Abstract: A mud flap which can be easily installed and removed from its mounting bracket is provided. The mud flap is substantially planar in form with a predetermined thickness. The mud flap has a peripheral edge whose cross section is larger than the predetermined thickness of the mud flap. The mounting bracket includes a bracket body from which two flanges extend downwardly. The flanges converge towards one another at their lower ends, forming a slot therebetween. The mounting bracket is provided with any conventional method for mounting the mounting bracket behind the tire of a vehicle. The mud flap is suspended from the mounting bracket by engaging the peripheral edge of the mud flap with the slot of the mounting bracket. The peripheral edge of the mud flap is engaged with the slot of the mounting bracket by inserting the peripheral edge through either end of the slot.

Abstract: In the representative embodiment of the apparatus of the present invention disclosed herein, a first ported or grooved cylindrical member is coaxially disposed within a drill string for directing drilling fluids flowing through the apparatus along one or more selected flow paths .[.through.]. .Iadd.and .Iaddend.a second ported or grooved cylindrical member .[.which.]. is coaxially arranged in the drill string adjacent to the first member for rotation in a transverse plane cutting the flow paths to cyclically obstruct these flow paths. An electric motor is cooperatively coupled by a shaft to the rotatable member for driving this member at a selected speed for developing an acoustic signal of a desired frequency as the flow paths are momentarily obstructed at periodic intervals.