GB615321A - - Google Patents

Abstract

615,321. Automatic level control systems. TENNESSEE COAL, IRON & RAILROAD CO. 11, Oct. 1945, No. 26550. Convention date, March 6. [Class 38 (iv)] [Also in Group II] In a jig for cleaning or separating materials such as coal in which a stratification of material is effected by water pulsations through a grid, automatic control of the feed is effected by a float " resting on the lower (heavy) stratum in conjunction with a system of switches controlling an electric motor which operates to raise or lower a gate at the material inlet. Further provision is made for similarly closing the discharge valve for the heavy stratum when the latter falls below a predetermined level. In the arrangement shown, to ensure a constant level of the " rock " (heavy) layer R for efficient working, a suitably weighted " float " 111 resting thereon is arranged to close one or other of a series of switches FL1, FL2 ... (Fig. 5) in its vertical up or down movement. This in turn energizes a relay 1L, 2L ... and one coil (136 or 147, see Fig. 10) of the reversing'contactor RC, and allows current from a supply L1, L2, L3 to pass to a motor 70 via one of the switches 1D, 2D ... in the "limiting box " 77. The motor then rotates the screw 73, 80 and through the agency of the nut 82, as in 88 and frame 68, raises or lowers the gate 66 and at the same time also raises or lowers the arm 94 (see Fig. 6). The switches are so arranged that a rise in level of the layer R lowers the gate 66, and vice versa; while the motor is stopped when one of the switches 1D, 2D ... or 1U, 2U opens due to the motion of the arm 94 and its associated fingers 100, 101 ... , thus breaking the relay 1L, 2L ... circuit, to de-energize the contactor RC and cut the motor circuit. Should the level R fall below that allowed for by the positioning of switches FR1 and FR2, the contact FVC (Fig. 5) is made, which operates the relay VC and energizes the coil 248 (Figs. 1 and 9) so attracting the pawl 256 to prevent rotation of the discharge valve 34 and so allow the layer R to build up. U.S.A. Specifications 997,609, 1,077,876 and 1,327,537 are referred to.