An Improved Lever and Linkwork Mechanical Movement.
Year: 1887

page_text: Date of Application, 16th Aug., 1887
Specification Accepted, 25th Oct., 1887
[Communicated from abroad by ALBERT PARSONS MASSEY, of Watertown, N. Y.
United States of America, Machinist.]
An Improved Lever and Linkwork Mechanical Movement.
I, ALEXANDER HENRY REED, of Suffolk House, Lawrence Pountney Hill, Cannon
Street, in the County of Middlesex, Engineer, 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 :-
This invention relates to a new mechanical movement, which can be advantageously
embodied in a car brake mechanism, and said invention consists in a lever having
fulerums in two links which can vibrate about fixed points, all of which is more fully
pointed out in the following specification and claim, and illustrated in the accompanying
drawing which represents a side elevation of the mechanical movement.
In this drawing the letters A B designate the two arms of a bent lever which is
pivoted by suitable pins as G and at two points to the free ends of two links C and D.
Said links are pivoted by suitable pins as F and J to a rigid support E. N is a rod
which is pivoted at H to the arm B of the lever A. B, and which connects said lever
with a motor P of any description whereby a linear motion can be imparted to said
rod N to turn the lever A B. The opposite end K of the lever A B can be connected
by a rod L and chain L' with the body to be actuated. If force is applied to the rod N
to turn the lever A B toward the position indicated by dotted lines, the path of the
point H of the lever is such as indicated by letters H H' and the path of the
point K is that indicated by letters K K. In the beginning of the stroke,
the virtual fulcrum of the lever A B is at I in link C, while the link D acts
simply as a guide; in the latter part of the stroke, the pin G in the
link D is the fulcrum, and the link is the guide; in intermediate positions
of the lever, the virtual fulcrum is a point somewhere between the pins.
I and G. To clearly illustrate the relative movement of the two points H and K
of the lever A B, the path H H¹ of point H is divided into equal spaces, and each
point is marked by a Roman numeral, and the path K K' of the point K is marked
with Arabic numerals at points corresponding to those marked with Roman numerals
in the path of the point H. On comparing these marked divisions it is observed that
the point K at the beginning of the stroke of the lever moves through greater. arcs

page_text: than the point H but its movement gradually decreases until it becomes smaller than
that of the point H. In other words, when the pull on the lever A B begins, the
same is revolved about the fulcrum I in the link with a short leverage IH on the
arm B, and a long leverage I K on the arm A so that the movement of the point K
is much greater than that of the point H. As the point H is drawn toward the
point H, the virtual fulcrum travels along between the points I and G thus decreasing
the actual leverage I K, and increasing the leverage I H. When the lover A B has
been turned through about one half its stroke, the lever turns about the point C of
link D, and the leverage G K is now shorter than leverage G H so that the point K
moves slower than point H.
From this description it will be seen that a small movement of the motor suffices
to move the point K through a comparatively large space, while the subsequent
movement of the motor moves the said point through a comparatively small space,
and consequently a large force can be exerted by said point in the last half of the
stroke of the rod N.
Having now particularly described and ascertained the nature of the said invention
and in what manner the same is to be performed, I declare that what I claim is:
The links C and D pivoted at fixed points F and J, in combination with a lever A B
fulcrumed at I and G to the links, substantially as shown and described.
Dated this Sixteenth day of August 1887.