Improvements in and Connected with Indicators for Steam and other Fluid-pressure Motive-power Engines.
Year: 1887

page_text: Date of Application, 9th May, 1887
Complete Left, 7th Feb., 1888
Complete Accepted, 16th Mar., 1888
Improvements in and Connected with Indicators for Steam and
other Fluid-pressure Motive-power Engines.
I JOHN BUCHANAN, of 75 Robertson Street, Glasgow, Lanarkshire, Indicator
Maker, do hereby declare the nature of my invention to be as follows:-
This invention comprises an improved ratchet spring detent device or arrangement
for being fitted to Engine indicators for retaining or preventing the rotation of the
spring cylinder carrying the card or paper on which the indicating diagram is to be
taken, until all is ready for taking the diagram when it may be released, and for
stopping its motion while taking off and putting on fresh cards, and instantly setting
it on again; and which will be more simple and convenient and not so liable to burn
the fingers as the detents heretofore fitted on such indicators.
The nature and novelty of the improvements consist as follows:-
In forming or mounting the usual spur ratchet wheel at the lower edge of the
rotating spring barrel below the cord groove for actuating it against the power of the
spring within, in place of above this groove as heretofore; and then in mounting a
ratchet pawl vertically on a joint at the lower front edge of the disc bracket carrying
the barrel and its spindle, so that the upper end on which the gripping pawl is formed
may either be tilted into or out of action with the teeth of the ratchet wheel, on its
horizontal joint pin, by the action of a light curved moving spring lever acting on
the back of the pawl, preferably working within a curved groove formed for it on the
back or outer face of the pawl, the one end of the spring lever oscillating on a joint
pin, secured by a washer and circular bearing on the. front edge of the bracket
carrying the barrel and pawl, preferably in a horizontal plane with the joint pin of
the pawi, and with the small handle at the free end of the spring lever beyond the
pawl and slot in it, in which the spring works and acts. This narrow slot is preferably
formed of a curved or cam shape on the back of the pawl, in the vertical direction,
considerably above and below its fulcrum, so that when the free end of the spring

page_text: lever is pressed up in the groove above the fulcrum, it retains the pawl in action in
the teeth of the ratchet wheel, and yet allows and the barrel to turn when actuated
by its motive cord attached to the moving part of the engine, and holds it there,
preventing it turning in the backward direction by the internal spring of the barrel.
But when the spring lever is pressed down in the groove of the pawl to its lower end
below the fulcrum, it immediately takes the pawl at the other end out of action with
the ratchet teeth of the wheel and barrel, and allows the barrel to be turned in the
backward direction by the power of its internal spring, thus leaving the barrel free to
act in both directions while taking the diagram on the card.
Dated this 9th love of Nov 1887

page_text: Improvements in and Connected with Indicators for Steam and
other Fluid-pressure Motive-power Engines.
I, JOHN BUCHANAN, of 75 Robertson Street, Glasgow, Lanarkshire, Indicator
Maker, do hereby declare the nature of my Invention and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement in writing, reference being had to the accompanying Sheet of
Drawings, and to the letters and figures marked thereon, that is to say:
My said Invention comprises an improved ratchet spring detent device, or arrange-
ment for being fitted to engine indicators for retaining or preventing the rotation of
the spring cylinder carrying the card or paper on which the indicating diagram is to
be taken, until all is ready for taking the diagram when it may be released, and for
stopping its motion while taking off and putting on fresh cards, and instantly setting
it on again without detaching the moving cord, and which will be more simple and
convenient and not so liable to burn the fingers as the detents heretofore fitted on
such indicators. And in order that the nature and novelty of my said invention and
the manner of performing or carrying the same into effect or practice may be
properly understood, I have hereunto appended an explanatory Sheet of Drawings in
which the same reference letters are used to indicate corresponding parts in all the
figures where shown. Figures 1 and 2 show a front and side elevation respectively
of a Richard's indicator with my improvements as applied thereto, and with the
ratchet pawl as out of action and indicator with the paper card indicated in dotted
lines as in the act of going to take a Diagram. Figures 3 and 4 show a corresponding
front and edge view respectively of the spring barrel with the improved ratchet
pawl lever as in action holding the barrel from turning in its extreme drawn up
position, ready for taking off the diagram card, and putting on a fresh one. Referring
to these Drawings.-The nature and novelty of the improvements consist as follows
In forming or mounting the usual spur ratchet wheel A, at the lower disc of the
rotating spring barrel B, below the cord groove B', for actuating it against the power
of the spring within, in place of above this groove B' as heretofore, or a part only of
this wheel A, need have ratchet teeth a formed in it; and then in mounting a
ratchet pawl lever a vertically on a joint a², at the lower front edge of the fixed disc
bracket C, carrying the barrel B, and its spindle, so that the upper end of the
gripping pawl a may either be tilted into or out of action with the teeth of the
ratchet wheel A, on its horizontal joint pin a' by the action of a light curved moving
spring lever b, acting on the back of the pawl lever a', and preferably working within
a curved groove a³ formed for it on the back or outer face of the pawl a¹, the one end
of the spring lever boscillating on a joint pin 6 secured by a washer and circular
bearing on the front edge of the bracket C carrying the barrel B and pawl a',
preferably in a horizontal plane with the joint pin a², of the pawl, and with the small
knob or handle on the free end of the spring lever b, beyond the pawl a' and

page_text: slot as in it, in which the spring works and acts. This narrow slot a³ is preferably
formed of a slightly curved or cam shape on the back of the pawl a¹ in the vertical
direction considerably above and below its fulcrum a² so that when the free end of
the spring lever b, is pressed up in the groove above the fulcrum a', it retains the
pawl a¹ in action in the teeth a of the ratchet wheel A, as shown in this position in
Figures 3 and 4, and yet allows it and the barrel B, to turn in the forward or pulling
direction when actuated by its motive cord B, attached to the moving part of the
engine, and holds it there to its extreme pulled up position, preventing it turning in
the backward direction by the power of the internal spring of the barrel B. But
when the spring lever b is pressed down in the groove a² of the pawl a¹ to its lower
end below the fulcrum a² as seen in this position in Figures 1 and 2, it immediately
takes the pawl a' at the other end out of action with the ratchet teeth a of the wheel A,
and barrel B, and allows the barrel B, to be turned in the backward direction by the
power of its internal spring, thus leaving the barrel B, free to act in both directions
while taking the diagram on the card. And when, the spring is turned to put the
pawl a¹, into action as before explained, it immediately holds the barrel B, with the
card on it, and. allows the card then taken to be removed and a fresh one put on, all
without releasing the cord; and when the pawl a' is taken out of action the barrel B
again acts ready for turning and applying the tracing point to take the diagram on
a new card all without any slackness on the cord b*.
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 :-
First. In Indicators for taking the diagrams of steam engines the construction and
application of ratchet teeth on the lower disc part of the spring cylinder having a
vertical reverse oscillating or lateral acting pawl and spring lever over and below the
ratchet wheel, all substantially as and for the purposes herein described, in reference
to and shown on the accompanying Drawings.
Second. In indicators for taking the diagrams of steam engines the use of a lateral
acting pawl with spring lever for both moving and retaining it in its engaged and
disengaged positions, substantially as and for the purposes herein described in
reference to and shown in the accompanying Drawings.
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7000