27 which roll in tracks 29 of carrier beams 28 when trolley 26 is fully moved to its extended trolley position 32 the gripper rake assembly 34 is opened if it is not already open hydraulic assembly 45 hydraulic lines 44 and hydraulic cylinders 43 allow gripper rake assembly 34 to be opened and closed a control on control station 56 will allow for the opening for the gripper rake assembly 34 when gripper rake assembly 34 is open and trolley 26 is in the extended position gripper hoist motor 40 is actuated and gripper rake assembly 34 is lowered on hoist cables 42 to engage the bar grate or weedscreen 14 to be cleaned rear line assembly 38 of gripper rake assembly 34 engages bar 16 of the screen 14 and as gripper rake assembly 34 is lowered debris 18 is cleaned from the weedscreen 14 and gathered by gripper rake assembly 34 when gripper rake assembly 34 has been lowered to bottom 46 of weedscreen 14 and all debris 18 has been cleaned from weedscreen 14 hydraulic assembly 45 is actuated and hydraulic fluid flows through hydraulic lines 44 to actuate hydraulic cylinders 43 and close gripper rake assembly 34 so that front tine assembly 36 and.