Abstract: A measuring device for universal application includes a parallel-crank mechanism directly rotary mounted on the slider of an isosceles centered slider-crank mechanism. The measuring element or pin is adapted on the coupler of the constrained guide mechanism. All points of coupler plane including the measuring element are moved along exactly straight lines parallel to each other at right angle to the axis of the slider. The simple change-over of a lever against its other abutment turns the active direction of a spring and enables the resetting of the measuring device from internal to external measurement. Alternatively, two-point or three-point or relative measurements can be executed. The modular unit system permits, if desired, an arrangement of two or more of the constrained guide linkages according to the invention on the sliding axis whose sliders are rigidly connected in groups of preferably three.

Abstract: A compass, comprising a sliding rod with a handle at an upper end, and a drawing portion. A slider is slidably mounted on the sliding rod. Two links are pivotally connected to the slider and to the drawing portion at respective first pivot points forming at least approximately a parallelogram. A crank is operatively pivotally connected to the sliding rod and to a center of one of the links at respective pivot points, the crank having a length between its pivot points equal to half the length of the link to which the crank is connected between the first pivot points of the one link.