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steering wheel.

When used as a steam gear, the change-over is effected by a sliding
clutch, worked by a small horizontal hand- wheel at the top of the casing.
The power is given by a pair of diagonal cylinders 4 in. diam. by 5 in. stroke,
at the forward end of the machine ; to secure compactness the piston-rods
terminate in kite-shaped loops in which swing the return connecting-rods,
and these act on a crank fixed on the shaft of the epicyclic gearing previously
described. The steam cylinders have simple slide valves worked by a single
eccentric, but this eccentric is carried on a block and is capable of being
moved across the shaft between the positions for forward and backward
gear. This motion is given by a radial screw, driven by bevel gear from a
loose sleeve that is rotated indirectly by the steering wheel; when the
steering wheel is moved in one direction, a corresponding movement takes
place in the position of the eccentric, and the steam gear starts ; but, as the
engines revolve they carry round the eccentric sheave and so cause a
relative motion, that, if the steering wheel remain stationary, will screw the
eccentric into the mid-gear position again and so stop the motion.

In additional to this differential arrangement there is an extension from
it, which automatically cuts off steam from the engines except when they
are called upon to do steering work.

The steering wheel shaft is fitted with stops and a sliding nut, to prevent
damage by over-running the limits ; there is also a small indicating finger
which constantly shows the position of the rudder.

1059. Sectional model of steam steering gear. (Scale 1 : 2.)
Made by the Harrison Patent Steering Engine Co., 1894.

N. 2038.

In this small steam " quartermaster " the chains from the tiller are led
to a helically- grooved barrel, to the shaft of which a worm wheel is secured.
Above the wheel is a worm, formed on the crank-shaft of a double cylinder
horizontal engine with cranks at right angles. Each cylinder has a piston
valve, driven by an eccentric without lead, and the engine is reversed by
interchanging the steam and exhaust passages.

The steering wheel is carried on a small box above the steam chest, and
by worm gear rotates a circular slide valve. This slide valve rests on a
circular disc or valve, provided with ports that correspond with ports on the
steam chest face, and this disc is secured to a vertical spindle below, which
through bevel gear is rotated by the chain barrel. When standing, the
upper valve closes the ports in the lower one ; any rotation of the upper
valve lets steam through, and past the lower one into the valve chests and
cylinders, so causing the engine to run. In so running, however, the lower
valve is slowly carried round by the engine until its motion has closed the
opening that resulted from the movement of the upper valve and the engine
stops. Rotating the upper valve to the right lets the live steam into the
ends of the piston valves, and places their centres in communication with
the exhaust ; movement in the opposite direction places the ends to exhaust
and the centres under steam, so causing a reversal of the engine.

1060. Diagrams showing steering arrangements of warships.
(Scales 1 : 12 and 1 : 24.) Made by the Admiralty, 1887.

*N. 1800.

The two upper diagrams show the steering arrangements on vessels of
the " Inflexible " type.



The gear is alternatively hand or steam, the latter being wholly below
the protective deck for use in action, while the hand gear is in a poop house.
The steam gear can also be used as a hand gear.

The tiller is held by a socket, through which it slides as it is put hard
over. The tiller chains, which are attached by right and left-hand adjust-
able screws, are led by pulleys along the starboard side ; there is a locking
plate to the rudder head.

The two lower diagrams show in elevation and plan the arrangement
on vessels of the " Admiral " class. Steering is performed by a form of
Rapson's slide moved by either steam or hand power from the lower deck
forward or aft, or by steam alone from either of the conning towers.

The rudder is double with the two posts connected by links, and there is
a locking plate. The tiller is embraced by a socket, as above, while the
chain lies in a slide and is continuous, passing over sprocket wheels arranged
at the quarters and driven from below by the steering engine on the after
lower deck. Connections from this engine are made by bevel gearing and
shafting, led under the deck beams to clear the funnel hatches. The whole
of the gearing in this design is protected.

1061. Diagrams of the steering arrangements of H.M.S.
" Daring." (Scale 1 : 6.) Contributed by Messrs. John
I. Thornycroft & Co., 1895. N. 2059.

This torpedo-boat destroyer is fitted with twin rudders of the balanced
type, placed outside and abreast of the twin screw propellers ; the outer
edges of the screws revolve within 3 in. of the faces of the rudders, which
are curved to correspond. These rudders are turned simultaneously, by
means of worm quadrants driven by a worm-shaft connected with a steam
steering engine. By arranging the quadrants on alternate sides of the worm
shaft the end thrusts neutralise.

The extreme helm angle is 35 deg. and a complete circle is performed
in 1 min. 27 sees, with a diam. of about 3 5 times the vessel's length.

Owing to the great pressure upon the rudders at full speed, the rudder-
heads are of solid steel 7 in. diam. It has been found that twin rudders
offer their least resistance to progress when inclined at 7 deg. to each other,
the after edges being the nearer.

1062. Buffer for tiller chain. Lent by Messrs. Loveridge, Ltd..
1902. N. 2290.

Buffers of coiled steel spring have for a considerable time been inserted in
the chain, between the tiller and the steering engine, with the object of
minimising the stresses resulting from the rudder being struck by a heavy
sea.

The small example shown, which is for insertion in 75-in. diam. chain,
embodies improvements patented by Mr. T. Loveridge in 1899, by which the
spring is protected from entanglement and from corrosion by being enclosed
in a cylinder of oil. One end of the buffer spring beds upon one cover of
an oil cylinder while the other end of the spring abuts upon a slack piston,
the rod of which passes within the spring and through a stuffing-box in the
cylinder cover. The chain is connected to the rod and to one end of the
cylinder in such a way that any excessive stress, due to shock in the chain,
compresses the spring, but the ordinary travel of the chain in steering is
not interfered with, as the cylinder is free to travel on rollers on its bed.
An accompanying drawing shows this buffer in longitudinal section.

1063. Model of Rapson's slide steam steering gear (working).
(Scale 1 : 12.) Made in the Museum from information
supplied by the Admiralty, 1908. Plate XII., No. 1.

N. 2453.

This gear was patented by Mr. J. Bapson in 1839, as a hand gear, to
remedy the trouble caused by the slackness of tiller ropes due to the fact



353

that whereas the end of the tiller moves in an arc, the ropes work in a
straight line. It has the advantage of being compensating, although in its
earliest form it was designed to provide uniform turning moment. The
model illustrates the gear and adjacent ship structure of one of the
" Formidable " class of battleships.

A long and heavy tiller is attached by parallel rods to a cross-head on
the rudder spindle. The forward end of the tiller is of parallel section and
passes through a saddle which is free to swivel inside a block which can
only move transversely. To the ends of the block is attached a sprocket
chain of heavy design, which passes over guide pulleys at the ship's sides
and under a sprocket wheel at the centre line of the vessel. The sprocket
wheel can be actuated either by steam or by manual power, the general
arrangement of both these methods being very similar to that shown in
No. 1064. Provision is made for tightening the chain by inclined bottle-
screws and guide pulleys, the latter being attached to the casting carrying
the sprocket wheel. Side thrust is provided for by grooved gun-metal
guides carried by a special frame. The maximum angle of inclination of
the rudder is 35 deg. on either side of the mid-position. In common with
other well-known gears, however, this one is reversible, a disadvantage which
is provided for, as far as possible, by fitting a friction brake to hold the
rudder in case the sprocket chain or wheel should break. This brake is
also required to hold the rudder when the gea,r has to be changed from hand
to steam or vice versa. It consists of three fixed horizontal plates fastened
to the ship's sides, and embraced by four small sliding plates hanging from
a bracket which is attached to the under side of the saddle plate. This
bracket and its connections slide with the tiller. The plates are gripped
together by two lugs, whose upper ends are forked and contain nuts on a
screwed shaft in the bracket. One half of the shaft has a right-handed
thread and the other half a left-handed one, hence when this shaft is
rotated through the medium of bevel wheels, the lugs, whose fulcra are at
their centres, close on the friction plates or vice versa. A hand-wheel applies
the brake, but its actual position on the ship is on a longitudinal bulkhead
considerably further forward.

This model also shows constructional details of the vessel, which has an
arched or overhanging stern. A steel casting forms the rudder-post and
heel ; this is connected with the hull by the ordinary shell-plating and also
by a special horizontal steel plate, 2 in. thick, which rigidly joins the two
lower arms of the casting and extends sufficiently forward to make a good
connection with the vertical keel. It likewise forms a suitable palm-plate
for the lower scarf of the propeller brackets. Strong, closely- spaced
plate-frames, fitted vertically below this plate, give further stiffness to the
overhanging heel; the cellular spaces beween the frames are usually
filled with a mixture of cement and coke.

For a separate model of the stern casting, see No. 706.

The steering flat itself is about 13 ft. below the normal water-line of the
ship and about 9 ft. below a curved protective deck, 2 -5 in. thick ; a portion
of this deck is represented at the extreme after end of the model.

The gearing, through which the. hand- wheels or either of the two steam
steering engines actuate the main driving shaft, is not shown, but would be
placed in the rectangular recess, or well, partially indicated at the forward
end of the steering flat.

1064. Model of Harfield's steam steering gear (working).
(Scale 1:8.) Made in the Museum from drawings
supplied by Messrs. Harfield & Co., 1901, Plate XII, No. 2.

N. 2262.

The model represents, in detail, the modification of this type of gear
adopted in a cruiser with double rudders, but if the lower links are discon-
nected, it shows the simple arrangement used for a single rudder.

The rudders shown are of the balanced type, and the weight of each is
earned by a casting attached to the rudder-head and capable of turning on
u 6773. T



354

a circular channelled slide secured to a horizontal table forming part of the
main stern casting. The heads of the main and auxiliary rudders are
connected by parallel links to a supplementary head to which is keyed a
quadrant taking the place of a tiller. This quadrant is formed as a toothed
rack engaging with a driving pinion keyed eccentrically on a vertical shaft
from which the steering effort is received ; this mechanism constitutes the
compensating gear, since when the rudders are amidships the longest radius
of the pinion is acting on the rack, while when the resistance of the rudders
increases, through their being set over, the acting radius of the pinion is in
the meantime diminished, so that approximately the same steering effort is'
required throughout. The shaft of the eccentric pinion is driven by a
horizontal bevel wheel, secured to it and engaging with the driving shaft
which is common to both the hand and the steam operated gears.

The hand gear is separated from the steering mechanism by a watertight
bulkhead, through which the driving shaft passes by a stuffing-box ; three
hand-wheels are provided and their shaft is connected to the driving shaft
by spur gearing having a ratio of 1 to 4 and so arranged as to increase the
turning effort exerted. To the hand shaft is also fitted a friction clutch
controlling gear, patented in 1894 by Mr. "W. H. Harfield, which auto-
matically checks any tendency of the rudders to take charge should they be
struck by a heavy sea. It consists of a friction disc and two loose pawl
wheels placed between two fixed collars on the shaft ; the pawls are arranged
as nipping levers acting in opposite directions, and the friction disc is, by an
internal screw which carries the driving pinion, forced against one or other of
the discs, so securing it to the shaft ; the one thus secured acts as a ratchet
wheel in preventing the reverse motion until it is automatically released
by any movement of the hand- wheel. Eight complete turns of the hand-
wheel suffice to move the rudder from the central position to the maximum
angle of 35 deg. on either side, and there is an index finger near the hand-
wheel which shows the position of the rudder ; there is also a travelling nut
on the hand- shaft which engages with safety stops when the maximum angle
is attained, and there are also projecting stops on each side of the main
rudder frame.

For locking the rudder head in any desired position two arrangements
are provided. The first is a hydraulic brake patented by Mr. W. H. Harfield,
in 1895, which consists of an oscillating cylinder containing fluid and
provided with a bye-pass controlled by a valve, while the piston-rod is
connected to the head ; the other arrangement consists in the provision of
suitable holes through which locking pins can be passed so as to connect the
heads with the deck plates.

The whole steering mechanism is carried upon a combination of deep
transverse girders and crown plates, extending the full breadth of the vessel
and riveted both to the side and the deck plating. A number of the plate
frames supporting the steering flat are shown, and these indicate the general
character of the ship's framing in this locality ; the model also shows the
usual method of connecting the cast steel stern post with the flat keel plates,
the vertical keel, and the transverse framing of the ship. To protect the
steering arrangements from gun fire they are arranged below the water-line
and completely covered by a 2-in. protective deck made in two thicknesses.

1065. Model of steam steering engine (working). (Scale
1 : 4.) Made in the Museum from drawings supplied bjr
Messrs. Bow, M'Lachlan & Co., 1903, Plate XII., No. 3.

N. 2327.

This represents the steam steering engine fitted to H.M.S. " Gladiator,"
built in 1896 ; similar engines are now generally employed in all large vessels
to supply the power necessary for rapidly moving the rudder, while being-
capable of control from a steering wheel on the bridge and also from below
the water level. For many years steering engines for warships were
arranged horizontally and in a separate compartment, but space is now



355

saved by fixing the engine in the main engine-room on a vertical bulkhead,
as shown, specially stiffened to prevent vibration.

The essentials for such an engine are, that it should continually follow
the movement of the steering wheel, both in amount and direction, so that by
its aid the rudder can be placed and retained in any position by the slight
effort necessary to move the small wheel controlling the steam supply.
There are many arrangements for obtaining this result, but the principle
in all is the same, namely : that the engine as it revolves always tends to
undo the change made by the movement of the steering wheel.

The steering engine represented has two simple cylinders 8 in. diam. by
9 in. stroke, each provided with a piston slide valve and a single eccentric
set without lead. Control and reversal are effected by a third piston valve
known as the "differential" valve, which is arranged between the two
cylinders ; it is without lap, and its function is to interchange the steam and
exhaust connections of the ports to the valves of the cylinders. When the
steering wheel is turned, it screws the differential valve from its middle
position, thus allowing steam to pass to the cylinder valves and causing the
engine to rotate. This motion of the engine, however, commences to again
close this central valve, owing to a worm on the crank-shaft being in gear
with a worm-wheel which acts as a nut for the screwed end of the valve
spindle, so that the nut being fixed laterally, the valve is screwed back to
the mid or closed position. The engine is connected with the mechanism
working the rudder by the large shaft, shown broken off, on which is a
heavy worm-wheel gearing with a worm on the engine crank-shaft.

ATI indicator shows the number of turns of the steering wheel that the
rudder is from its mid position, eight being sufficient to place the rudder
from hard over to hard over ; safety stops are provided which, at the limits,
prevent further motion of the steering wheel. As the engine has to work
with steam from the main boilers, it has to be capable of standing high
pressure, the present example using boiler steam of 300 Ib. reduced by
throttling to 200 Ib. A sectional elevation through the valves is shown on
an accompanying drawing.

Another working model shows to a smaller scale the steering gear and
rudders which this engine is employed to drive, and also the hand gear
that is provided for use should manual power have to be resorted to
(see No. 1064).



CAPSTANS, WINCHES, ETC.

The capstan, with its vertical drum and numerous long
radial arms, is the most elementary device for using the
advantage of a lever for the exertion of great hauling power.
The arms are about 10 feet long and of considerable number,
while on ship-board there may be arms at two or more decks,
so that it is possible to employ the effort of as many as
100 men in this way for special purposes. Backward motion
is prevented by pawls dropping into teeth fixed to the deck,
but the arrangement possesses a serious element of danger
owing to the consequences that follow the breaking of the
hauling rope or its blocks. Some efforts have been made to
construct geared capstans, but the introduction of steam power
has generally resulted in the abandonment of an arrangement
that occupies such a serious amount of deck room as does any
form of hand capstan.

z 2



356

The windlass, or horizontal arrangement of the capstan
with loose bars, is much more compact than the vertical form,
but cannot employ many men ; it, however, readily admits of
the introduction of gearing and so becomes the winch, in which
the convenient short handle is used to obtain a powerful,
though slow, haul. The general application of steam power
to winches and capstans is at the present time being superseded
by electrical power on board ship, and electric motors are taking
the place of steam engines for modern capstans.

For lifting cargo some form of jib or derrick to support
the overhead pulley is necessary, but a form of automatic
derrick, known as the Temperley transporter, is now success-
fully used. By its aid the load is lifted, then moved
horizontally any required distance, and finally lowered, all by
the motion given to the lifting rope of a single winch or
jigger cylinder.

The modern steam capstan or windlass for anchor cables
(see No. 1069), in addition to its hauling capabilities, also
controls the cable while being run out and holds it where
required, but to give further security when anchored the cable
is usually given one or two turns round a massive post, called
a " riding-bitt," which is fixed to the anchor deck.

1066. Model of geared capstan. (Scale 1 : 8.) Presented by
Messrs. Bullivant & Co., 1902. N. 2284.

The capstan type of lifting or hauling appliance, now so generally
adopted on ships, is believed to have been introduced into this country from
Portugal in the 16th century. It then consisted merely of a vertical post
turned by bars fixed through the head, but from it the later shape represented
in the model has been developed.

The winding drum, or barrel, has its diameter increased by the addition
of a number of renewable ridges or " whelps " tapering upwards, which, in
addition to increasing the grip of the rope, facilitate its surging upwards
while being wound on. The drum head is provided with sockets into which
removable capstan bars are fitted, so that the space occupied when not in
use can be greatly diminished ; at the lower end of the drum is a series of
reversible pawls of different lengths engaging with a fixed spur ring secured
to the deck, so that accidental backward motion is promptly prevented and
the drum can be retained in any position.

The example shows, moreover, the addition of gearing to further increase
the mechanical advantage derived from the use of levers, an extension which,
with the application of an epicyclic train, was patented in 1819-27 by
Captain C. Phillips, R.N. In the model ordinary gearing is employed and
the head, which, by lifting a pin, can be unlocked from the barrel and the
gearing thrown into action, can revolve at three times the rate of the
barrel ; in Phillips's capstan the gearing increased the advantage in the
same ratio.

1067. Model of elastic windlass for ships. (Scale 1:8.)
Contributed by W. H. Muntz, Esq., 1862. N. 785.

This was introduced in 1860 by Mr. Muntz as a means of reducing the
shocks experienced by a cable when holding a vessel at anchor.

The windlass is mounted on horizontal rods, which are bolted to the
riding bifcts secured to the deck. On the rods are buffer springs of steel or
rubber which take up the strain on the windlass.



357

1068. Model and drawing of Baxter's cable windlass.
(Scale 1 : 12.) Lent by H. C. Baxter, Esq., 1898.

N. 2161.

This form of vertical windlass for working anchor cables, introduced by
Mr. S. Baxter, was first adopted in the British Navy on the " Admiral "
class of battleships. Power is supplied by a double cylinder engine driving,
through bevel gear, a horizontal shaft that, by a single worm, rotates two
chain drums ; a bevel pinion on this shaft drives also a capstan for general
purposes, in which rope is used and less power required. Reversal of the
motion is accomplished by a claw clutch on the crank-shaft, by which either
of the two bevel pinions can be made the driver. In an adjacent drawing a
reversing engine is shown, which is arranged below the deck.

To prevent excessive stresses on the cable, through shock, the sprocket
drum of each windlass is connected to its gear-driven vertical shaft by
friction discs, forming a " Weston's " friction clutch. The closing pressure
is applied by a cap screwed on this shaft and rotated by a suitable lever.

The cable from the locker passes through a hole in the casting, then:
round the windlass, and along to a stopper fixed on deck close to the
hawse pipe. This stopper forms an inclined guide for the cable, but has a
portion fitted with a lowering lever, which when depressed allows the link
on it to drop into a recess resembling the space on a sprocket wheel ;
by this means the cable may be temporarily held while making fresh
connections.

The rope capstan is fitted on the top with two plugs which act as
drivers ; by removing these the capstan can be worked independently with
handspikes.

1069. Model of "overlead" cable windlass (working).
(Scale 1:8.) Made in the Museum from information
supplied by Messrs. Harfield & Co., 1909. Plate XII.,
No. 4. N. 2513.

"With the application of the stockless anchor to vessels of the mercantile
marine, it was found desirable to modify the existing type of " underload "
windlass, in order that a direct pull might be obtained on the anchor when
stowed in the hawse pipe, The present type of steam windlass was
introduced by Mr. W. H. Harfield for this purpose. In the model shown,
the cables from the hawse pipes pass over the tops of the cable-holders, and
thence through chain pipes formed in the bed-plate into chain lockers
directly underneath. In the " underload " type of windlass the direction of
the out-going cable as it leaves the cable-holder is horizontal. This arrange-



Online LibraryScience Museum (Great Britain)Catalogue of the naval and marine engineering collection in the ... museum .. → online text (page 50 of 58)