1. IN A RAILWAY HOPPER CAR, A ROOF COVERING THE HOPPER CAR, AN ELONGATED HATCH OPENING EXTENDING LENGTHWISE LONGITUDINALLY OF THE CAR, HATCH FRAME SURRONDING THE HATCH OPENING, AN ELONGATE HATCH COVER OVER THE HATCH OPENING SLIDABLE TRANSVERSELY OF TH E CAR BETWEEN OPEN AND CLOSED POSITIONS, SAID HATCH COVER BEING SEEATED ON THE HATCH FRAME IN THE CLOSED POSITION AND BEING REMOVED FROM THE HATCH OPENING IN THE OPEN POSITION TO PERMIT ACCESS TO THE HATCH OPENING, AN ARM SECURED ADJACENT ON SIDE OF THE ELONGATE HATCH COVER AND EXTENDING LATERALLY FROM THE HATCH COVER OVER THE ADJACENT ROOF TRANSVERSELY OF THE CAR, A GUIDEWAY MOUNTED ON THE ROOF AND EXTENDING TRANSVERSELY OF THE CAR GENERALLY PARALLEL TO THE LONGITUDINAL AXIS OF THE ARM, ANTI-FRICTION MEANS ON THE EXTENDING END OF THE ARM ENGAGING THE GUIDEWAY FOR SLIDING MOVEMENT BACK AND FORTH TRANSVERSELY OF THE CAR UPON OPENING AND CLOSING OF THE COVER, AND RELEASABLE MEANS TO SECURE THE HATCH COVER IN CLOSED POSITION ONTO THE HATCH FRAME AND TO RELEASE THE HATCH COVER FROM THE HATCH FRAME FOR SLIDING MOVEMENT TRANSVERSELY OF THE CAR.