Image Number 4 for United States Patent #4415314.
A fluid pump for location within a reservoir and which is operable with rise and fall of liquid within the reservoir. The pump comprises a tube of a resiliently deformable material, an abutment surface which is engaged by the tube and a float device which is mounted to the tube. Liquid entering the reservoir causes upward movement of the float device and such movement of the float device causes increasing engagement between the tube and the abutment surface. The increasing engagement between the tube and the abutment surface causes the tube to deform resiliently and a localized reduction in the contained volume of the tube is thereby effected to cause expulsion of fluid from the tube. Conversely, as the liquid level falls in the reservoir, the float device moves downwardly to reduce the extent of engagement between the tube and the abutment surface, so that the tube tends to resume its initial contained volume.