M. L. Magneto Syndicate
M-L Magneto Syndicate of West Orchard, Coventry. (1929)
1915 Formed by Morris and Lister
1914 Patent with Graham Parmley Thompson on "Improvements in Coil Winding and similar Machines."
1915 The directors of the M-L Magneto Syndicate were David King Morris, George Anslow Lister and E. A. Watson
1919 January. Advert - More than 60,000 magnetos have been supplied to HM Government in past three years.
1919 Became part of Smiths Industries. [1]
1920 Catalogue of magnetos. [2]
1920 June. Article on their Oscillating High-tension Magneto. [3]
1924 Article in Engineering, accompanied by illustrations: 'For mines provided with a compressed-air supply, but not having underground electric supply, a portable, turbine-driven self-contained generator and lamp, illustrated in Figs. 172 to 174, is made by the M.L. Magneto Syndicate, Limited, of Coventry. A short hollow shaft, running on ball bearings in the upper part of the lamp casing, carries on its upper part a ring of turbine blades built into a disc flywheel; to the lower part of this disc is attached a permanent magnet rotor, which revolves within a laminated stator carried in the lower part of the casing by a clamping ring. The magneto-generator is designed to supply alternating current at a practically constant voltage over a wide range of speed. The nozzle is mounted in a branch that projects tangentially from the casing and is fitted with a gauze air-filtering cap. The exhaust passes to the atmosphere through a port at the top of the casing, closed by a spring-loaded disc valve opening outwards. The glass cap covering the lamp bulb is continuously scavenged by air received from the lamp casing, and escaping through a hole in the recessed portion of the bottom wall. In order to ensure that the terminals may be dead if the protecting glass should be broken, a cut-out is provided, consisting of a flexible sided metallic chamber, similar to that of an aneroid barometer. The chamber is in connection with the atmosphere, but it is placed at the back of the lamp holder, where it is exposed to the exhaust pressure. The chamber carries a platinum contact, which engages with a fixed contact on the body of the lamp. If the pressures inside and outside the chamber equal, the contacts are pressed together, short-circuiting the generator. Breakage of the glass or tampering with the points will therefore automatically make the lamp dead. An emergency governor is provided on the generator, and operates for an excess speed of 10 per cent. The lamp is of about 32 candle power (24 watts), and the ordinary 12-volt automobile lamp bulb can be used. In the lamp in question, with an air pressure of 100 lb. per square inch, the consumption is stated to be nearly 3 cub. ft. of free air per minute ; the total weight of the lamp is between 14 lb. and 16 lb. Wherever electric lamps are used in coal mines, it is, of course, necessary to retain a small number of oil safety lamps for use as gas detectors.'[4]
1929 Description of a bakelite turbine rotor of 5 in. in external diameter, and weighing 5.5 oz., considerably less than the steel rotor it replaced, 'while this
reduction of weight, being proportionate to the tensile
strength of the material compared with steel, the factor
of safety is equally high in the two materials. The
reduced weight, further, naturally reduces the losses
in the mechanism concerned, and increases the life
of the spindle bearings. Another advantage over a
steel rotor is that the material is non-corrodible in a
damp atmosphere, and, clearly, a moulding of this sort
is much cheaper to produce than a built-up metal
rotor. We have drawn attention to this construction
rather as illustrating what may be done by the enlightened use of new materials and as forming an example, small though it may be, of British engineering
enterprise. It is not, of course, suggested that the
material is suitable for all turbine rotors, but only in
cases where the temperature of the working fluid is
low, as with compressed air.
It is for use with compressed air in the M. L. pneumatic-electric lamp that the rotor has been designed.
This lamp is manufactured by the M.-L. Magneto
Syndicate, Limited, Coventry, and, in its original form,
was described in Engineering, vol. cxxiv, page 709.
The sole agents for Great Britain are Messrs. John
Davis and Son (Derby), Limited, All Saints Works,
Derby. The lamp, it may be recalled, is intended for
use in mines, and is distinctive in that the lighting
current is produced in the lamp casing itself by means
of a small turbine-driven generator actuated by compressed air. Besides eliminating fire risk, the casing and
lamp being virtually gas-tight, this type of lamp permits efficient lighting to be provided without the necessity of running electric cables to the working face, it
being assumed that compressed air is already in use
as a motive power, for driving coal cutting or other
machinery, &c. In normal working the generator is
designed for an output of 60 watts at 25 volts. With
gas-filled bulbs of this capacity, the candle power is
very much greater than any of the battery lamps as
at present made. The turbine rotor is carried on a
short steel spindle adjacent to the generator rotor.
The generator is of the revolving field pattern, and,
the windings being stationary, there are no rubbing
contacts.
In addition to the lighter turbine rotor, several
other changes have been made in the design of the
lamp since we previously described it. One of these is
the compounding of the turbine which has resulted in
a reduction in air consumption of approximately 30 per
cent, as compared with previous figures, and another
is the incorporation of a reducing valve in the lamp
casing. The compounding is effected by fitting an
internal port across the inside of a portion of the
circumference of the rotor, the blades of which are
shrouded, as indicated by the projecting pins in the
figure. The air is directed on to a portion of the
exterior edge of the blades by a tangential nozzle in
the usual fashion, and, then, by means of the transfer
port on to a different portion of the interior edge of
the blades, as it escapes in an outwards direction to the
exhaust port. The reducing valve has been provided
to make the lamp independent of the air pressure, as per square inch. The reducing valve is consequently
set to maintain the latter pressure. It is estimated
that these lamps cost to run, per candle power of the
illumination provided only, from one-fifth to one-sixth
of that of the system of acetylene lighting previously
used in this particular case.' See illustration.[5]. Challenging work for the mould-maker.
1929 Advert for: Anode Converters; Rotary Transformers; Motor Generator Sets for Anode and Filament supply to Power Amplifiers for Radio, Public Address, Gramophone Reproduction, etc.; Synthetic Resin Mouldings in Bakelite; and various other products - of all descriptions. (Wireless Section - Stand No. MM.75) [6]
1930 M. L. Magneto Syndicate Ltd was a lighting, starting and ignition business owned by Smiths. Its sale by Smiths to Joseph Lucas Ltd for the sum of £116,250 was related to a general trading agreement made between Lucas and Smiths "to remove the competition between the two companies in connection with magnetos, lighting and starting."
See Also
Sources of Information
- ↑ The Autocar of 4th January 1919 p7
- ↑ The Engineer of 6th Feb 1920 p130
- ↑ The Engineer of 11th June 1920 p600
- ↑ Engineering 1924/10/10
- ↑ Engineering 1929/01/25
- ↑ 1929 British Industries Fair Advert 242 and p109
- [1] MMC report