Abstract: An electrodynamic tachometer has a rotor connected to the end of an axle and a stator. An annular element having substantially a C-shaped cross section connects the outer surface of the stator to a bearing housing enclosing the end of the axle. The annular member is of a flexible rubber material so as to be relatively stiff with respect to torsion but flexible with respect to axial and radial deflections.

Abstract: The pressure in an air line in an air braking system for a railway vehicle is controlled by an operator's brake valve which is also constructed to maintain the pressure therein. A pressure monitor is responsive to the pressure drop across a restrictor in the air line or in a supply line leading from a source of compressed air. A control line is connected to an energy source through a shut-off device operable by the pressure monitor and through a two-position switch to be connected to a monitor device for brake release operation or to a second monitor device for the flow of air in the air line caused by defects or application of the emergency brake. The shut-off switch will move to the energy passing position only when a certain pressure difference in the restrictor is excceded. The two-position switch is actuated by the operator's brake valve and connects the brake release monitor device to the control line only when the operator's brake valve is in its brake release position.