Open top hopper window and frame

An open top hopper window comprising:

• a hopper window including at least one locking system disposed at sides of the hopper window, the locking system comprising
• an elongated member having a half endless screw disposed about a surface of the elongated member, the half endless screw comprising helical threads,
• a gear having a gear axis hole and helical teeth separated by tooth spaces, the gear configured to rotate about a gear axis perpendicular to a member axis extending along a length of the elongated member, and
• a handle joined to the elongated member;
• and
• a frame joined to the hopper window, the frame having
• a top edge,
• a bottom edge,
• a left side, and
• a right side,
• inner parts of the left and right sides of the frame each having a guide groove disposed at the bottom edge and a frame hole defined in the frame above the guide groove,
• wherein the hopper window is joined to the frame by two bolts disposed on outer bottom edges of the hopper window sliding into the guide grooves and through two arms linking the holes in the frame with two holes in the hopper window on outer sides of the hopper window,
• the two arms are two bars each having
• at one end, a first bolt configured to fit into the frame hole, and
• at another end, a second bolt disposed opposite to the first bolt and configured to fit into the hole at the hopper window, the second bolt being configured to extend into the gear axis hole along a direction of the gear axis for the gear to rotate about thereto, and
• the elongated member is configured to be turned by an operational rotation of the handle to lock and unlock the half endless screw into engagement with and disengagement from the teeth of the gear.