IMPROVEMENTS IN BREAK APPARATUS WORKED BY FLUID PRESSURE
Year: 1878

page_text: LETTERS PATENT to George Westinghouse, junior, of No. 20, Southampton.
Buildings, in the County of Middlesex, for the Invention of "IMPROVEMENTS
IN BREAK APPARATUS WORKED BY FLUID PRESSURE,"
Sealed the 6th August 1878, and dated the 7th June 1878,
PROVISIONAL SPECIFICATION left by the said George Westinghouse at the
Office of the Commissioners of Patents on the 7th June 1878.
GEORGE WESTINGHOUSE, junior, of No. 20, Southampton Buildings, in the
County of Middlesex. "IMPROVEMENTS IN BREAK APPARATUS WORKED BY FLUID
PRESSURE."
It has been found that in applying breaks to the wheels of railway rolling stock,
the friction increases to a marked degree as the speed of rotation of the wheels
diminishes, and in consequence of this, the wheels are apt to skid, and the stoppage
of the train is often effected with a disagreeable jerking action.
My Invention is intended to remedy this defect in all cases where fluid pressure
acting on a piston, diaphragm, or flexible vessel operates as the force applying the
breaks, and I effect this by the use of a valve arrangement applied to the pressure
part of the apparatus so as to reduce the acting pressure by permitting leakage in
the following manner :-I provide a valve box in which is fixed a flexible dia-
phragm pressed on by an adjustable spring. From the centre of this diaphragm a
stem extends through a hole opening to the outer air. This stem has on it a collar
which acts as a valve, completely closing the hole when the diaphragm is pressed
down by the spring, and the part of the stem beyond the collar is grooved or
flattened off on one or more of its sides, such grooving or flattening being effected
in a taper form, so that according to the position which the stem occupies in the
bole, there is a greater or less area of passage through it. The operating fluid, when
it acts so as to apply the breaks, passes through, or is in free communication with
this valve box under its diaphragm, which it presses in opposition to the spring
thereby causing the stem to move in the hole (when the pressure exceeds the

page_text: minimum to which the spring is adjusted), and so permitting more or less escape of
the working fluid, and causing corresponding reduction of its pressure.
By suitably grooving or flattening the stem as above described, the reduction of
pressure can be adjusted to suit the increase of friction as the velocity diminishes.
It may be readily understood that a piston working in a cylinder or a valve may
be substituted for the diaphragm above mentioned.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Westinghouse in the Great Seal Patent Office on the 6th
December 1878.
GEORGE WESTINGHOUSE, junior, of No. 20, Southampton Buildings, in the
County of Middlesex. "IMPROVEMENTS IN BREAK APPARATUS WORKED BY FLUID
PRESSURE."
It has been found that in applying breaks to the wheels of railway rolling stock
the friction increases to a marked degree as the speed of rotation of the wheels
diminishes, and in consequence of this, the wheels are apt to skid, and the stoppage
of the train is often effected with a disagreeable jerking action.
My Invention is intended to remedy this defect in all cases where fluid pressure
acting on a piston, diaphragm, or flexible vessel operates as the force applying the
breaks, and I effect this by the use of a valve arrangement applied to the pressure
part of the apparatus, so as to reduce the acting pressure by permitting leakage.
The valve arrangement which I employ for this purpose is represented in the
accompanying Drawings, Fig. 1 being a plan of the valve box, Fig. 2 a longitudinal
section, and Fig. 3 an elevation of the valve and stem.
The valve box is connected, at its two ends A and B to the pipe which forms
a communication between the reservoir of compressed air and the break cylinder
or its equivalent, or one end, such as A of the valve box may be closed, the upper
end B being connected to the break cylinder or to a branch pipe communicating
therewith. A flexible diaphragm C of caoutchouc or such like material, is at its
centre held in a recess in the valve stem D, and at its circumference is clamped
under the cap of the valve box.
The valve stem D is at its upper part surrounded by a helical spring, the force of
which is adjusted to the maximum pressure desired in the break cylinder. The
lower part of the stem is formed as a valve E which fits the seating at the edge of a
hole through the bottom of the valve box. The stem projects into this hole, filling
it, but not tightly, and a part of the side of this stein is grooved or flattened in
taper form, as shewn at x, so as to give passage for air, varying in area according
to the position of the valve. While the pressure in the pipe A, B, and therefore in
the break cylinder with which it communicates, remains lower than that to which
the spring is adjusted, the valve remains closed, but should the pressure oxceed

page_text: that amount, then the diaphragm C is bulged upwards, as shewn in Fig. 2, the stem
D rising and opening the outlet valve, so that air escapes by the passage x, and the
pressure within the valve box becomes reduced.
By making the passage a tapered in the manner shewn in the Figures, the escape
of air and consequent reduction of pressure is rendered most rapid when the valve
begins to open, the form of the notch or flattened part x may however be varied to
suit the conditions of the break apparatus to which the escape valve is applied.
It is obvious that a piston fitting the cylindrical cavity in the upper part of the
valve box might be substituted for the disc and diaphragm.
The arrangement shown is generally to be preferred, as it admits of no leakage,
such as might take place round a piston, unless it were packed so tightly as to
interfere with the delicacy of the valve's action.
Having thus described the nature of my said Invention, and in what manner the
same is to be performed, I claim the use in break apparatus worked by fluid
pressure, of an escape valve constructed and operating in the manner and for the
purpose herein set forth.
In witness whereof, I, the said George Westinghouse, junior, have hereunto
set my hand and seal, this Fourth day of December, in the year of our
⚫Lord One thousand eight hundred and seventy-eight.
GEO. WESTINGHOUSE, JB. (L.S.)