The Square Four,
introduced in 500cc form during 1931 was the
work of Edward Turner. Conceived as a luxury
tourer it utilised a chain driven over camshaft
and four cranks with the gearbox being driven
by the rear left hand example. The new model
was joined by a 601cc variant the following
year which eventually replaced the smaller machine.
Unfortunately for Ariel, the introduction of
complex, luxury model into an already crowded
market place at the height of a recession resulted
in limited sales, many admired the machine but
those that could afford a luxury mount tended
to opt for the known qualities of one of the
large capacity vee twins, consequently examples
of either over head cam model are rare. More
Ariel Square
Four information.
| Bike |
Image |
Description |
Ariel Square Four |
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Engine - 997cc, OHV, square four
Top Speed - 100mph
Horsepower - 42bhp @ 5800rpm
Transmission - 4-speed
Frame - tubular single loop
Brakes - drum/drum |
1932 Ariel 600cc Square Four |
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One of Ariel's most notable engines was
the Square Four, the first prototype emerging
in 1930. As the name suggests, the cylinders
were configured with two cylinders directly
behind the front two cylinders. Starting as
a 500cc engine, then increased to 600cc and
finally the 1000cc configuration. The 'Squariel'
was plagued with heat problems as one might
imagine having two cylinders directly behind
the front pair. Despite the heat issues it
remained in production until 1954. |
1933 Ariel Square Four Race, 500cc |
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1934 Ariel Square Four
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1934 601cc version, has been in the
same family ownership for over fifty years.
The machine was purchased by the present
owners father for £15 and she recollects
being a pillion on the machine during
the 1950's. A comprehensive restoration
was carried out during 1996 at which time
new main roller bearings, big ends and
pistons were fitted. The mag/dyno was
rewound and the wheels were rebuilt with
new tyres being fitted. Items such as
the chains, cables and battery were replaced
as a matter of course and new wiring was
installed. The chrome tank and black and
gold paintwork are described as being
in "as new" condition as are
the cycle parts and electrics. The engine
is described as having had a "total
rebuild" and the transmission is
described as being in good working order.
Won the "Best Pre-war Bike award"
in the 1996 Festival of 1000 Bikes concours
competition following her restoration
and was subsequently placed on display
at RAF Manston, nestling under the wing
of a Hawker Hurricane, as an example of
an RAF pilots wartime transport. Image
provided by www.classic-auctions.com.
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| 1939 Ariel Square Four |
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1952 Ariel Square Four Combination
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When "The Motor Cycle" tested
an example of the Ariel Square Four Mark
II in April 1953 they found that the machine
was capable of just shy of 100 mph describing
it as being "a unique high-performance
mount with gentle manners and outstanding
acceleration" resulting from twenty
years of development. The Square Four
had been conceived by Edward Turner during
his time at Selly Oak and was introduced
as a 500cc, soon to be increased to 600cc
over head cam design in 1931.
However the early engine suffered from
a weak and insufficiently cooled cylinder
head prone to blowing its head gasket.
Edward Turner consequently developed a
new 997cc over head valve engine retaining
the name and layout, but little else for
the 1936 season. The new engine, typed
the 4G provided the basis for all Square
Four production until 1948 when it was
joined by the Mark II "alloy engine",
which featured an alloy barrel and head
in place of the iron units previously
employed. Equipped with telescopic forks
and "Anstey" link rear suspension,
the Square Four provided the discerning
rider with a luxurious mount capable of
covering long distances at high speed
in comfort in either solo form, or as
with this example, attached to a sidecar,
surpassed only by the twins emanating
from Stevenage.
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1952 Ariel Square Four
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Ariel replaced the cammy 600cc Square
Four with an overhead valve design displacing
997cc during 1936. The redesigned engine
retained the geared twin crankshafts first
seen in the overhead cam engine, although
the gears had moved to the left hand side
of the engine, but little else, other
than the name, remained unchanged from
the cammy Square Four. 1939 saw the introduction
of a compensated-link, plunger equipped
frame which continued in use, complimented
at the front by Ariel telescopic forks,
when production of the 4G Mark 1 resumed
in 1946. The model continued with very
little change for the next two years,
until in late1948 a redesign took place,
resulting in a new version equipped with
an all alloy engine. The redesign was
well timed as the Square Four had been
putting on weight as a result of the increased
specification, the alloy engine and other
measures resulting in a saving of approximately
100lbs over the iron engined version.
Image provided by www.classic-auctions.com.
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1953 Ariel Square Four Mark II |
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Introduced in 1953, the 'four-pipe' MkII
with re-designed cylinder head was a genuine
100mph machine. With its limitless reserves
of pulling power and innate smoothness, the
model was always a favourite of the sidecar
brigade. |
| 1953 Ariel Square Four |
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Ariel Square 4 Mk 2 - four pipe. This
is the first year of the Mk 2, with dual
seat. |
1957 Ariel Square Four Mark 4 Prototype |
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| 1958 Ariel Square 4 |
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| 1959 Ariel Square Four 1000cc |
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Image supplied by www.andybuysbikes.com |
