Allison was asked to modify several thousand surplus Liberty engines for higher power capacity and greater durability. The principal limiting factor in these engines was in the crankshaft and connecting rod bearings.
So in 1921 Allison was in the bearing business. It was trial and error for these men who pursued excellence. They didn't know the best proportion of lead and copper. They didn't know what the thickness of the bearing of the bearing liner should be for best results, and they didn't know how thick it should be cast. They later learned thickness and temperature control were very important in relation to the size of the bearing and the method of quenching.
They knew nothing of micro finishes, x-ray or ultraviolet light inspection. Bearings then in use consisted of a bronze shell with a babbit lining. Allison developed a method to use a steel shell, thus giving the strength and stiffness needed in the bearing to support the horespower loads.
The craftsmen in this tiny foundry of Allison's machine shop learned to make good bearings, bearings which were in every way superior to anything that had been available - Allison steel-backed bronze-lined bearings were on their way.
Even Charles Lindbergh had insisted that the engine in his 'Spirit of St. Louis' have Allison bearings prior to his famed flight across the Atlantic to Paris.

This famous engine was designed by two engineers in a Washington hotel suite between 30 May and 4 June 1917. A twelve-cylinder version went quickly into mass-production at auto-factories, 20'478 being delivered till the end of 1918.

Allison got into aviation in 1926 with an inverted version of the Liberty. In 1930 they received an oder from the Navy for a 750 hp liquid-cooled engine. The first V1710 engine was delivered to the Navy in 1932. Later the V1710 was redesigned and passed the 1000 hp qualification test in April 1937. Throughout the war the V1710 remained in Volume production, some 47'000 being built. Late models developed more than 2000 hp.

Work on piston engines stopped in 1947. Allison delivered its first jet engine in February 1945. Allison moved into production and further development of gas turbine engines. Allison would also get into the development of the turboprop engine, becoming a true pioneer in that field. At right you see a picture of an AE 2100 as used in the Saab 2000.

Jim Allison had sold out to General Motors back in 1935. The company remained a GM division until 1993. Today, Allison is a part of Rolls-Royce North America who employes 6'200 people in the US and 1'600 in Canada.

Your job:
1) Make sure you do understand most of the text.

2) Make notes of the adavantages and disadvantages of plain bearings. Consult your 'Fachkunde Metall'.

3) How are multi-layer bearing shells built?

4) Convert 1710 cubic inches to cubic centimeters.

5) Why have jet engines replaced large piston engines?

http://www.leo.org
http://www.rolls-royce.com/northamerica/