LOAD SENSING DEVICE FOR MANIPULATORS AND BALANCERS

摘要

In a first aspect, the invention is directed to a load handling system that includes a load movement assembly, a lift cylinder, a load holding member, a release control member, a load movement assembly control device and a load sensing device. The load movement assembly is movable between a raised position and a lowered position. The load holding member is connected to the load movement assembly and controllable to hold a load and to release the load. The lift cylinder is operatively connected to the load movement assembly and movable to raise and lower the load. The release control member is operatively connected to the load holding member to control release of the load. The load movement assembly control device is actuatable between a first state wherein the load movement assembly control device connects the lift cylinder to a source of fluid at a first pressure, and a second state wherein the load movement assembly control device connects the lift cylinder to a source of fluid at a second pressure. The first pressure is selectable so that the lift cylinder at least partially supports the weight of the load movement assembly and the load. The second pressure is less than the first pressure and is selectable to be sufficient for the lift cylinder to at least partially supports the weight of load movement assembly without the load and to be insufficient for the lift cylinder to support the weight of load movement assembly with the load. The load sensing device includes a housing having a first port and a second port, and a piston movable between the first and second ports. The first port is fluidly connectable to the lift cylinder. The second port is fluidly connectable to a source of fluid at a third pressure. The piston is operatively connected to the release control member. When the lift cylinder is at the second pressure the piston is driven to a first position which permits the release control member to be actuated to release the load, and wherein when the lift cylinder is at the first pressure the piston is driven to a second position which prevents the release control member to be actuated to release the load.