From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Specification table detailing the dimensions of servo-operated brakes for different vehicle models.
| Identifier | ExFiles\Box 12\5\ 05-page245 | |
| Date | 4th December 1930 guessed | |
| DIMENSIONS OF SERVO OPERATED BRAKES TYPE | FRONT BRAKES | REAR BRAKES --- | ARC OF CONTACT OF EACH BRAKE STRAP | WIDTH OF SHOE | DIA. OF DRUM | ARC OF CONTACT OF EACH BRAKE STRAP | WIDTH OF SHOE | DIA. OF DRUM --- | LENGTH | ANGLE | --- | --- | LENGTH | ANGLE | --- | --- Silver Ghost & Phantom I | 13.0" | 99°* | 1.70" | 15.0" | 17.8" | 120° | 2.00" | 17.0" Phantom I (Later Series) | 11.3"* | 86°* | 1.75" | 15.0" | 15.2" | 109° | 1.75" | 16.0" Phantom II | 14.0" | 107° | 1.75" | 15.0" | 15.2" | 109° | 1.75" | 16.0" Phantom II (Later Series) | 13.9" | 106° | 1.75" | 15.0" | 15.2" | 109° | 2.25" | 16.0" Phantom II (Locomotive Type) | 14.1" | 108° | 1.75" | 15.0" | - | - | - | - 20 H.P. | 11.7" | 103° | 1.30" | 13.0" | 14.4" | 118° | 2.00" | 14.0" 20 H.P. (Later Series) & 25 H.P. | 11.7" | 103° | 1.30" | 13.0" | 15.3" | 125° | 2.00" | 14.0" *INCREASES TO AN ADDITIONAL 3.0" & 23° RESPECTIVELY WITH WEAR. | ||