OutdoorKing Repair Forum Forums The History Forum Model Histories ENGINES BRIGGS & STRATTON - SonoDuct - c1960

Hello ODK History Lovers
The Briggs & Stratton Sonoduct Series of engines were revolutionary when
introduced in 1960. They were a commercial flop ... in the vain of the Ford
Edsel and the Bristol Brabazon. It wasn't a fault of the design.

Perhaps too radical for the day, the design would prove its worth decades
later, and was a design inspiration to the Victa Power Torque engine. The
radical feature was the moving of the ignition flywheel and recoil starter
to the under-deck.

There is scarce information on these engines. There is certainly miss-
information on them. Some comments I have read say they were designed as
a cheaper engine, or they were designed for a lower centre of gravity.
That is nonsense.

The name gives it away. 'Sonic' relates to sound. This was an early attempt
to make a quieter engine. A spin-off advantage from this was in styling potential.
Lawnmower makers could make a lower silhouette rotary lawnmower.



TO BE CONTINUED ...

PART TWO - Detail & Failure
The Sonoduct never sold in Australia - certainly not on any AUS made lawnmower,
and no evidence exists of any imported machines. The reason is probably pretty
simply ... it didn't take-off in the homeland either.

In a 1980s Briggs publication, a brief story is told [with accompanying image]:

" the SonoDuct, a totally enclosed, quiet engine, was in the experimental stage
in 1958 when examined by Ed Oehler, Hugh Brown, Bob Harkness and Jack Ebershoff.
The SonoDuct was unique in that the flywheel was located under the unit rather
than on top. It did go into production, but acceptance was hampered by the fact
that a large, odd-shaped hole was required on the deck to install the engine."


SOURCE: https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/60454/BRIGGS_&_STRATTON_-_Histor.html
p.s. Who would use a suitcase on mower deck styling?

I have found some extra information from a private website, but I have
been unable to verify some of the comments:




TO BE CONTINUED ...

There is very little evidence of production lawnmowers using the
Sonoduct engine.

I have these images - from collector Greg S of New Zealand.
Many thanks to Greg for recognising this rare lawnmower.

The make is unknown. How it arrived in NZ is unknown.

In this extract from a Briggs 2008 publication, the factory lists 'highlights'
from the 1960s. I have used this to date this brochure.


NOTE: Easy-Spin starting and the 'Coffee Grinder' starter appeared
in 1961. Brigg's Sound Lab was operational in 1967. I feel that is a
good indicator of how seriously Briggs took 'noise' at that time.

The History of Briggs & Stratton c1980s:-
https://www.outdoorking-forum.com.au/forum/ubbthreads.php/topics/60454/BRIGGS_&_STRATTON_-_Histor.html


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