GB585472A - Improvements in and relating to raking apparatus for sewage screens - Google Patents

Abstract

585,472. Strainers. HARVEY, J. B., and ADAMS-HYDRAULICS, Ltd. June 9, 1944, No. 11047. [Class 46] [Also in Group XXXVII] In apparatus for cleaning sewage screens of the kind in which a rake is drawn along the bars of a substantially vertical screen, the reciprocation of the rake is effected by means of a reversible electric motor which is controlled by means of switches actuated by tappets movable with the rake, and also by means of a time switch, so that the rake is brought to rest only in the uppermost position. As shown, a rake frame 22 provided with teeth 23 for entering between the bars of a screen 24 is carried by chains 16, which pass over sprocket wheels 14, and under sprocket wheels 18 with a counterweight 21, and are connected to a transverse member. The sprockets 14 are adapted to be driven, through a slipping clutch, by a reversible electric motor. Switches 66, 74 are normally closed but the switch 66 is opened by means of a tappet on the chain 16 as the rake approached its uppermost position and the switch 74 is opened by means of another tappet as the rake approaches its lowermost position. These switches co-operate with a time switch (see Group XXXVII) whereby the motor is reversed, and stopped only when the rake is uppermost. The sewage is collected in a chamber 25 provided with channels 28 in which slide guide pins 29 on the rake frame 22, the rake being withdrawn from the screen during its downward movement. As the frame approaches the uppermost position tappets thereon engage levers 42 connected to counterweighted arms 36 which support a frame 35 carrying teeth 34 whereby the teeth are operated to detach screenings from the frame 22 and deliver them to a trough 47. Alternatively, the cleaning members may be mounted on a rotary shaft driven by a toothed rack and pinion from the rake frame.