To provide a simple mechanism for reducing swing bounce, in hydraulically powered equipment.
When a swinging boom 15 driven by a hydraulic cylinder 19 stops, inertia causes continued motion of the boom which increases pressure in a chamber 40, 42 of the hydraulic cylinder. Eventually that pressure reaches a level which causes the boom to reverse direction. Then pressure in an opposite cylinder chamber 42, 40 increases until reaching a level that causes the boom movement to reverse again. This oscillation continues until the motion is dampened by other forces acting on the boom. As a result, an operator has difficulty in properly positioning the boom. To reduce this oscillating effect, a sensor 48, 49 detects when the cylinder chamber pressure increases above a given magnitude and then a determination is made when the rate of change of that pressure is less than a defined threshold. Upon that occurrence, a control value 33, 34 is opened to relieve the pressure in that cylinder chamber 42, 40.
PFAFF JOSEPH L
STEPHENSON DWIGHT B
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