Abstract: A device for checking involutes and helix angles of cylindrical gears by electronically compensating for mechanical errors, which includes a mechanically operating transmission chain, especially a rolling transmission, a sine bar, a sliding block linkage and/or a lever transmission, which transmission chain guides a measuring feeler relative to a gear to be checked on the required reference curve. The device furthermore includes one length pick-up each at both ends of the transmission chain for measuring their respective motions, a computer unit for multiplying the signal of one of the length pick-ups with the put-in rated transmission ratio of the transmission chain and for subtracting the multiplied signal from the signal of the other length pick-up, and also includes a device for subtracting with the proper prefix + or - the thus formed difference signal as correction value from the measured value of the measuring feeler.

Abstract: A feeler for measuring lengths operable in a controlled measuring direction provided as an additional device for two-coordinates measuring heads. The feeler includes a feeler lever which has one end designed as a circular feeler tip for feeling engagement with the workpiece to be measured. The feeler is mounted in a bi-valent joint on a base plate carried by the measuring head which joint permits a displacement of the feeler tip in the measuring plane in any desired direction. The other end of the feeler lever is linked to a straight line guide which is mounted on a disc arranged on the base plate so as to be rotatable by any desired angle about an axis extending in a direction perpendicular to the measuring plane. At the above mentioned other end the feeler lever is subjected to a measuring force which acts in the direction of the straight line guide. The disc has connected thereto an indicator for measuring the displacement of the above mentioned other end.