Multi-cylinder pump for heavy flowable materials

A sludge pump, comprising:

• a casing for receiving sludge;
• a pump body with a deck surface, said deck surface extending in said casing;
• a pair of cylinder bores in said pump body opening at said deck surface;
• a piston reciprocating in each cylinder bore in charging and discharging strokes;
• a valve conduit comprising a port for transferring sludge between said valve conduit and said cylinder bores, said valve conduit being pivotable about an axis to cause a translational movement of said port across said deck surface between two operative positions, in each operative position said port is in register with a respective cylinder bore;
• a drive shaft extending along said axis and being mounted to said valve conduit;
• means rotating said drive shaft for producing the movement of said port across said deck surface;
• and
• a fluid operated piston-cylinder assembly acting on said drive shaft for producing a force thereon with a direction generally coicident with said axis for urging said valve conduit toward said pump body for creating a sealing engagement between said port and said deck surface.