| 摘要 |
A jar provided with an adjustable preload has a housing defining an anvil surface and a mandrel, movable relative to the housing under an applied load, defining a hammer surface to impact the anvil surface. A trigger mechanism for releasing the mandrel to cause the hammer surface to impact the anvil surface includes a trigger sleeve axially positioned within the housing and a collet that engages the mandrel during application of a load to the mandrel. he ollet he mandrel to cause the hammer surface to impact the anvil surface upon being moved into registration with the trigger sleeve against the resistance of a biasing spring disposed within the housing. The preload is adjusted by an adjustment mechanism carried by the housing and coupled to the biasing spring. The adjustment mechanism includes an adjustment mandrel disposed between an end of the upper housing section and an end of the lower housing section. The adjustment mandrel is axially movable relative to the upper and lower housing sections. An adjustment sleeve disposed between the housing sections and around the adjustment mandrel is coupled to the adjustment mandrel such that rotation of the adjustment sleeve relative to the housing sections produces axial movement of the adjustment mandrel relative to the housing sections and adjusts compression of the spring such that a required applied load for the mandrel to be moved against the resistance of the spring preload is adjusted.
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