Improvements relating to Steering Gear for Navigable Vessels.
Year: 1896

page_text: Date of Application, 16th Nov., 1896
PROVISIONAL SPECIFICATION.
Improvements relating to Steering Gear for Navigable Vessels.
I, GEORGE RITCHIE BRACE, of 25 Water Street, Liverpool, in the County of
Lancaster, Naval Architect, do hereby declare the nature of this invention to
be as follows:-
My present invention relates to steering gear for navigable vessels and more
particularly to means for providing an elastic connection between the source of
power and the rudder head, so as to ease the effect of any sudden shock such as
occurs when the rudder is struck by a sea.
According to my said invention, I firmly secure a tiller to the rudder head,
and to the end of this tiller I pivotally attach an arc of considerable length which
is normally concentric with the rudder head.
The power to actuate the rudder is conveyed to the rim of this arc by chains,
wire ropes or the like, in the ordinary way, and the desired elasticity is given
by the method of further connecting the arc to the tiller, which I will now describe.
As already stated, the arc is pivoted on the end of the tiller, the point of attachment
being between the rim of the are and the rudder head; the arc is also linked,
at each end, to the tiller near the rudder head by a pair of links arranged after
the manner of a toggle joint, the apex of the toggle being in each case drawn
in towards the tiller by a spring linked thereto, and the links of the toggle lying
approximately in a radial direction.
It will be seen that if the arc be rotated slightly on its pivot relatively to the
tiller, the effect will be to partially straighten the toggle on one side in opposition
to the spring thereof, the other toggle being, of course, affected in the opposite
manner. Owing to the well known property of the toggle joint, that its mechanical
advantage, (that is to say, the ratio of the force transmitted along the links
to that transmitted through the spring),-increases rapidly as the links approach the
same straight line, and becomes infinite when the links are drawn into line,
the arrangement described is particularly suitable to the purpose intended. When
the arc is in its normal position, comparatively little force is required to deflect
it relatively to the tiller, and the force increases in a much more rapid ratio than
the amount of the deflection. Owing to the high mechanical advantage, com-
paratively light springs may be used, and they cannot be overstrained, as neither
toggle can ever become absolutely straightened.
The springs are preferably arranged in the well known manner so as to be in
compression, and instead of forming the toggles of pairs of links, as described,
chains or wire ropes may be used; to picvide against the contingency of failure
in the springs or toggles, means are provided for locking the arc to the tiller if
desired.

page_text: Improvements relating to Steering Gear for Navigable Vessels.
I, GEORGE RITCHIE BRACE, of 25 Water Street, Liverpool in the County of
Lancaster, Naval Architect, 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 present invention relates to steering gear for navigable vessels and more
particularly to means for providing an elastic connection between the source of
power, and the rudder head, so as to ease the effect of any sudden shock such as
occurs when the rudder is struck by a sea.
According to my said invention, I firmly secure a tiller to the rudder head,
and to the end of this tiller I pivotally attach an arc of considerable length which
is normally concentric with the rudder head.
The power to actuate the rudder is conveyed to the rim of this arc by chains,
wire ropes or the like, in the ordinary way, and the. desired. elasticity is given
by the method of further connecting the arc to the tiller, which I will now describe.
As already stated, the arc is pivoted on the end of the tiller, the point of attachment
being between the rim of the arc and the rudder head; the arc is also linked,
at each end, to the tiller near the rudder head by a pair of links arranged after
the manner of a toggle joint, the apex of the toggle being in each case. drawn.
towards the tiller by a spring linked thereto, and the links of the toggle-lying
approximately in a radial direction.
In the accompanying drawings which illustrate my invention, Fig. I. is a plan
view and Fig. II is a sectional elevation on the line A. A. of Fig. I; the same parts
are indicated by the same reference figures in the two views...
1 is the rudder head to which the tiller 2 is securely keyed, and 3 is the arc,
pivoted by the pin 4 to the end of the tiller 2. This are comprises. a flat plate 3
with chain races formed at its periphery in the ordinary way by rivetting steel
or iron angles thereto, and a central jawed forging or steel casting 31 which is
rivetted to the plate and receives the pin 4 by which the pivotal attachment to
the tiller 2 is made. The lower boundary of the lower chain race is preferably
formed of a continuous angle 5, but the upper boundary of the upper chain race
may be discontinuous and formed by the short angles 6. The weight of the arc
is partially supported on a pair of bearing rollers 7 arranged in convenient, positions
under the circular rim thereof and running over the race. 8 fixed to the deck
concentric with the rudder head.
9 are the chains or wire ropes or the like, running over the leading pulleys 10,
by which the power is conveyed to the arc; these are attached to the arc in the
ordinary way, by the stretching screws 11, of which only one is shown.
12 are the links of the toggle joints connecting the ends of the arc to the lugs 13,
and 14 are the springs by which the apices 15 of the toggles are drawn towards the
lugs 16 on the tiller. The springs are preferably arranged in the well known
manner so as to be in compression instead of tension, that is to say, the draw
bars 17 are bifurcated and attached by nuts to the washers 18 between which the
spring is compressed. Instead of forming the toggles of pairs of links, as shown,
chains or wire ropes might be used, and to provide against the contingency of
failure in the springs or toggles, means may be provided for locking the arc to the
tiller.
It will be seen that if the are 3 be rotated slightly on its pivot relatively to the
tiller 2, the effect will be to partially straighten the toggle on one side in opposition
to the spring thereof, the other toggle being, of course, affected in the opposite
manner, so that the power to actuate the rudder is ultimately transmitted thereto

page_text: through the agency of one or other of the toggles. Owing to the well known
property of the toggle joint, that its mechanical advantage,-(that is to say,
the ratio of the force transmitted along the links to that transmitted through the
spring),-increases rapidly as the links approach the same straight line, and
becomes infinite when the links are drawn into line, the arrangement described
is particularly suitable to the purpose intended. When the arc is in its normal
position, comparatively little force is required to deflect it relatively to the tiller,
and the force increases in a much more rapid ratio than the amount of the deflec-
tion. Owing to the high mechanical advantage, comparatively light, springs
may be used, and they cannot be overstrained, as neither toggle can ever become
absolutely straightened.
While I have described my invention in the form which I consider best
adapted for ordinary cases, it is obviously susceptible of modification without
departing from the main feature thereof, that of applying the steering power
to a piece which is not rigidly connected to the rudder head but the position of
which relatively thereto is controlled by toggle joints and springs.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what I
claim is:-
1. The herein described method of transmitting the actuating power to a rudder
through the agency of spring-controlled toggle joints, substantially as set forth.
2. A steering gear comprising a tiller adapted to control the rudder; an arc
or its equivalent mounted on the tiller so to be capable of movement relatively
thereto; and toggle joints and springs adapted to control the position of the
arc relatively to the tiller; substantially as described.
3. The combination and arrangement of parts forming the improved steering
gear; substantially as described and illustrated.
DL14
1007
SLOAN & LLOYD BARNES,
Castle Chambers, 26 Castle Street, Liverpool, Agents for the Applicant.