IMPROVEMENTS IN APPARATUS FOR INDICATING AND REGISTERING THE SPEED OF MACHINERY AND OTHER MOVING OBJECTS
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by Marshall Arthur Wier at the
Office of the Commissioners of Patents, with his Petition, on the
5th May 1875.
I, MARSHALL ARTHUR WIER, of No. 33, Abchurch Lane, in the
City of London, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN APPARATUS FOR INDICATING AND REGISTERING THE SPEED
OF MACHINERY AND OTHER MOVING OBJECTS," to be as follows:-
My Invention relates to that class of apparatus in which the speeds
may be ascertained at any time whilst the machinery or other object is
in motion by the simple inspection of a dial face, having a pointer or
index moving over it, or of the height of a column of fluid in a tube,
referred to a suitably graduated scale without counting or reference to a
timepiece.
In certain arrangements of this class of apparatus any suitable kind of
pump, bellows, or other air forcing apparatus, set in motion by and at a
speed proportioned to that of the machinery or other moving object of
which the speed is to be ascertained, is employed to exert a pressure
upon air in such manner as to impart motion thereby to the aforesaid

page_text: pointer, index, column of liquid, or other suitable or convenient indi-
cating medium.
Heretofore this arrangement of apparatus has been found subject to
certain defects, of which the most important are the following,-
Firstly. The air forcing instruments usually employed if of the
cylinder and piston type rapidly wear and become leaky, whereby their
effects vary from time to time.
Secondly. The valves of such instruments are arranged to close air-
tight and consequently the air is forced or pumped forward continuously,
and a special regulator or relief valve has to be applied to allow of the
escape of the excess above what is required.
And, Thirdly. The air blown forward carries along with it and deposits
on or in the indicating liquid (when such is employed) particles of dust,
which after a time clog up the apparatus and render it inoperative.
The object of my Invention is to obviate these defects, and for this
purpose I employ the following arrangements :-
A reciprocating air pump is worked directly or indirectly by the
machine or other object of which the speed is to be ascertained. The
piston of the said pump moves freely inside the cylinder without
touching the sides of the latter. The inlet and outlet valves for the said
pump are also purposely adapted so as not to be air-tight. By these
means the necessary pressure of air to act upon the indicating medium
(which is connected to the pump by a tube) is maintained, without the
necessity of a regulatór or relief valve for letting off the excess of air,
and also without the use of a packed piston, whereby much friction and
wear and tear is avoided.
In connection with the tube leading from the above mentioned air
pump to the indicating medium I in some cases employ what I call an
equalizer for neutralizing more or less the pulsations due to the
reciprocating motion of the pump piston. This equalizer may be made
in the form of a flexible bag or bellows, or of a bell or other open
mouthed chamber inverted in a cistern of liquid, after the manner of the
well known "governor" employed to regulate the pressure of gas, such
bag, bellows, or other equalizer, being 'pressed upon by a weight or
spring in proportion to the greatest speed the machine is ever intended
to attain.

page_text: It
The indicating instrument I prefer to employ consists of a hollow
chamber of any convenient form, connected to which is the glass or
other indicating tube. Inside the hollow chamber is a flexible air
chamber connected by a tube with the equalizer above mentioned, or if
preferred directly to the air compressing pump; the part of the hollow
chamber not occupied by the flexible air chamber is to be filled with
liquid. The air forced by the pump into the flexible bag will expand
the latter more or less according to the speed of the pump, and the
liquid in the hollow chamber will thereby be displaced to an extent
proportionate to such expansion; the liquid so displaced will flow into
the indicating tube, and its upper surface will indicate by reference to a
graduated scale the speed of the machinery driving the air pump.
will be seen that in this arrrangement the air employed to impart.
motion to the indicating medium does not come in contact with the
liquid, and dust is therefore wholly excluded therefrom. When this
form of indicator is used with the exhausting apparatus to be here-
after mentioned, the indicating tube in connection with the hollow
chamber must be filled with liquid to a certain height as well as the
said hollow chamber. The flexible air chamber will then be contracted
by the action of the exhausting apparatus, and the liquid will recede
more or less from the indicating tube in proportion to the withdrawal of
the air, and the speed of the machinery will then be indicated by the
amount of such recession. Indicators constructed in accordance with
this arrangement are especially adapted for use on board ship as they
are not affected by the rolling or pitching motion.
1
To enable any number of the above mentioned indicators to be used
with one air pump, when such indicators are situated at various
distances from such pump, I place taps or valves in the tubes leading
from such pump to the indicators and by preference close to the latter,
whereby changes in the level of the liquid in each indicator can be
made to take place synchronously with those of all the others although.
situated further from or nearer to the pump, as the case may be.
Instead of a pump I may sometimes employ an exhausting apparatus
consisting of one or more bellows mounted at the end of a hollow arm
projecting from a hollow spindle to which rotary motion is given from
the machinery or other object of which the speed is to be ascertained.
The hollow spindle is connected by means of a suitable air-tight joint to
the tube coming from the flexible air chamber in the indicator above

page_text: described. The revolution of the hollow spindle with its arm and
bellows causes the latter to expand by centrifugal action and thereby to
cause a partial vacuum in the communicating tube and flexible air
chamber, the latter contracts and a recession of the liquid in the
indicator tube takes place proportioned to the speed of the machinery as
already explained.
Instead of the liquid indicator above referred to I sometimes employ
flexible chambers or bellows, the expansion of which by the action of
the pump is caused to operate upon an index, pointer, or other suitable
mechanical indicating medium, by means of rods, levers, toothed wheels,
or racks, and balance weights or springs, in such manner as to indicate
at sight the speed of the machinery or other moving object driving the
pump.
When it is desired to distinguish in which direction the machinery is
revolving, as well as to indicate the speed, as for example on board ship
or in winding engines, I employ two flexible chambers or bellows in the
indicator, one being operated upon when the machinery is revolving in
one direction, the index being thereby moved to the proper extent, say
to the right hand, the other bellows being operated upon when the
machinery is revolving in the opposite direction, the index being then
moved to the proper extent to the left hand, the one flexible chamber or
bellows being thrown out of action and the other into action, on
reversing the direction of motion of the machinery by means of a change
apparatus in connection with the tubes leading from the pump to the
indicator.
The motions of the indicator instrument may if desired be registered
graphically on a moving sheet of paper by means of a pencil or other