OK, I'll bite...
Mmm, this sounds like familiar territory.
Compacts & Tristars have always had a magnesium/aluminum alloy body shell. But they were not the first to employ this strong light alloy for vacuum cleaners.
I believe it was Hoover under the design & engineering leadership of Henry Dreyfus that raised this material to it's high desirability in lightweight appliances. Up until Dreyfus was hired Hoover's chassis were diecast aluminum highly polished. For all it's superior strength and resistance to torsional forces, magnesium is lighter and the casting can be thinner for the same structural rigidity.
"In the mid-1930s, Hoover USA pioneered the use of professional industrial design in vacuum cleaners by employing Henry Dreyfus, one of the first industrial designers, to consider the design, manufacture and ease of use of their vacuum cleaner as a whole. The result was a new generation of cleaners, starting with the model 150 (1936)/160 (1938), which used less components, new light alloys and plastics and more benefits for the user. This development indicated the fact that by the late-1930s, at least in America, the electric vacuum cleaner was a common-enough product and required a 'design overhaul' to stimulate the next generation of sales. The basic component layout and manufacturing approach of these new models continued until the first 'clean-fan' plastics uprights in the mid-1960s, such as the Hoover Dial-A-Matic.
1936 Hoover model 160 Cleaning Ensemble - UK version of innovative US Hoover model 150(1936); prime example of modern 1930s streamlined design. Designed by pioneering US industrial designer Henry Dreyfus, 1933-36. Stove-enamel grey magnesium chassis. Aluminium and 'stratosphere blue' streamlined trim. Wide use of phenol plastics for motor, motor hood and tools. Tools in portable storage rack can be inserted while motor running. Modern handle and bag graphics. Additional grip halfway up handle for carrying. Big 385 watt two-speed motor, automatic height control. Hoover's luxury model, sold as 'Cleaning Ensemble' alongside model 262 (from 1939); both replaced by UK model 612 (1949).
1939 Hoover model 262 - Cheaper, lightweight version of Hoover model 160, based on US model 26 (1938). Designer: Henry Dreyfus, New York. Exhibited on Bakelite stand at 1939 New York World's Fair. Beige stipple-finish stove enamel magnesium chassis (final examples have gold hammerite finish from model 612), brown phenol plastic shroud enclosing plastic motor casing and headlamp, brown bag. Rare 1939 version has full wrap-around band on motor casing; common post-war version has specification panel on front only. Phenol plastic and 'duralium' tools with portable storage rack. Single-speed motor. Produced 1939, 1945-49. Replaced by Hoover UK model 612 (1949)"
Evidence of the durability of the material is that I have never seen a shattered Compact casing and I've seen one fall off a truck and bounce down the hiway with nothing more than a shallow dent. This is also attributable to the body's egg shape. Plastics will never provide such structural integrity and the newer Tristars are more and more loaded with plastic outer fittings and internal components. Gawd knows what screaming girly motors they are putting in them now...
I don't care for the TriStar re-design of the Compact basic shape and prefer the uber ugliness of the Vortech Force, Miracle Mate or Haley's Comet to round out my evolutionary display of this type of powerful vacuum cleaner styling.
To sum up I don't know nuthin' 'bout no EXL A101, MG1 and MG2.
Dave
A Hoover 160 being used on the Queen Mary in the late 1930s.
http://www.azom.com/details.asp?ArticleID=2603
