Year: 1886

page_text: We, DAVID DEHANE NAPIER, and WILLIAM DIXON NAPIER, of the Windlass
Engine Works, Hyde Park Street, Glasgow, in the County of Lanark, North
Britain, Engineers, 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, that is to say :-
Our said Invention relates to frictional clutches of the kind described in the
Specification of Letters Patent granted to Robert David Napier and numbered 299
of 1867; and whereas clutches of the description referred to were suitable for only
one direction of rotation, the object of our present Invention is to render such
clutches suitable for both directions of rotation.
Our improved frictional clutch is shown on an accompanying sheet of explanatory
drawings, figure, 1, being an elevation of one side, figure, 2, a front elevation, and
figure, 3, an elevation of the other side.
The clutch is constructed for communicating rotation from a driving shaft, S, to
a disk, D, from which latter the motion may be transmitted by a pinion or spur-
wheel fixed to the disk; or the rotation may be communicated from the disk, D,
to the shaft, S. On the shaft, S, there is fixed a pulley, P, to which there is applied
a frictional or brake strap, R, consisting of two sides united by a bolt, B, and
connected by links, K, to a lever, L. The lever, L, is shaped with recesses on its
inner edge to fit on two fulcrum pins, F 1, F 2, and when it rocks to either side from
its middle position, in which it is shown in the drawings, it moves away from one
fulcrum pin, the other pin being then the effective fulcrum. When the lever, L, is
in this way bearing on only one of the fulcrum pins, F 1, or F 2, it is a differential
lever acting like the differential lever of the clutch shown and described in the
earlier patent Specification hereinbefore referred to, in a manner to make a -
strap, R, tighten on the pulley, P, through the frictional action between the strap
and pulley. If the pulley, P, is driving, then, in whichever direction the rotation
is, the following link, K, is the one which is connected to the longer arm of the
lever, L, that lever then bearing on the fulcrum pin, F, nearest the preceding
link, K.
For the purpose of engaging and disengaging the clutch, there is loosely fitted
on the shaft, S, a boss, A, made with a groove, C, for the forks of a clutch lever
by which it can be moved along the shaft. This boss is also made with a
diametrical plate, E, having notches or slots formed in its ends, to receive and act

page_text: upon helical horns, H1, H2, one of which is fixed on the disk, D, the other being
formed or fixed on the friction or brake strap, R. When the shaft, S, is driving
and rotating in the direction of the arrow and the boss, A, is moved towards the
pulley, P, the action of its diametrical plate, E, on the horns, H, is to move the
strap, R, into frictional contact with the pulley, P, in other words, to put the
clutch into gear, the pin, F1, then becoming the fulcrum. When the shaft, S, is
moving in the opposite direction the boss, A, has to be moved away from the
pulley, P, to put the clutch into gear. The opposite movement of the bos+, A, in
each case disengages the clutch by moving the strap, R, slightly away from the
pulley. As regards its self-holding or automatic action our improved clutch acts
exactly like that described in the earlier Specification herein before referred to, the
only difference, but which is one of considerable importance in many practical
applications of the clutch, being that it will act for either direction of rotation
instead of being as formerly suited for only one direction.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed we declare that what
we claim is :-
The improved clutch, and particularly the arranging of the lever to which the
two parts of the friction strap are connected, to rock on different fulcrum pins
according to the direction of rotation substantially as herein before described.
Dated this seventeenth day of February 1886.
EDMUND HUNT,
Applicants' Agent.