be turned toward their upstream sides when in their vertical position to trap water also sufficient clearance may be provided between the paddle edges and the chute walls only to permit water flow therebetween to act against and drive the downstream paddle in the chute it will be noted that the outer end of the lower horizontal member 102 is fitted with a bracket 110 to which a first horizontal roller assembly 112 is secured by bolt and nut means 114 another second vertical roller assembly 116 is secured to a bracket 118 by bolt means 120 that is as seen in fig1 the roller 112 is adapted to roll on a horizontal surface while the roller 116 is adapted for a vertical surface fig8 illustrates a modified roller structure wherein a single pivot 122 is secured to a member 124 attached to bracket 110 so as to be disposed at an angle of 45 u00b0 to the horizontal the single roller 126 is formed with a 90 u00b0 groove 128 providing horizontal and vertical rolling surfaces for the rollers the function of the rollers 112 and 116 or 126 is to support the outer ends of the paddle assemblies 90 the inner ends of which are supported by the chain 54 normal to the chute and in a manner so that the paddle assemblies can drive and move.