Debenham Sisters
Betty and Nancy Debenham, with their dog, Poncho, were keen motorcyclists. Nancy won a Gold Medal at Brooklands in 1926.
The Debenham Sisters
This general specification gives full details of the 1938 A.J.S. Models illustrated on pages 4, 5, 6 and 7 of this catalogue.
These four models are similar in their general design. The Models 38/12 and 38/22 have engines of 246 c.c. capacity, while the Models 38/16 and 38/26 have engines of 347 c.c. capacity.
The Models 38/12 and 38/16 have single-port cylinder heads with one exhaust pipe and silencer and black and gold petrol tanks, and are fitted with dynamo coil ignition and lighting equipment.
The Models 38/22 and 38/26 are deluxe editions of the aforementioned models, having two-port cylinder heads with two exhaust pipes and silencers and black and chromium petrol tanks, and are fitted with separate magneto ignition in addition to full dynamo electric lighting equipment.
All models are fitted with high frequency electric horns as part of the standard specifications.
ENGINE. Designed and manufactured throughout in the A.J.S. factory, these engines are of the overhead valve type combining high power output with unusual mechanical silence in operation, complete reliability, and great durability. Cylinders and cylinder heads are of the very latest design with large streamline shaped ovate cooling fins. The overhead valve gear is totally enclosed and is flood lubricated with oil supplied from the main engine oil pump. A special adjustable feed supplies oil to the inlet valve guide. The enclosed valve springs are pedestal mounted to prevent the springs becoming overheated. The rocker box is fitted with a handsome finned cover giving easy access to the valve clearance adjustment.
Other features of these engines include "Lo-ex" alloy pistons, roller big-end bearings with duralumin roller cages, exceptionally stiff flywheel and crankshaft assemblies, twin camshaft timing gear running in oil-bath, etc., etc.
Models 38/12 and 38/16 are fitted with single-port cylinder heads and models 38/22 and 38/26 with two-port cylinder heads.
LUBRICATION. Engine lubrication is provided by a full dry-sump system operated by a sturdy rotating plunger pump driven direct from the crankshaft. One end of this pump draws oil from the oil tank and forces it to all working parts of the engine, while the other end draws excess oil from the crankcase sump and returns it to the oil tank. The pump plunger is the only moving part in the whole system. All oil passes through a pressure type fabric oil filter which removes all impurities from the oil. This filter, which is situated the oil tank, can easily be removed for cleaning.
Oil is forced to all working parts, including the big-end bearing and overhead rocker gear, while a constant level of oil is maintained in the timing case so that the timing gear and cams run in an oil bath. A special feed from the pump supplies oil to three points on the wall of the cylinder, oil thus being fed direct to the piston. The design, however, is such that the feed of oil to the cylinder wall is reduced as the engine warms up, the result being that there is a considerable supply of oil on the cylinder when the engine is first started-this being the time when wear is likely to occur if there is not ample lubrication. When the engine warms up, less oil is required on the piston and this variation is automatically provided by the design, which also reduces the supply to the cylinder at high engine speeds, when a higher proportion of the total oil in circulation is passed through the big-end bearing, from whence it is thrown off by centrifugal force on to the cylinder and piston.
The operation of the lubrication system can instantly be checked by removing the oil tank filler cap, when the return feed from the pump to the tank is immediately visible.
GEARBOX. Provides four-speeds with carefully chosen ratios. The clutch is designed to give very sweet engagement and is provided with an accessible adjustment. Entirely enclosed automatic stop foot gear-change is incorporated. Hand gear-change cannot be supplied. Gear ratios: 38/12 and 38/22 - 6.25, 8.74, 11.2 and 18.6 to 1. Gear ratios: 38/16 and 38/26 - 5.52, 7.73, 9.88 and 16.4 to 1.
TRANSMISSION. By chain throughout. Front chain completely enclosed in pressed steel oil-bath chaincase of A.J.S. patent design with combined filling hole and oil level indicator. Rear chain completely protected by new design deep-section rear chain-guard with front and back panels giving almost complete enclosure.
CARBURETTOR. "Amal" two-lever semi-automatic carburettor, with twist-grip control for throttle.
FRAME. Sturdy duplex loop frame designed to provide exceptional torsional and lateral rigidity, so ensuring perfect steering properties on bad roads. centering head bearings. Forged rear fork-ends. Single front down tube with new design front engine lug which continues under crankcase and thus provides an effective crankcase shield.
STEERING DAMPER. A duplex frictional steering damper, instantly adjustable by means of a handsome knurled knob with inset A.J.S. medallion, is provided on Models 38/16, 38/22 and 38/26.
SPRING FORKS. Latest design locked-link fork girder assembly. Double anchor plate pattern adjustable fork dampers fitted on left-hand side.
PETROL TANK. A.J.S. deep contour petrol tank made from steel pressings and welded throughout. Capacity, 3 gallons. The tank top carries a flush-fitting instrument panel containing the electric lighting switch, ammeter, and on the Models 38/22 and 38/26 a detachable inspection lamp. There is provision for fitting an eight-day clock if desired. The tanks on Models 38/12 and 38/16 are finished in usual A.J.S. black and gold. On Models 38/22 and 38/26 the tanks are chromium-plated with black panels and gold lines in the design familiar on A.J.S. deluxe models. Handsome large-area knee-grips.
OIL TANK. Pressed steel oil tank, welded throughout, carried on substantial brackets below saddle. Fitted with large quick-action filler-cap. Capacity, 4 pints.
HANDLEBARS. Carried on sports pattern adjustable trailing links giving infinite adjustment for position and angle, thus ensuring to a rider of any stature a comfortable riding position. All controls are adjustable for position.
SADDLE. "Lycett Aero" flexible top saddle, with semi-roll back. Three-point mounting.
TYRES. 26 in. x 3.25 in. studded cord tyres on both wheels.
BRAKES. Internal expanding brakes on front and rear wheels fitted with hand adjusters, dust and water excluders. Cooling-fins fitted to front brake drum. Improved type high friction brake linings front and rear. Rear brake operating mechanism greatly improved to ensure smooth and powerful action. Quickly detachable brake connections.
WHEELS. Wheel rims heavily chromium-plated, black centred with gold lines. Adjustable taper roller bearings to both wheels.
STANDS. Low-lift spring-up rear stand and tubular stand for front wheel.
MUDGUARDS. Improved dome section mudguards with centre ribs and flared ends. Rear guard hinged to facilitate wheel removal.
ELECTRICAL EQUIPMENT. Models 38/12 and 38/16, six-volt electric lighting and coil ignition system. Thirty-watt dynamo rigidly mounted on engine plates and driven by roller chain enclosed in main oil-bath chaincase. Contact breaker built into engine timing case. Large head-lamp with parking-light and dipping switch on handlebar. Extra large battery carried on special platform beneath saddle. Electric horn.
Models 38/22 and 38/26 as described above, except that ignition is by separate magneto carried in a protected position in front of the cylinder and driven by roller chain enclosed in cast aluminium chaincase, formed integral with timing case cover.
All models incorporate constant voltage control for the dynamo, thus ensuring perfect regulation of battery charging.
EQUIPMENT. Full kit of tools, grease gun, and tyre inflator.
Special Note...
All these models can be fitted with either high or low exhaust pipes. The illustrations on the following pages show examples of both types of exhaust systems. It is essential that when ordering, customers specify whether high or low exhaust pipes are required; if this is not specified we supply as the illustration of the corresponding model. Unless specially ordered otherwise all machines are supplied with speedometers at the extra charge shown on page 24. Speedometer dial illuminated when lights are in use.
Prices:
PAGE 3
Source: AJS Factory Catalogue 1938
