US1684887A - Pantograph - Google Patents

Description

Im/ENTOR. L. R/dgway ATTORNEYS.

sept. 18, -19:28.

L. RIDGWAY PANTOGRAPH Filed Aug. 4, 1927 Patented Sept. 18, 1928.

LAT BIDGWAY, OF CANON, GEORGIA.

PANTOGRAPHI. f

Application ledfAugust 4', 1927. Serial No.' 210,642.

Thisinvention relates to improvements in pantographs, and it has for-its object the provision of a device of simple and sturdy construction; more particularly, it is sought to 5 provide means for transmitting the movement of the tracing stylus to the reproducing stylus so that lost motion and slipping of the driving parts is reduced to a minimum. The means employed for the purpose is described in detail hereinafter, pointed out in the appended claims and illustrated in the accompanying drawings. E

the accompanying drawings,-in which similar reference characters 'designate corre- !5 sponding parts:

Figure 1 is a plan view of a. embodyingthe invention. Y

Figures 2, 3, 4, 5 and 6y are, respectively, detail sectional views on the lines 2*-2, 3-3,

Referring to the drawings in detaihthe frame of the machine is of'an elongated'rectangular formation and comprises the longitudinal members -10 joined at their ends by 25 the cross members 11` to form a rigid structure. Extending across the vunderside ofthe frame is the pivot member 12 positioned so that Vone-third of the length of the frame is on one side of said member and'two-thirds is on the other side. Projecting from the under side ofthepivot member is the lug 13 in which is mounted the pin 14 to be forced into the drawing board or othersupport when the device is operated. This pin, seated in the drawing board, forms the pivot'about which the frame is turned. At the ends of the frame are mounted the rollers 15 journaled in the brackets 16 attached to the corners of the frame. These rollers travel on a 40 plane including the lower end of the lug `13 and in practice this'plane is formed by the surface of the drawing board on which the devicefis mounted. With thepin 14 journaled inthe drawing board the frame can be freely oscillated about the pivot so formed, the rollers 15 riding on the board carrying the frame. and maintaining it in its parallel relation `to theboard. p

'Extending across the upperv part of the 5oV frame and parallel to the pivotmember 12 is pantog-raph the uppermember 17 secured at its ends to the yspacing blocks 18, secured in turn to the loni gitudinal members 10. These members, so connected, form a transverse frame in the longitudinal main frame.v Mounted in tho 5. transverse frame is the pulley 19v having concentric rims 20 and 21 with the latter of twice the diameter of the former. The pulley is carried by the integral' sha-ft 22 journaled at its lower end in the pivotmember 12 and at, its upper end in the set-screw 23 threaded in A the upper member17 of the transverse frame.V By backing out the set-screw the pulley can be readily dismounted, The axis of the double-rimmed pulleyis coincident with the pivotal axis of the main frame.

Mounted. in the main frame on opposite sides ofthe transverse frame are thecarj riages 25 and 26 of like construction. Each, carriage comprises a frame of H-shape formation having grooved rollers 27 journaled in the extremity of eachV arm. Each carriage travelsbetween the longitudinal members 10 of the main frame with the grooved rollers 27 engaging the tracks 28 extending along the li5 inner faces of the longitudinal members'. In: each carriage is centrally located a stylus 29 frictionally held for vertical adjustment therein. The axes of the two styli and of the double-rimmed pulley are in the same vertical plane and these relative positions are maintained irrespective of the travel of the carriages in the main fram Y v In the cross-pieces 11 at the opposite ends of the main frame are journaled the `pulleys 30 and 3l, respectively. Looped around the idlerpulley 30 and the rim 2O of shorter diameter of the double pulley is the band32 attached at its ends to opposite sides'of the carriage 25. Likewise, a band 33 .is looped around the idler pulley 31 andv the rim 21 of greaterl diameter of they double pulley and j its ends are attached to opposite sides of the carriage 26.` The pulley 30 andthe rim 20 are of the same diameter, as'are thepulley 31, and the'rim 21, to maintain their respective bands in longitudinal parallel relation Vto the main frame. Each band is under tension to provide frictionalA engagement between it and the pulley rim with 'which it is engaged, 10

so that the drive of one will be imparted to the other without relative slip. It is to be observed that the length of the guideway for the travel of the carriage 25, which is connectthe distancel between the axial centeroi` the pulleyand the axial center of the carriage l,

25, the axial centers of the carriages being indicated by their respective Styli. VConso quently, the proportionate travel of the two carriages on the supporting frame is the same'` as the proportional1 relation ofthe diameters otthetwo rimsofthe double pulley that is, as one to two.

From the foregoing it is obvious that. if the carriage 25 isrmoved in eitherv direction on its guideway, there will be a corresponding movement ofthe carriage 26 on its guideway, but the lattcrl will travel twice thedistance travelled by thev former. Also, the movement of the carriages will be in opposite directions; lfor an instance, if the carriage 25 is moved to the left, as shown in Fig. 1, the carriage 26.'will move to the right.` 'The proportional travelof the two carriages may be varied by substituting for the double pulley, other pulleys with rims of differentlproportionate relations. SuchV substitution is facilitated-by the adjustable setfscrew 23.`

yIn the operation of the device, for anvers` ample, to reproduce the given triangle a, b, c, enlarged to twice the size, asat d, e, f, the-paper-with the given triangle displayed there` on is affixed to a drawing boardin the usual manner. The pantograph is then mounted on the board by forcing the pin 14 into Vthe same so that the Wheels 15 ridethereon; Itis positionedso that the given triangle is containedwithin the-field of travel of the car-l riage 25 as the device is turned on 'its -pivot formed :by the Vpin 14 journaled in the board.

The main frame is turned on its pivot and;

the carriage 25 is moved on vits guideway to position thestylus 29 mounted in said carriage directly` abovethe `angle a of the given triangle.. Then both Styli 29 are forced" downwardly into contact with the paper. For convenience,.the stylus mountedin the carriage 25 may be designatedas the tracing stylus and the one in the carriage 26 thereproducing stylus, the latter being a pencil `or apen; also the carriages 25 and `26 may be Vrespectively designated as the tracing and reproducing carriage.`

After the device has been initially positione'd, the tracing stylus is moved along the line aff-b. This movement of the"` tracing stylus causes the device to turn on its pivot lliand the tracing carriage to move on the yguideway, outwardly toward the left end of the frame as shown in Fig. 1. As the tracing carriage 25 moves along tne guideway the band or belt 32 is drawn the same distance around the Vpulley rim 20. Through the frictional engagementof the band with the pulley rim, the double pulley is rotated and the rim 21 draws the band wtopropel the reproducin carriage 26'along the guideway. Y

linefd-fibeing twieethe'length of the yline a-1-b.. Likewise, as thetracingstylurssucoessively followsv the lines b`o ando-a ofthe given triangle the reproducing` sytlus successively format e lines. fL-e'an `e-dito comeV plete the enlarged reproduction'oithegiven` triangle. While the example given of:` the i operation of the device is a simple one yet itfisA particularly adapted to thereproduction of` com licated work, such as maps.

hat Ilclaim is:

1. In a .pantograph,` the combination of@` an elongated frame having a longitudinal guideway', means for pivoting the frame atan intermediate point, a carriage,mounted in each endiofithe frameto travel inthe guide-l way with the carriages Aonopposite rsides of Y the pivotal point; of the ia'me, a stylus' mounted in each i carriage, a. doubleimmed pulley mountedion the frame-.with its, axis: alinedi with the pivotal axisoffthe frame,

the rims of1tl`1epulliey` having diameters in proportional relation to. eachother, and bands respectively connectedwiththe oppo` site carriages and, each band being looped aroundone of the rima` ofithe double'pulley so that thetravelof` one offthe carria es 1s transmittedto the other-carriageiwit the--` travel f of, the carriages in proportional` rei lation.

2.. In a pantograph, the combination Vof an;r

elongated frame having a lon itudinal guideway, means for pivotingrthen rame at.`

an intermediate part, carriages: mounted inj Vthe frame to travel in theguideway on oppo-L.;

site sides of the `pivotal pointfof the frame,.l

a stylus mountedin each carriage, a double:

rimmed pulley mountedinithe frame'with its axis coincident with lthe pivotsA of.` the frame, and bands in` `opposite extension` looped around the. rims of t Vpulley andere spectively connected with the opposite car-v. Y

1251` moved on the guideway aproportional travel.

riages so that when one of thelcarriages is is transmitted to the other carriage.

3. In a pantograph, thecombination Otan elongated frame having. a longitudinal guideway, .idler pulleysmounted in the frame at malezas? y c 3 opposite ends of the guideway7 means for tension looped around the rims of the doupivoting the frame at an intermediate part, ble-rimmed pulleys and the idler pulleys and l0 carriages mounted in the frame to travel in respectively connected with the opposite carthe guideway on opposite sides of the rivotal riages so that when one of the carriages is 5 point of the frame, a stylus mounted 1n each' moved on the guideway a proportional travel carriage, a double rimmed pulley mounted in is transmitted to the other carriage. the frame with its axis coincident with the In testimony whereof I alx m signature. pivot of the frame, and bands in opposite exn LAT RI GWAY.

Images