Abstract: System for monitoring the working of rotation or roll dampers in rail vehicles provided with a superstructure which rests on at least two chassis, in which the motions which can be generated as a consequence of the self-seeking character of a wheel set are damped in at least one of the chassis by the said rotation or roll dampers which are mounted between chassis and superstructure, on one side each of the chassis. The working of the dampers is monitored by means of suitable sensors, which emit electric signals dependent upon the working of the particular damper. The system is provided with means for comparing the signals of both sensors and for determining a differential signal. The system is further provided with means by which the differential signal is compared with a reference value, which means emit a warning signal if the differential signal exceeds the said reference value.

Abstract: Double-acting shock absorber, comprising a piston-cylinder shock absorber which is known from the prior art. During the reciprocating movement of the piston, which is provided on one side with a piston rod which extends to outside the cylinder, an interplay of forces of different magnitudes is generated in the different directions of movement. This is caused by the fact that the surface area on which the liquid situated in the shock absorber acts is smaller on that side of the piston rod which has the surface of the piston rod than on the other side of the piston. According to the invention, these forces are made substantially equal by connecting said other side of the piston to a compensation chamber of variable volume which essentially corresponds to the instantaneous volume displaced by the piston rod in the cylinder.