Release mechanism for a hydraulic post driver

A release mechanism for an hydraulic post driver having a hammer, guide means for directing the hammer from a raised release position along a substantially vertical downward impact path, and a fluid expandable cylinder disposed above the hammer and having a telescopically extendible piston serving as means for lifting the hammer to the raised position, the improvement comprising:

• a hammer having a female top member with inwardly directed gripping dogs;
• a piston having a generally "V" shaped male member with arms outwardly biased by a spring, the outwardly biased arms having gripping rollers at each extremity and tripping rollers adjacent the gripping rollers, the tripping rollers being vertically aligned with and move along the guide means;
• and
• inclined planes on the guide means, such that the tripping rollers move along the guide means until they engage the inclined planes, as the tripping rollers move up the inclined planes the outwardly biased arms of the "V" shaped male members move together thereby releasing the gripping rollers from the inwardly directed gripping dogs of the female top member on the hammer to let the hammer fall by force of gravity.

A release mechanism for an hydraulic post driver having a hammer, guide means for directing the hammer from a raised release position along a substantially vertical downward impact path, and a fluid expandable cylinder disposed above the hammer and having a telescopically extendible piston serving as means for lifting the hammer to the raised position, the improvement comprising:

• a hammer having a female top member with inwardly directed gripping dogs;
• a piston having a generally "V" shaped male member with arms outwardly biased by a spring, the outwardly biased arms having gripping rollers at each extremity and tripping rollers adjacent the gripping rollers, the tripping rollers being vertically aligned with and move along the guide means;
• inclined planes on the guide means, such that the tripping rollers move along the guide means until they engage the inclined planes, as the tripping rollers move up the inclined planes the outwardly biased arms of the "V" shaped male members move together thereby releasing the gripping rollers from the inwardly directed gripping dogs of the female top member on the hammer to let the hammer fall by force of gravity;
• and
• cylinders mounted to the guide means, the cylinders containing springs with depending engagement members, the hammer having external pockets that receive the engagement members as the hammer is raised by the fluid expandable cylinder to the raised release position such that as the hammer is raised the springs are compressed resulting in the spring imparting a violent downward acceleration to the hammer upon the hammer being released.