"لنش بحري للوكيل السياسي في البحرين. مراسلات تتعلق بمحرك كيلفين." [و‎‎١‎٣] (٣٩٨/٥٧)

Reprinted from " ENGINEERINC
v O
A NEW
Improvements in both the!
of internal-combustion engin*
moderate size have been n
years, and may be said to :
production of reliable airless:
higher powers and speeds whic
practice have, however, impos
on the engine ancillaries, ari
frsquent occurrence in which
tion and reversing gears have
tively short period of servic,
stresses to which they have t
particular importance that the
thoroughly reliable, as model
demand long periods of reverse
points in view, Messrs; Jo]
Company, Limited, Thomycro:
S.W.I, have introduced the ne 1
It has been designed for
use in all classes of motor era
equal in reliability to the avi
vehicles. It is equally suitab]
heavy-oil engines, although tb
speed airless-injection engines
kept in view. The gear is des
between 1,200 r.p.m. and 1,81
A produc
JOHN I.
Designers and builders of all types of motor ct
THOHNYCROFT HOUSE, iEuTH
Works: READING, (Marine Motors). SOUT]
Reprinted from " ENGINEERING."
• o
A NEW REVERSING GEAR FOR MARINE ENGINES.
I mprovements in both the design and construction
of internal-combustion engines for craft of small or
moderate size have been most marked in recent
years, and may be said to have culminated in the
production of reliable airless-injection engines. The
higher powers and speeds which characterise the latest
practice have, however, imposed much heavier duties
on the engine ancillaries, and cases are of not in
frequent occurrence in which such units as the reduc
tion and reversing gears have failed after a compara
tively short period of service under the additional
stresses to which they have been subjected. It is of
particular importance that the reverse gear should be
thoroughly reliable, as modern conditions frequently
demand long periods of reverse running, and with these
points in view, Messrs; John I. Thomycroft and
Company, Limited, Thomycroft House, Smith-square,
S.W.I, have introduced the new gear illustrated.
It has been designed for continuous and heavy
use in all classes of motor craft, and is claimed to be
equal in reliability to the average gear box on road
vehicles. It is equally suitable for petrol, paraffin or
heavy-oil engines, although the requirements of high
speed airless-injection engines have been particularly
kept in view. The gear is designed for engine speeds
between 1,200 r.p.m. and 1,800 r.p.m., this covering
the requirements of the majority of modem engines,
and will transmit 80 brake horse-power at the first-
mentioned speed, with proportionately greater powers
at higher speeds. The speeds ahead and astem are
equal, thus giving the maximum retarding effect to
the propeller when reversed. The gear can be
arranged for bolting directly to the engine, and is
provided with adjustable feet, as shown in Fig. 3, to
facilitate alignment!
The gear consists essentially of three parts, the
driving-shaft assembly, the planet-wheel casing, and the
driven-shaft assembly. These parts are shown, res
pectively, to the right, centre, and left in Fig. 1, and
assembled together in Fig. 4. The driven shaft can
be coupled to the planet-wheel casing at will, by
means of the multiple-plate clutch, clearly shown in
both figures, and the casing itself can be either held or
allowed to run freely by means of the band brake shown
in Figs. 4 and 6. The operation is as follows : Assum
ing the gear to be in the neutral position, shown in
Fig. 4, both the clutch and brake will be free. In
these circumstances, the planet-wheel casing will spin
round freely, as less resistance will be offered to its
motion than to that of the driven shaft, to which the
propeller is, of course, coupled. For the ahead posi
tion, the control handwheel, shown in Figs. 3, 4 and 6,
is turned in the direction to raise the nut threaded on
the lower end of its spindle. This nut can be seen in
Figs. 3 and 4, and it will be noticed that it is mounted
in the forked end of a lever. At its centre, this lever
is keyed to the brake-operating shaft, shown in Fig. 6,
passing over the top of the brake drum. The other
end of the lever is also forked, and is connected by a
link, as indicated in Fig. 4, to the clutch control gear.
The operation of the clutch, through adjustable
fingers, will be obvious from this figure, and from
Fig. 5. The rise of the nut on the handwheel spindle
rotates the brake-operating shaft in the direction to
free the brake, and actuates the cam-shaped sliding
sleeve, clearly seen on the driven shaft in Fig. 4.
The sliding of the sleeve aft causes the rollers to
mount the cam, the other end of the roller lever
coming into contact with the master plate of the
clutch, the pressure exerted being adjustable by means
of operating screws. When the clutch is fully engaged,
the pinion on the end of the driven shaft will be coupled
to the planet-wheel casing, and since this will prevent
relative rotation between this pinion and the planet
wheels, a direct drive will be obtained between the
two shafts, the whole gear rotating as one piece. For
the reverse motion, the handwheel is turned in the
opposite direction, lowering the nut to tighten the
F ig. I. C omponent P abts of G ear.