Spool centering mechanism of two stages for a working machine in an excavation area

摘要

Valve arrangement comprising: a spool (120) movable from a central position in a first direction along a first path yen a second direction along a second path; and a first element (145) biasing quetiene a first spring constant and a first preload; and a second member (150) having a second deviation lower elastic constant of the elastic primeraconstante and a second higher than the first preload preload; wherein the first biasing element and not the second biasing member biases the spool toward center laposición along the entire first path and during movement of the spool from the posicióncentral to an intermediate position within the second path; and wherein the first and second deflection members act in series to bias the spool into central laposición during movement of the spool from the intermediate position to an end of segundorecorrido, wherein the biasing force of the first and second biasing elements They are acting on serieinferior to the first elastic and less than the second spring constant, characterized constant because ladisposición valve further comprises an element (160) power transmission comprising unborde (190) having first and second faces against which abut the first and segundoelementos respective deflection, functionally arranged between the first and second elements for transmitting dedesviación biasing forces of the first biasing member during the second dedesviación second path.