Abstract: A scraper device discharges a filter cake on a filter plate of a pressure filter, which includes fixed bracket and movable carriage parts, and hoist rack and scraper parts. The fixed bracket part has transverse and vertical bracket beams. The movable carriage part has a movable carriage base, bottom and upper transverse beams, and an upright column. The hoist rack part, mounted in the movable carriage, includes upper and bottom transverse beams of the hoist rack, which are connected by an upright column of the hoist rack. A hoist slide plate connects with a connection plate of the hoist rack, and the hoist slide plate is movably connected to a chain. Scrapers are placed at both sides of the filter plate, and position limiters are placed in the movable carriage part and the hoist rack part. The position limiters are connected to clamping and unclamping proximity switches.