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The design originated with a William Barton Wright's 4-4-0 of 1880 with driving wheels of 6 feet 0 inches (1.83 m) and boiler pressure of 140 psi (0.97 MPa). Aspinall then produced a modified version with 6ft wheels which was the basis for the class 3.
Class 3
John Aspinall succeeded Barton Wright in 1886. He initially order more locomotives of Barton's Wright's 4-4-0 design. but determined a driving wheels of 7 feet 3 inches (2.21 m) and boiler pressure increased to 160 psi (1.10 MPa) should give increased speed for the same tractive effort.
There were two different versions of the rebuild. One had 19" bore cylinders and Joy valve gear. The other had 20" bore cylinders and Walschaerts valve gear.
Numbering
The L&YR numbered them 1093-1229 and then randomly, using numbers between 318 and 498. The LMS numbered its 34 Class 3 locomotives 10150-10183. The six which had been rebuilt to Class 4 were numbered in a separate series, LMS 10190-10195.
Class 4 numbering
L&YR no.
LMS no.
Cylinders
1112
10190
19"
1110
10191
20"
1104
10192
20"
1098
10193
20"
1105
10194
20"
455
10195
19"
Withdrawal
Withdrawals began in 1925 and the Class 4 superheated locomotives were all withdrawn by 1926. The last members of the type were withdrawn in 1930. None have been preserved.