IMPROVEMENTS IN SELF-ACTING DAMPERS FOR STEAM BOILERS, AND IN APPLIANCES CONNECTED THEREWITH
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Charles Edward Ramsbottom Isher-
wood at the Office of the Commissioners of Patents on the 25th March 1876.
CHARLES EDWARD RAMSBOTTOM ISHERWOOD, of Burton-on-Trent, in the County
of Stafford. "IMPROVEMENTS IN SELF-ACTING DAMPERS FOR STEAM BOILERS, AND
IN APPLIANCES CONNECTED THEREWITH."
This Invention relates to improvements in self-acting dampers for steam boilers,
and in appliances connected therewith, and consists in an arrangement of pistons,
one within the other, and enclosed in a graduated cylinder, so that the area of the
pistons on which the pressure of steam acts will be diminished as the steam pressure
rises by the disengaging of the pistons successively from the exterior to the inner
one, thus closing the damper, and vice versa, as the steam pressure decreases the
centre piston descends, and the area on which the steam acts is increased by the
pistons becoming attached one after the other as the steam pressure falls, and
thereby the damper is again opened.
The graduated cylinder connected to the boiler by steam pipes contains, say,
four pistons. These pistons are turned and ground so as to accurately fit the
respective portions of the cylinder. The centre piston rests its outside edge on the
inside edge of the next piston. This piston has its outside edge resting on the
next piston, which similarly rests on the external piston of the series. Three of
such pistons have directing legs. The centre piston acts on a rack which passes
out of the cylinder cover and turns a pinion which is keyed on a bar, on which is
also keyed a chain pulley. The rack is kept in contact with the pinion by a small
friction block. One end of a chain is attached to and passes over a pulley, the
opposite end being fastened to a balance weight. On this weight other adjusting
weights can be placed if necessary. The balance weight and damper are connected
by a separate chain passed over a pulley.
The action is as follows:-The proper adjusting weight being placed at the
desired elevation the steam tap is turned on, and steam admitted into the cylinder
beneath the pistons. As soon as the pressure becomes 15 lbs. to the inch the
pistons are all forced up together to the top of the first division of the cylinder;
the rack is thus forced up and turns the chain pulley, winds up the balance weight,
and closes the damper 1/, or 6 inches. On pressure increasing to 25 lbs. other pistons
are forced up to the next shoulder or second cylinder, the first piston being left at
the top of the lower cylinder. This closes the damper another 6 inches, making 1 foot
altogether closed.
At 35 lbs. the two remaining pistons are forced to next shoulder
[Price 2d.]

page_text: of, say, No. 3 cylinder, closing damper another 6 inches, these being left at the top
of their respective cylinders. At 45 lbs. pressure the last piston is sent home and
the damper closed with the exception of 3 inches for smoke. As the steam falls
the weight of the rack forces the upper piston back to that immediately below.
Should steam fall still more the two pistons come down together on to the third
and as each piston descends the damper is opened 6 inches.
At last, steam pressure being less than 15 lbs., the whole of the pistons are down
in original position and the damper again wide open under the action of its
descending balance weight.