Improvements in Screw and Nut Mechanism.
Year: 1892

page_text: Date of Application, 1st Dec.; 1892-Accepted, 4th Feb., 1893
COMPLETE SPECIFICATION.
Improvements in Screw and Nut Mechanism.
A communication from OTTO KRELL, of 31, Vestnerthorgraben, Nürnberg, Empire
of Germany.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I. Mech. E., and Chartered Patent Agent, 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 :-
The invention hereinafter described and shown in the accompanying drawing
relates to a mechanism for converting a rectilinear reciprocating motion into an
oscillating circular one, and it is advantageously employed for actuating rudders,
turning bridges, opening and closing sluice-gates on turning cranes, turn-tables,
anchor-capstans, for turning armour plated towers, gun-carriages and the like.
The mechanism is very simple and its action quite sure. It consists essentially
of a screw spindle freely movable in its axial direction and to which the recipro-
cating motion is imparted, and of two nuts, one of which causes the spindle to
revolve, which motion is transmitted then to the other nut.
Figure 1 shows an arrangement illustrating the application of the invention to
the rudder of a ship.
Figure 2 shows the arrangement of the two nuts, the screw spindle being
omitted.
Figure 3 is an axial section of the mechanism through the screw spindle, which
has a particular shape.
The screw spindle a has worked in its surface two or more threaded right and
left handed screw threads crossing each other; the pitch of the latter must be great,
but it is not necessary that it is the same as shown in the drawing.
This screw spindle is freely movable in its longitudinal axis and it engages with
its two different threads at the same time with two corresponding nuts c and d,
(Figures 1 and 3), one of which, c for instance, is provided with a left handed
thread, and the other, d for instance, with a right handed one.
The nut c is firm and absolutely immovable, while the nut d is arranged in such
a manner, that it is allowed to turn, but only round its axis of revolution, which
motion can be transmitted then, say, to the rudder of a ship, as shown by way of
example in Figure 1.
The mechanism works in such a manner, that, if the spindle is led in one
direction, for instance to the outside, a rotary motion is imparted by the stationary
nut c and its threads-in the case suggested the left ones, and as the spindle
engages at the same time with the nut d, the latter is turned in the opposite
direction by the right handed screw threads. On the return motion of the spindle
the revolution of d of course an inverse one. The reciprocating motion can be
imparted to the screw spindle a in several ways.
As shown in Figure 1 for instance, a second spindle f is arranged in the interior
of the hollowed main spindle and may directly or indirectly be actuated by hand
or power.
According to Figure 3 the interior of spindle a is completely bored out so as to
form a hydraulic cylinder having a stationary perforated piston b, on both sides of
which the pressure liquid is led through the piston rod 9 imparting thereby a
reciprocating motion to the cylinder which is also the spindle.
This reciprocating motion of the spindle may of course be obtained also by any
other suitable means, say by means of connecting rods, eccentrics, racks and so on
and is not limited to these two arrangements.

page_text: Having now particularly described and ascertained the nature of the said inven-
tion, as communicated to me by my foreign correspondent, and in what manner
the same is to be performed, 'I declare that what I claim is :—
1. A mechanism for converting a rectilinear reciprocating motion into an
oscillatory circular motion by means of a screw spindle freely movable in its axial
direction and carrying both right and left handed screw threads engaging into two
corresponding right and left handed nuts one of which is stationary while the other
is held so that it is allowed only to receive rotary motion substantially as above
described and shown in the accompanying drawings.
2. In the mechanism characterized in Claim I the use of the screw spindle as a
pressure cylinder carrying on its outer cylindrical surface the right and left handed
screw threads while its interior contains a stationary piston through the piston rod
of which the pressure liquid is supplied and discharged substantially as set forth
and shown in the accompanying drawing.
Dated this 1st day of December 1892.
W. P. THOMPSON & BOULT,
London, Liverpool, Manchester, and Nottingham, Agents for the Applicant.