Mobile constant pressure pumping assembly

An assembly for pumping liquid at a constant, preselected outlet pressure comprising;

• (a) an engine;
• (b) a variable displacement hydraulic pump having a swash plate, said pump driven by said engine;
• (c) a servo control cylinder and control valve assembly for controlling a swash plate angle of said variable displacement hydraulic pump;
• (d) a fixed displacement hydraulic motor in fluid communication with and driven by said variable displacement hydraulic pump, said fixed displacement hydraulic motor including a motor speed transducer;
• (e) a liquid pump with intake and outlet for liquid, said liquid pump driven by said fixed displacement hydraulic motor, said liquid pump including a liquid outlet pressure transducer;
• and
• (f) a controller device operatively connected to said servo control cylinder and control valve assembly for modulating the swash plate angle of said variable displacement hydraulic pump and hydraulic output thereof, said controller in communication with said liquid pump outlet pressure transducer, and in communication with said fixed displacement hydraulic motor speed transducer, said controller thereby modulating the hydraulic output of said variable displacement hydraulic pump to maintain a constant, preselected liquid pump outlet pressure that is independent of engine speed.

A system for independently pumping liquid at a plurality of constant preselected outlet pressures comprising;

• (a) an engine;
• (b) first and second liquid pumping assemblies, each assembly including
• (i) a variable displacement hydraulic pump driven by said engine;
• (ii) a fixed displacement hydraulic motor in fluid communication with and driven by said variable displacement hydraulic pump, said fixed displacement hydraulic motor including a motor speed transducer;
• (iii) a liquid pump with intake and outlet for liquid, said liquid pump driven by said fixed displacement hydraulic motor, said liquid pump including a liquid outlet pressure transducer;
• and
• (c) a controller device operatively connected to said variable displacement hydraulic pump of each assembly for modulating the hydraulic outputs thereof, said controller in communication with said liquid pump outlet pressure transducer of each assembly, and in communication with said fixed displacement hydraulic motor speed transducer of each assembly, said controller thereby independently modulating the hydraulic output of said variable displacement hydraulic pump of each assembly to maintain an independent, constant, preselected liquid pump outlet pressure that is independent of engine speed for each assembly.

A mobile assembly for pumping liquid at a constant preselected outlet pressure comprising:

• (a) a fire truck vehicle having an engine.
• (b) a variable displacement hydraulic pump driven by said engine
• (c) a fixed displacement hydraulic motor in fluid communication with and driven by said variable displacement hydraulic pump, said fixed displacement hydraulic motor including a motor speed transducer;
• (d) a liquid pump with intake and outlet for liquid, said liquid pump driven by said fixed displacement hydraulic motor, said liquid pump including a liquid outlet pressure transducer;
• and
• (e) a controller device operatively connected to said variable displacement hydraulic pump for modulating the hydraulic output thereof, the controller in communication with said liquid pump outlet pressure transducer, and in communication with said fixed displacement hydraulic motor speed transducer, said controller thereby modulating the hydraulic output of the variable displacement hydraulic pump to maintain a constant, preselected liquid pump outlet pressure that is independent of engine speed.