Patent ID: 7631591
Filing Date: 2009-12-15
Classification: E02F,F15B,F16K,Y10T

Abstract:
1. A valve arrangement comprising: a spool movable from a center position in a first direction through a first stroke and in a second direction through a second stroke; a first biasing member having a first spring constant and a first preload; a second biasing member having a second spring constant lower than the first spring constant and a second preload higher than the first preload; a force transferring member operably interposed between the first and second biasing members to transfer biasing forces from the first biasing member to the second biasing member during the second stroke including a flange having first and second sides against which the respective first and second biasing members bear and first and second portions extending away from the respective first and second sides of the flange, wherein the first and second biasing members surround the respective first and second portions of the force transferring member; and wherein the first biasing member and not the second biasing member biases the spool toward the center position through the entire first stroke; wherein the first biasing member and not the second biasing member is deflected during movement of the spool from the center position to an intermediate position within the second stroke; and wherein the first and second biasing members are deflected during movement of the spool from the intermediate position to an end of the second stroke, the biasing force of the first and second biasing members acting in series being less than the first spring constant and less than the second spring constant.