Modulated overpressure valve structure for fluid operated device

A pressure releasing valve structure for a fluid operated device, the device having an orifice constructed and arranged to be in fluid communication with a pressure chamber, the valve structure comprising:

• a body having first and second ends,
• first means, at the first end of the body, for sealing the orifice,
• second means, associated with the first end of the body, for causing the first means to seal the orifice under certain pressure conditions in the pressure chamber, and
• third means, associated with the second end of the body, for reducing a force exerted by the second means, thereby permitting the first means to move to a non-sealing position to open the orifice under pressure conditions in the pressure chamber lower than would be require absent the provision of the third means.

A fluid operated device comprising:

• surfaces defining a pressure chamber constructed and arranged to contain fluid,
• surfaces defining an orifice in fluid communication with the pressure chamber, and
• a valve structure comprising:
• a body having first and second ends,
• a valve member at the first end of the body constructed and arranged to seal the orifice,
• a first spring associated with the first end of the body and constructed and arranged to cause the valve member to seal the orifice under certain pressure conditions in the pressure chamber, and
• a second spring associated with the second end of the body and constructed and arranged to compress thereby reducing a force exerted by the first spring.