PURPOSE: To reduce the number of parts and make manufacturing costs lower by a method wherein a filter plate feed pawl and a block stopping pawl provided on a filter plate moving block movable parallel to a side plate are made movable into a raised position under the force of gravity.

CONSTITUTION: A filter plate moving block 10 movable parallel to a side plate 2 under a hanger 8 for a series of filter plates 7 is provided with a filter plate feed pawl 11 and a block stopping pawl 12 arranged parallel to each other and mounted together freely rotatably on a pivot 13 at their nearly central parts. The pawl 11 is provided at the front end thereof with an upwardly projecting engaging part 14 having a sloping cam face 15 and a vertical engaging face 16 and a counter weight 17 at the rear end thereof. The pawl 11 is supported by an engaging pin 19 mounted to the block 10 near the counter weight 17 at the rear end thereof, the pawl 12 is provided at the lower end thereof with a block stopping raised part 18 projecting forwardly, the engaging part 14 of the pawl 11 and the upper edge 12a of the pawl 12 are positioned extending higher than the lower end of the hanger 8 and at least either of the counter weight 17 of the pawl 11 and the raised part 18 of the pawl 12 is provided with an engageably extended part 17a or 18a for lifting the counter weight.