Daimler Double-Six sleeve-valve V12
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Daimler Double-Six
piston engine A reciprocating engine, also often known as a piston engine, is typically a heat engine that uses one or more reciprocating pistons to convert high temperature and high pressure into a rotating motion. This article describes the common featu ...
was a
sleeve-valve The sleeve valve is a type of valve mechanism for piston engines, distinct from the usual poppet valve. Sleeve valve engines saw use in a number of pre-World War II luxury cars and in the United States in the Willys-Knight car and light truck. T ...
V12 V12 or V-12 may refer to: Aircraft * Mil V-12, a Soviet heavy lift helicopter * Pilatus OV-12, a planned American military utility aircraft * Rockwell XFV-12, an American experimental aircraft project * Škoda-Kauba V12, a Czechoslovak experim ...
engine manufactured by The Daimler Company Limited of Coventry, England between 1926 and 1938 in four different sizes for their
flagship A flagship is a vessel used by the commanding officer of a group of naval ships, characteristically a flag officer entitled by custom to fly a distinguishing flag. Used more loosely, it is the lead ship in a fleet of vessels, typically the fi ...
cars.


The colossus of roads

Daimler required an advanced new model to compete with Rolls-Royce's New Phantom of 1925. Though
Packard Packard or Packard Motor Car Company was an American luxury automobile company located in Detroit, Michigan. The first Packard automobiles were produced in 1899, and the last Packards were built in South Bend, Indiana in 1958. One of the "Thr ...
had introduced its Twin-Six many years earlier it was to be a decade or more before luxury manufacturers like
Rolls-Royce Rolls-Royce (always hyphenated) may refer to: * Rolls-Royce Limited, a British manufacturer of cars and later aero engines, founded in 1906, now defunct Automobiles * Rolls-Royce Motor Cars, the current car manufacturing company incorporated in ...
,
Hispano-Suiza Hispano-Suiza () is a Spanish automotive–engineering company. It was founded in 1904 by Marc Birkigt and Damian Mateu as an automobile manufacturer and eventually had several factories in Spain and France that produced luxury cars, aircraft en ...
,
Lincoln Lincoln most commonly refers to: * Abraham Lincoln (1809–1865), the sixteenth president of the United States * Lincoln, England, cathedral city and county town of Lincolnshire, England * Lincoln, Nebraska, the capital of Nebraska, U.S. * Lincol ...
,
Voisin Voisin (French for "neighbour") may refer to: Companies *Avions Voisin, the French automobile company :*Voisin Laboratoire, a car manufactured by Avions Voisin *Voisin (aircraft), the French aircraft manufacturer * Voisin, a Lyon-based chocolat ...
and
Lagonda Lagonda is a British luxury car brand established in 1906, which has been owned by Aston Martin since 1947. The trade-name has not had a continuous commercial existence, being dormant several times, most recently from 1995 to 2008 and 2010 to 2 ...
made their own (and Packard returned to it). In fact by the mid-1930s flexible engine mountings and improved carburation had made so many cylinders unnecessary. What did return them to a certain level of popularity was the push for higher performance requiring higher crankshaft speeds. Daimler introduced their first 26 hp
straight-eight The straight-eight engine (also referred to as an inline-eight engine; abbreviated I8 or L8) is a piston engine with eight cylinders arranged in a straight line along the crankshaft. The number of cylinders and perfect primary and secondary engi ...
in mid-1934 and their last (poppet valve) V12s were built in 1937 or 1938. From 1929 Daimler Double-Sixes were distinguishable from the six-cylinder cars by a chromium bar down the centre of the radiator. A similar distinguishing mark was placed on the later Jaguar-made versions. Aside from Daimler only Voisin in France ever attempted production of a sleeve-valve V12 engine. Voisin's production—between 1929 and 1937—was "minimal and spasmodic". The same Daimler Double-Six name was used for the badge-engineered ''Daimler'' V12 engine used in the largest Daimlers between 1972 and 1997.
Lofty England Frank Raymond Wilton "Lofty" England (24 August 1911, Finchley, Middlesex – 30 May 1995, Austria) was an engineer and motor company manager from Britain. He rose to fame as the manager of the Jaguar Cars sports car racing team in the 1950s, dur ...
,F R W England and J Mercer drove a Double-Six to second place (to a 15/18 Lanchester) in the 1932 ''
RAC Rally Wales Rally GB was the most recent iteration of the United Kingdom's premier international motor rally, which ran under various names since the first event held in 1932. It was consistently a round of the FIA World Rally Championship (WRC) calen ...
''
a Daimler apprentice 1927–1932, joined Jaguar in 1946 and became its chief executive. He ensured the Double-Six name was used for the Jaguar V12 when installed in Daimler cars.


Design

This engine was designed byThis information may relate to the second series 30/40 and 40/50 engines with alloy blocks. Pomeroy was in the United States until October 1926 and, it appears, could not have designed the first series, which was exhibited to the public that month. consultant Chief Engineer L H Pomeroy (1883-1941) to achieve high power with quietness and, particularly, smoothness. Pomeroy made the engine by taking the cylinder blocks of two existing 25/85 hp Daimler engines and putting them on a common crankcase. Pomeroy was to be appointed managing director in 1929. The same design was produced in different sizes depending on the different
engine displacement Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is commonly used as an expression of an engine's size, and by extension as a loose indicator of the ...
s.


7.1-litre Double-Six 50


Engine

Announced 15 October 1926 and observed by The Observer's motoring correspondent to be Britain's first twelve-cylinder car engine. :Bore and stroke 81.5 mm x 114 mm gave a
swept volume Engine displacement is the measure of the cylinder volume swept by all of the pistons of a piston engine, excluding the combustion chambers. It is commonly used as an expression of an engine's size, and by extension as a loose indicator of the ...
of :7136 cc Power output @ 2480 rpm.
Tax rating 50 hp * Cylinders arranged in blocks of three * Pistons were of light alloy and split-skirted "like the modern girl" * Double light steel sleeves controlled the inlet of fuel and the outlet of exhaust, they were operated by short connecting rods from their eccentric-shafts * Separately detachable cylinder heads * 60 degree angle V * Crankcase aluminium * The big-ends lay in pairs, the right-hand ones forked so that diagonal pairs of cylinders were in the same plane * Connecting rods were H-section * Crankshaft ran in seven bearings and had an external Lanchester-type vibration damper at the front * Two sleeve-operating eccentric-shafts were driven by chain at the rear of the engine each ran in four bearings * Daimler seven-jet carburettor, water-pump,
magneto A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current. It is categorized as a form of alternator, ...
, exhaust pipe and silencer were duplicated, each block of cylinders having its own components * Petrol was supplied to a reservoir by the engine from the rear-mounted tank by air pressure * Each ''Daimler'' carburettor had an independent pre-heated air supply and four jets plus a primer which acted as a pilot with a separate air supply * Inlet manifolds were water-heated and mounted on the outside of each cylinder block * With the primer lubricant was passed to the cylinders and with the depression of the starter pedal oil delivered to the lower end of the sleeves * Oil was forced to the main and big-end bearings, the sleeve-shafts and the sleeves * Oil was cooled through a radiator :::: 6a 5a 4a 3a 2a 1a :::: 1b 2b 3b 4b 5b 6b :order of firing: 1b 1a, 5b 5a, 3b 3a, 6b 6a, 2b 2a, 4b 4a * Dual ignition was fitted * Distributors were coupled as were all the change-over switches from the coil to
magneto ignition An ignition magneto, or high-tension magneto, is a magneto that provides current for the ignition system of a spark-ignition engine, such as a petrol engine. It produces pulses of high voltage for the spark plugs. The older term ''tension'' ...
* Magnetos and water pumps were driven through transverse shafts by skew gearing from the nose of the crankshaft * Dynamo operated by silent chain * Two vertical shafts from the same source drove contact breakers and distributors set above the cylinder banks * Belt-driven four-bladed radiator fan * Fuel was pumped from the rear tank by air pressure from a mechanical pump mounted near the carburettor :The exhaust pipes passed through the V of the cylinder blocks and were covered with an aluminium plate to dissipate heat. :The engine and clutch were mounted as a unit separately from the gearbox The result was an engine which idled at 150 rpm and ran with uncanny silence "the only audible sound made by a Double-Six (if you opened the bonnet and went right up to it) was the almost imperceptible tick as the ignition points opened and the faint breathing of the carburettor". This largest engine faded from the catalogue after 1930


Chassis

* Chassis frame was channel section * Gearbox: driven through a single dry plate disc clutch mounted on the engine a separate four-speeds and reverse gearbox was mounted on a very substantial cross-member and controlled by a central ball-gate gear lever. * Hand brake operated shoes in a brake drum mounted at the back of the gearbox * Power was taken by open propeller-shaft with metal universal joints to a (virtually silent) underslung worm-drive to the rear axle * Suspension was by gaitered half-elliptic leaf springs - beneath the axle at the back * Brakes on four wheels were rod-operated with assistance from a Dewandre vacuum servo positioned beside the gearbox. Adjustment could be made by hand * Steering: the width of the engine necessitated mounting the worm and sector reduction box on the scuttle. From there a coupling lever dropped to a bell-crank pivoted on the chassis side-member. A normal drag-link ran to the front axle. * Wheelbase: ::Type O wheelbase Track ::Type P wheelbase Track ::Type W wheelbase Track * Tyres: :: x or :: x or :: x * Dimensions of standard saloon de luxe: ::Length :: Width ::Height


Prices

* Chassis prices: Type O £1,850, Type P £1,950, Type W £1,950 * Standard saloon de luxe by Daimler £2,450 * Standard enclosed limousine by Daimler £2,800


3.7-litre Double-Six 30

Announced 1 August 1927. Formed around a pair of 16/55 cylinder blocks :Bore and stroke 65 mm x 94 mm gave a swept volume of :3744 cc Power output ,
Tax rating 31.4 hpCars Of To-Day.''The Times'', Tuesday, Mar 06, 1928; pg. 22; Issue 44834


Design change

:Petrol was lifted to a reservoir by the engine from the rear-mounted tank by
Autovac Manifold vacuum, or engine vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere. Manifold vacuum is an effect of a piston's movement on the induction stroke and t ...
* Wheelbase: ::Type Q wheelbase Track ::Type M wheelbase Track ::Type V wheelbase Track ::Type O wheelbase Track * Tyres: :: x on the coupé tested by The Times * Dimensions of standard saloon: ::Length :: Width ::Height


Prices

* Chassis prices: * Standard saloon by Daimler £1.300 Production ended in 1932, none with fluid flywheel and pre-selector gearbox.


5.3-litre Double-Six 30/40 or Light Double-Six

Announced October 1930 and matched with the new Daimler
fluid flywheel A fluid coupling or hydraulic coupling is a hydrodynamic or 'hydrokinetic' device used to transmit rotating mechanical power.
and Wilson pre-selective half-automatically changing four-speed gearbox. :Bore and stroke 73 mm x 104 mm gave a swept volume of :5296 ccThe Olympia Show. by Our Motoring Correspondent, ''The Times'', Thursday, Oct 23, 1930; pg. 8; Issue 45651 Tax rating 40.18 hpNew Royal Cars.''The Times'', Friday, Apr 17, 1931; pg. 12; Issue 45799. In November 1930 a car was shipped to
Edsel Ford Edsel Bryant Ford (November 6, 1893 – May 26, 1943) was an American business executive and philanthropist who was the son of pioneering industrialist Henry Ford and his wife, Clara Jane Bryant Ford. He was the president of Ford Motor Company f ...
with the new Daimler transmission. It aroused so much interest Cadillac's chief engineer, Ernest Seaholm, came to the following Olympia show and bought another for technical investigation. It inspired Earl Thompson, who invented syncromesh, to develop the
Hydramatic Hydramatic (also known as Hydra-Matic) is an automatic transmission developed by both General Motors' Cadillac and Oldsmobile divisions. Introduced in 1939 for the 1940 model year vehicles, the ''Hydramatic'' was the first mass-produced fully-a ...
transmission. This light double-six was one of the first cars designed using ergonomics. Switches buttons and stalks were all placed within finger tip reach of the driver and accessible without taking hands from the wheel. The cars would run up to before requiring engine decarbonisation.


Design changes

Engine :Cylinder block a one-piece light alloy casting :Distributors were moved to the back of the engine :Cover plates provided in the crankcase which could be removed to reveal the sleeve-eccentric links :Carburettors moved forward :Lubrication by two submerged helical-gear pumps, one feeding all moving parts, the other circulating oil through the oil radiator :Oil radiator to maintain a constant :Cold viscid oil forced open valves allowing oil into troughs below the big-ends to provide cold-start
splash lubrication Splash lubrication is a rudimentary form of lubrication found in early engines. Such engines could be external combustion engines (such as stationary steam engines), or internal combustion engines (such as petrol, diesel or paraffin engines). ...
of the sleeves :Hand-operated oil cleaner :Water pumps on outside of each cylinder bank mounted in tandem with dynamos This model was usually supplied with a taller and more slender radiator. Chassis :Grouped chassis lubrication :Back axle incorporating dip-stick cum oiling syringe :Hydraulic shock absorbers * Wheelbase: ::Short wheelbase Track ::Medium wheelbase Track ::Long wheelbase Track


Prices

* Chassis prices: Short £1,100, Medium £1,200, Long £1,350 * Short wheelbase standard saloon by Daimler from £1,600 * Medium wheelbase limousine by Daimler from £1,900 * Long wheelbase limousine by Daimler from £2,300


6.5-litre Double-Six 40/50

Announced October 1930 and matched with the new Daimler Fluid Flywheel and Wilson pre-selective half-automatically changing four-speed gearbox. :Bore and stroke 81.5 mm x 104 mm gave a swept volume of :6511 cc Tax rating 49.4 hp Cylinder block a one-piece light alloy casting


Double-Six 40/50 with poppet valves

From 1935 to 1938 nine Double-Six 40/50 engines were made with poppet valves - possibly to use surplus components.


Performance

''The Autocar'' reported in April 1927 the big cars needed no other gears once they were rolling, even climbing a hill. Petrol consumption was not so savage as might have been expected at 10 miles per gallon. "2 to 82 mph in top gear in the highest degree of smoothness and quietness" said ''The Autocar'' ". . . fortunate beings will leisurely survey the moving surface of the earth through the windows of their Daimler Double-Sixes as they pass onward in silent dignity". A letter from Tony Bird in the January 1967 issue of Motor Sport recounted how Double-Six models could develop violent front axle "wheel wobble" which could only be overcome by stopping the car.


Bodies

Bodies were all mounted after the Daimler pattern on a separate frame flexibly held.


Presence

A contemporary press report remarked that "when the Double-Six arrives at the door there is no obvious pomp and circumstance. Here is a car that looks clean-cut and aristocratic in its speckless grey paintwork. It is not until one comes close to the car that its great size is realised. The Daimler bonnet is nearly level with the chin of the observer." ''Autocar''


Difficulties

William Boddy of ''
Motor Sport ''Motor Sport'' is a monthly motor racing magazine, founded in the United Kingdom in 1924 as the ''Brooklands Gazette''. The name was changed to ''Motor Sport'' for the August 1925 issue. The magazine covers motor sport in general, although from ...
'' commented that the difficulty with sleeve valves was lubrication. So much oil near the combustion chambers led to a gummy engine prone to seize if left standing for any length of time. Attempts to tow-start invariably led to sleeve-driving link breakage if not damage to the sleeves. There was also difficulty in timing the sleeves once pistons had been out of the block and also synchronising carburation and ignition between the two banks of cylinders. Daimler introduced their new
Straight-Eight The straight-eight engine (also referred to as an inline-eight engine; abbreviated I8 or L8) is a piston engine with eight cylinders arranged in a straight line along the crankshaft. The number of cylinders and perfect primary and secondary engi ...
in 1934 and Double-Sixes slipped slowly from the catalogue.


Notes


Footnotes


Citations


References

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External links

Images not otherwise available
Double-Six hire car and driver and another Daimler, 1937

Double-Six 50 four-seater drophead coupé
YouTube
Double-Six Thirty coupé on the road

Double-Six Fifty on the road
{{DEFAULTSORT:Daimler Double-Six Engine Double-Six sleeve-valve V12 Gasoline engines by model Sleeve valve engines