A railcar system including a railcar having a longitudinal axis and a movable cover. The movable cover including a plurality of linear bearing devices and at least one slidable hatch connected to the plurality of linear bearing devices. The slidable hatch being movable substantially normal to the longitudinal axis. The linear bearing devices each including a shaped bar and a low friction bearing having a hole therethrough. The slidable hatch has two opposite sides that define a width of the slidable hatch, the shaped bar extending substantially the full width of the slidable hatch. The shaped bar being attached to the two opposite sides of the slidable hatch. The hole through the low friction bearing being shaped to accommodate the shaped bar.