Material handling machine with bucket shake control system and method

A material handling machine:

• A. a mobile chassis;
• B. a boom that is raiseable and lowerable relative to the chassis, the boom having a first end mounted on the chassis and a second end;
• C. a bucket that is mounted on the second end of the boom;
• D. a tilt cylinder that is connected to the bucket and that is selectively actuatable to tilt the bucket up and down relative to the boom, the tilt cylinder having a rod end and a cylinder end;
• and
• E. an electrohydraulic control system comprising
• (1) a fixed displacement pump,
• (2) a reservoir,
• (3) an electronically actuated proportional control valve that is hydraulically coupled to the rod end of the tilt cylinder, the cylinder end of the tilt cylinder, the pressurized fluid source, and the reservoir,
• (4) a manually operated joystick that is moveable bidirectionally about an axis from a neutral position thereof,
• (5) an electronic controller that is electronically coupled to the joystick and to the proportional control valve and that is responsive to manual manipulation of the joystick to control the proportional control valve to selectively and alternatively a) connect the barrel end of the tilt cylinder to the reservoir and the rod end of the tilt cylinder to the pump when the joystick is moved in a first direction from the neutral position thereof and b) connect the rod end of the tilt cylinder to the reservoir and the bucket end of the tilt cylinder to the pump when the joystick is moved in a second direction from a neutral position thereof, and
• (6) a manually operated bucket shake activation switch that is located on the joystick and that, upon activation thereof, is active to override control of the proportional control valve from a first control mode in which proportional flow control valve opening degree and thus a rate of fluid flow through the tilt cylinder are at least generally proportional to joystick stroke magnitude from neutral, to a bucket shake control mode in which proportional flow control valve opening degree and thus the fluid flow rate through the tilt cylinder are maximized at all joystick stroke magnitudes from neutral.

A method of operating a material handling machine comprising a bucket of material, a tilt cylinder under the physical manipulation caused by a proportional control valve, an electronic controller coupled to a mechanical bucket tilt controller to direct hydraulic movement based on the proportional control valve for mechanically affecting motion of the tilt cylinder, the bucket tilt controller being an input device to mechanically set a bucket tilt mode, and a bucket shake switch device to initiate bucket shake control that, in turn, is subjected to the electronic controller combined with operational state at the proportional control valve, where electronic control and its energizing effect on the proportional control valve coupled to detection of state of bucket tilt control and the bucket shake control implements the material handling method, the latter comprising:

• (A) during a standard operating mode, detecting a triggering event as act of manually moving the bucket tilt controller from a neutral position thereof and, in a response to the movement, automatically opening the proportional control valve at least generally proportionally to a magnitude of bucket tilt controller movement from the neutral position thereof so as to tilt the bucket of the material handling machine at a rate which is dependent on the magnitude of bucket tilt controller movement from a neutral position;
• then
• (B) responsive to a triggering event as act of manually actuating the bucket shake control activation device, initiating the bucket shake switch in a position to start a bucket shake control mode;
• then
• (C) responsive to a triggering event as act of manually moving the bucket tilt controller from the neutral position thereof and, in a response to the movement, automatically opening the proportional control valve a maximum degree regardless of the magnitude of bucket tilt controller movement from the neutral position thereof so as to tilt the bucket of the material handling machine at a rate which is independent on the magnitude of bucket tilt controller movement from a neutral position.