A NEW OR IMPROVED TUBE STOPPER FOR THE TUBES OF STEAM BOILERS
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by John Robinson at the Office of the
Commissioners of Patents on the 27th April 1876.
JOHN ROBINSON, of Dovecot Terrace, High Southwick, near Sunderland, in the
County of Durham. "A NEW OR IMPROVED TUBE STOPPER FOR THE TUBES OF
STEAM BOILERS."
This Invention relates to an instrument to be used for stopping up the ends of
the small tubes of tubular boilers without drawing the fires. It consists of a centre
bolt or stay somewhat longer than the tube required to be stopped. One end of
this bolt is made with a round head and conical neck, the diameter of the head
being slightly smaller than that of the tube inside, and the other end is screwed.
and provided with an ordinary button and nut. A cottar hole fitted with a cottar
is made in this bolt somewhat near its conical end; a washer capable of sliding on
the bolt is placed between this cottar and the conical end, and both the washer and
cottar are made of such a size as to pass without difficulty into the tube required
to be stopped. To this moveable washer a number of strips or straight pieces of
iron or steel or other suitable material arc attached, these strips lying nearly longi-
tudinal or lengthwise with the centre bolt, being slightly inclined to it; their loose
ends, which are towards the conical neck, but which do not quite reach up to it
when the washer is against the cottar are flanged outwards so as to form a seg-
mental ring or collar round the centre bolt. The edges of the segments of the ring
overlap each other, and are bevelled so that when in their normal position the joints of
the segments are flush, and the segmental ring is of an even thickness, the plane of
either face of the ring being at right angles to the centre bolt. One half of the
strips are rivetted to the washer, but every alternate strip is allowed to have a
little play in the direction of its length. Every alternate segment of the ring can
thus be put slightly out of the plane of the ring, so as to clear the other segments,
and thus the whole of the segments may be compressed, and the diameter of the
ring, which is at first larger made smaller than the inside diameter of the tube.
thin washer of asbestos or other suitable material is placed on either side of the ring
and a third on the button on the other end of the stay.
A
When a tube is to be stopped the segmental ring is compressed and drawn down
to centre bolt until the washer is against the cottar. The centre bolt and com-
pressed ring are then passed into the tube from the smoke box end, and pushed
.

page_text: forward through the tube, the cottar preventing the washer and therefore the
segmental ring from slipping on the rod.
When the segmental ring has passed the further end of the tube the ring springs
out, and when the rod is drawn back the ring is held firmly between the bolt head
and the tube plate, whilst the coned neck prevents the possibility of the ring being
compressed. The nut on the near end of the centre bolt is then screwed up against
the button; the ends of the tube are then effectually stopped, the surfaces between
the head of the bolt and the segmental ring, the segmental ring and back tube plate
and between the front tube plate and button being rendered perfectly tight by the
packing or washers of asbestos placed between them.