Earth-moving machine with boom, dipperstick and bucket, equipped with means for directionally-adjusting the bucket

An earth-moving machine of the loading type, having a frame, a boom mounted for pivoting with respect to said frame, a dipperstick mounted for pivoting with respect to said boom, a bucket for loading the material, mounted for pivoting with respect to the stick, a double-acting boom member controlling the relative pivoting movement of the boom with respect to the frame coupled between the boom and frame and comprising two supply connections for respectively "raising" and "lowering" the boom, a double-acting stick member controlling the relative pivoting movement of the dipperstick with respect to the boom coupled between these two elements and comprising two supply connections for respectively "extending" and "retracting" the stick, a double-acting bucket member to adjust the relative pivoting movement of the bucket with respect to the dipperstick, coupled between these two elements and comprising two supply connections for respectively "filling" and "emptying" the bucket, at least one source of power, a three-position boom main control valve connected via three separate connections to a source of power and to the said boom "raising" and "lowering" connections, said boom main control valve connecting the said source of power, in its first position, with the boom raising connection, in its third position with the boom lowering connection, and in its second position, isolating said source of power from said connections, a three-position dipperstick main control valve connected by three separate connections with a source of power and with the stick- "extending" and "retracting" connections, said dipperstick main control valve connecting said source of power, in its first position, with the stick-extending connection, in its third position with the stick-retracting connection, and in its second position, isolating said two connections from said source of power, and a three-position bucket main control valve connected by three separate connections with a source of power and with the bucket "filling" and "emptying" connections, said bucket main control valve connecting said source of power, in its first position, with the bucket filling connection, in its third position, with the bucket emptying connection, and, in its second position, isolating said connections from said source of power, and said bucket main control valve being provided with a first means to adjust its position, said means being adapted to place said control valve in any one of its three positions be direct actuation by the machine operator, the bucket main control valve having second means to adjust its position adapted to place said bucket main control valve in its third position automatically from its second position, and being to this effect connected to a source of power by a control connection, an auxiliary control valve assembly with at least two positions being interposed on said control connection to ensure its continuity on either of its sides in its first position and break off said connection in its other positions, the auxiliary control valve assembly being placed in its first position solely when the boom and stick main control valves are in their third and first positions respectively and wherein in the first position of said auxiliary control valve assembly, the second means for adjusting the position of the bucket main control valve, effectively connected with the source of power, places said bucket main control valve in its third position.