tion, the center of gravity of the weight connected te. the Section. le reared te erle Side er the ether ci trie lirie eeniieetirre the/beltelit ariel. decerielirie. uren Wirth trie. eeetienie tiered., with. the result. that the, weielit. 0rvieleiita balance eeirriterpeise the paralleli metten arm.- tfie also. tc. be noted. that the. eecnterpeieirie effect ef the weights varies as the. beard. ariele le elcarieea trie. result ci, which le, that theceunterreiee mechaaien le cperalele ier all beard' alleles Without attention en the. part ei'tliev operator er., inV etherl Werde, is automatically alterable vier different. board angles.'

Eiern the foregoing description. ci the preferred einbedimerits 0f theinveriticn, it Will be apparent that theA Objects heretofore enumerated and others have been accomplished. and that a nevel and improvedJ drafting machine cr. like device hasbeen provided comprising ccnnternlse mechanism. of. imprinted design andccnstruction, which counterpoisemechanism does not interfere, with .the otherwise full movement of the. parallel mo.-

tiQn arm, does not.` givetheA device a bulky and ungainlyalpearance, is out of the way of the operator, and. is eiective throughout the range fimove'ment of the parallel. motion'v arm and for all,` dierentfboard' angles.

'While the 'preferred embodiments of the invention have 'been' described with considerable detail, the inventionis' not 'limited to the par-` vor arm of the wheel and banditype adapted to have connected one end thereofr to a drawing board or theVV like, 'counterpoise means for a sec-v tioaof 'the parallel motion drin, Comprising a weightV adapted to be pivotallysupported at the side of the' drawing board opposite the parallel motion arm for` rotation at, a constant predetermined., radius about anV axis.: at right angles to the2 working surface ofthe' drawing board, and fo".v operatively connecting .said Weight to asection"of's'aidarm'.v

2. In a drafting` machine or like device including a multi-section, wheel and band type, parallel motion mechanism or arm adapted to have one end thereof connected to a drawing board or the like, a weight for counterpoising a section of said arm, means adapted for pivotally supporting said weight at the side of the drawing board opposite said arm for rotation at a constant radius about a fixed axis, means including two relatively rotatable members for operatively connecting said weight to the section of said parallel motion arm to be balanced thereby, and

eaiei @enters aiierilarlr relative t`eac'h other. n 3. In a drafting 'machine or like device in; cluoling a multi-section, parallel motion mecha'- nism or 'arm etlptedfto have. one. end thereof -connectedtohamdr Uig boardor. the like,` counterpoise meansI 'for each se'tenori of said parallel motion arnsoconstuc'ted as to permit` rotation of 'said arnthicpgh substantially ecce and come riisiiie 'ccaiite're e? iree; melueirieraeeri-ariieli1 ity' Of Weights. Piretellv elle.: pcntedY at thefside of said drawing board opposite the'plaraiiei in'ticii afm roil rotation at acon; Staet'rallii 'erteilt' a. iiirecl'axie, and means fer connecting aid weight to'fsaid arm.` n

Il'.v In"a"d`rafting machine or likeI device in,- cluding a multi-section'parallel motion mechanism or arm adapted tohave. one end thereof connect'edftd a "dra'wmg board or they. like, means foncounter'poising ythe sectic'uiv of said parallel motion arrn 'atth" free, endl thereof when it pro: jectstoV veither s" e, ofr the longitudinal center line"of the sectionfto which it is connected, said means comprising aY weight` pivotally supported at the sic'iebf said drawing. board opposite the parallel motion yarm for. rotationV at 'accnstant radius about an axis atright angles tothe. work.

Ineens. ier ediuetlrle ingy s'i'irfaceof Ysaid drawing 'board` and means for connecting saidweight vto the, arm.

"5, In v`a drafting" machine. or like. device. including a parallell friction,v meclfianismI on arm adapted to beconnected toa drawing. 'boardY or tlielikefor movement. over at leaat a, portionv of one side thereof, av weight; for. co'unterbalancing said arm, said'weglit being adapted'tcbe pivotally connected'tothe sideof said'drawing board cppcsite'the" parallel motion' arm and adjacent to .the .center thereof -for rotation at a constant -pr'edeterminedradius about. axisv at right angles to the working surfaceX of the drawing board, andineansfor'. roperatively. connectingI said weight tolsaidlcaraiia mctigamechanism;

6. In a'draftingnachine or likedevice a paral? lel motion mechanism or v4a'rn'i adapted to .be con,- nected Vto adrawing board or the like for move,e nient over at leasta portion 'offone side thereof, a weight pivotally supported at thel side. of said drawing boardA opposite the.` parallel motion arm for, counterbalancing said arm, and `means in; ellittica iilterriaileeare. leeat'eii.Y .at credette Sides ef, the drawing. beard arid; ceririeeltetl by. eleriait providedk with pinions meshing with said gears fer iteratively eenrieetirie. 'Salti Weielit tetti- 1 arm.

7, In a drafting machine-orlike device a paralleal motion mechanian or arm adapted to be connected to agdrawing board of the. like for move;- ment over at least, a portion ofl'cneA side thereof, a, Weight adaptedk to bev pivotallyA connected v`to the side of saidvdrawing board opposite the parat lel motion arm for counterbalancingl said arm, and Ameans includingY apair ofy Wheels encircled by a flexible member for operatively connecting said weight to said parallel motion arm.

8. In a drafting machine or like device a parallel motion mechanism or arm adapted to be connected to a drawing board or the like for movement overat least a portion of one side thereof, a weight adapted to be pivotally connected to the side of said drawing board opposite the parallel motion mechanism for counterbalancing said arm, a spindle extending to opposite sides of said drawing board, means for operatively connecting one end of said spindle with said parallel motion arm, and means including a pair of wheels encircled by a flexible member for operatively connecting said weight to the opposite end of said spindle.

9. In a drafting machine or like device including a multi-section, parallel motion mechanism or arm having an instrument adjacent to one end thereof and means adapted to connect the other end of said arm to a drawing board or the like, a weight adapted to be pivotally connected to the side of said drawing board opposite the parallel motion mechanism for counterbalancing the section of said arm at the free end thereof, a spindle extending to opposite sides of said drawing board, pinions on opposite ends of said spindle, an internal gear in mesh with said` pinion adjacent to said arm, means comprising a pair of wheels encircled by a flexible member for operatively connecting said internal gear to said section, an internal gear in mesh with the other of said pinions, and means including a pair of wheels encircled by a flexible member for operatively connecting said weight to said last-named internal gear.

10. In a drafting machine or like device adapted to be used on an inclined drawing board or the like, an anchor member adapted to be connected to a drawing board or the like, a wheel fixed with respect to said anchor member and adapted to be located at one side of the drawing board to which the anchor member is attached, a strut rotatably supported concentric with said wheel, a second wheel spaced from said rst wheel, means for pivotally connecting said second wheel to said strut, a flexible band encircling said wheels, a third wheel concentric with said second wheel and fixed with respect thereto, a second strut, means for `pivotally connecting said second strut to said third wheel for rotation about an axis concentric therewith, a member located adjacent to said rst wheel, means for supporting said member for rotation about an axis concentric with the axis of said first strut, means for operatively connecting said member with said second strut, a weight for counterpoising said second strut and adapted to be located at the side of the drawing board opposite said wheels, and means for operatively connecting said weight to said member.

11. In a drafting machine or like device adapted to be used on an inclined drawing board or the like, an anchor member adapted to be connected to a drawing board or the like, a wheel xed with respect to said anchor member and adapted to be located at one side of the drawing f second Wheel and fixed with respect thereto, a

second strut, means for pivotally connecting said second strut to said third wheel for rotation about 8 an axis concentric therewith, a fourth wheel located adjacent to said rst wheel, means for supporting said fourth wheel for rotation about an axis concentric with the axis of said first strut, a iifth wheel concentric with said second and third wheels and xed to said second strut, a iiexible band encircling said fourth and fifth wheels, a weight for counterpoising said second strut and adapted to be located at the side of the drawing board opposite said wheels, and means for operatively connecting said weight to said fourth wheel.

12. In a drafting machine or like device adapted to be used on an inclined drawing board or the like, an anchor member adapted to be connected to a drawing board or the like, a wheel xed with respect to said anchor member and adapted to be located at one side of the drawing board to which the anchor member is attached, a spindle rotatably supported in said anchor member concentric with said wheel and adapted to extend to opposite sides of the drawing board, a strut fixed with respect to said spindle, a second wheel spaced from said rst wheel, means for pivotally connecting said second wheel to said strut, a flexible band encircling said wheels, a weight adapted to be located at the side of said drawing board opposite said wheels, means for operatively connecting said weight to said spindle, a third wheel concentric with said second wheel and xed with respect thereto, a second strut, means for pivotally connecting said second strut to said third wheel for rotation about an axis concentric therewith, a fourth wheel spaced from said third wheel, means for pivotally connecting said fourth wheel to said second strut, a flexible band encircling said third and fourth wheels, a fifth wheel located adjacent to said rst wheel, means for supporting said fth wheel for rotation about an axis concentric with the axis of said spindle, a sixth wheel concentric with said second and third wheels and fixed to said second strut, a flexible band encircling said fth and sixth wheels, a second weight located adjacent to said rst strut, and means for operatively connecting said second weight to said fifth wheel.

CHARLES HENRY LITTLE. CHARLES HUBBARD LITTLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

Images