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FLIGHT

MAGNETO

ROLLS-ROYCE

GRIFFON

(65)

the war the Griffon was rather displaced by the

Vulture until the latter Griffon was resurrected engine than the Merlin

necessity.

The

various

was discarded, then the as the need for a larger was again realised as a marks of Merlin Spitfires

ENGINE COOLANT OUTLETS TO HEADER TANK

were

capable

of

handling

enemy

aircraft

at

height,

but.

when

the

Fw 190

was

de-rated

to

mum performance low down we were pressed. A quick decision was reached

give

maxi-

somewhat to put the

MAGNETO INCLINED DRIVE

Griffon II came the numbers,

into some Spitfire VIII's, which then be- mark XII; these were built in limited but effectively squashed the opposition.

F.A.A. and R.A.F. Requirements

'] hese models of the Griffon wer,e all fitted with single-stage, two-speed blowers, and this basic type has progressed for Fleet Air Arm use (vide the Fairey Firefly), whilst the special needs ofthe

AIRSCREW REDUCTION WHEEL

  • R.

    A.F. have

    • -

      stage engine

been met by the two-speed, two-

for

high-altitude

use.

As

may be

expected, the Grifton owes a fair amount to Merlin

development, that various Griffon have Merlins.

but what is peculiarly interesting is practices initially proved on the

been

incorporated

in

the

later

Basically the engine is, of course, on the same lines as the Merlin, although the detail design is new pretty well throughout. Oneofthe most important innovations is in taking the cam- and mag-drives

CAMSHAFT-

STELLITE-

Detail of front end showinghow •cam drive and magneto drive are taken from re- duction gear.

VAIVE ROCKER

ROCKtR SPINDLE

from

the

front.

This

was

decided

upon in order to relieve operation from as much

the valve variation

.BRIDGE-PIECE

as possible: semi-floating

by interpolating a coupling between the

crankshaft

and the driving

wheel

of

the reduction gearing and, in tion, by taking the camdrives

addi- from

the

airscrew-driving

gear,

angular

variations

in

crankshaft

speed

are

I COOLANT CONNECTION1 I FROM SKIRT TO HtAO

greatly sion to

reduced in their transmis- the camshafts. Further, air-

screw inertia constant rate

results in a reasonably of r.p.m., and,to top-

off the allows 'overall

advantages, the front drive

a

comparatively

shorter

length

which,

in

turn, per-

mits the larger and more engine to go into existing

powerful fighters

.._ CYLINDER BLOCK SECURING STUD

Whilst onthe subject ofthe cank- shaft, we might as well deal with

that interesting component. ol course, machined all over

It is, from a

  • --

    BUBBERRING

  • -

    0 1 BRAIN TO CRANKCASE

C8ANKCASE'

forged billet,

and is fully

counter-

balanced, the

front throw

of No. 1,

cection through cylinder and head illustrating simple valve gear and large coolant areas.

Three-quarter front view of crankshaft with semi-floating toothed annulus in front coupling. Note the detachable counterweights on crank throws.

SEPTEMBER 2OTH,

1945

PORT CAMSHAFT DRIVE

both throws of No. 4 and the reai throw of No. 6 bearings each hav- ing a separate balance weight bolted to them. Vibratory troubles inthe crankshaft have been very few, but a pointer to the Derby standard is that the firing order geography was selected to give optimum crankshaft harmonics.

Crankshaft Lubrication

Perhaps the most novel feature of the crank assembly is that the main bearings and big ends are all

lubricated from the hollow interior

of the novel, having

shaft.

This scheme, though

is by no first tried

means new, Rolls it years ago ; how-

ever, the Griffon engine in which it

is the first has become

Kolls .prac-

tice. Feed is into each shaft and,in addition to pressure, shaft rotation

end ofthe the system provides a

"built-in"

centrifuge.

A great is that the

advantage

of the system

amount

of oil supplied

to each

bear-

ing is not influenced by shaft / bearing movement.

relative Jn ad jr"""

tion, each main journal has internal standpipes which act as sludge traps as well as permitting, by a variation in their diameter, a means

of

metering

or controlling

amount of oil supplied ticular bearing.

to

any

the par-

Another interesting feature ofthe crankshaft is that it is rigidly connected neither to the front nor

the rear driven members. front end an internally annulus is bolted on, this

At the toothed meshing

with ring

and housing

which

itself

a

semi-floating is internally

splined to a coupling latter is splined at its

shaft. The front endto

the

driving

wheel

of

the

reduction

gear

so

that

this

mechanism

is

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