CH606617

A method and apparatus for indicating the density of a mass of course particles, such as track ballast, uses the immersion of a tool capable of penetrating into the mass, for instance a tamping tool. The degree of the density is a function of the time of the immersion stroke, the length of the immersion stroke and the immersion force. One of these parameters is measured while the other two parameters are predetermined to determine the measured value of the degree of density, and the measured value is indicated. In a mobile track tamping machine, this is accomplished by actuating a time measuring device by switching elements arranged to be actuated by the immersing tool for measuring the time required by the tool for immersion in the ballast through a predetermined immersion stroke. The time measuring device transmits corresponding time signals to an indicator.