Apparatus for Checking the Speed of a Marine or other Engine.
Year: 1898

page_text: Date of Application, 29th Sept., 1898-Accepted, 4th Mar., 1899
COMPLETE SPECIFICATION.
Apparatus for Checking the Speed of a Marine or other Engine.
I, ERIK LUND, of s.s. "Erling Jarl," Bergen, in the Kingdom of Norway, Ship-
master, 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:-
The object of this invention is an apparatus which, through the medium of an
electric circuit or in another suitable way, automatically registers revolutions of
a steam or other engine upon a device which is graduated in seconds, minutes
and hours, like an ordinary watch, so that the number of revolutions of the engine
is transformed into units analogous to the time-units of an ordinary watch. For
example, if an engine makes 100 revolutions a minute, this is transferred to the
registering apparatus, of which one hand--the second hand-makes one revolution
whilst the engine is making 100 and the other hands-the minute and hour hands-
are connected by suitable gear to the first hand, so that they record the revolutions
not as a sum, but in units corresponding to those of the minute and hour hands
of an ordinary watch.
As long, therefore, as the engine runs normally, that is to say, as long as it has
a speed for example of 100 revolutions a minute, the hands of the apparatus will
indicate the same time as that of an ordinary watch.
If the number of revolutions of the engine, however, varies above or below the
normal, the apparatus will, after a certain period for instance that of one watch,
show a time in front of or behind the real time.
To enable the invention to be fully understood I will describe it by reference to
the accompanying drawing, which indicates diagrammatically an apparatus con-
structed according to the invention.
The figure shews apparatus having three dials provided with hands or index
fingers one of which indicates hours, another minutes and the third seconds. The
seconds hand is adapted to be operated by any suitable mechanism from any suit-
able moving part of the engine and the minute and hour hands are adapted to be
operated from the second spindle by suitable ordinary gear.
To operate the clockwork mechanism from the engine I may employ an electrical
arrangement of which the following is a description:
-
a is an electromagnet and the armature thereof, the said armature being
pivoted at c d is a pawl which is pivoted to the armature 6 and e is a spring by
means of which the said pawl d is held in engagement with the teeth of the ratchet
wheel keyed to a spindle c. upon which the seconds hand is fitted and which
serves as the axis for the armature b. h is a battery which supplies current to the
circuit in which the electromagnet a is connected and g and are two spring ter-
minals which are normally held out of contact with one another so that the circuit
is normally broken. In order that the circuit be closed once for each revolution
of the crank-shaft of the engine I provide means whereby the spring g is operated
at each stroke by a part of the engine which reciprocates in accordance with the
rotation of the crank-shaft so that the said contact g is pressed against the contact i
once for each revolution of the said crank-shaft and the circuit closed whereby the

page_text: electromagnet a is energised and attracts the armature 6 thereby causing the pawl d
to turn the ratchet wheelf through a distance equal to the length of a tooth. The
contact g, being then broken the current is interrupted and the armature b is
withdrawn from the magnet a by the spring k so as to bring the pawl d into
engagement with another tooth of the ratchet wheel f.
The electromagnet, armature and the indicating apparatus are advantageously
arranged in a box or case adapted to be placed upon the bridge of the vessel,
the seconds, minute and hour dials and hands being fitted to the outside of the said
case or otherwise so arranged that their indications can be read off at a glance.
I am aware that speed counters are employed by means of which a normal speed,
of 100 revolutions per minute for example, will always register 100 if the normal
velocity of rotation is constant but if the said speed varies the speed counter shews
for example 97, 98, 99, 100, 101, 102 and so on at different instants so that it is
a difficult matter for the officer in charge to collect these various indications so as
to form a reliable result. My apparatus obviates this difficulty.
To compensate for the variations in the slip of the propeller at different speeds
a table of variations in slip for different speeds can be drawn up so that allowance
may be made therefor...
Although I have shewn my apparatus arranged to be operated through the
medium of an electromagnet it will be obvious that it can be controlled by other
suitable known means and that a disconnecting device can be employed whereby
the apparatus can be set so that the time indicated by it corresponds with the
real time.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
1. Apparatus for checking the speed of a marine or other engine, such apparatus
comprising watch or clockwork mechanism operated from a crank shaft or another
suitable moving part of the engine through the medium of an electric or other
suitable device in such a manner that the hands of the watch or clock mechanism
indicate the number of revolutions made by the engine in units analogous to the
time-units of an ordinary watch or clock, substantially as, and for the purpose,
herein before described.
2. In apparatus of the kind described in Claim 1 the combination with the
watch or clock mechanism of an electromagnet which is connected up in a circuit
adapted to be made and broken by a contact operated at each revolution of the
engine, the electromagnet having a pivoted armature which is attracted by the
magnet once for each revolution of the engine and is provided with a pawl adapted
to actuate a ratchet wheel the rotation of which operates the clockwork mechanism,
substantially as herein before described.
Dated this 29th day of September 1898.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.