Abstract: Implementations of the accessory and associated methods allow for excavation of a ditch, wherein rotating grating means are used for expelling rubble and form a ditch. The accessory includes grating means which are moved with respect to the ditch to ensure contacting of the grating means with the road and alignment of a rotation axis of the grating means with the ditch axis. The ditch is progressively excavated when the grating means are rotated and displaced along the ditch axis. The grating means may be connectable to a mobile device through an arm assembly configured to controllably move the grating means from the mobile device. The accessory may be used for connection to a mining device for excavating the ditch along the road of an underground mining tunnel.

Abstract: In an electronic apparatus for measuring a difference of elevation between two points, said apparatus comprising: a tube made of a flexible material; a fluid with a low viscosity completely filling said tube; two piezoelectronical pressure transducers each connected to a source of electrical power and mounted at one extremity of the tube in contact with the fluid filling said tube to produce signal a proportional to the pressure of this fluid; electronic means connected to each of said piezoelectrical pressure transducers for processing the signals received from said transducers, said processing means comprising means for generating a signal proportional to the difference between the signals received from the transducers and means for converting said generated signal into a value indicating the difference of elevation between the extremities of the tube, and means for displaying said value indicating the difference of elevation, the improvement wherein it further comprises means for generating a signal propor