Improvements in Steam Engine Indicators.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Steam Engine Indicators.
1, JOHN CLARK DOBBIE, of 45, Clyde Place, in the City of Glasgow, Nautical
Instrument Maker, do hereby declare the nature of this invention to be as
follows:
This invention relates to steam engine indicators of the type described in the
Specification of Letters Patent No. 16258 of 1887, and Application No. 11026
of 1898, in my name, and it has for its object the further improvement of certain
details or parts of the indicator.
Referring to the card drum of the indicator, the card clip of this drum is
under the present invention hinged at its lower end close to the pulley or cord
bed, and retained against the drum by means of a slotted spring piece attached
to the upper surface of the drum and engaging the free ends of the clip arms.
The hinge may be so arranged that the two arms of the clip (which are hinged
slightly apart) when opened out may be disposed either radially to the card
dium or parallel to each other. The card drum is further provided with a stop
near its lower end diametrically opposite to the clip, which stop serves to prevent
the card being placed other than at the proper height upon the drum with
respect to the indicator pencil.
Referring to the swivelling bracket which carries the pencil arm and parallel
motion a lug is formed on the jaw which carries the vertical lever of the parallel
motion and this lug has a screw threaded hole into which the usual adjustable
screw pin is entered, the pin abutting against a stop on the framing directly in
front of the indicator.
Referring to the main framing the open bracket described in the Application
No. 11026 of 1898 is dispensed with and a bracket of approximately T shape is
carried up from the steam cylinder, one side of the horizontal portion of the
bracket overhanging said cylinder. An orifice is formed in that end of the
bracket which overhangs the cylinder of sufficient diameter to permit of the
removal or replacing of the piston, piston rod and spring, the cylinder cover
which has the gland formed on it is made in two portions which are first separated
to permit of this, the portions being hinged to the cylinder opposite the vertical
portion of the T shaped bracket. The free ends of the cover each enter opposite
sides of a recess in the vertical portion of the bracket which recess has its upper
surface inclined towards its mid point so as to have a wedge like action upon the
cover and thus bring it down tight upon the cylinder end. The gland which is
screw threaded has a nut strung upon it in order to draw the two portions of the
cover tightly together. The piston rod is made in two portions in the manner
described with reference to the last mentioned application and the spring is
inserted and carried on the piston rods as herein stated.
As a means of strengthening the T shaped bracket it may have a jointed
vertical arm opposite the fixed vertical portion, the joint being formed at the
lower end between lugs on the cylinder and the upper end being secured by a

page_text: removable pin passing through lugs on the horizontal portion of the T shaped
bracket; the jointed part permitting of the removal of the spring when necessary.
Or instead of a removable pin for fastening the jointed arm, a set pin may be
carried in an eye at the upper end of said arm, the pin being screw-threaded and
adapted to engage a screw-threaded hole in the stationary † shaped bracket, or
the set pin may be otherwise secured to the bracket.
A detent is provided in connection with the card drum and consists of a loop-
shaped piece centred on the main framing under the pulley or cord bed, this
looped piece having a series of teeth on its inner periphery which is caused to
engage with a spring pawl centred on the under side of the pulley or cord bed,
when it is desired to place a new card on the drum, the looped part being
normally held out of action by means of a spring.
Dated this 95th day of Ail 1900.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
62, Saint Vincent Street, Glasgow,
Agent for the Applicant.
I, JOHN CLARK DOBBIE, of 45, Clyde Place, in the City of Glasgow, Nautical
Instrument Maker, 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:―
This invention relates to steam engine indicators of the type described in the
Specification of Letters Patent No. 16258 of 1887, and Application No. 11026
of 1898, in my name, and it has for its object the further improvement of certain
details or parts of the indicator.
The invention is illustrated by the accompanying drawings, Fig. 1 being an
elevation partly in section and Fig. 2 a plan of an indicator having the improve-
ments applied thereto. Fig. 3 is a detail hereinafter referred to.
Referring to the card drum A of the indicator, the card clip B of this drum is
under the present invention hinged at its lower end B close to the pulley or
cord bed C, and retained against the drum by means of a slotted spring piece D
attached to the upper surface of the drum A and engaging the free ends of the
clip arms. The hinge B may be so arranged that the two arms of the clip
(which are hinged slightly apart) when opened out may be disposed either
radially to the card drum A or parallel to each other, as illustrated particularly
at Fig. 2, which shows the clip arms opened outwards. The card drum A is
further provided with a stop A¹ near its lower end diametrically opposite to the
clip B, which stop A¹ serves to prevent the card being placed other than at the
proper height upon the drum A with respect to the indicator pencil E.
Referring to the swivelling bracket which carries the pencil arm E¹ and
parallel motion a lug F is formed on the jaw F2 which carries the vertical lever
G of the parallel motion and this lug F has a screw threaded hole into which the
usual adjustable screw pin H is entered, the pin H abutting against a stop I¹ on
the framing I directly in front of the indicator.
Referring to the main framing I the open bracket described in the Application
No. 11026 of 1898 is dispensed with and a bracket of approximately shape is
carried up from the steam cylinder J, one end of the horizontal portion of the

page_text: bracket overhanging said cylinder, and the other end carrying the card drum A.
An orifice I is formed in that end of the bracket I which overhangs the cylinder J
of sufficient diameter to permit of the removal or replacing of the piston K,
piston rod K and spring L. The cylinder cover which has the gland N
formed on it is made in two portions which are first separated to permit of the
removal of the piston, piston rod and spring, the portions constituting the
cover M being hinged to the cylinder J opposite the vertical portion of the
Tshaped bracket I. The free ends of the two portions of the cover each enter
opposite sides of a recess I³ in the vertical portion of the bracket I which
recess I has its upper surface inclined towards its mid point so as to have a
wedge like action upon the cover M and thus bring it down tight upon the
cylinder end. The gland N which is screw threaded has a nut strung upon it
in order to draw the two portions of the cover M tightly together. The piston
rod may or may not be inade in two portions in the manner described with
reference to the last mentioned application and the spring is inserted and carried
on the piston rod as therein stated.
As a means of strengthening the T shaped bracket I it may have a jointed
vertical arm opposite the fixed vertical portion, the joint being formed at the
lower end between lugs on the cylinder and the upper end being secured by
a removable pin passing through lugs on the horizontal portion of the T shaped
bracket I; the jointed part permitting of the removal of the spring when
necessary. Or instead of a removable pin for fastening the jointed arm, a set
pin may be carried in an eye at the upper end of said arm, the pin being screw-
threaded and adapted to engage a screw-threaded hole in the stationary shaped
bracket I, or the set pin may be otherwise secured to the bracket.
A detent shown at Fig. 3, is provided in connection with the card drum A and
consists of a loop-shaped piece P centred at R on the main framing I under the
pulley or cord bed C this looped piece P having a series of teeth on its inner
periphery which is caused to engage with a spring pawl Q centred on the under
side of the pulley or cord bed C when it is desired to place a new card on the
drum A, the looped part being normally held out of action by means of a spring.
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:-
1. A steam engine indicator the several parts of which are constructed and
arranged, substantally as described.
2. In a steam engine indicator the combination, with the usual card drum, of a
card clip, the arms of which are hinged to the lower end of the drum to permit of
the placing of the card, said arms being retained against the drum by means of
a slotted spring piece, substantially as described.
3. In a steam engine indicator the combination of a T shaped bracket constituting
the main framing and a cover for the steam cylinder made in two portions hinged to
said cylinder, the said cover being pressed tightly down upon the cylinder end by
a double incline on the main framing, and being locked by a nut engaging the
two parts of the gland, substantially as described.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents,
62. Saint Vincent Street, Glasgow,
Agent for the Applicant.