Reversible Back Stop for Turnstiles and other Revolving Apparatus.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Reversible Back Stop for Turnstiles and other Revolving
Apparatus.
I, LEICESTER BRADNEY STEVENS of Darlington Works, Southwark Bridge Road,
London S.E. 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:—
My invention relates to improvements in reversible back stops for turnstiles and
other revolving apparatus, and has for its object, to provide means for readily per-
mitting of rotation in either direction as may be desired while effectually stopping any
rotation in the opposite direction.
One form of my invention when applied to turnstiles consists preferably of a double
converging roller race or of two fixed inclined planes one on each side of a vertical
wheel, which wheel is geared with the upright shaft of the turnstile (to which the
arms are attached) in such a manner that the arms when operated cause the wheel to
rotate in either direction according to which way the arms are turned. This wheel
is prevented from turning in the wrong direction by means of a ball or a roller
placed between the wheel and one side of the race or one inclined plane in such a
position, that the wheel can only turn in the direction desired, as the act of turning in
that direction frees the ball or the roller and enables it to work freely, but on
attempting to turn it in the wrong direction the ball or the roller jains itself between
the wheel and the race or inclined plane and prevents any back motion. To enable
the wheel to work in the reverse direction the ball or roller is placed between the
wheel and the inclined plane or race on the opposite side.
Another form of my invention consists of a horizontal ratchet wheel keyed to the
upright shaft of the turnstile to which the arms are attached the wheel having a single
ring of teeth on its uppermost side, these teeth being cut at an equal angle at either
side. Above these teeth two pawls are arranged to act as a back stop for either
direction according to their position.
On sheet 1 of the accompanying drawings Fig. 1 is a vertical section, Fig. 2 a
horizontal section and Fig. 3 a transverse section respectively of one form of
reversible back stop constructed according to my invention.
A vertical wheel a mounted on a spindle b journalled in suitable brackets c and
geared to the upright shaft d of the turnstile by the bevel wheels ef is arranged to
rotate directly over a converging race g in which is placed a roller free to traverse
the said race to a limited extent so that when the wheel a is caused to rotate in the
direction shown by the arrow the roller is simply shifted to the wider part of the
race allowing the wheel to rotate freely. When however it is attempted to rotate it
in the reverse direction the roller jambs itself between the wheel and the race and
prevents any back motion. By placing the roller on the opposite side of the wheel
the working conditions are obviously reversed.
On sheet 2 of the drawings, Figs. 4, 5 and 6 represent similar views to Figs. 1, 2
and 3 of another form of my invention.
A horizontal ratchet wheel i mounted on the upright shaft d is formed on its upper
side with teeth k of equal obliquity on either side as clearly shown; and engaging with
two pawls 7 working on horizontal pins m passing through the casing n and secured to
the bracket o guiding the shaft p.
The wheel as shown is free to turn in the direction of the arrow but rotation is
stopped in the opposite direction. When however it is required to reverse the
direction of rotation of the turnstile arms the pawls are turned over on their pins m
as shown in dotted lines in Fig. 6.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is
1° A reversible back stop for turnstiles and other revolving apparatus comprising
a wheel working with a ball or roller in a double race or inclined planes and connected
to the rotating shaft so that the direction of rotation is determined according as the
ball or roller is placed on the one side or the other of the said wheel substantially as
described.
2° A reversible back stop for turnstiles and other revolving apparatus comprising,
a horizontal ratchet wheel mounted on a rotating shaft and having formed on its
upper side teeth of equal obliquity on either side engaging with two pawls free to
turn on a horizontal axis so that by rotating them from one side to the other of their
axes the direction of rotation of the shaft is reversed substantially as described.
4. The arrangement and construction of reversible back stops for turnstiles
substantially as described with reference to Figs. 1, 2 and 3 and to Figs. 4, 5 and 6 of
the drawings.
Dated this 20th day of Man 1000