1948-04-15 — Page 8

BE CHINA MAIL, THURSDAY, APRIL 18, 1948.

"YORK"

REFRIGERATION AND

AIR CONDITIONING EQUIPMENT

-

THE JARDINE ENGINEERING

CORPORATION LTD.

14-10 PEDDER STREET, HONG KONG,

Telephone 30311.

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The KELLEFLEX

ENGINEERING PAGE

THE PHYSICS OF ARC

It has sometimes been said that the high efficiency of many types of electrical machine may be attributed to the fact that the

WELDING

conclusions of one investigator, which are quoted, are that the purposes of the coverings are to dissolve impurities in the plate and thus act as fluxes; to change the surface tension of the molten metal and thus make tho

dow more uniform; and increase aro stability by introducing materials

Although coated molarily or alternating | In the first case, a comparatively which are easily lonised in the

which

G

Perkins

DIESELS

A Power Motor Cruiser smaller and leave

trode are insulated so that the 用 concentrated at the tip.

this netion being of Importance

theoretical basis on which they in the downward,” horizontal, [as large globules falling under operate is well understood and vertical and overhead positions; gravity, as smaller globules pro- that their, performance and vari- it may be carried out with bere,jected from the electrode tip, or lowes lend themselves to dipped, lightly coated and heavily as a shower of fine particles or precise measurement.

direct current droplets with appreciable velocity outputs

of mechanical

prime of either movers and other appilances may current may be employed; and it large quantity of the electrode arc streami, These effects occur be accurately determined,

ed, the may be

be utilised with a

electrodes. of melted and the hanging drop with lightly-coated sorting out of the various in-ferrous and

a variety of non-ferrous metals.

rod With 'a heavy covering, #ddi- separated from the welding fuences which affect their em- These very varied conditions can

Iew seconds under the tional actions occur. ciency is difficult and sometimes

imes not necessarily be combined at combined

action gravity, the the impossible, so that the improve random, but all are aspects of pinch effect and

A reducing or non-oxidising the ment on earlier days which has some sphere of practice, and al- turbulence of the arc

atmosphere is produced around! now been achieved is mainly though there must be some This type of action usually takes of the metal in the are by oxygen the arc, preventing contamination based on ad hoc experiment, fundamental factors basic to the place in an inert atmosphere. Al- and nitrogen in the air; a layer which, however, has been sup-welding process, they have, so though gravity may be of some of slag is provided to protect the ported by much theoretical rea- far, not been traced amid the effect when large globules soning.

are molten metal in the weld pool;; widely varied types of procedure

formed, it is

is clearly not a funda- the cup provided around the end An exception to the super which are possible. The report mental factor in transference of the electrode concentrates and fority, or advantage, of electrical states that "there appears to be since overhead welding is pos directs the arc; metal may be methods in this matter of accur- no one criterion which must be sible. In

diatomic gases, ate and selective measurement satisfied in all welds." Might it particles are

the introduced to alloy with the wald

metal; and the aides of the elec appears to be furnished by are be suggested that the true pori- the electrode at the rate of 10 to welding

as the physical and tion is that that criterion has not 20 per second, but

but the method chemical terma which define the yet been discovered?

by they are

are propelled requirements

of a satisfactory The report is divided into three not fully understood. When the weld are, to a large, extent, un-secviong dealing, respectively, welding are is short, these Pro known

Arc welding has now with "Transfer of Material in cesses are modified; the molten

Among the comments made on established a Orm position both Welding

and "Stablilty at is severed by the pinch effect and are that the term "non-oxidising" use in the field, but, desplie much Welding Ares." The fint of drawn into the weld pool by sur-] can hardly be applied to gases theoretical And experimental these is concerned with the prac-face tension. The fine shower evolved from a cellulose coating work, its development appears to tical aim of electric welding; the of particles moving with appre- since, at the are temperatures have been essentially empirical, others are incidental conditions clable velocity is associated with existing, most of the gas will be It is hardly too much to say that of the process. The review of the presence of oxygen or special the definition of a good welding the literature of the subject electrode coatings. method is

one that produces which is presented appears to good weld.

establish that some 60 per cent. This point of view is sustain-of the transferred metal crosses ed by recent technical report, from the welding rod to the weld published by the British Elec-in a liquid state and about 10 per In view of the wide variations trical and Allied Industries Re-cent, as condensation and vapour. of practice the function and ac search Association, from which | Experiment indicates that tion of electrode coverings is of the quotation in the preceding material traverses the gap either' interest and importance. The molten metal, less oxides and paragraph has been taken. The report has been prepared in co- ing Research operation with the British Weld- Association. Its contents give an indication of the large amount of experimental work which has been devoted to

the

В

when welding in a deep V groove.

workshop method and for Welding ***," "Temperature of metal short-circuits the arc and these conclusions, in the report,

Wide Variations

A New Mobile

dissociated; and further, that

Ren is

required for crater formation, which occurs when welding with heavily-coated rod. The arc, however, behaves aimilarly to one in an atmosp of carbon monoxide and gen and the reactions are such that, during the cooling of the

nitrides are finally formed than in the case of the bare

Crane

atr.

If

Stability

rod In

Few mobile cranes on lorry together on the prepared site in problems of are welding, but chassis can have been constructed 20 minutes. Several of these M.

In connection with the ques- are not able

record any gen-with alifting capacity greater E. cranes have since been deliver tions of temperature and stability, erally-accepted opinions about than that of the Foden eight-ed or are on order, they have is stated that "ather things be- the physical basis of the process. wheeler, with specially reinforced obvious advantages at the presenting equal...the stability is de- But little consideration la neces-chessis.

for

time when mobility is an invalu pendent on the are temperature" The chassis frame is made up able asset. Unlike the more con are stabilising produced by elec- Д realisation of the

con- and that "probably part of the dimculties attached from a reinforced rolled steal ventional four-wheeled mobile

- investigation of the

joist or 18 in. depth and inte- crane, which has restricted road) trode conting la due to the ordi-

arc at

maximum

by

ay not available:

particularly in view of grally carries the crane turret and speed, these units are capable of tion of elements of low ionising the fact that any instrumental the four Jacking beams. Special 20 m.ph. and are therefore ideal- patented to the are column, there- procedures which may be adopted rear, bogle road springs are, of ly suited to purposes whi

which in-

reducing temperature." for the purposes of observation cou

course, fitted. With standard 200

30 volve lifting or digging operations temperature has been carried out The measurement of the are and measurement may, in them.b by 8 in. tyre equipment the at

the at a number of scattered sites, by various methods,

which in selves, alter the

the recommended load figure of two with a minimum the quality of phenomenon under investigation. tons per tyre is alightly exceeded travelling time.

of delay include the introduction of probe It is clear that the basic factor and a tyre pressure of 105 lb. able load capacity and immediate measurement of the electron cur

Their consider-into the electric discharge and In arc welding must be the arc, per sq. in. is required. The com- availability once on location are rent flowing to it; estimation from but "little of a fundamental na-plete machine is 23 ft. 3 in. In attractive features. ture is known about the electric overall length and

gas-density measurements, in-

the com atmospheric

volving knowledge of As width is 8 ft. For travelling pur- cric pressure."

of the are gases, which the report is concerned with elec- poses, the. Jlb (shortened to 30 iric welding as a practical pro- ft.) in

sound- supported over, the cab does not enter Into and overall height is then 13 ft.

velocity method in which a high- a consideration of the Various

intensity sound wave is passed 2005 in. theories of the physics of the arc

through the are; and pyrometric per se which have been advanced.

A new type of electrode boller, measurements. Stability in prac- Ita subject in the summarising of

with an efficiency of 97 to 98 per tical walding means that the are available information on the

cent. in which steam can be is easy to maintain in spite of phenomena peculiar to welding

raised in from five to seven min- continual change in physical arca, and its object is to draw

utca

itch conditions. merely by "closing a switch, attention to the more important

dustries Fair in Birmingham, stability is dependent on the are will be shewn at the British In- "Other things being equal... felds in which further research is desirable.

temperature Electric temperature...high

Works, welding aros tend to be unstable."

cess

A Wide Field!

As is pointed out, the condi- tions under which successful are welding may be carried out cover a wide field. It may be applied

OR KELLER'S FLEXIBLE SHAFT MACHINE IS A MECHANICAL MUSCLE

. 1/8 H.P..to 3 H.P.

WHICH WILL PERFORM COUNTLESS JOBS -RANGING FROM THE MAKING OF SMALL JEWELRY DIES TO THE FINISHING OF LARGE-

CASTINGS.

This is a new small, high speed, Kellerflex machine, Model JB-O, parilcularly designed for work with small grinding wheels and Gem points as well as fine burs. It will be found of great value in Anishing dies, molds and all sorts of tools. Silversmiths, jewelers and the glass and rubber Industries and others will find this machine a great labor saving device. There is plenty of surplus power in its H.P. high speed, ball bear Ing Universal motor.

Offered by

YU TUNG TAI LTD.

Department

PRATT & WHITNEY, WES

"sis Queen's "Bldg: Tel 29145; On babhif, of MIRZAS NACE HARTFOR CONN NILES:REMENT-

Crane Or Excavator

manufac-

NEW ELECTRODE BOILER

Known as the M.E.C... (mobile excavator_crane) and tured by Thomas Smith and Sons, this equipment has great possi England,

wide а range of duties, Furnaces Ltd. including crane operations

bilities

In

by G.W.D.

all the usual digging, excavating from May 3 to 14. The boller Buctuations, it is suggested that and piling movements.

In many from cases it will replace

controlled automa- further work is desirable directed three-pressure is A leg derrick and save the time and cally and an auto-load control to a rapid, and preferably direct, expense involved in erecting and of steam raised does not exceed ture. which is

device, ensures that the amount method of measuring tempera- probably the fundamental factor in stability.

and Dudley, Word, England. As the arc is subject to rapid

dismantling a a derrick. The crane the demand. structure revolves on a live ring

a

of twelve tapered rollers and is connected to the chassis by centre spigot and three hook rollers. The crane machinery in essentially that of the Smith Five- Twenty excavator, including Fowler 55 b.h.p. engine and hydraulic coupling; a similar mo- bile crane for a Leeds public Work

contractor has electric

drive.

the

Holsting speeds vary according to the blocks used; if a two-part block Is employed, maximum speed is 68 ft. per min., If a four- part block, then it

it in 84 ft. per min. Slewing speed enables one complete revolution to be

made minimum time of 20 High tensile steel in welded sec-

makes up the Jib, the sec tions being joined by nickel steel pins which facilitate speedy erec- tion and dismantling of the jib and its conversion in length when desired. There are in All six sections, giving centres of 30, 40, 60, 76 and 90 11.

tions

Load Ratings

Load ratings with Jacks down are as follow-

Jib length" "Load

45 ft.

75 ft

Radius

12 tons 10 ft.

D ́tors

60 21. 7 tons

90 ft.

24 ft.

20'IL

17 ft.

5 tons 35% to 25 It

Test loads considerably in exe cess of the above hayo, been such |cessfully lifted. Without" packing bozma, in use, tests showed that five tone could be lifted at 101£t. radium

the 30 ft. lb.

with

..

3.3 cu. ft. MODEL

THESE UNITS NOW IN STOCK.

7 cu. ft. model, similar to the 4.4 cu. cabinet shewn, is now in production,

AGENTS

Twin Parking § 8 M*Engines.

F. PERKINS LTD.

MAKERS OF

VEHICLE, MARINE & STATIONARY DIESEL ENGINES

SOLE AGENTS

GILMAN & CO., LTD.

ENGINEERING DEPARTMENT Telephone: 81148.

CARTER & SUTTON

Employed On Housing FAR EAST ASSOCIATED MERCHANTS Ltd.

Sites

TA

TAS"TIFIT" "JOU5%" given the vehicle” was the placing on, sites an Boulland - oly fabricalad

jaliministas" hotare, most

Tosa #atločia, which house Armye complet

and cea

DISTRIBUTORS.

REISS, BRADLEY & CO. LTD.

Mutjanai". Oity Rank: 26 New York, Buliding :400

INDUSTRIAL AND COMFORT

Air Conditioning

23GA HONG KONG &

Engineers SANGHAI BANK BLDG.

Telephone 28904.

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