GB1340339A - Control system for material handling equipment - Google Patents

Abstract

1340339 Excavators INTERNATIONAL HARVESTER CO 22 Dec 1970 [22 Dec 1969] 60857/70 Heading E1F [Also in Divisions Gl G2 and G3] The hydraulic motors 21, 22, 23, 30 of a backhoe are controlled by a common lever 35 through respective electro-hydraulic circuits each including a reversing valve 61 (Fig. 7) whose spool 70 is positioned by double-acting motor 85 connected to 3-way pilot valves 110, 111. Rotary potentiometers 40, 92 having their wipers connected to the lever 35 and the spool 70 respectively have their wiper heads connected to a comparator 109 which actuates valves 110, 111 selectively to exhaust one side or the other of motor 85 to position the spool in accordance with the movements of the lever 35 in a particular sense. Positional control of the motor in question (motor 30 in Fig. 7) can be provided by including a further potentiometer 131 controlled by the motor. The bridge circuit could alternatively comprise two series-connected variable resistances in parallel with two series-connected fixed resistances, the comparator being connected between the resistances of each branch. The handle 35 has four distinct operating modes, one for each of the motors 21, 22, 23, 30. Rotation about stem 36 (Fig. 3) actuates potentiometer 40 to control motor 30; pivotal movement about pin 53 actuates potentiometer 44 to control motor 21; axial movement of 47 actuates potentiometer 49 to control motor 22; and rotation of twist grip 54 actuates potentiometer 56 to control motor 23. A sleeve (57) surrounding the vertical portion of the lever has holes in its upper end to receive stop pins which can be located to define the limits of rotation about 36. The reversing valves 61 are arranged in bank which includes similar valves controlling the motors 15 of stabilizers 14. (For Figures see next column)