Patent GB-1139515-A (GB)
Title: Arrangement for dispensing materials from a moving vehicle
IPC: A01C7/16
Filed: 1966-05-11
Abstract: 1,139,515. Powder distribution. EUROPEAN ENG. TRUST REG. 11 May, 1966 [11 May, 1965], No. 20835/66. Heading A1D. Apparatus for dispensing pulverulent or granular material regulates automatically the rate at which the material is dispersed in response to changes in the speed of a vehicle on which the apparatus is mounted by either varying the speed of a distributing conveyer belt 2 or varying the size of an opening 11 which feeds the material to the belt from a storage bin 1, wherein electrical signals representative of the vehicle speed and delivery rate of the material are applied to a difference circuit whose output controls the distribution. The conveyer is driven by a hydraulic motor 3 fed by a pump 4 via a valve 6 which meters the flow of oil to the motor according to the speed of travel of the vehicle. The valve 6 is controlled by a positioning motor 13 which will cause the positive or negative values of a disc (7), mounted on the valve, Fig. 3 (not shown), to lie opposite a fixed indicator (9) according to whether the conveyer is moving faster or slower than a given particular speed due to speeding up or slowing down of the vehicle. The circuit, Fig. 4, controlling motor 13 comprises a potentiometer 16 whose sliding contact is geared to the motor and which is connected across a D.C. supply 19 via trimming resistors 17 and 18. A bridge is formed by resistors 20, 21, transistors 22, 23 and motor 13. The vehicle speed detector in the form of a tachometer 25 provides a signal, converted to D.C. by bridge 26 and applied across the winding of a potentiometer 27. Positioning of the sliding contact 28 provides no current in line 24 for the normal speed of the vehicle. If the vehicle speed increases an increased signal from tachometer 25 diminishes the current through transistors 30, 31 and hence through transistor 23. The connection 32 and the base of transistor 22 become more negative and increases the current through transistor 22 producing a current flowing through resistance 21 and motor 13 in direction 33. The motor thus rotates its gear (12), Fig. 3, causing disc (7) to rotate until the positive values come opposite indicator (9), and the dispensing rate increases. At the same time contact 15 is moved towards negative potential and the positive potential of connection 29 is reduced towards null, in creasing the current through through transistors 30 and 31. The potential of connection 32 becomes more positive and the current increases through transistor 22. The greater flow of current through transistor 31 produces a potential in the connection 34 by which the transistor 23 is retained in the partially conducting state. Further positioning of the sliding contact 15 causes finally the transistors 22, 23 to exhibit identical resistance values and the current in line 24 ceases causing motor 13 to stop with valve 6 allowing an increase in the through flow of oil corresponding to the increase in vehicle speed. If the vehicle speed is reduced the operation is reversed. If the hydraulic motor 3 runs at a constant speed the motor 13 may operate the up and down movement of slide 10 thereby varying the size of opening 11 by a rack and pinion movement. In an alternative embodiment, Fig. 5 not shown, a slide 36 is operated by a piston 43 moving in a double acting hydraulic cylinder 37. Fluid is supplied to the cylinder via a valve 40, Fig. 6 not shown. The sliding contact 15 of potentiometer 16 is operated by a piston rod 45. In the circuit, Fig. 6, associated with valve 40 an increase in vehicle speed causes connection 41 to become more positive, the current through transistor 42 to decrease, connection 43 to become more negative, current flow through transistor 44 to decrease. Fluid flow through valve 40 is thereby increased until the movement of contact 15 reduces to null the positive potential in connection 41 and the flow ceases. Reduction of vehicle speed reverses the above operation.