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Page SII
Fue/ lnjection System-conlinued
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FIG. 57. Atomiser Testing Pump.
ExaminadoD and TestiDg.
A bench suitable for working with atomisers is
preferably linoleum-covered with glass 00 top.
It should he enûrely reserved for this work and
kept absolutely free from din. The use of cotton
waste or fluffy rags must be absolutely forbidden.
The bench should have a dust proof drawer
for holding the atomiser cleaning tools and equip-
ment described in detail below.
A plate, made up as shown in Fig. 5.6, should
he secured to the bench. lts purpose is to hold the
atomiser securely whilst various maintenance
operaûons are proceeding.
An atomiser testing pump No. ET .122A (Fig. 5.7)
should he available. This outfit bas been specially
designed to provide a reliable means of tesûng
and setting the atomisers. It is made up of parts
similar to the injection equipment fitted to engilles.
The doubtfuI atomiser should
be removed from its wrappings
and fitted nozzle downwards, and
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still unwiped, (0 the testing pump
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No observaûons should be
made until at least ten fuil strokes
of the hand pump have been given
to expel all air from the system.
Atomiser Pressures.
The pressure at which the spray
breaks should then be recorded
and checked against the recom-
mended pressure which is 120
atmospheres.
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The only exception is in the case of atomisers
fttted to L4 Engines installed in Marshall Crawler
Tractors where the setting is 160 atmospheres.
Atomisers set at 120 atmospheres have white
painted caps and the caps of atomisers set at 160
atmospheres are painted silver.
An altemative means of identiftcation is a tab
washer fttted under the atomiser cap nut bearing
the letter .. J " for 120 atmospheres, or the letter
" V .. for 160 atmospheres.
L4 atomisers supplied under the Perpetuity
Scheme have green painted caps with white Ol
silver on the top or a tab washer under the atomiser
cap nut signifying the setting and type.
The spray should now be observed for uni-
formity at a rate of pumping of not less than
20 strokes per minute.
Each should be a misty spray spreading to about
3 inches (75 mIn) diameter at about one root away
from tbc atomiser nozzle, then breaking into a
vcry Me mist. There should be two sprays from
cach atomiser nozzle, one pointing outwards from
the top hole, and the other pointing downwards
from the lower hole, when the atomiser is in a
position correspunding to its working position.
An atomiser is good for service if, when operating
tbc atomiser testing pump at the abovc speed, it
gives two etfectivc sprays as above described.
An atomiser is dirty and requircs recondition-
ing if (a), when procceding as abovc it throws out
solid wet jets and not braken up spray or (b),
if eithcr of the holes are choked or partially choked
so that spray issues from one hole in the
atomiscr only or appreciably more spray issues
from one hole than the othcr.
In this connection, as tbc Perkins enginc idles
at about 500 r.p.m. the atolniser is never called
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'TOMIS" 00.., ,.asu.. 'Acr
NO~
VALV!
the letters have
'rCMISD
NOULI
FIG. S8. Diagrams of Atomiser and Atomiser Body
referencc in the lext.
J
J
J
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