Differential Speed Indicators.
Year: 1893

page_text: Date of Application, 9th Nov., 1893
Complete Specification Left, 7th Aug., 1894-Accepted, 29th Sept., 1894
PROVISIONAL SPECIFICATION.
Differential Speed Indicators.
I, SIDNEY ALEXANDER HOUGHTON of 2 Broadfield Villas Colwall in the
County of Hereford, Engineer in the Royal Navy do hereby declare the nature of
this invention to be as follows:-
My invention has for its object the indication of the difference of the number of
revolutions of marine engines in twin screw ships, but it is also applicable to all
kinds of engines or machines whose relative speed it is desired to ascertain.
A differential speed indicator according to my invention consists essentially of
three bevel cog wheels, two of which revolve independently about the same axis,
called hereafter the primary axis, and a third wheel gearing into both the aforesaid
wheels and revolving round an axis at right angles to the primary axis. This
second axis is also capable of revolving round the first axis, carrying the aforesaid
third wheel with it.
The two first mentioned wheels are caused to revolve in opposite directions by
the respective engines, at the same number of revolutions or at a certain ratio of
that number, then if both engines are moving at the same speed the axis carrying
the third wheel will remain stationary, but if one engine moves faster than the
other it will revolve round the primary axis at a speed proportional to the difference
of speeds of the engines.
The movement of the third axis may be shewn by fixing it to the primary axis,
or by mounting it radially in a fourth wheel, (capable of revolving round the
aforesaid primary axis), which wheel will indicate either directly or by means of
gearing the difference of speeds of the engines.
If instead of one of the two first mentioned wheels, the fourth wheel be driven by
one engine, then the aforesaid first mentioned wheel will become the indicating
wheel.
Dated this Eighth day of November 1893.
SIDNEY ALEXANDER HOUGHTON.
COMPLETE SPECIFICATION.
Differential Speed Indicators.
I SIDNEY ALEXANDER HOUGHTON of Spa Lodge (late of 2 Broadfield Villas)
Colwall in the County of Hereford, Gentleman (late Engineer in the Royal Navy)
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 has for its object the indication of any difference in the number
of revolutions in a given time of the engines of twin screw ships, but it is also
applicable to all kinds of engines or machines the difference of whose speed it is
desired to ascertain.
The following is a description of a differential speed indicator according to my
invention reference being had to the accompanying sheet of drawings making a
part of this Specification and to the letters and figures marked thereon, like letters
and figures being used to denote like or corresponding parts throughout the views.

page_text: DESCRIPTION OF THE DRAWINGS.
Figure 1 is an athwartship sectional elevation through the centre line a a of an
indicator according to my invention, as fitted to a twin screw ship.
Figure 2 is a fore and aft elevation of Figure 1 with half of the front of the
casing removed.
M represents the fore and aft midship bulkhead, and for convenience of reference
the right hand side will be supposed to be the starboard and the left the port side
of the bulkhead. Also the main engines are to be understood as either both going
ahead or both astern.
Referring to Figures 1 and 2, the toothed bevel wheel B is driven by the
starboard engines by means of the worm wheel D, (keyed to a sleeve forming part
of the wheel B), the worm E, and the shaft F. This shaft (F) is rotated by the
starboard engines at the same speed or at a constant ratio of that speed by means
of cog wheels and shafting, or a ratchet and wheel, or electricity, or other suitable
⚫ means. In a similar way the toothed bevel wheel A is driven in the opposite
direction by the port engines by means of the worm wheel D, and the worm E₁.
Both the wheels A and B rotate freely round the central shaft G which revolves
independently in bearings in the casings L₁ and L, C is an intermediate toothed
bevel wheel gearing into both A and B, and revolving freely on the shaft H
perpendicular to G of which it forms part or is rigidly connected. Any rotative
movement of the shafts H and C is shewn by means of the pointers K, and K,, the
fronts of the casings L, and L, serving as dials.
The size of the worm wheels D₁, D2, or the gear for driving them is so pro-
portioned that when the engines are making the same number of revolutions the
bevel wheels A and B will revolve at the same speed, but in opposite directions.
When so proportioned and the engines are making the same number of revolutions
per minute the movement of the wheels A and B will only cause the wheel C to
rotate on a fixed axis, and the shaft G and pointers K₁ K2, will remain stationary,
but if the speed of one engine be greater than the other the wheel C (and con-
sequently the pointers K₁ K,) will rotate round the central axis G at a speed
proportional to the difference of speed of the engines. Consequently the difference
in the number of revolutions of the engines in a given time may be ascertained by
noting the number of divisions of the dials the pointers have moved over in the
same time.
Two intermediate bevel wheels on opposite sides of the shaft G may be used
instead of only one (C) as shewn, and such intermediate wheel or wheels may be
mounted on a radial shaft or shafts in a wheel rotating round or fixed to the central
shaft G between the wheels A and B.
Also if the radial shaft H whether mounted in another wheel or as shewn be
rotated by one engine round the central axis, and one of the wheels A or B by the
other, then the movement of the remaining wheel (B or A) may be made to
indicate the difference of speed of the engines.
The movement of the shaft G can be shewn directly or increased or diminished
by suitable gearing, and if the shaft H is mounted radially in another wheel, this
wheel may be made to gear into another on a secondary shaft thus shewing in an
increased or diminished manner the rotative motion of H. Although the wheels A
and B are shewn as being driven by worms and wheels yet bevel wheels or any
other suitable means may be used. Also though the indicator is shewn as being
fitted to the midship bulkhead, yet it may be fitted in any convenient position
either on a bulkhead or not. Brackets or standards may be used to support the
shafts, either with or without a casing.
It is evident that if one of the wheels, heretofore described as being driven by
one of the engines, be moved at a constant speed by clockwork or other suitable
means, then the indicator will shew whether the speed of an engine or machine
varies from a fixed number of revolutions or strokes.

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 :-
1. In a differential speed indicator, the combination of two similar toothed
bevel wheels revolving round the same axis and driven by the respective engines or
machines in opposite directions, and a third toothed bevel wheel gearing into both
the aforesaid bevel wheels and revolving on a shaft at right angles to and capable
of motion round the first mentioned axis, substantially as set forth.
2. In a differential speed indicator, the combination of two similar toothed
bevel wheels revolving round the same axis and driven by the respective engines or
machines in opposite directions, and a third toothed bevel wheel gearing into both
the aforesaid bevel wheels and revolving on a shaft mounted radially in a fourth
wheel capable of motion round the first mentioned axis, substantially as set forth.
3. In a differential speed indicator, the combination of two similar toothed
bevel wheels revolving round the same axis, one being driven by one engine or
machine, and a third toothed bevel wheel gearing into both the aforesaid bevel
wheels, and revolving round an axis perpendicular to the first mentioned axis,
round which it is rotated by the second engine or machine, substantially as set
forth.
4. In a differential speed indicator, the combination of two similar toothed
bevel wheels revolving round the same axis, one being driven by one engine or
machine, and a third toothed bevel wheel gearing into both the aforesaid bevel
wheels and revolving round a shaft mounted radially in a fourth wheel which is
rotated round the first mentioned axis by the second engine or machine, substantially
as set forth.
5. The combination with a differential speed indicator substantially as specified
of clockwork or other means for rotating one of the wheels, heretofore described as
driven by one of the engines, at a constant speed, for the purpose of shewing if the
speed of an engine or machine varies from a fixed number of revolutions or strokes
per unit of time.
6. The combination and arrangement of parts substantially as described and
illustrated in Figures 1 and 2 of the drawings hereto annexed.
Dated this 4th day of August 1894.
SIDNEY ALEXANDER HOUGHTON.