Shuangjia pump is widely used in the municipal, industrial, mine and other sewage treatment projects, with favorable conveying capacity for dewatered sludge, thickened sludge paste liquid, retardant liquid and other media. Especially, the liquid feed pump for filter press shows superior performance advantages, solving many technical problems in the industry, such as rapid stator wear, complicated maintenance of machine seal, reverse operation, fragile cardan joint, etc. At the same time, many patents have been applied for the pump.