Improvements in or relating to mechanisms, instruments and machines for drawing, tracing or otherwise generating or defining the locus of a point revolving about a second point which itself is revolving about a third point

摘要

752,022. Curve-describing instruments. JONES, H. Nov. 12, 1954 [May 27, 1954], No. 15724/54. Class 97 (3). The instrument shown has a bracket A comprising a sleeve bearing bSP1/SP joined by arms cSP1/SP to sleeve bearings dSP1/SP. A horizontal shaft aSP1/SP and a vertical shaft aSP2/SP turn freely in bearings bSP1/SP and dSP1/SP respectively. A bevel gear 2 fast on shaft aSP1/SP engages a bevel gear 1 on shaft aSP2/SP, bearing against one sleeve dSP1/SP and against a distancepiece i bearing against the other sleeve dSP1/SP. A lug on gear 1 engages a groove f on shaft aSP2/SP so that the gear rotates with the shaft but may slide therealong for adjustment, the gear being held in the adjusted position by friction or by a set-screw jSP1/SP. A second bracket B has an arm cSP2/SP joining a bearing sleeve fSP2/SP, in which shaft aSP1/SP turns freely, to a flaring sleeve dSP2/SP for a short vertical shaft aSP3/SP. A bevel gear 3, fast on shaft aSP3/SP engages a bevel gear 4 which rotates with shaft aSP1/SP by reason of a lug engaging a groove f, but which is slidable along the shaft for adjustment, being held in the adjusted, position by friction or by a set-screw jSP4/SP. A shoulder-piece k fixed to or frictionally engaging shaft aSP3/SP below the bearing sleeve dSP2/SP carries two legs l hinged to the shoulder-piece like the legs of a compass. The legs l terminate in drawing points eSP2/SP, and the shaft aSP1/SP has a hard point eSP1/SP at its. lower end. The gearing is such that, when shaft aSP1/SP is rotated about shaft aSP2/SP, the shaft aSP3/SP is rotated in the opposite direction at twice the angular speed. If desired, rotation of shaft aSP1/SP relative to shaft aSP2/SP may be effected by means of a crank. In this case a bracket similar to bracket A is placed on shaft aSP2/SP above bracket A. One bearing sleeve of the second bracket has a lug engaging the groove f in shaft aSP2/SP, while the other surrounds the hub of a bevel gear fast with bracket A. A bevel gear driven by the crank journalled in the second bracket engages the bevel gear fast with bracket A so that bracket A and shaft aSP1/SP may be rotated about shaft a2 on turning the crank. Several horizontal shafts aSP1/SP with vertical shafts aSP3/SP and attachments may be used to draw several curves at once. The shoulder-piece k may carry, instead of legs l, a horizontal bar with adjustable vertical marking bars. To draw a straight line, the point eSP1/SP is set on a fixed point, bracket B is set a distance from shaft aSP2/SP, and bracket A is adjusted along shaft aSP2/SP until the point eSP2/SP of one leg l is set at the same point as point el. On rotation of shaft aSP1/SP, a straight line is drawn. The other point eSP2/SP, if also in contact with the paper, traces a straight line at rightangles to the first. To draw a pair of ellipses, the points e2 are,made to touch the paper at positions separated from point eSP1/SP. Rotation of shaft aSP1/SP about shaft aSP2/SP causes points eSP2/SP to draw a pair of ellipses with their major axes at rightangles. By allowing only one point eSP2/SP to touch the paper, and rotating shafts aSP1/SP, aSP2/SP together about point eSP1/SP, a circle may be drawn.