US1260486A - Planimeter. - Google Patents

Description

lVi. VAN METER.

PLANIMETER.

APPLICATION FILED AUGJ ISHI. o Patented. Mar. 26, 1918. Z SHEET$-SHEET I.

M. VAN METER..

'PLANiMETER. APPLICATION FILED AUG-8.1917.-

2 SHEETS-SHEET 2.

R a M d m m Di MORTON VAN METER, 0F CADILLAC, MICHIGAN.

PLANIMETER.

Specification of Letters Patent. P a-tented IWaJr. 26, 191%.,

Application filed August 8, 1917. Serial No. 185,030.

To all 'wh0m it may concern Be it known that I, MORTON VAN METER, a citizen of the United States, residing at Cadillac, in the county of VVeXford and State of Michigan, have invented certain new and useful Improvements in Planimeters, of which the following i a specification.

This invention relates to improvements in planimeters and more particularly to an instrument of the rolling type in which the entire instrument is rolled bodily over the surface of the board and thus can be used to evaluate the area of extended figures such as cannot be accomplished by the polar type planimeter without resetting.

One of the objects of my invention is to provide a planimeter of sturdy, rugged construction, capable of standing rough usage without injury and in which error due to wearing of its parts under long usage is. substantially negligible.

Another object of my invention is to provide such a planimeter which can be manufactured at a comparatively small expense and yet will possess as much, if not greater accuracy than those commonly used.

Another object of my invention is to provide such a planimeter in which no correction of reading is necessary in evaluating large areas as isrequired in using the polar type planimeter.

Still other and further objects will become readily apparent to those skilled in the art from a consideration of the following description and drawings wherein Figure 1 is a plan view of my improved planimeter.

Fig. 2 is a vertical sectional view on the line 22 of Fig. 1, and;

Fig. 3 is a transverse vertical sectional view on the line 33 of Fig. 1.

In polar planimeters, as for example of the Amsler type, a pair of pivoted arms are provided, the end of one arm being secured to the board surface and the end of the other arm provided with a tracing point for outlining the configuration of the area to be measured. On the latter arm at the rear of the point of connection with the first arm, a record wheel is provided which travels upon the surface of the board and indicates the area included within the outline traced.

One difficulty encountered in using a polar planlmeter is in having to account for the area of the zero circle when evaluating large areas and furthermore it will be evident that when used on papers of glazed surface there is always the likelihood of the record wheel giving an erroneous result through slippage in traveling over this mooth surface having but slight tractive engagement with the wheel. In my improved type of planimeter this is eliminated by having the recording wheel travel at all times upon the same surface, namely a conical roller, thus giving a satisfactory and efficient tractive surface. In addition to the above advantage it is possible to evaluate elongated areas, such for example as occur in railroad grade indication drawings, which would require frequent resetting of the polar type planime ter. The roller type planimeter such as I have evolved may be made to travel along a grade line of this character without resetting, giving at the end the desired area reading.

In general the instrument comprises an open frame having front and rear bars 10 and 11 connected at the sides by side pieces 12-12, and 13-13 offset and joined by short bars laparallel with the front and back bars.

In the area inclosed within the ends 13, 13, I have mounted a pair of heavy traction wheels 15-15 upon a shaft 16 mounted t its end in journals 17 These large traction wheels provide the driving mechanism for the planimeter, their motion being transmitted through a gear 18 upon the shaft 16 to the pinion 19 carried upon the end of the cone 20 against which the recording wheel travels. This cone is mounted at its ends in pivot bearings 21, set in brackets 22 secured at the junction of the side members 12 and 14. A shaft 23 parallel with the shaft 16 is positioned between the side members 12, 12, carrying at its center a small wheel 28 which serves a a third point of support for the frame.

The front member 10 is provided with a comparatively wide upper surface 24 with a V-shaped longitudinal groove 25 extending across its front edge portion and upon which the rollers 26 of the carriage indicated in general by the numeral 27 rest. This carriage 27 is of U-shape having an upper legs 29, in which are pivoted, as'at 30, the ends of the two rollers 2626 which are of cylindrical form adapted to bear upon the surface 24 and have at'their forward ends heads 31 of V-shaped cross section for engagement with the groove 25. This carriage is transversely slidable upon the front bar 10 and is provided at its front leg 29 with an outwardly extending bracket 32' carrying a pointed screw orpointer 33 by means of which the outlines of the figure to be evaluated is outlined. A record wheel carrying frame indicated in general at '34 has a pair of U-shaped arms 35, the ends of which are provided with pivot bearings 36 for engagement with the carriage 27 at opposite ends of the table 28. The U-shaped arms '35 are joined at their base 36 and at the opposite sides thereof-extend outwardly forming arms 37 within which the record wheeliand its associated mechanism i mounted.

At the ends of the arms 37, 37 pivot bearings 38 are provided in which the record wheel shaft 39 is mounted. The record wheel "40 carried upon the shaft 39 at one end portion thereof registers with a Vernier scale 41 and at the other side of its midpoint isprovided with a'worm 42 engaging with aworm wheel 43 carried on a shaft 44 which extends outwardly at right angles to the shaft 39 and carries on its upper end a counter wheel 46. The length of the bracket 34 is such as to position the record wheel 40 approximately on line with the axis of the cone'20, so that as the carriage 27 travels along the front frame member 10, the rec- 0rd wheel 40'is moved upwardly or downwardly upon the cone according to the movement of the carriage.

In the particular embodiment which I I have illustrated the diameter of the driving wheels 15, the reduction of gearing between gear 18 and pinion 19, the pitch of the cone and the diameter of the record wheel are so proportioned and related that the indicating surface of the recordwheel is divided into five equal spaces each indicating a square inch. The worm and worm wheel give a reduction of 1 to 20 so that the counter wheel 46 is divided into 10 spaces each equivalent to ten square inches.

' In the form illustrated the arrangement of the pivoted yoke in which the record wheel is mounted happens to be suchthat asit travels from one end to the other of the frame member 10 the point of contact of the indicator wheel with the cone does not follow exactlyin a plane including the axis of the conical roller and a slight advancing or retarding of the record wheel is "caused as it is'moved along the cone independent ofa'ny cone rotation. This error, however, it will be noted, is self correcting as any inwithout departing fromthe spirit of the invention or the scope of the appended claims. Having described'my invention, what I claim is r 1. A planimeter comprising a frame, *a

traction wheel, a cone driven by the tr'action wheel, a carriage slidable on the frame' on a line'parallelto the axis of the cone, a figure outlining pointer carried-by the carriage, and a record wheel movable with the carriage and in'engagement withthe cone.

2. A planimeter comprising a frame, a pair of spaced apart traction'wheels, cone pivoted in the frame on an axis parallel to the axis of the traction wheels, gearsconnecting the cone and traction wheels, a member movable on the carriage on a l ine parallel with the axis of the traction wheels, a pointer carried by the memberand arecord wheel carried by the member and inengagementwith the surface of the cone.

3. A planimeter comprising a'frame, a pair of traction wheels, a cone, gears con necting the cone to the traction wheelsy-acarriage slidable on theframe on-"a line parallel with the axis of the traction: wheels,

a record wheel carried by the carriage'with its axis of'rotation parallel with the axisof the cone and in engagement therewith, and

a-figure outlining pointerprojecting from the carriage.

4. A planimeter comprising a generally rectangular frame, a pair of spaced apart traction wheels journaled within the frame, acone journaled in the frame, gears connecting the cone and traction wheels, a supporting roller journaled in the frame at' a point remote from the traction wheels, a carriage slidable upon the frame'on a line parallel with the axis of the tractionwhe'els, a figure outliningpoi'nter thereon; a" record wheel for engagement Wl'tlllth) cone, --andrecord wheel carrying frame pivotally con- 7 nected to the carriage.

5. A planimeter' comprising a fr ame, a

traction wheel, a cone, gearingconnecting the traction wheel and' cone, a carnage slid able on the frame on a line parallel with the axis of the cone, a record wheel engaging the upper side-of thecone, are'cord wheel supporting frame, pivoted'to the carriage on an axis parallel witlrthe'ax-is of 'the'rec 0rd wheel, and a pointer carried'by the "car ria'ge.

i 6. A planim'eter comprising a "cone, a

frame in which the cone is mounted, means In testimony whereof I hereunto set my for rotating the cone at a speed rate proporhand in the presence of two subscribing 1O tional to the speed rate of frame movement, witnesses.

a carriage slidable upon the frame, on an 5 axis parallel with the axis of the cone, a MORTON VAN METER figure outlining pointer on the carriage, and In the presence of-- a record wheel carried by the carriage and. ESTHER E. VAN METER, in engagement with the surface of the cone. 0. W. CUNNINGHAM.

copies of this patent may be obtained for five cents each, by addressing the Commissioner 01? JPutentu,

- Washington, D. C.

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