Improvements in Manhole Doors for Paper Machine Drying Cylinders.
Year: 1895

page_text: Date of Application, 15th June, 1895-Accepted, 20th July, 1895
COMPLETE SPECIFICATION.
Improvements in Manhole Doors for Paper Machine Drying
Cylinders.
I, JOHN WHITE, of the Firm of James Bertram and Son, Limited, Leith
Walk Foundry, in the City of Edinburgh, Engineer, do hereby declare the nature
of this invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
My invention, which relates to manhole doors for paper machine drying cylinders,
has for its object to ensure the formation of a joint that may be maintained at all
times steam and water tight. To that end the improved manhole door is so
constructed, jointed and secured that the packing ring or other jointing material
between the door and cylinder end remains unbroken by the insertion of bolts,
screws or studs around which leakage may take place, the studs, bolts or other
fastenings being fitted out with the joint and beyond the reach of the fluid under
pressure in the cylinder or other vessel.
In the accompanying drawings which illustrate my invention
Figure 1 is a vertical section and Figure 2 a plan of a manhole door applied to
a cylinder end and shewing one modification of the mode of forming the joint and
securing the door.
Figures 3 and 4 are corresponding views of a manhole door shewing another mode
of jointing and securing the door.
The manhole door or cover represented at Figures I and 2 is composed of a dished
plate A having a suitably formed rim or flange a adapted to overlap the edge of
the manhole B in the usual way. Between the rim a and a ring b or other seat
within the cylinder end C a packing ring or rings D of any well known kind is or
are interposed, and the door is drawn up tightly against its seat by means of screw
studs E passed through orifices in a bridge or holding plate F fitted to bear on the
edge of the manhole outside the cylinder. The studs E are screwed into holes
bored and tapped into, but not through, the door plate A which is swelled or made
of extra thickness at the points where these holes are made, and nuts E' are fitted
on their opposite ends; or headed screw bolts may be used and fitted in like manner
to draw up the door. By this means the joint at D is rendered absolutely tight,
and the studs, bolts or other fastenings being fitted out with the joint and so as not
to pass through the door or otherwise communicate with the steam space of the
cylinder, risk of leakage is avoided; and should leakage take place at the joint the
defect can be easily remedied. A central hole G is tapped in the door A and a
corresponding orifice H made in the bridge F in order that by temporarily
screwing a rod into the door the latter may be easily held in position whilst the
bridge is slipped over the rod and the holding nuts E¹ screwed up, after which the
rod is withdrawn.
In the modification shewn at Figures 3 and 4 the door A is made considerably
larger than the manhole, and the seat b on which the joint is formed is at such a
distance from the edge of the manhole aperture that space is left for carrying the
holding studs E (which are screwed into the door) through the cylinder end between
the aperture and the joint, and therefore clear of the steam space.
In this case the use of a bridge or clamp is or may be dispensed with the holding
nuts bearing on the outside of the cylinder end.

page_text: Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is
In paper machine drying cylinders a manhole door constructed, jointed and
secured so that the holding studs or bolts are out with the joint and clear of the
steam space, substantially as described.
Dated this 14th day of June 1895
WALLACE FAIRWEATHER,
Chartered Patent Agent,
62 St. Vincent Street, Glasgow, Agent for the Applicant.