AN. INSTRUMENT FOR MEASURING THE PITCH OF SCREW PROPELLERS
Year: 1885

page_text: WILLIAM KINLEY Engineer 19, Winchester Road Anfield Liverpool, do hereby
declare the nature of my invention for AN. INSTRUMENT FOR MEASURING THE PITCH
OF SCREW PROPELLERS, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
This instrument is constructed for quickly and accurately ascertaining the
Pitch of Screw Propellers, in any position, and also for adjusting loose blades on
Propellers to the required pitch.
It is graduated in feet on an Arc reading plate, and its compass ranges from
2 feet to 25 feet diameters, and measures from one foot pitch, to any required
pitch. On the one I have made, I have graduated it to 40 feet.
On the outer edge of the Arc reading plate the angular advance is shewn in
degrees. Some of the advantages of this instrument are, that it does not require
to be removed from the Propeller in order to take a reading, and is not liable to be
put out of adjustment, as in some already in use.
As the reading is taken on an Arc placed as far as possible from the centre, the
delicacy of the reading is as great as possible.
In applying this instrument it can be adjusted to the Propeller by the spirit
level, or by the plummet, or by sighting, the latter if convenient is the way I should
recommend.
It may be constructed of Metal, Wood, or any suitable material.
The one I have made is of brass, and measures when closed about 27 inches,
by 7 inches, by 1 inch, and weighs about 5 pounds, it is a very convenient size,
but it may be made larger or smaller if desired.
In the drawings attached to the Specification.-Fig I. represents the instrument
complete.-A and B are two legs jointed together at C. The leg A is attached to
the Arc reading plate D, at the end E. by a screw F. or other suitable device; the
end of the leg B. slides round on the Arc reading plate, and may be clamped at
any position by a plate and screw G, or any other suitable device; H is a sliding
pointer to be set to the scale corresponding to the diameter of the propeller at
which the measurement is to be taken; K is a spirit level jointed to the leg B. or L.
and capable of being fixed in any position by the slotted quadrant M, and
screw N.
On the Arc reading plates D. Fig I. and P. Fig 2. several scales are drawn, the
outer scales represent the angle. in degrees between the two legs.

page_text: The inner scales represent the Pitch of the Screw Propeller, the reading being
taken from a scale marked with the diameter at which the instrument is applied.
On the Arc reading plate P. Fig 2. scales are drawn for diameters ranging
from 1 up to 13 feet.-On the Arc reading plate. D. Fig I. scales are drawn for
diameters ranging from 14 to 25 feet.-The scales may be calculated by constructing
a right angled triangle, one side of which is the given circumference of the Pro-
peller, and the adjacent angle is the angle as measured by the instrument, between
the surface of the blade and a plane at right angles to the axis of the Propeller.-
The Pitch will now be represented by the other side of the right angled triangle.
This instrument may be used for several other purposes, for example when the
legs A and B are opened to the full extent, it forms a true square, The leg A. may
be divided to form a measuring rule.
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
An Instrument for measuring the Pitch of Screw Propellers, substantially as and
for the purposes, herein before described.