Control system for material placement buckets

Claim 1

A control system for opening and closing the gate means of a material placement container, said control system comprising clam shell gate means, a double-acting cylinder operating said clam shell gate means and having respective gate opening and gate closing sides and a piston in operating association with the gate means, a fluid pressure receiver, a high pressure fluid supply line having a supply end adapted to be connected in the alternative to a high pressure fluid supply and to exhaust, said high pressure fluid supply line being connected to said receiver and to the gate opening side of said cylinder, a low pressure fluid supply line from said receiver to the gate closing side of said cylinder, a pressure regulator in said low pressure fluid supply line, a simultaneous exhaust valve in said low pressure fluid supply line between said regulator and the gate closing side of said cylinder, said simultaneous exhaust valve having a chamber therein with a first port in exclusive constant communication with said pressure regulator and continuously subject to said low pressure fluid supply, a second port in communication with the gate closing side of said cylinder and a third port adapted to communicate with the atmosphere for exhausting said gate closing side, one valve seat of said exhaust valve being in communication with said first port, another valve seat of said exhaust valve being in communication with said third port, and a self acting pressure responsive valveelement in said chamber being constantly acted upon by said constant low pressure fluid supply at said first port and having a succession of positions relative to said valve seats, said valve element in one of said succession of positions being closed against said first port and subject to said low pressure fluid supply and the pressure therein, said valve element being adapted to effect an opening between said second and third ports only when pressure in the gate closing side of said cylinder exceeds that of the low pressure fluid supply whereby said gate closing side of said cylinder is exahusted, said valve element in another of said succession of positions being adapted to effect an opening between said first and second ports when said gate opening side of the cylinder is open to atmosphere and while having a closed position relative to said third port whereby all of the pressure determined by said regulator is applied to the closing side of said cylinder while the opening side is connected to exhaust.