Abstract: A vertical and longitudinal force sensor for use in a fifth wheel hitch. The sensor comprises a beam and transducers for measuring the horizontal and vertical deflections at true center of the beam. The beam comprises two outer parts and an inner part which serves to actuate the transducers.

Abstract: A capacitive electro-mechanical transducer for responding to both push and pull, for example in a road vehicle drawbar, involves axially spaced flanges (3) on the one force-transmitting member lying on opposite sides of a transverse portion (1) of the other member. The force is transmitted resiliently between the flanges and the portion, and there are capacitor plates (11) between the flanges (3) and the portion (1), so that on relative displacement the capacitance of one set of plates increases and that of the other set decreases. The plates are symmetrically disposed, e.g. of annular form, and they, or the dielectric (13) between them, can be wavy.

Abstract: A sensor in the drawbar (or fifth-wheel coupling) of a tractor-trailer road vehicle combination senses both push and pull force in a linear proportional manner and produces an electrical signal which is used to act on a continuously proportional solenoid valve in the fluid pressure supply to the trailer brakes to control the trailer braking continuously, during application, in a sense tending to reduce the force in the drawbar to zero. There may be a base pressure applied to the trailer brakes, modified positively or negatively by the pressure from the sensor signal.