Humber 15
| Company type | Automobile model |
|---|---|
| Industry | Automotive |
| Predecessor | Prewar Humber 3.3-litre model |
| Founded | 1919 |
| Defunct | 1927 |
| Successor | Humber 14/40, Humber 20/55 |
| Products | Automobiles (15 hp models including Fifteen .9 and Fifteen 40) |
Humber Fifteen vehicles, equipped with 15 horsepower engines, were classified as medium to large automobiles featuring less potent powerplants aimed at lowering yearly tax obligations while maintaining dignified performance. These cars gained a reputation for their exquisitely crafted coachwork, particularly the tourer variants, making them favored choices among professionals.
Manufactured between 1919 and 1924 and then again from 1924 through 1927, the Fifteen held an important role within Humber’s range until it was succeeded by models with smaller engines such as the 14/40 and later by a six-cylinder 20-horsepower 20/55 in 1927 and 1928 respectively.
Introduction
The first post-World War I Motor Show at Olympia in November 1919 featured these automobiles prominently. The design received commendations for its functional qualities and meticulous craftsmanship. A blue saloon model, distinguished by its shiny black roof and trim, drew considerable attention.
Engine
Powered by a 2.8-litre inline four-cylinder engine cast as a single block with a removable cylinder head, the Fifteen .9 incorporated Humber’s innovative overhead inlet valves paired side-by-side with exhaust valves. This contrasted with the prewar version which had a larger 3.3-litre unit equipped with twin overhead camshafts.
Bodies
Available configurations for the 15.9 included a saloon and a five-seat tourer. Notably, the driver's door was omitted due to right-side placement of brake and gear levers, with an externally mounted spare wheel situated at the same location.
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A pull control mounted on the dashboard operated the CAV starter mechanism. The steering wheel integrated timing advance and retard levers along with an ignition switch, complemented by an adjustable steering column rake. The split windscreen extended seamlessly into the curved dashboard without a wooden trim. Instrumentation comprised a cupboard, two drawers, a Jaeger speedometer driven by the gearbox, clock, and air control vents enhanced by scuttle ventilators. Additional storage spaces were located beneath the bonnet as well as in the passenger door and front floor areas. The tourer could be swiftly converted into an All-Weather vehicle using aluminium-framed celluloid side curtains stored beneath the driver’s seat; these curtains could remain upright even when the hood was lowered. Rear occupants enjoyed protection from a combined cowl and screens; the cowl shielded knees while two individual Auster windscreens by Auster were installed inside for wind deflection and secured via butterfly nuts. Later iterations featured a single large Auster windscreen equipped with hinged wings to improve passenger comfort. |
The lineup also included a saloon landaulette emphasizing luxury, which featured a glass partition with sliding panels between front and rear compartments plus an additional fold-away rear seat that could be positioned facing either side.
Brakes suspension steering
Rear-wheel internal expanding brakes were engaged by a hand lever located next to the gear-change lever, while foot braking activated a contracting band on a drum positioned behind the gearbox. Both braking systems allowed manual adjustment to compensate for wear. According to The Times, suspension comfort was generally satisfactory despite some longitudinal movement. The half-elliptical springs were mounted above the axles with minimal camber; from 1923 onward, Hartford shock absorbers were installed at the rear. Steering utilized worm-and-sector mechanisms that could be adjusted to account for wear over time.
Test
The Times conducted a road test of Humber's Fifteen horsepower five-seat open tourer, noting that despite its high price, the automobile demanded daily maintenance from the owner-driver, as it lacked dedicated personnel for upkeep.
The vehicle's design thoughtfully addressed the requirements of owner-drivers, though minor inconveniences were observed, such as the complexity of draining engine oil due to the need to remove an undershield and the somewhat intricate rear tappet plate complicated by carburettor control springs. It was recommended to regularly lubricate the tappets to avoid operational noise.
Highlighted advantages included:
- convenient access to components like the magneto, dynamo, starter, and carburettor
- clutch spigot and withdrawal mechanism equipped with automatic lubrication
- hand-operated brake adjustments
- chassis-wide spring-loaded ball-valve greasers supplied with a specialized grease gun
- tool storage positioned to avoid passenger disturbance
- fuel tank gauge visible even when the luggage rack was fully loaded
- a fuel filter funnel for added convenience
- an all-weather hood featuring side curtains that allowed signaling arm use
The Times also pointed out that checking oil levels beneath the floorboards before travel was unnecessary.
Regarding performance, the car demonstrated moderate speed capabilities, reaching a top speed near , though it was expected to achieve . The seating arrangement provided ample front knee space and was comfortable; however, accommodating five passengers resulted in a slightly narrow fit, while legroom remained adequate.
On the road, the engine exhibited lively responsiveness, quiet operation, and flexible power delivery with smooth acceleration. Although clutch engagement occasionally felt grabby, gear changes were smooth and silent. Steering received commendation for its enjoyable handling characteristics, while both braking and suspension systems were deemed satisfactory.
Fifteen 40
Introduced at the Olympia Motor Show in October 1924, the 15-40 hp represented a modest update to the earlier 15.9 model.
Engine
The engine and its separate gearbox were mounted on a subframe engineered to reduce vibration transmission. This setup employed two pairs of enclosed springs at the front and semi-circular steel trunnion blocks at the rear secured by spring-loaded bolts. This arrangement ensured firm fore-and-aft engine positioning while permitting controlled movement to dampen vibrations.
Bodies
All variants adopted four-door configurations instead of three, featuring wider rear seats that extended over the wheel arches. Mudguards were repositioned closer to the wheels to minimize mud splatter. The saloon landaulette model incorporated two folding occasional seats situated beneath the glass partition.
The petrol filler cap was moved from beneath the luggage rack to a side location for easier refueling access. Improvements in all-weather equipment included side screens made of glazed celluloid set within rigid metal frames; these folded neatly into the lower half of the doors and had overlapping frame edges to enhance sealing. Humber promoted this feature as "Exclusive! Ready-In-a-Moment All-Weather-Windows and One-Man Hood."
Brakes, suspension
The 15-40 hp was equipped with Humber-Perrott semi-servo front wheel brakes actuated by a foot pedal alongside a transmission brake. The semi-servo effect was achieved through a floating shoe mechanism that leveraged forward momentum but delivered less braking force when applied in reverse. To accommodate greater braking demands, enhancements included strengthened front axle and stub axles, wider springs, and a new cross tube linking the dumb irons (front chassis members). Front brake adjustment required lifting the vehicle’s front end and manually balancing pressure on each wheel. A compensating device between brake sets was introduced in the following year. Additionally, shock absorbers were fitted on both front and rear suspension systems.
Test
In August 1924, The Times conducted an evaluation of the 15/40 model and determined that "traveling proved enjoyable."