Today in 1905, US Patent 784596 A was issued, an invention of Simon Schlangen, for his “Filling Apparatus for Liquids.” There’s no Abstract per se, but this is pretty close, from the introduction:

The invention relates more particularly to apparatus for filling barrels, kegs, and similar packages with liquid, such as beer, under pressure, and has for its objects to improve the suspending means by which the closing head and filling-tube are carried, so as to insure the proper contact of the closing-head with the bung-hole or filling-hole of the barrel, keg, or package, to insure the positive opening-of the valve controlling the discharge of the filling-tube when the filling-tube has reached the limit of its descent, to improve the construction and operation of the appliance carrying the closing-head and the filling tube in connection with a fluid-pressure cylinder having therein a piston by which the cross-heads carrying the closing-head and the filling-tube are raised and lowered, to utilize the waste pressure from the filling-package in actuating’ the piston by which the closing head and the filling-tube are raised and lowered, to place the control of the pressure and the liquid under a single valve, to improve the construction and operation of the valve by which the fiI’Iid-pressure and the liquid are controlled, to improve the means by which the inflow and outflow of the pressure between the filling-tank and the to be filled package is regulated and controlled, to prevent the foaming of the liquid within the package and insure the fillingI of the package with the liquid to its full capacity without waste of liquid, to furnish an intermediate controlling means for the pressure between the one controlling-valve and the to be filled package by which the flow of the pressure in either direction will be regulated and controlled, to furnish a relief-valve by means of which the requisite amount of pressure from outside will be supplied to prevent an explosion at the withdrawal of the filling-tube, and to improve generally the construction and operation of the several parts and mechanisms which enter into the “construction of the apparatus as a whole.