IMPROVEMENTS IN BUPPERS AND DRAW ROD FITTINGS TO BE USED ON RAILWAYS
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by Håkan Steffanson at the Office
of the Commissioners of Patents, with his Petition, on the 7th
November 1868.
I, HÅKAN STEFFANSON, of Hans Place, Brompton, in the County of
Middlesex, Engineer, do hereby declaro the nature of the said Invention
for "IMPROVEMENTS IN BUPPERS AND DRAW ROD FITTINGS TO BE USED ON
RAILWAYS," to be as follows:-
This Invention relates, firstly, to improvements in the construction of
railway buffers which will enable them to resist severe pressure, and
where required modify the rebound.
Secondly. To means for increasing the clastic resisting power of draw
rods used on railways.
Instead of relying wholly or mainly as heretofore on the springs
enclosed within the buffer for resisting the blows or sudden pressure
they are destined to sustain I provide that air confined in the buffer
shall receive and sustain the pressure of the plunger, the duty of the
contained spring being mainly to return the plunger to its quiescent
position. This enables me to use springs of much lighter construction
than are at present employed, and thus a great economy is effected..

page_text: The buffer admits of various modification. Thus I cast the box or
cylinder with a hollow central corc, the upper end of which forms a
guide for a stop or retaining rod connected with the head of the plunger,
and outside this core and within the plunger the spring for keeping
the buffer extended is coiled. The plunger works through an air-tight
packing in the cylinder, and I provide in the side or end of the cylinder
a valve or valves opening inwards for admitting air to the interior to
remove any tendency to vacuum on the return of the plunger; or the
spring may be coiled within a core cast in the plunger and round a central
rod affixed to the box; or again the spring may be sustained in position
by means of a central sliding collar, and by its ends resting in cups
formed in the plunger and the closed end of the cylinder. To modify
the force of the recoil, which will be found very desirable in buffers
applied to station blocks, I provide for an escape of the compressed
air as the plunger is returning to its quiescent position. This I effect
by piercing holes in the core of the cylinder or box, or in the plunger as
the case may be. In the arrangement where the core of the cylinder
is pierced I fit within this core a cylindrical valve open at both ends,
and this valve I secure to the stop or retaining rod of the plunger. As
the plunger is thrust home the valve attached to its rod will gradually
uncover the holes in the core, and thus allow the compressed air to
escape through the holes over the edge of the valve and through its
centre to the atmosphere. The internal pressure will thereby. be relieved,
and on the return of the plunger to its quiescent position an attenuation
of the confined air will take place which will retard this back motion
of the plunger; by the pressure however of the internal spring the back
movement will be completed and fresh air will enter through the elastic
or self-closing valves to supply the deficiency. When the cored plunger
is pierced with air holes it will as it moves inwards bring those holes in
communication with the compressed air of the cylinder or box, and air
will then escape through the holes into an annular chamber of uncom-
pressed air formed in the plunger; thus the pressure within the cylinder
will be relieved and the return motion of the plunger will leave the
air that has left the cylinder free to escape.
In some cases I propose to increase the elastic resisting power of the
buffer by employing exhaustion as well as compressed air; to this end
I provide a piston or plunger and fit in an air-tight cylinder closed at
both ends. The rod of this piston carries the buffer, head and the

page_text: cylinder at its opposite ends and at opposite sides of the piston is fitted
with self-acting supply and escape valves. The supply valve is to admit
air to the cylinder when the piston or plunger is advanced under the
pressure put on the buffer head, and the escape valve is to allow any
air driven forward by the return motion of the piston to escape. By
this arrangement the piston when thrust forward is made to act as an
exhauster in addition to a compresser of air. To increase the clastic
resistance of draw rods I provide them with plungers, as described,
whereby the compression and exhaustion of air is made available in lieu
of powerful springs to produce the elastic resistance required in those
rods.