4306 4310.output

* GB784713 (A)

Description: GB784713 (A) ? 1957-10-16

Improvements in fire-alarms for combustible material

Description of GB784713 (A)

PATENT SPECIFICATION

Go Date of filing Complete Specification July 12, 1955.

Application Date July 14, 1954.

Complete Specification Published Oct 16, 19570

Index at Acceptance:-Class 118 ( 1), D( 1: 4).

International Classification: -GO 8 d.

COMPLETE SPECIFICATION

Improvements in Fire-Alarmn for Combustible Material We, THE BRITISH

CECA COMPANY LIMITED, a British Joint Stock Company, and JOHN RONALD

FOXCROFT, a British subject, both of 175, Piccadilly, London, W l, do

hereby declare the invention, for which we pray that a patent may be

granted to us, and the method by which it is to be performed, to be

particularly described in and by the following statement:-

This invention relates to fire-alarm apparatus for detecting incipient

combustion in a stack or layer of granulated combustible material

exposed to air or other gas containing oxygen The combustible material

may be, for example) ian adsorbent carbon, Catering charcoal or

granulated carbon having a catalyst deposited thereon.

Combustion detectors or fire-alarms for this purpose generally

comprise a number of ternperature-sensitive elements or tappings

distributed in the combustible material, for ex ample electrical

elements of resistance varying with the temperature; these detectors

generally involve delicate and expensive apparatus.

Fire-alarm systems are also known comprising one or more pipe lines

containing fluid which is maintained at a pressure different from that

of the atmosphere by a pump, each of said pipe lines being fitted with

one or more fusible plugs by which the pipe is vented to the

atmosphere automatically when the temperature rises above a preset

limit, the said pipe or pipes being connected to one or more pressure

actuated devices by which an alarm is given when a change of pressure

occurs in the pipe line owing to the opening of one or more of the

fusible plugs.

The present invention consists essentially of an alarm comprising at

least one continuous detector tube, made of fusible or thermally

plastic material, to be arranged in the combustible material, means

for connecting one end of the tube to a source of fluid pressure, and

means for connecting the other end of the tube to a device sensitive

to said pressure and adapted to control an alarm signal, normally

holding it out of operation, in such a way that melting or softening

of the detector tube due lPnu.

to rise of temperature of the combustible material will reduce the

pressure in the tube 50 and cause the operation of the alarm signal.

When spontaneous combustion or ignition occurs in the combustible

material, combustion is maintained by the air traversing this

material, and an incipient fire is created which 55 is liable to

spread gradually through the material When the heat reaches the

vicinity of a detector tube, the rise of temperature immediately or

very soon causes the melting or softening of the fusible or plastic

tube where 60 by the pressure therein is reduced, so that the alarm

signal operates.

One er more detector tubes may be provided, and the tube or each tube

may have the shape of a sinuous line with numerous bends 65 to and fro

within the combustible material.

The invention is hereinafter described with reference to the

accompanying drawing, which illustrates diagrammatically an embodiment

comprising two detector tubes a, b, arranged 70 in parallel and both

connected at one end by way of a pipe c fitted with a pressure gauge

d, safety valve e and reducing valve f, to a single source of gas

under pressure at g, and connected at the other end by way of a second

75 pipe k fitted with a pressure gauge i to a single alarm-control

device j This device consists of a pressure switch in the form of a

bellows normally holding down a counterweighted contact arm k so as to

keep open a pair of 80 contacts t in an electric circuit m energized

by a mains supply at N and including the winding o of an audible alarm

such as a bell p.

If it is desired to supervise a stack of combustible material

comprising several beds or 85 layers q, as shown, each tube a, b may

control two or more beds or layers connected in series.

Each tube has preferably the shape of a sinuous line with numerous

bends to and fro within the combustible material, as shown, the 90

parts of the tube being sufficiently close together for melting or

softening to occur at some point thereof after a fairly short time of

heating.

A system of valves r may be provided for 90 isolating the several

tubes; when the alarm 704,713 No 20561/54.

784,713 signal is operated, due to melting of a tube a or b at any

point and resulting closure of the contacts 1, it will then be

possible by closing the several valves r so as to isolate the tubes a,

b in turn, to identify the tube wvhich has melted and thereby to

determine the precise situation of the incipient fire For example, if

the closing of the two valves r on the right, which isolate the tube

a, does not stop the alarm, then the failure must be in the other

detector tube b Where each tube controls two beds or layers, as in the

embodiment illustrated, a third valve S may be interposed in each tube

between the two beds or layers, which will allow a further

determination of the particular bed or layer in which the incipient

fire is located.

In another arrangement, each bed or layer may be provided with a

separate detector tube, or again each tube may control a given zone of

one and the same layer covering a large area, the several tubes being

connected in parallel and fed from the same source of pressure.

The alarm may be tested from time to time by means of a test cock t

which will allow the fluid pressure to escape from near the control

device j The pressure gauges d and i will show at all times whether

equal pressure is maintained throughout the apparatus and the latter

is in proper condition for operation; any difference between the

readings of the two pressure gauges will indicate that leakage is

taking place, due for ex ample to a small local failure of a detector

tube.

The detector tubes a, b may be made of lead or of another metal or an

alloy melting at relatively low temperature, or they may be made of

plastic material, such as nylon or polyvinyl chloride, which softens

sufficiently under relatively low heating to reduce the fluid pressure

just as with the melting of the fusible tubes.

The gas employed is preferably inert as regards combustion, for

example nitrogen, but in some cases the tubes may be connected by way

of the pipe c to a compressed air line under constant pressure, where

the use of an inert gas is not considered necessary.

Where several beds cr layers of combustible 50 material are providerd

with separate detector tubes, each bed will have its own alarm control

device, each bed being thus self-contained; in addition to controlling

the audible alarm, common to all the beds or layers, each control 55

device may cause the lighting of an individual warring lamp to

indicate which bed or layer has developed the excessive rise of

temperature.

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* 5.8.23.4; 93p

* GB784714 (A)

Description: GB784714 (A) ? 1957-10-16

Improvements in or relating to spark gap arrangements



Inventor: HORACE FREDERICK JONES 784,714 Date of filing Complete

Specification Aug 30, 1955.

Application Date Aug 6, 1954.

Complete Specification Published Oct 16, 1957.

No 22947/54.

Index at Acceptance:-Classes 22, J( 2: 17: 28); and 39 ( 1), D( 8: 12

86: 38).

International Classification: -C 04 b H 01 j.


Improvements in or relating to Spark Gap Arrangements We, THE GENERAL

ELECTRIC COMPANY LIMITED, of Magnet House, I Kingsway, London, W C 2,

a British company, do hereby declare the invention, for which we pray

that a patent may be granted to us, and the method by which it is to

be performed, to be particularly described in and by the following

statement: -

This invention relates to spark gap arrangemenrits for use in electric

surge diverters Electric surge diverters take a number of forms and in

one known form, a plurality of metal electrodes are spaced apart in a

stack, the gaps between the electrodes being defined by spacers of

insulating material The usual material used for this purpose is

steatite and one object of the present invention is the provision of a

spark gap arrangement which shows great advantage over the known

arrangements.

According to the present invention, a spark gap arrangement for a

surge diverter includes at least a pair of metal electrodes spaced

apart or separated by a spacer or member of insulating material of

high permittivity compared with steatite.

One particularly suitable material is bariumor

barium-strontium-titanate with a small addition of zinc titanate and

spacers of either of these materials may be made up in the form of

flat rings, the rings being disposed in a stack and separating a

plurality of circular plate-like brass electrodes.

In order that the invention may be clearly understood, one

construction of a multi-spark gap arrangement of a surge diverter and

in accordance with the invention will now be described by way of

example with reference to Figures 1, 2 and 3 of the accompanying

drawings in which Figure 1 shows a side view partly in section of the

arrangement, Figure 2 shows a side view of a spacer and Figure 3 shows

a top plan view of a spacer Figure 4 shows a side view, in section, of

a modification having inserts to improve the impulse sparkover ratio

of the arrangement.

lNce 3 s 6 d l Referring now to Figures 1, 2 and 3, the multi-spark

gap arrangement comprises a plurality say, eighteen, circular

plate-like brass electrodes 1 ail of identical form and pressed 50 on

one side with one or more protuberances 2 arranged to act as sparking

regions Except for the two electrodes 1 at the two ends of the stack,

the electrodes are grouped in pairs back to back with the

protuberances 2 direc 55 ted outwardly, and the protuberances of the

end electrodes are directed inwardly, that is, towards the

protuberances of the adjacent electrode 1 Between the adjacent pairs

of electrodes 1 and between the end pairs and the 60 single end

electrodes 1 are disposed spacers 3 of insulating material of high

permittivity and these spacers are in the form of flat rings or short

hollow cylindrical annuli of outer diameter equal to the diameter of

the electrodes 65 1 The end faces of the spacers are ground flat and

conform with the adjacent electrode surfaces and in order to malke

good electrical contact with the metal electrodes, the end faces are

silvered This silvering may be effected 70 either by firing on a

silver paste of known type or by metal spraying, and the inner and

outer peripheral surfaces, the curved surfaces, of the rings are

protected against surface tracking by coating with a good

anti-tracking glaze 75 or varnish.

One composition of spacer found suitable in an experiment had the

composition 9 99 mole (Ba, Sr) Tio, 01 mole Zn Tio,, the ratio of

barium to strontium being 65:35 This 80 composition was made up by

using quantities of barium carbonate, strontium carbonate, titanium

oxide and zinc oxide in the following specimen amounts:Ba CO, 1270 g

85 Sr CO, 511 4 g.

Ti O 2 791 8 g.

Zn O 0 814 g.

and the constituents were milled together under water, filtered, dried

and sieved, pressed 90 into blocks with a suitable binder and fired in

an electric furnace After firing, the blocks2 784,714 were crushed,

milled dry and then -wet, filtered and dried again, mixed with a small

amount of camphor as a binder and pressed into spacers of the desired

size The pressed spacers were then fired with or without a glaze on

the curved surfaces and finally given surface grinding on their flat

end faces.

Spacers formed by the method and of the composition described above

have a peak permittivity of the order of 12000 at 12 C and a

permittivity greater than 3000 over the temperature range minus 20 C

to plus 45 ' C.

This value is high compared with that of steatite usually used which

is of the order of 6 and where the expressions "material of high

permittivity compared with steatite" and "material of high

permittivity" are used in this specification and its claims, a

material is meant whose permittivity is measured in hundreds or

thousands rather than in units or tens as is steatite The power factor

of the spacers is of the order of 0 01 at 255 C rising to a peak at G

C, the d c resistance at 500 V greater than 1000 megohms for a spacer

a" thick, about 2 " external diameter and 15 " internal diameter, and

the breakdown voltage for such a spacer about 7 k V.

Spacers of the nature described above are very effective in reducing

the impulse sparkover voltage and in improving the operating

consistency of surge diverter spark gaps The relation of spark-over

voltage to the number of gaps is practically linear for both power

frequency and impulse voltages and the effect of impulse polarity on

the spacers appears to be negligible Spark gap arrangements according

to the present invention may be mounted in air nitrogen or other

suitable inert gas and may be housed in standard sealed containers and

in series with non-linear resistors in known manner, the spacers of

high permittivity associated with each spark gap in air, nitrogen or

other suitable inert gas producing intense loca' ionisation when a

voltage approaching the breakdown value is applied Due to the high

capacitance of each section, the voltage grading on the ordinary 50

cycle power frequency supply is better than with known spark gap

arrangements using steatite spacers.

Referring now to Figure 4 which shows the modified construction and in

which the same reference numerals have been used for those parts

similar to parts in Figures 1, 2 and 3, the electrodes 1 are again

provided with protuberances 2 and separated by spacers 3 of high

permittivity In order, however, to improve the impulse spark-over

ratio of thed arrangement, with each gap is associated a Tsection

cylindrical insert 4 of material similar 60 to that used for the

spacers 3, each insert 4 being a press fit in an aperture 5 in one

electrode 1 of a pair of electrod:s of a gap and there being a small

gap between the end of the insert and the other electrode of the rair

Each 65 insert acts as a pre-ionising member upon the gap being

subjected to ar over-voltage, to facilitate breakdow-n of the gap and

thereby to improve the impulse spark-over ratio of the complete

arrangement 70

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* GB784715 (A)

Description: GB784715 (A) ? 1957-10-16

Churn



Churn

We, LA CIA J. A. GOSSELIN LIMITeES of Drummondville, Province of

Quebec, Canada, a Canadian Company, do hereby declare the invention,

for which we pray that a patent may be granted to us, and the method

by which it is to be performed, to be particularly described in and by

the following statement :-

The present invention relates to machinery for making butter and more

particularly to a combined churn and butter worker.

The general object of the present invention is the provision of a

combined churn and butter worker having novel means for access within

the churn drum, improved means for maintaining suitable temperatures

for the cream during the churning operation and for the butter during

the working operation, and novel means for thoroughly washing the

butter in the drum or the churn itself when empty.

A more specific object of the present invention is the provision in

acombined churn and butter worker of means, easily operable from an

exteriorly controlled valve, which will alternately circulate water in

the drum beaters in order to maintain the temperature of the cream or

butter at the most suitable temperature for efficient churning and

working, and inject water directly into the drum so as to thoroughly

wash the same when empty or to wash the butter contained therein free

from the buttermilk prior to working.

An important object of the present invention is the provision of a

butter churn and worker in which the drum has a cylindrical shape and

is supported only from one end thereof while its outer end is provided

with a central circular manhole for easy access into the interior of

said drum whatever be the angular position of the same.

Still another important object of the present invention is the

provision in a combined churn and butter worker of an improved drain

valve for drawing off the buttermilk and wash water after the churning

operation while retaining the butter in the churn drum, said drain

valve being easily and quickly removable from the drum for cleaning,

repairs or other purposes.

Still another important object of the present invention is the

provision of an improved air vent for the drum of a combined churn and

butter worker of the type described.

Yet another important object of the present invention is the provision

of a drum for a butter churn which is constructed of metal and

provided with beaters so designed as to renforce said drum.


of a combined churn and butter worker which will give a prolonge and

trouble-free service.

The present invention also relates to a leakproof closure for butter

churns and the like.

Doors for hermetically closing drums or other receptacles under

pressure, and more particularly butter churns, are provided with a

complicated mechanism in which a plurality of wheels or levers have to

be rotated for opening or closing the door.

The operation of this mechanism is time consuming especially in

connection with a butter churn which has to be opened and closed

several times during one churning operation.

Accordingly, a further object of the present invention is the

provision of a drum door and clamping ring therefor which will obviate

the above mentioned defect.

Another important object of the present invention is the provision of

a drum closure of the character described which is readily and easily

opened or closed.


of a door closure of the character described which will be completely

leakproof for both liquid and gases and in which a uniform pressure

will be applied on the entiro periphery of the door.

Still another Important object of the present invention is the

provision of a drum closure of the character described which is

relatively simple and inexpensive to manufacture and will give a

prolonge service.

The foregoing and other important objects of the present invention

will become more apparent during the following disclosure and by

referring to the accompanying drawings in which :-

Figure 1 is a perspective rear end view of the churn according to the

invention.

Figure 2 is a side view mainly in longitudinal section of the same.

Figure 3 is a broken fractional longitudinal section of the same.

Figure 4 is a fractienal elevation of the rear end wall of the churn

drum showing the beaters in cross-section.

Figure 5 is a section along line 5-5 of

Figure 4.

Figure 6 is a longitudinal section of the drain valve of the churn

drum.

Figure 7 is a perspective view of said drain valve about to be removed

from the churn drum.

Figure 8 is a perspective view of the drain valve plug and filter in

disengaged position.

Figure 9 is a fractional elevation of the same elements in assembled

position.

Figure 10 is a fractional sectional view of a bayonet joint used for

securing the filter to the drain valve plug.

Figure 11 is a sectional elevation of the air vent provided for the

churn drum.

Figure 12 is a view at right angles of the e same.

Figure 13 is a longitudinal section of the thermometer assembly

provided in the churn drum.

Figure 14 is a view at right angles of the same.

Figure 15 is an elevation of the drum closure according to the

invention in closed position.

Figure 16 is a cross-section along line

16-16 of Figure 15.

Figure 17 is a detailed cross-section of the door assembly showing the

clamping ring in non-clamping position.

Figure 18 is a cross-section similar to that of Figure 17 showing the

ring in clamping position.

Figure 19 is a partial longitudinal section of the door assembly

showing the clamping ring in non-clamping position; and

Figure 20 is a section similar to that of

Figure 19 showing the ring in clamping position.

Referring now more particularly to the drawings in which like

reference characters indicate like elements throughout, the numeral 1

denotes a base of substantially rectangular cross-section supporting

and forming a housing for the driving mechanism of the churn. The rear

face 2 of the base 1 is provided with an opening normally closed by a

removable closure 3. The base 1 is surmounted by a hood 4 which is

also removable.

Said base supports an interior frame 5, shown more particularly in

Figure 2, by means of corner bracket 11 and bolts 5'. A heavy duty

bearing 7, the axis of which is horizontal, is mounted on the frame 5

and projects through the front 6 of the base 1. The frame 5 is

provided with a rearwardly extending yoke portion 8 passing through a

rear opening 9 of the hood 4 and terminated by a vertical ring 10

coaxial with the bearing 7. A rearwardly extending hood 12 is rigidly

supported by the ring 10 to which is secured, by means of a bolt 13,

an inner projection 11 of said hood.

The front portion of the hood 12 engages the opening 9 of the hood 4.

A cover 14 and flanged bushing 15 are rigidly secured to the ring 10

by means of bolts 16. The ring 10 and bushing 15 support a ball

bearing 17 as shown in Figure 3.

A hollow, horizontally disposed shaft 18 is journalled in bearings 7

and 17. Said shaft 18 has a tapering rear end portion 19 abutting

against the ball bearing 17 and is provided with an inner cylindrical

tubular extension 20 rigidly secured thereto and journalled in the

ball bearing 17. The hollow shaft 18 has an intermediate portion 21 of

conical shape which increases in diameter towards its front end, and a

cylindrical portion 22 journalled in the bearing 7 and termmated at

its front end by an outward radial flange 23.

The churn drum, generally indicated at 24, is made of metal and has a

cylindrical shape.

Its rear end wall 25 is slightly concave and is secured to the flange

23 of the hollow shaft 18 by means of bolts and nuts 26 in such a

manner that the drum 24 will be coaxial with the shaft 18.

The front end wall 27 is also slightly concave and is provided with a

central circular manhole 28 which may be closed by a quick acting

hermetic closure 29 which will be more particularly described

hereinafter with reference to Figures 15 te 20 inclusive.

From the above described arrangement, it is seen that the churn drum

24 is totally supported from its rear end by the shaft 18 and that the

front end thereof is completely free of obstructions, whereby very

easy access is provided to the interior of the drum through the

manhole 28.

In order to firmly support the drum 24 and its load, the base 1 is

provided with forwardly extending integral legs 30 terminating

underneath and at the sides of the drum 24 opposite the middle portion

thereof.

The shaft 18 and drum 24 are rotatively driven by means of the

electric motor 31, shown in Figure 2, mounted in the bottom ot the

base 1 and dring the pulley 32 by means of the endless belt 33. The

pulley 32 is keyed to a shaft 34 journalled in the bottom portion of

the frame 5. A pinion 36 is keyed to the shaft 34 and meshes with a

gear 37 rigidly secured by bolts 39 to a flange 38 upon the conical

portion 21 of the shaft 18. The bottom portion of the frame 5 forms an

oil pan 40 into which dips the pinion 36. Thus said pinion 36 and gear

37 are well oiled at all times. An eccentric oil pump 41 is also

mounted on the shaft 34 and feeds oil under pressure to the bearing 7

by means of pipe 42. Return of the oil is made through the drain pipe

43. As it is very important that the bearing 7 be kept lubricated at

all times, a gauge 45 is mounted on top of the bearing 7 to provide an

indication of the oil pressure within said bearing.

A switch, not shown, is mounted at a suitable location in front of the

drum 24 to control the electric motor 31 in order to stop and start

rotation of said drum.

Refrring to Figures 2,4 and 5, the drum 24 is provided with inner

beaters 50 longitudinally extending in adjacent spaced relationship to

the cylindrical wall 51 of said drum.

Each beater 50 has a substantially rectangular cross-section with a

bevelled outer longitudinal edge 53 and is mounted so that its side

walls 54 extend radially of the drum 24.

The front end of each beater 50 is directly secured to the front end

wall 27. The beaters 50 are hollow and provided with a longitudinally

extending middle partition 55 defining an outer chamber 56 and an

inner chamber 57 in communication with each other at the front end of

said beaters 50 as shown at 58. The rear end of the beaters 50 is

closed by and rigidly secured to radially extending conduits 59 of

substantially trapezoidal cross-section and having side flanges 60

rigidly secured to the rear end wall 25 of the drum 24. The conduits

59 converge toward the center of the circular end wall and are in

communication with each other.

Alternate beaters 50 are provided at their front end with a triangular

reinforcing member 61 secured to the inner edge of said beaters and to

the front end wall 27 of the drum 24. The remaining beaters 50 are

similarly provided with triangula reinforcing members 62 secured to

the rear end wall 25 of the drum 24.

The churn, according to the invention, is provided with means to

circulate water through the beaters 50 and to inject cleaning or

washing water directly into the drum 24.

These means will be described presently.

Referring to Figure 3, a return pipe 70 extends through the whole

length of the hollow shaft 18 and its forward end threadily engages a

sleeve 71 welded to the rear end wall 25 of the drum 24. The rear

portion of the return pipe 70 is centered within the hollow shaft 18

by means of a collar 72 engaging the inner face of the rear end of

the tubular extension 20. The rear end of the return pipe 70 projects

from the cover 14 and is provided-with inner threads 73 to engage the

threaded shank 74 of a hand wheel 75.

Moreover, the return pipe 70 is provided with a series of radial

discharge openings 77 in alignment with an annular groove 78 made in

the cover 14.

A nipple 79 is aligned with the forward end of the return pipe 70 ; it

is secured to the sleeve 71 and extends through the converging ends of

the conduits 59 which are covered by a disk 80.

The nipple 79 is provided with a first series of radial openings 81 in

communication with each conduit 59, and with a second series of radial

openings 82, each in communication with a pipe 83 extending in each of

the conduits 59 and discharging into the outer chamber 56 of each

beater 50 through an opening 84. The inner chamber 57 of each beater

communicates with a conduit 59 through an opening 63.

A feed pipe 85 extends within the return pipe 70 and is coaxial

therewith. The forward end of the feed pipe 85 is provided with a

valve member 86 having an axially bored piston-like portion 87 in

slidable contact with the inner face of the return pipe 70 inter-

mediate the two series of openings 81 and 82.

A transverse bore 88 is made in the valve member 86 forwardly of the

piston like portion 87 to establish communication between the inner

feed pipe 85 and the plurality of pipes 83 for feeding water to the

outer chambers 56 of the beaters 50. The front portion 89 of the valve

member 86 has a frusto-conical shape adapted to seat against the

bevelled forward end of the nipple 79 and close communication between

the feed pipe 85 and the interior of the drum 24.

The rear end of the feed pipe 85 is centered within the return pipe 70

by means of a spacer ring 90 and said feed pipe 85 is extended

rearwardly by means of an inner nipple 91 which is secured to it and

to the head 92 of a bolt 93 extending within the shank 74 of the hand

wheel 75. The bolt 93 is held against axial movement with respect to

the hand wheel 75.

Feed water is admitted to the churn by means of supply pipe 94

connected to an opening 95 made in the cover 14 and in communication

with the feed pipe 85 through the annular groove 96, the radial

openings 97 made in the return pipe 70 and the aligned radial openings

98 made in the nipple 91.

When the feed pipe 85 is in the position shown in full line in Figure

3, the water discharged therefrom passes through the transverse bore

88 of the valve member 86, the series of openings 82 and the pipes 83

to reach the outer chamber 56 of each beater 50. Said water will

return through the inner chamber 57, the conduits 59, the openings 81,

the return pipe 70 and finally through the series of openings 77 and

the annular groove 78 to be discharged to the exterior by pipe 100,

shown in Figure 1.

Upon rotation of the hand wheel 75 clockwise, the inner feed pipe 85

will be displaced forwardly and, consequently, the valve member 86

will assume the position shown in dot dash lines in Figure 3. In this

position, the piston-like portion 87 closes the openings 82 thereby

preventing water circulation through the beaters 50, and the feed

water is discharged directly into the churn drum 24.

The feed water is discharged into the drum while the latter is

rotating, thereby resulting in efficient cleaning of the drum or

washing of the butter.

Mixing of the ingoing and outgoing water is prevented by means of the

packing gland 101 disposed between the annular grooves 78 and 96 made

in the cover 14, while escape of the circulating water to the exterior

is prevented by the packing glands 103 and 104 disposed on the outer

side of the said. grooves 78 and 96. Any water which may leak through

the packing gland 103 is collected within the internal annular groove

106 and discharged to the exterior through the opening 107 made in

cover 1. 4. Additional packing glands 108 and 1. 09 are also provided

to prevent water from reaching the ball bearing 17 and from leaking

around the hand wheel shank 74. The rear hood 12 is provided with a

bottom opening 110 for easy access to the hand wheel 75 and to the

connections of the pipes 94 and 100 to the cover 14.

The churn drum 24, according to the invention, is also provided with a

drain valve, generally indicated at 105 in Figure 1, and more

particularly shown in Figures 6 to 10 of the drawings. Part of the

rear snd wall 25 and cylindrical wall 51 is cut off at their junc-

tion and a cylindrical sleeve 111 is inserted in the cut off portion

of said walls and welded at 112 to the end wall 25 and at 113 to the

cylindrical wall 51. The sleeve 111 is completely cylindrical at its

inner end 114 and is slotted at 115 along its outer part. The inner

wall of the sleeve 111 defines an inner shoulder 116 and a bevelled

plug seat 117. Moreover, segmental lugs 118 project nwardly from said

sleeve 111 in spaced relationship with the shoulder 116.

A plug disk 119 is adapted to abut the seat 117 for tightly closing

the drum 24. A thrust plate 120 is adapted to removably engage the

space between the lugs 118 and the shoulder 116 and supports an

inwardly threaded sleeve 121 which receives an operating screw 122

provided at its outer end with an int gra' knob 1221 and abutting the

plug 119 at it" inner end.

The operating screw 122 is rof-afbly mounted and encloses a spindle

123"'eldsd at its inner end to the plug 1195 as sko vn at 124 and

threadily receives at its outer end a bolt 125 retaining a washer 126

to prevent disengagement of the operating screw 122 from said spindle

123.

A wire mesh, or preferably a perforated metal cylindrical filter

screen 127, open at one "end, is inserted within the drum 24 and is

removably secured to the inner face of the plug 119 by means of two

diametrically oppsed longitudinally extending fingers 128 welded to

the annular band 129 secured to one end of the cylindrical screen 127.

The fingers 128 have a groove 130 at their outer end adapted to

removably engage the bayonet slots 131 made in the inner face of the

plug 119

Two additional spacer fingers 132 also diametrically opposed are

secured to the band 129 and are adapted to abut against the inner face

of the plug 119.

The operation of the drain valve described is as follows: To drain the

wash water or the buttermilk from the drum, while retaining the butter

clots therein, the knob 1221 is rotated and displaces the plug 119 and

screen 127 outwardly. The wash water or buttermilk will flow through

the screen 127 and will be discharged to the exterior through the slit

115.

To remove the entire drain valve unit, the thrust olate 120 is rotated

to disengage the lugs 118. The screen 127 may be detached from the

plug 119 by a relative lateral displacement so that the fingers 128

may be disengaged from the bayou, et slots 131. The screen 127 may

then be cleaned, repaired or replaced.

The drum 24 of the churn, according to the invention, is also provided

with an air vent in order to allow the escape of gases which may be

formed within the drum during the churning operation. This air vent is

shown more particularly in Figures 11 and 12. It comprises a-cup

shaped member 133 welded around its periphery to the edge of a

circular hole made in the front wall 27 of the drum 24. This cup

shaped member 133 is provided at the center of its bottom wall 134

with a bevelled circular opening 135 and is normally closed by the

tapsred inner end 136 of the cylindrical valve member 137. Said valve

member 137 is slidabis in a sleeve 144 secured to the bottom wall 134,

and has at its outer end a cylindrical extension 138 of smaller

diameter than the body 137 grooved at its free end at 139 for

receiving a spring clin 140 retaining a hexa, onal cap 14141 vhich

abuts against the shoulder 142 and is provided with a cylindrical

flange 143 having inner threads engaging the outer threads of the

sleeve i44. Partial unscrewing of the cap 141 allows the gases to

escape through the discharge openings 145 made in the flange 143 of

the cap 141. This air vent is not automotic because it ha-ben found

that an automatically operated air vent is liable to open while in a

lower position during rotation of the drum 24 thereby dis charging

liquid as well as gases. This air vent is easily cleaned and may be

taken apart by removing the spring clip 140.

The butter churn according to the invention is provided with a

suitable thermometer to indicate the temperature of the materials

inside the churn drum 24. A dial thermometer- 146 (Figs. 13 and 14) of

the bi-metal type is mounted in a cup-shaped member 147 welded to the

edge of a circular hole made in the front end wall 27 oi the drum 24.

The shank 148 of the thermometer 146 is protected against damage by an

outer sleeve 149 closed at its outer end 150 and welded to the

cup-shaped member 147. In order to further protect the thermometer 146

against damage it is preferably located adjacent a beater 50.

The interior surface of the metal drum 24 may be treated by any known

suitable process in order to prevent the butter from sticking to said

surfaces.

Referring now to Figs. 15 to 20, the access door or closure 29 for the

churn is lodged in a ring member 151 of substantially the same

internal diameter as the circular manhole 28 rigidly secured to the

outside face of the front end wall 27 and is co-axial with said

opening 28. The inner face of the ring member 151 is provided with a

V-shaped groove 152 for removably receiving an annular gasket 153 made

of rubber or the like elastic material and of circular cross-section

when released.

Adjacent the front end wall 27, the ring 151 is also provided with an

inwardly projecting rim 154 adapted to form an abutment for the

marginal portion of the door 29.

The door 29 is a flat disc preferably made of transparent

non-breakable material and is provided with a center knob or handle

155 rigidly secured thereto by a screw 156.

A slit clamping ring 157, preferably made of steel, is adapted to be

removably inserted against the inner surface of the rubber gasket 153.

The clamping ring 157 is provided near its free ends with the

respective brackets 158 and 159. A toggle lever 160 is pivoted at 161

to the bracket 158 and is provided at its outer free end with an

operating handle 162. A connecting rod 163 is pivoted on the bracket

159 at 164 and its threaded outer end engages a sleeve 165 pivoted on

the lever 160 on pivot 166 spaced from the pivot pin 161. Pivotal

movement of the toggle lever 160 towards the clamping ring 157 moves

the ends of the latter away from each other whereby said clamping ring

157 tightly engages the gasket 153 and compresses the same within the

groove 152 to deform said gasket and bring it in contact with the

outer marginal face of the door 29 as shown in Figure 18. In this

manner, a completely leakproof closure is obtained.

The clamping force exerted by the ring 157 is uniform over its entire

surface and may be adjusted by screwing or unscrewing the connecting

rod 163 into or away from the sleeve 165.

To open the churn or drum, it is only necessary to unclamp the ring

157 by inward movement of the lever 1. 62, whereby said clamping ring

157, the gasket 153 and the door 29 may be removed successively. The

reverse operation s effected to close the churn or drum.

The complet closing or opening of the drum may thus be effected in a

very short time.

The drum closure, according to the invention is completely leakproof

and will remain so despite vibrations to which it might be subjected.

From the foregoing description it will be apparent that the churn,

according to the invention, possesses a number of advantages over

butter churns known in the art.

Due to the fact that the churn drum 24 is mounted on the shaft 18 only

through its rear end wall 25 and is completely fr. ee of obstruction

at the front portion thereof, the manhole 28 may be located in the

center of the front end wall 27 whereby said opening is always at the

same easily accessible level in any position of the drum 24. This

important because the operator must have access to the interior of the

drum several times during butter making.

Due to the fact that the beaters 50 are provided with a water

circulation, the mixture of butter and liquid inside the drum may be

kept at the most suitable temperature for churning or working ; for

example, during churning the temperature is maintained preferably at

between 57 and 58 F. while during the working operation, the

temperature is lowered to within the range of 52 to 54 F.

The churn according to the invention is also provided, as described

previously, with very simple means for injecting cleaning water

directly inside the drum in such a manner as to effect efficient

cleaning of the drum walls or of the butter inside the same. These

means consist of the valve member 86 which forms a cone-like water

spray inside the drum and which is operated by the hand wheel 75.

Because water circulation through the beaters 50 is cut off during the

cleaning operation, a maximum water pressure is available.

Care has been taken to design the beaters 50 and the conduits 59 so as

to reinforce the drum walls and thus achieve maximum strength.

Finally the drain valve 105 is considered an important and novel

arrangement ; it closes the drum efficiently and may be quickly opened

for filtering the mixture of materials in the drum or bodily removed

for completely draining the drum and for washing or changing the

filtering screen 127.

While a preferred embodiment according to the present invention has

been illustrated and described it is understood that various

modifications may be resorted to without departing from the spirit and

scope of the appended claims.

What we claim is :-

1. A churn comprising a cylindrical drum supported at one end only by

attachment to a coaxial shaft mounted substantially horizontally in

bearings in a base, the drum being equipped vrith beaters extending

lengthwise along its wall, and having a door at its other end.

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* GB784716 (A)

Description: GB784716 (A) ? 1957-10-16

Manually-operated lifting and transporting appliances



Date of filing Complete Specification Dec 2, 1955.

Application Date Sept 20, 1954.

Complete Specification Published Oct 16, 1957.

784, 16 No 27116/54.

Index at Acceptance:-Class 108 ( 1), E 5.

International Classification: -162 bo COMPLETE SPECIFICATION

Manually-Operated Lifting and Transporting Appliances I, ALBERT HENRY

SMITH, a British Subject, of 2, Church Street, Burton Latimer,

Kettering, do hereby declare the invention, for which I pray, that a

patent may be granted to me, and the method by which it is to be

performed, to be particularly described in and by the following

statement:-

The present invention is concerned with appliances by means of which

articles can be engaged, lifted and transported by manual effort.

There are many articles which have to be moved from place to place

but, because of their bulk, their weight, their temperature, and so on

are awkward or difficult to handle.

Examples of such articles are foundry dies, castings, pipes, paving

stones, curbstones, and slabs, to mention a few only It is an object

of this invention to furnish convenient appliances for handling

articles of this character, which latter will hereinafter be included

generically in the term "slab ".

The appliance provided for this purpose by the present invention

comprises a main carrying frame with a pair of spaced clamping jaws

and at least one lever arm or handle for lifting the frame, one at

least of said jaws being mounted relatively to the frame so as to move

arcuately in response to the lifting operation of said lever arm or

handle and engage one side or end of a slab suchwise as to urge the

latter against the other jaw and suspend the slab from the appliance

between the said clamping jaws.

Various forms of this appliance have been devised, some of which will

be described and illustrated hereafter in this specification.

Thus, in one such form, the frame is wheeled at one end part and

furnished at this end part with an arm (representing the first jaw)

pivoted on said frame and carrying a propelling handle, whereby

downward pressure on this handle will, through the arm, urge the slab

against another jaw (the second jaw) at the other end part of the

frame.

In this arrangement the propelling handle may be hingedly mounted on

the arm and have a cross member for coupling the handle and arm for

downward swinging movement in unison about the pivot of the arm on the

50 frame The second jaw may be a transverse member depending from the

frame and pivotable on this frame about an axis at right angles to the

pivot axis of the first jaw or arm.

In a specific form incorporating the features 55 mentioned in the

preceding paragraph, the frame conveniently comprises a bar or tube

extending longitudinally and medially of the appliance, with the first

jaw or arm passing therethrough, the second jaw depending in 60

pivoted fashion from the leading end thereof, a pair of wheels

depending from the rear end thereof, and a foot piece at this rear end

to assist the rocking of the frame about the wheels by the propelling

handle 65 With the structure set forth immediately above, a slab will

be removed by placing the frame of the appliance around the same, and

then throwing over the operating handle and tilting the frame, so that

it can be wheeled 70 away Instead, however, the appliance may be such

as to provide for raising the frame by a handle at each end, this

action simultaneously producing a grip on the slab between the jaws In

such an arrangement the frame 75 is therefore provided with a lifting

handle at each end, and one of these may be pivoted to the frame and

carrying the arcuately-movable jaw.

In accordance with a further feature of the 80 invention the other of

said handles is adapted to be connected to said frame at variable

positions therealong by fastening means Moreover, this other handle

may be detachably secured to the fastening means 85 The frame may

further comprise a pair of parallel arms having a first lifting handle

pivoted thereto at one end, this handle in turn having the first and

pivotable jaw articulated thereto, and said arms slidably carrying a

90 bracket which is adapted to be secured at a variable position along

these arms and carries the second jaw and a sleeve for attachment of

said other handle.

784,716 In another and simpler form embodying this principle of

lifting by means of handles at each end of the frame and

simultaneously imparting clamping pressure between the jaws, the

"first" jaw may be rigidly connected to one of the handles and the

other jaw affixed to the frame.

If desired the width of the frame may be adjustable to cater for

different widths of slab.

Form of lifting appliance constructed in accordance with the invention

are illustrated by way of example in the accompanying drawings, in

which:Figure 1 is a side view of a first form of the appliance, with

parts seen in cross-section on the line I-I of Figure 2.

Figure 2 is a plan view of the structure illustrated in Figure 1.

Figure 3 shows a second embodiment in side view.

Figure 4 is a plan view of the appliance of Figure 3.

Figure 5 is a cross section on the line IVIV, seen in the direction of

the arrows.

Figure 6 is a side view of a third embodiment and Figure 7 is a plan

view of this third embodiment.

The mechanism illustrated in Figures 1 and 2 is intended more

particularly for lifting and transporting large solid objects, such as

the slab 1 illustrated, but as will clearly be evident, can be used

for similar handling of various other forms of body which are heavy,

bulky or otherwise difficult to transport.

In this case the appliance comprises a central spine 2 which is in the

form of a steel tube slotted at 3 towards one end and having depending

therefrom, at this end, brackets 4 carrying a shaft 5 with wheels 6 at

its outer ends.

At its opposite end the steel rube has a spindle 7 passing loosely

therethrough and welded at its lower end to an angled cross bar 8, the

inner limb of which is provided with a pair of spaced pads 9 together

constituting one of the clamping jaws of the app D Dliance.

Passing through the slot 3 and pivoted by a cross pin 10 therein is an

arm 11 vwhich, towards its upper end is provided with a cross bar 12

extending to either side of the arm and having, at its ends, lugs 13

receiving pivot pins 14 by means of which a pair of propelling arms 15

is articulated to the cross bar 12 The arms 15 extend rearwardvly of

the appliance and together form a propulsion and lifting handle, being

joined towards their outer ends by a cross rod 16 and, towards their

leading ends, by a further cross red 17.

In use, the trolley-like appliance described is moved over the slabs 1

to be lifted and manoeuvred to bring the jaw pads 9 against the

leading edge thereof The handle arms 15 are then swung downwards and,

after the cross rod 17 has abutted the upper end of the arm 11, the

handle and this arn are coupled together to swing as a unit, thiereby

to bring the nose 13 of the arn, which nose forms the "first" clamping

jaw referred to above, against 70 the coposite end of the slab 1 Zter

this position has been reached, any further pressure exerted

do-wnwardis on the outer ends of the handle arms 15 increases thie

grin, et-ween the clamping jaws 9 and 18 75 To transport the article

gripred in this way, the spine 2 is swung up at an angle about the

wheels 6, thie dowrnrd pressure on the arms 15, for this purpose being

assisted by foot pressure on the foot piece 19, which is 80 secured to

the rear end of the spine 2 The slab can therefore be vwheeled away in

the appliance, the downward pressure on the handle 15 to keen the

snine raised ensuring that a tight clamping grip is applied by the 85

jaw 18 against the slab.

As will quickly be appreciated, the actual form of the structure

described can be modified in various ways, whfilst still retaining the

essential features of the device Thus, for 90 example, the centre

spine might be adjustabl-e in length, may be upwardly inclined,

cranked or bowed, so as to acconmmodate a taller article than the slab

illustrated, the forms of the jaws used may be modified to suit

differently-shaved 95 articles and so on As regards the last cf tlese

modifications, it is pointed out that these jaws might, for exampnle,

be curved for the purpose of icking up Trums, cylinderso pines and

like circular articles 100 The appliance illustrated in Figures 3 to 5

is suitable for picking up and transporting narrow articles such as a

curbstone 20, but again this is only an example of the type of body

with which it cwn deal, whether in the 105 formi showvn or modified.

In this instance the frame of the device comprises a pair of parailel

spaced tubzs 21 which are connected at both ends by cro s plates 22 At

one end decenclng bars 23 are 110 welded to the respective tubes 21

and serve to mount a cross spindle 24 on h ih is pivoted a lifting

hanlmle 25 in the form of an elbowed steel tube Adjacent its

articulated end the handle 25 has an outstanding fin 26 which is 115

connected by a pivot pin 27 to a bracket 28 carrying a "first" jaw 29.

Slidably mounted at the oipposite end of the frame is a bracket 30

which is of inverted channel f Grm with thle downturned limbs 120

adjoined by a cross piece 31 A pair of ears 32 extends laterally from,

the side limbs of the bracket 30 for a nurpose to be referred to

below.

Welded to the upper side of the bracket 30 125 is a tubular sleeve 33

forming a socket for receiving a second lifting handle the end only of

which is seen at 34 in the drawings A push-in pin 35 is used to secure

this removable handle 34 in the sleeve 33 130 of the slab and thereby

to urge the latter against the second jaw 43 An upward lift on the

handles 46 and 48, in raising the slab 42 from the ground,

simultaneously produces a tightening of the clamping effect between

the 70 two jaws.

It is to be noted that provision is made for varying the effective

width of the frame in this appliance Thus the cross member 52 is made

telescopic, as will be seen froin Figure 75 7, whilst the cross plate

50 is provided with additional apertures 53 for receiving the bolts 54

by means of which it is attached to the lugs 49 Although only two such

additional apertures 53 have been shown, it will be 80 appreciated

that a series may be provided At the other end of the frame, the arms

41 can be inserted through a similar series of apertures in the jaw

bar 43 and be affixed by nuts, such as 55 85 Again, this embodiment of

the invention may be varied by replacing the handle and jaw mechanism

43-47 by another handle assembly of the form used at the left hand end

of the frame 90

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* GB784717 (A)

Description: GB784717 (A) ? 1957-10-16

Improvements in or relating to commutators for dynamo-electric machines


PA Th M' SPPECIFICATION

7

Date of filing Complete Specification Sept 27, 1955.

Application Date Sept27, 1954 No 278 j) Complete Specification

Published Oct16, 1957.

Index at Acceptance:-Classes 83 ( 2), A 44; 83 ( 4), 54; and 95, B 4

X.

International Classification: -105 B 23 k, p.


Improvements in or reiating to Comnmutators for DynamoElectric

Machines We, WATLIFF COMPANY LIMITED, a British Company of Lombard

Road, Morden Road, South Wimbledon, S W 19, and WILLIAM ELI ARNOLD, a

British Subject, of The Old Beech Cottage, Dene Road, Ashstead,

Surrey, do hereby declare the invention, for which we pray that a

patent may be granted to us, and the method by which it is to be

performed, to be particularly described in and by the following

statement: -

The present invention relates to commutators for dynamo-electric

machines having a wound rotor.

When a commutator is fitted to such a dynamo-electric machine the

commutator is first slipped on to the armature shaft The armature

leads are then positioned in contact with the commutator segments and

are attached thereto, often by dip-soldering In this latter process,

the axis of the rotor to which the commutator is affixed is held

vertically with the cotmmutator lowermost The rotor is lowered into a

bath of molten solder until the surface of the solder reaches the

connections and soldering of the armature leads to the commutator

segments is effected In this case, substantially the whole of the

commutator is immexsrd in the molten solder.

Impregnation of the armature leads with varnish follows at a later

stage after which the commutator is finished, e g by turning on a

lathe or by grinding to remove excess solder forming electrical

bridges between the segments Finally, in one method of commutator

construction, saw cuts are made in the intersegment insulating

material where its surface lies flush with the surface of the

segments, and where, as is well-known, it is desirable for the outer

surface of the intersegment insulating material to be recessed with

respect to the commutator segments.

This saw-cutting is a costly operation and it has been appreciated for

some time that it would be an advantage if the recessing between

commutator segments could be carried out during the manufacture of the

commutators.

lPrice 3 s 6 d l Hitherto, when commutators made with undercut

intersegment insulators have been assembled on rotors and soldered by

dipping or other means, a serious difficulty has been encountered in

that solder collects in the recesses causing short-circuits The

removal of this solder is tedious and there is a risk of leaving small

particles of solder or other matter in the recesses which may cause

subsequent electrical trouble In addition, when the rotor is

impregnated with varnish some of this varnish is also liable to

collect in the recesses.

There are also methods of making commutators in which no insulating

material is left between the segments For example, commutators may be

made by a method in which a tube of disc of metal is anchored to a

moulded core by inwardly extending lugs or the like, the tube or disc

being subsequently divided up into segments by saw-cutting The saw

cuts leave comparatively deep recesses which extend down to the

moulded core and into which solder, varnish and dirt is liable to

enter during the processes carried out in connection with the fitting

of such a commutator on the shaft of a dynamo electric machine.

It is already known for electric motor manufactures to fit a

protective cap over the commutator prior to dip soldering, this cap

being a loose fit on the commutator so as to enable it to be removed

therefrom Such a loose cap does not, however, guarantee prevention of

solder running into the inter-segment recesses; and its removal is a

difficult and inconvenient operation since the cap becomes very hot

during dip soldering The cap also has to be cleaned before being

stored for re-use Moreover, if the motor manufacturers produce a wide

range of motors, it will be necessary for them to stock a number of

caps of different sizes and shapes to suit different sizes and shapes

of commutators.

It is also known to arrange above the solder both a cap into which the

commutator is inserted after being mounted on the motor shaft In this

case, either the cap is arranged < 7 84,717 73/54.

so that it can be lowered together with the armature into the solder

bath, or the solder bath is arranged so that it can be raised the

required distance for effecting the dip-soldering operation Both

arrangements necessitate the provision of a relatively complicated

raising and lowering mechanism and, as in the previously described

known method, it is desirable to provide different sizes and shapes of

cap to suit different sizes and shapes of commutator The substitution

of one such cap for another is likewise a difficult and inconvenient

operation.

The present invention has for its object to remove these disadvantages

and with this object in view there is provided according to the

present invention a method of masking a commutator of the kind in

which the intersegment insulators are shaped to provide intersegment

recesses between the parts of the commutator segments constituting the

commutator brush surface, so as to prevent solder and/or varnish from

becoming lodged in the intersegment recesses when, after the

commutator has been mounted on the rotor shaft of a dynamoelectric

machine, said commutator is dipped in a bath of molten solder for

connecting the commutator segments to the rotor windings and/or said

windings are treated to impregnate them with an electrically

insulating varnish, comprising the step of fitting a mask of

protective material tightly over the completed commutator so as to

cover said intersegment recesses and to engage in surface-to-surface

contact with all those external parts of the commutator segments which

border the sides and ends of said intersegment recesses.

The term " intersegment insulators ", except where the context

indicates otherwise, is to be interpreted to include not only

separately formed intersegment insulating components but also parts of

insulating material between adjacent segments which are integral with

the commutator body.

The invention also includes a masked commutator prepared by this

method as well as the utilization of such a masked commutator in the

manufacture of a rotor for a dynamo electric machine by methods

comprising the steps of fitting the said masked commutator on the

shaft of the rotor, positioning the terminal wires of the rotor

windings adjacent the parts of the segments to which they are required

to be connected; thereafter either making electrically conducting

connections between the terminal wires and the segment parts by dip

soldering, or alternatively making electrically conducting connections

between the terminal wires and the segment parts and then treating the

rotor with an electrically insulating varnish so as to impregnate the

windings thereof; and finally removing the mask The resulting rotor

also forms part of this invention.

The invention is illustrated by way of example with reference to the

accompanying drawings, in which: Fig 1 is a vertical longitudinal

section of a commutator fitted with a mask, Fig 2 is a perspective

view of the commutator and mask shown in Fig 1, Fig 3 is a fragmentary

perspective view 70 showing this commutator and mask assembled on the

rotor shaft of an electric motor, and Fig 4 is a view similar to Fig 2

illustrating a modification.

The same references are used to indicate like 75 parts in all these

figures.

Referring to the drawings and particularly to Figs 1 and 2, the

commutator comprises an assembly of contact segments 1 and

intersegment insulators 2 embedded in a moulded 80 synthetic resin

core 3 carried on a metal sleeve 10, the intersegment insulators 2

being shaped to provide intersegment recesses 4 Fitted tightly over

this commutator is a cap of thin aluminium foil indicated generally by

reference 85 The crown portion 6 of the cap 5 is formed with a

circular opening 7 of slightly larger diameter than the interior bore

8 of the commutator so that it covers the ends of the segments 1,

while the rim 9 thereof finishes a short 90 distance away from the

lugs 11 of the contact segments 1 The cap thus completely masks the

intersegment recesses 4 and tightly grips the parts of the segments

which contain them.

After the completed assembly consisting of 95 the commutator and cap

has been fitted over the rotor shaft 12 of an electric motor, the

terminal wires 13 of the rotor windings are inserted into slots 14

provided in the lugs 11.

The rotor is now tilted into a position in which 100 the axis of its

shaft 12 is vertical and the commutator lowermost, after which it is

dipped in a bath (not shown) of molten solder to such a depth that the

surface of the solder covers the terminal lugs As a result of this

operation, 105 the ends of the terminal wires 13 in the slots 14 are

soldered to the lugs 11.

In a subsequent operation, the rotor is treated with an electrically

insulating varnish so as to impregnate the windings 110 The cap 5,

being made of aluminium foil, is not easily wetted by solder and

effectively masks the brush surface of the commutator during the

above-mentioned soldering and varnishing operations, so that no solder

or 115 varnish can become lodged in the intersegment recesses 4.

The mask is subsequently removed either by tearing it off or by

turning it off on a lathe.

In order to enable the electrical insulation 120 between the segments

of the commutator to be tested while the cap 5 is in position, either

this cap or the outside of the commutator or both may be given a

coating of an electrically insulating synthetic resin varnish Any

coating 125 on the commutator if of course eventually removed after

removing the cap 5.

Fig 4 illustrates a modification in which the commutator is provided

with a boss 15, but is otherwise similar to the commutator 130 1

784,717 -784,717 described with reference ot Figs 1 to 3 In this case,

the cap 5 is extended as at 16 to cover this boss and part of its end

surface.

Among the advantages of the masks described above are that they offer

protection to the copper segments against annealing in the solder bath

In the embodiment according to Figs 1 to 3, where the mask extends

over the front face of the commutator, substantially all insulating

material between the segments and the centre sleeve of the commutator

is protected against the effects of solder dipping, mechanical damage

or dirt until the cap is removed at the final stage of manufacture In

commutators made with a synthetic resin core, the cap thus extended is

particularly valuable in reducing temperature effects such as

blistering of the resinous material.

While aluminium foil is a particularly advantageous material for the

masks for the reasons just mentioned, many other materials can be used

instead, such as for example heavy fibrous materials which may, if

desired, be impregnated with a synthetic resin When using electrically

non-conducting materials such as this, there is of course no need to

coat the mask or the commutator in order to enable the latter to be

tested electrically with the mask in position.

Although the embodiments of the invention described above and

illustrated in the accompanying drawings all utilize drum type

commutators, it will be appreciated that the invention is likewise

applicable to " disc type " commutators i e to commutators in which

the segments combine to form a disc with a brush surface on one face

thereof.

Moreover, the invention is applicable to rivetted type commutators as

well as to moulded type commutators.

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