DEVICE FOR EQualizing tiie LeVERAGE OF A CRANK MOTION
Year: 1877

page_text: 38
LETTERS PATENT to Robert Duncan Milne, of Santa Barbara, California,
United States of America, Gentleman, for the Invention of an
DEVICE FOR EQualizing tiie LeVERAGE OF A CRANK MOTION"
IMPROVED
COMPLETE SPECIFICATION filed by the said Robert Duncan Milne, at the
Office of the Commissioncis of Patents on the 29th January 1877
ROBERT DUNCAN MILNE, of Santa Barbara, California, United States of America,
Gentleman "IMPROVED DEVICE FOR EQUALIZING THE LEVERAGE OF A CRANK
MOTION"
The object of my Invention is to provide a novel method for the conversion of
reciprocating rectilinear motion into rotary motion by a mechanism, by means of
which the inequality of crank power is equalized and balanced in such a manner that
the direct pressure of a piston or other motor is transferred to the crank with greater
uniformity of action than in the case of an ordinary crank
The mathematical principle of the Invention consists in producing a series of
changes in the line of diect propulsion as it affects the crank, so that the point of
impact of force approaches oi iecodes from the centre of the crank during its
evolution, this point of impact being furthest from the centre of the crank at the
beginning and end of stroke, and nearest at the middle of the sti oke
My Invention is also designed to utilize the independent motion of the con-
necting iod thus acquired, by binging it to bear upon the clank at such angular
inclination as to be equivalent to direct propulsion in a line varying from the line
of force inversely as the angle which the connecting rod makes with the crank
varies from a right angle
In the present case I have adopted one mechanical means for accomplishing the
result, which will be more fully described in the accompanying Diawings, in which
Figure 1 is a side elevation, showing the crank at right angles, Figure 2 is a view
showing the crank just passing the centre A slot A is cut in the body of the
CD 271

page_text: crank B, extending from its end to a point nearly equidistant from its end and
centre Into this slot is fitted a square piece C, called the compensator, so that it
can slide fion and to end of the slot A pin D projects from the compensator and
forms and supplies the place of the crank pin, to which the connecting rod Ę is
attached in the usual manne Fixed to the end of the connecting 1od, and in line
with it and moving upon it with the crank pin, is an oblong piece F with curved
ends running to a point, and of sufficient thickness to ensure power and ease of
motion, the length of which is equal to twice the distance the compensator moves in
the slot The piece F is called the regulator Upon the body of the crank are fixed
bearings G, G, forming twin parabolic curves of the saine thickness as the regulator,
and running from a point in the centre of the mner end of the slot to another point
beyond and in line with the centre of the outer end of the slot, these curves
describing the figure which the regulator naturally makes upon the face of the
crank, while the compensator reciprocates once within the slot during a half
revolution of the crank, the distance between these points is equal to the length of
the piece called the regulator.
The operation of this combination of parts is as follows.-The pressure of the
connecting rod E upon the crank pin D at the beginning of a stroke causes the
compensator C, of which the clank pin forms a part, to move forward in the slot,
this forward motion is however checked by the piessure of the regulator F fixed to
and moving in line with the connecting rod, upon the curved bearings G, which
will only permit the regulator to move upon them at a certain angle, and until this
angle is assured by the connecting 1od, the compensator can slide no further This
condition causes the connecting rod to expend its power upon the compensator only
in proportion to the forward progress of the crank, and this action of the com-
pensator and regulator decreases in proportion as the angle between the connecting
rod and the clank grows nearer a right angle, and ceases altogether towards the
middle of the stroke When the connecting rod is acting duect upon the clank,
and the compensator having moved to the inner end of the alot, there is no longer
any necessity for then services When the middle of the stroke is passed, and the
crank is moving towards the opposite centre of its orbit, the angular inclination of
the connecting rod to the slot and the compensator is such that the compensator is
again pushed towards the outer end of the slot Meanwhile the regulator assumes
the function of compensator, and the angle at which it presses on the curved
bearings G is such as to be equivalent to duect propulsion in the duection in which
the crank is moving while the motion of the compensator forward in the slot
permits this independent action of the regulator to take effect until the end of the
stroke is reached, thus the functions of the compensator and regulator are inter-
changeable, the former doing the work at the beginning and the latter at the end
of the stroke
The novel points of my Invention are the application of the mathematical
pinciple defined above to the matter of crank motion, and also the mechanical
ineans which I employ to accomplish that end, as described specifically above,
separately and in combination
Having thus described my Invention, what I claim as new and desire to secure
by Royal Letters Patent 15,-
1st The method of equalizing and balancing the varying pressure exerted by a
piston or other motor upon a crank during its revolution, consisting in producing a
series of changes in the line of direct propulsion by means of the compensator C
moving in the radial slot A. or equivalent device, so that the point of impact of force
recedes from or approaches the centre of the crank during its revolution, substantially
as herein described
2nd The method for utilizing the independent motion of a connecting rod between
a crank and its reciprocating motor, consisting in bringing it to bear upon the crank
at such an angula inclination as to be equivalent to duect propulsion in a line i
varying from the line of force inversely as the angle of the connecting 1od and

page_text: crank vales from a light angle by means of the curves G acting upon the regulator
For an equivalent device, substantially on herein described
In witness whereof, I, the said Robert Duncan Milne, have hereunto set my
hand and seal, this Fourth day of Januniy, in the year of our Loid AD,
One thousand eight hundred and seventy-seven
Witnesses,
GEO H STRONG,
OLWYN F STACY
ROBERT DUNCAN MILNE
(LS)