AN IMPROVED ATMOSPHERIC BRAKE OR BREAK
Year: 1863

page_text: PROVISIONAL SPECIFICATION left by Michel Siégrist at the Office of
the Commissioners of Patents, with his Petition, on the 18th February
1863.
I, MICHEL SIEGRIST, of Ewell, in the County of Surrey, Gentleman, do
hereby declare the nature of the said Invention for "AN IMPROVED ATMOSPHERIC
BRAKE OR BREAK," to be as follows:-
The power relied on to bring into action my atmospheric brake is that of
rarified air or vacuum. Two metal bars are fixed horizontally under the
framing of a railway carriage (say about thirty inches apart), on the ends of
these bars which are nearest the wheels are hinged levers, one end of which
lever bears the brake block, and the other is so placed that it may be acted
upon as hereafter set forth. Behind the levers is a flat bar (fixed) and at
about a foot distance another flat bar (moveable). Between these bars is a
drum or box composed of two heads or solid framings, each being screwed to
one of the flat bars and connected to each other by any air-tight flexible
material. The moveable head is furnished at its inner centre with a rod or
tube, which passes through the fixed head, and acts (as piston) on the ends of
the levers not holding the brake blocks before mentioned. Springs are placed
on the moveable head to cause the drum or box to expand after use. On the
tender (which should be constructed somewhat longer than are those in ordinary
use) is fixed a cylinder or tube communicating with a pneumatic engine or
pump, and with the compartments hereafter described; also at the end of the
tender is placed a metal box with double compartment; one compartment of

page_text: about four cubic yards, and the other of about eight cubic yards capacity.
Separate pipes furnished with stop-cock's near the cylinder or tube connect the
box of two compartments with the cylinder; other pipes similarly furnished
with stop-cocks near the cylinder serve to connect the tube or cylinder with
the drums under the carriages, vulcanized india-rubber or other elastic material
being used to couple the ends of pipes when carriages are being placed to form
a train. The air in the two compartments being rarified, and as nearly as
possible a vacuum produced communication with the pneumatic machine is
shut off by means of a stop-cock, and the apparatus is ready for action. On
approaching a station the stoker opens the cock of the pipe communicating with
the drums, and the air therein contained rushes into the smaller compartment
and causes the pistons of these drums (or boxes) to act upon the ends of the
levers next them, and so press the brake blocks on to the wheels of all the
carriages composing the train, except those of the engine and the tender. In
case of apprehended collision, the communication with the larger compartment
is opened, and the braking power is not only greatly increased on the carriage
wheels, but is applied to the brake blocks on the driving wheels of the engine.
Two of the drums or boxes with their adjuncts may be placed under each
carriage, the size of the drums being about one cubic foot. In ordinary
braking, the collapse of these drums will scarcely exceed two inches. Indexes
will serve to shew the state of vacuum in the compartments. All the pneu-
matic apparatus as well as the vacuum box, may be placed in the luggage van
next the tender, with separate communication from the compartments to the
tender, and the braking worked from the tender.