Summing valve arrangement

Claim 2

A horsepower controlling system, said system comprising in combination: a plurality of variable displacement pumps driven by a common prime mover and including pressure responsive means for varying the displacement of said pump, a source of actuating pressure comprising a fixed displacement pump driven by said common prime mover for actuating said pressure responsive means; a valve having a bore in communication with said source of actuating pressure and with said pressure responsive means; a spool disposed in said bore and operative to control said communication; means comprising a plurality of individual pistons communicating with and responsive to the sum of the outputs of said variable displacement pumps to actuate said valve to thereby communicate said actuating pressure with said actuating means to alter the displacement of said pumps; and, a piston selectively communicating with said source of actuating pressure and operatively connected to said valve to oppose said plurality of individual pistons.

Claim 3

The invention of claim 1 wherein said source of actuating pressure is a fixed displacement pump driven by said common prime mover.

Claim 4

The combination of claim 1 comprising a pressure reducing valve operatively connected between said valve actuating means and the output of said variable displacement pump.

Claim 5

The horsepower Controlling system of claim 1 wherein said source is the one of said variable displacement pumps having the highest pressure output.

Claim 6

A horsepower controlling system for controlling the horsepower output of a plurality of variable displacement pumps driven by a single prime mover, said system comprising: a source of control pressure comprising a fixed displacement pump driven by said prime mover for controlling the displacement of said pumps; a valve having a pre-determined bias to a cut-off position for controlling the communication of said control pressure with said pump displacement means; means responsive to the sum of the output pressure of said pumps for moving said valve to control said control pressure; pressure responsive means responsive to the output of said variable displacement pumps to bias said valve in a direction to provide open communication between said source of control pressure and said pump displacement controlling means, said pressure responsive means comprising a plurality of pistons disposed in cylinders, said cylinders being in communication with the output of said pumps at one end of said piston; and, the other end of said piston in operative engagement with said valve means.

Claim 7

A horsepower controlling system for controlling the horsepower output of a plurality of variable displacement pumps driven by a single prime mover, said system comprising: a source of control pressure comprising a fixed displacement pump driven by said prime mover for controlling the displacement of said pumps; a valve having a pre-determined bias to a cut-off position for controlling the communication of said control pressure with said pump displacement means; means responsive to the sum of the output pressure of said pumps for moving said valve to control said control pressure; pressure responsive means responsive to the output of said variable displacement pumps to bias said valve in a direction to provide open communication between said source of control pressure and said pump displacement controlling means, said pressure responsive means comprising a plurality of pistons disposed in cylinders, said cylinders being in communication with the output of said pumps at one end of said piston; and, the other end of said piston in operative engagement with said valve means.

Claim 8

The system of claim 5 comprising: a piston disposed at the opposite end of said valve from said plurality of pistons; and, said piston being responsive to communicate one end of said piston with said source of control pressure when said valve is positioned for open communication, whereby said piston urges said valve toward a non-communicating position.

Claim 9

The system of claim 6 wherein said spool includes means to provide communication between said pump displacement controlling means and a sump.