10 and 15 H.P. Production cars
With Wolseley motor car sales in decline in the early 1920's, due in part to the introduction of technically advanced, but expensive cars, it was decided to promote the company's products through racing and record breaking attempts at Brooklands with specially designed cars based upon 10 h.p. and 15 h.p. models fitted with 4 cylinder overhead camshaft engines. The 10 h..p. and 15 h.p. models were announced in November 1919 based on pressed steel channel section chassis frames with wheelbases of 8ft 3ins and 9ft 10ins respectively and both models featuring quarter elliptic road springs, leading at the front and trailing at the rear with the axles cantilevered at their extremities. There the similarities ended, the 10 h.p. model having a 3 speed trans-axle which had been developed for the post war "Stellite" announced in February 1919 by the Electric & Ordnance Accessories Co. Ltd., whilst the 15 h.p. model had a 3 speed gearbox mounted separately from the engine and with a remote change speed lever to the right hand side of the driver. 

Transmission was via a long open shaft between the clutch and rear cross member on the 10 h.p. models, then through a torque tube, but on 15 h.p. models it was through a short drive shaft between the gearbox and cross member and then via a torque tube.  In August 1923 modifications were announced to the 15 h.p. models which included a four speed gearbox, spiral bevel drive rear axle, open prop-shaft drive to the rear axle and the fitting of a substantial torque member between the chassis frame cross-member and rear axle to give better control of the axle, probably as a result of experience gained through racing at Brooklands. The 10 h.p. trans-axle had gear ratios of 3.32:1, 1.68:1, 1.0:1 and reverse of 2.58:1 with an underslung worm drive ratio of 5.4:1 whilst the 15 h.p. models had gear ratios of 3.39:1, 1.7:1, 1.0:1 with an underslung worm drive rear axle ratio of 4.8:1.
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This site designed by G.McCutcheon 2009

10 h.p. chassis being erected in the Drews Lane works
but incorporated different valve actuation by the camshafts through rocker arms. The 10 h.p. engines had a bore of 65mm diameter, stroke of 95mm and capacity of 1,261 c.c. and the 15 h.p. engines had a bore of 80mm diameter, stroke of 130mm and capacity of 2,614 c.c. Surprisingly, the 10 h.p. engines only had a two bearing crankshaft whilst the 15 h.p. engines had a three bearing crankshaft. On 10 h.p. engines the pistons were of cast iron being flat topped, and of aluminium alloy slightly domed on 15 h.p. engines.
The single overhead camshaft engines had been developed as a result of the company's experience building Hispano V8 aero engines during the Great War,
15 h.p. Production model chassis drawing.
1922 10 H.P.
Trans-axle of 10 h.p. model showing 3 speed gearbox and underslung worm and worm wheel final drive. Timken taper roller bearings were used throughout this assembly.
Note the foot brake and hand brake actuation through cables to the rear drums and the mounting of the gear selector gate and lever on the outside of the chassis side member.

10 h.p. Production model chassis drawing
Close up showing the 10 h .p. front stub axle and king pin made in one piece. A similar design was used on 15 h.p. models

This drawing shows the general arrangement of the 15 h.p. chassis with the chassis frame cranked over the rear axle and extended rearwards to form a mounting for the petrol tank and to accommodate the bodywork.
Unlike the smaller 10 h.p. models, the front springs are mounted beneath the chassis side members and the front axle is positioned directly beneath the radiator and front cross-member.
Close up showing valve gear used on10 h.p engine

Sectioned views of 10 h.p. 1,261 c.c. engine.
Above:
Torque member fitted to rear axle of 15 h.p. models from 1923.

Below:
1922 10 H.P.
Both of these engines incorporated a combined chain and bevel gear drive between the crankshaft and camshaft in a design patented by the company in 1917 - Patent Number 117,553, (drawing to the right) the patentees being Alfred Remington Chief Engineer and Edward Reeve Chief Draughtsman. This combination of chain drive and bevel gear was proposed to eliminate gear chatter caused by deflection and cyclic variation of the crankshaft.
In early models the drive between the lower bevel gear and upper bevel gear at the camshaft was via a steel blade which slotted into the gear bosses to cater for any misalignment of the cylinder head to the crankcase. The blade was replaced by a solid shaft following the introduction of a dowelled cylinder head to prevent any possibility of misalignment.
Sectioned view of 15 h.p. 2,614 c.c. engine
Sectioned view of 15 h.p. 2,614 c.c. engine
Close up showing valve gear used on 15 h.p. engine.

Sectioned view of 15 h.p. 2,614 c.c. engine
By Norman Painting