Patent ID: 6085501
Filing Date: 2000-07-11
Classification: A01B,A01D,B60G,F16F,Y10S

Abstract:
Method for automatically adjusting a lightening of a working unit of a machine, which working unit is carried by a carrying structure in such a way as to rest on a ground during work and be held away from said ground when work is interrupted or during transport, said working unit being configured to be lowered so as to be brought to rest on the ground and to be raised so as to be brought away from said ground by means of at least one hydraulic-energy converter fed by an oil-supply source through a hydraulic circuit and having a first hydraulic ram equipped with a rod and associated with a hydropneumatic accumulator in which a pressure of a gas can be set initially to a value that corresponds to an amount of lightening desired for the working unit,and having a second hydraulic ram, the working unit being raised and lowered using the second hydraulic ram of which a piston, which can move as far as a predetermined position in a cylinder of said second hydraulic ram and which is detached from the rod of the first hydraulic ram, acts on said rod via an oil contained in the first hydraulic ram, the method comprising the steps of:raising the working unit whereby a volume of oil in the first hydraulic ram is increased only if, with the piston of the second hydraulic ram in the predetermined position, the working unit does not reach a predetermined height, and the volume of oil in the first hydraulic ram is decreased only if said working unit has reached the predetermined height, while the piston of the second hydraulic ram has not yet reached the predetermined position; whereby the working unit is always at the predetermined height at an end of raising travel when the piston of the second hydraulic ram is in the predetermined position; andlowering the working unit whereby the volume of oil in the first hydraulic ram is maintained when lowering the working unit.