Public works machine having a safety device for the manoeuvre of its working equipment

Claim 2

A loader comprising a body member; means on the body member defining a first pivot axis; a jib system mounted on said body member for pivotal movement about said first pivot axis and comprising at least one jib member; means on said jib system defining a second pivot axis; means for mounting an implement member on said jib system for pivotal movement about said second pivot axis; first fluid motor means for rotating said jib system about said first pivot axis; second fluid motor means for rotating said implement member about said second pivot axis; control valve means responsive to the relative angular positions of said members; means for applying fluid pressure to said fluid motor means; a fluid reservoir; and a discharge conduit extending from one of said fluid motor means to said reservoir via said control valve means, said control valve means being responsive to the relative angular positions of said implement with respect to said jib system about said second pivot axis and said jib member with respect to said body member about said first pivot axis to open said conduit to fluid flow when said angular positions enter pre-determined ranges, whereby operation of said one of said fluid motor means to raise said implement member is inhibited.

Claim 3

A loader in accordance with claim 1, wherein fluid means to which the discharge conduit is connected is of the double-acting type and has two chambers, a first chamber to which the discharge conduit is connected, and to which is also connected a first conduit connectable to the source of pressurized fluid, and a second chamber, which is connected to a second conduit connectable to the discharge reservoir, and including a distributor arranged in the first and second conduits, and having a first position producing continuity of the said first and second conduits at that point, and a second position in which the said first and second conduits connected to the two chambers of the said fluid motor means are blocked, a calibrated discharge valve in the discharge conduit between the control valve means and the reservoir, a linkage conduit connecting the discharge conduit between the said control valve means and the said calibrated discharge valve to the portion of the seCond conduit between the second chamber of the fluid motor means and the distributor, and a non-return valve which is arranged in the said linkage conduit to allow passage of fluid from the discharge conduit to the second conduit and to said second chamber, to prevent cavitation in said chamber.

Claim 4

A loader in accordance with claim 1 wherein the second fluid motor means consists of a ram and the discharge conduit being connected to that chamber of the said ram which is supplied with pressurized fluid on raising of the implement member.

Claim 5

A loader comprising a body member, a jib system pivotally mounted on said body member and including at least one jib member pivotally mounted on said body member about a first pivot axis; an implement member pivotally mounted on said jib system about a second pivot axis, first fluid motor means for rotating said jib member about first pivot axis with respect to said body member; second fluid motor means for rotating said implement member about said second pivot axis with respect to said jib system; means, including a fluid reservoir, for supplying fluid under pressure to said fluid motor means; a fluid discharge conduit operatively connected between one of said first and second fluid motor means and said reservoir to allow discharge of fluid therethrough; first and second control valve means located in said discharge conduit and each having two positions respectively blocking and opening the discharge conduit; said control valve means being respectively operatively associated with said implement member and said jib member with said first valve means being responsive to the relative angular position of the implement member to the jib system to open said discharge conduit at a predetermined angular position therebetween and said second valve means being responsive to the relative angular position of the jib member to the body member to open said discharge conduit at a predetermined angular position therebetween whereby when both said implement member and said jib member are at said predetermined angular positions said first and second control valve means open said discharge conduit to fluid flow from said one of said fluid motor means to said reservoir thereby inhibiting said one of said fluid motor means from operation.

Claim 6

A loader comprising a body member, a jib system pivotally mounted on said body member and including at least one jib member pivotally mounted on said body member about a first pivot axis; an implement member pivotally mounted on said jib system about a second pivot axis, first fluid motor means for rotating said jib member about first pivot axis with respect to said body member; second fluid motor means for rotating said implement member about said second pivot axis with respect to said jib system; means, including a fluid reservoir, for supplying fluid under pressure to said fluid motor means; a fluid discharge conduit operatively connected between one of said first and second fluid motor means and said reservoir to allow discharge of fluid therethrough; first and second control valve means located in said discharge conduit and each having two positions respectively blocking and opening the discharge conduit; said control valve means being respectively operatively associated with said implement member and said jib member with said first valve means being responsive to the relative angular position of the implement member to the jib system to open said discharge conduit at a predetermined angular position therebetween and said second valve means being responsive to the relative angular position of the jib member to the body member to open said discharge conduit at a predetermined angular position therebetween whereby when both said implement member and said jib member are at said predetermined angular positions said first and second control valve means open said discharge conduit to fluid flow from said one of said fluid motor means to said reservoir thereby inhibiting said one of said fluid motor means from operation.

Claim 7

A loader as defined in claim 4 wherein said one of said fluid motor means comprises a double acting ram having a piston therein separating the ram into first and second fluid chambers, said first fluid chamber being connected to said discharge conduit; a first conduit connected to said first chamber and to said discharge conduit; a second conduit connected to said second chamber; and a distributor valve operatively connected to said first and second conduits for selectively connecting the first and second conduits to said means for supplying fluid under pressure and said reservoir; said distributor valve having at least first and second positions and means for connecting said first and second conduits to said fluid pressure means and said reservoir respectively in the first position thereof and for blocking fluid flow in said first and second conduits in the second position thereof; a calibrated discharge valve in said discharge conduit downstream of said control valve means; a connecting conduit in fluid communication between said second conduit; between said second chamber and said distributor valve, and said discharge conduit at a position downstream of said control valve means and upstream of said calibrated valve; and nonreturn valve means in said connecting conduit for allowing fluid in said discharge to pass to said second conduit and into said second chamber to prevent cavitation therein.