British Rail  - Class 31 - Fault finding Data And Charts For Class 31 Locomotives With Vacuum E.Q, And Duel Brakes.
Issue Date: Unknown  -   BR 33056/41 Issue 2

More information can be found here Wikipedia - British Rail Class 31   A1A Locomotives Ltd
More Information Regarding Preserved Class 31 Locomotives can be found on the following websites:  Preserved-Diesels