| Description | Date | Identifier | |
| Urgent outsourcing of grinding for servo spur gears for the gearbox. | 7th May 1924 | Box 73 \ 1 scan0164 | |
| Finalization of the E.A.C. servo and the adoption of the RRM. Des. 60 braking scheme. | 8th May 1924 | Box 73 \ 1 scan0165 | |
| Material change for gears from 3.5% Nickel Steel to a harder 5% C.H.N.S. steel. | 9th May 1924 | Box 73 \ 1 scan0166 | |
| Confirming the decision to use a 7 to 1 reduction for the E.A.C.III servo mechanism. | 22th May 1924 | Box 73 \ 1 scan0167 | |
| Secret memo about successfully reproducing a 'jagger' fault on a servo mechanism and a proposed fix. | 23th May 1924 | Box 73 \ 1 scan0168 | |
| Secret memorandum discussing production difficulties and potential alterations for servo motor thrust washers. | 24th May 1924 | Box 73 \ 1 scan0169 | |
| Internal memorandum discussing defects and policy regarding the E.A.C. steering servo adjustment. | 26th May 1924 | Box 73 \ 1 scan0170 | |
| Technical discussion on brake performance, balance, skid characteristics, and materials. | 27th May 1924 | Box 73 \ 1 scan0171 | |
| Optimal angle for a Face Cam operating a Servo, debating a change from 45° to 55° for braking. | 27th May 1924 | Box 73 \ 1 scan0172 | |
| Secret memorandum on the development status of the four-wheel brake system. | 27th May 1924 | Box 73 \ 1 scan0173 | |
| Continued technical report discussing steering, braking systems, and wheel hub design. | 27th May 1924 | Box 73 \ 1 scan0174 | |
| Difficulties with a servo motor's ball bearing and thrust washer. | 27th May 1924 | Box 73 \ 1 scan0175 | |
| Letter from F.H. Royce detailing three schemes for a patented four-wheel brake system. | 3rd Jun 1924 | Box 73 \ 1 scan0176 | |
| Testing the efficiency of a servo with various cams. | 4th Jun 1924 | Box 73 \ 1 scan0177 | |
| Measuring servo torque multiplication on a car using spring balances. | 20th Aug 1924 | Box 73 \ 1 scan0178 | |
| The torque multiplication of a servo with Ferodo linings. | 20th Mar 1924 | Box 73 \ 1 scan0179 | |
| Feedback on a car's adopted braking scheme, including pedal pressure, servo, safety, production parts, and steering. | 5th Jun 1924 | Box 73 \ 1 scan0180 | |
| Test report page discussing the performance of the clutch, brakes, and servo system. | 18th Jun 1924 | Box 73 \ 1 scan0181 | |
| Four-wheel brake tests, including an extract about the countershaft and overrun mechanism. | 18th Jun 1924 | Box 73 \ 1 scan0182 | |
| Schematic diagram showing the motion of levers when the brake pedal is depressed. | 19th Jun 1924 | Box 73 \ 1 scan0183 | |
| Noise issues originating from servo gears in the four-wheel brake system. | 19th Jun 1924 | Box 73 \ 1 scan0184 | |
| Drive shaft reduction and brake pedal pressure, specifically regarding car 35-PK. | 19th Jun 1924 | Box 73 \ 1 scan0185 | |
| Instructions for testing servo torque multiplication using spring balances on a car. | 20th Jun 1924 | Box 73 \ 1 scan0186 | |
| Diagram illustrating the method for arranging 'set up' springs on a car, with a formula for servo torque multiplication. | 20th Jun 1924 | Box 73 \ 1 scan0187 | |
| Secret memo discussing the simplification of the servo and differential linkage by making the countershaft solid. | 21th Jun 1924 | Box 73 \ 1 scan0188 | |
| Patentability and originality of a plate clutch for a servo, comparing it to Renault and Hispano designs. | 1st Jun 1924 | Box 73 \ 1 scan0189 | |
| Secret internal memo regarding a delay with the E.A.C. car due to noisy servo gears. | 25th Jun 1924 | Box 73 \ 1 scan0190 | |
| Secret memo regarding the design of levers on the countershaft for four-wheel brakes. | 1st Jun 1924 | Box 73 \ 1 scan0191 | |
| Secret memorandum discussing noise issues in the servo drive and comparing different reduction ratios. | 27th Jun 1924 | Box 73 \ 1 scan0192 | |
| Modifications to reduce noise and vibration from servo gears. | 27th Jun 1924 | Box 73 \ 1 scan0193 | |
| Noise in a servo drive, comparing 7 to 1 and 10 to 1 reduction ratios and their implications. | 27th Jun 1924 | Box 73 \ 1 scan0194 | |
| From R. to HS. about successfully creating quiet gears for the servo drive by increasing worm teeth obliquity. | 30th Jun 1924 | Box 73 \ 1 scan0195 | |
| Brake and spring testing of two cars in France. | 30th Jun 1924 | Box 73 \ 1 scan0196 | |
| Procedure for testing the efficiency of a servo using a specialized apparatus. | 9th Jul 1924 | Box 73 \ 1 scan0197 | |
| Instructions regarding servo operation, 'Halo' friction lining, and test rig procedures. | 7th Sep 1924 | Box 73 \ 1 scan0198 | |
| Design and patent application for a shoe-type servo mechanism. | 7th Sep 1924 | Box 73 \ 1 scan0199 | |
| Shoe-type servo design (N.sch.1823) as a contingency for failing plate clutch negotiations. | 17th Jul 1924 | Box 73 \ 1 scan0200 | |
| Preference for a plate clutch servo and the patenting of an alternative shoe servo design. | 24th Jul 1924 | Box 73 \ 1 scan0201 | |
| Secret memo regarding the design and patenting of an automatic control oil servo system. | 24th Jul 1924 | Box 73 \ 1 scan0202 | |
| Issue of a noisy servo gear mechanism on the 'U' series chassis. | 19th Sep 1924 | Box 73 \ 1 scan0203 | |
| Ongoing issue with noisy servo gears. | 19th Sep 1924 | Box 73 \ 1 scan0204 | |
| Continued document discussing the results of experiments for noise reduction modifications. | 24th Sep 1924 | Box 73 \ 1 scan0205 | |
| Servo gear noise in 40/50 HP chassis fitted with 4-wheel brakes. | 24th Sep 1924 | Box 73 \ 1 scan0206 | |
| Testing different servo gear arrangements to reduce noise in the 46-PK car. | 24th Sep 1924 | Box 73 \ 1 scan0207 | |
| Fix for rattling Servo Reduction Gears by adjusting keyway slack. | 26th Sep 1924 | Box 73 \ 1 scan0208 | |
| Reducing servo gear noise by introducing slight torsional movement. | 29th Sep 1924 | Box 73 \ 1 scan0209 | |
| The proposal to make grinding the faces of the 40/50 HP servo drum and halo a standard practice. | 3rd Oct 1924 | Box 73 \ 1 scan0210 | |
| The importance of trueness for revolving members and 'Halo' surfaces on 40/50 HP servo gears. | 1st Oct 1924 | Box 73 \ 1 scan0211 | |
| Delays in 40/50 HP chassis deliveries due to issues with the servo gear and the progress on a solution. | 9th Oct 1924 | Box 73 \ 1 scan0212 | |
| Design considerations and adjustments for a 4-wheel brake system. | 16th Oct 1924 | Box 73 \ 1 scan0213 | |
| 'servo jagger' fault on the 48-PK car and a recommendation to send it to Derby for demonstration. | 17th Nov 1924 | Box 73 \ 1 scan0214 | |
| Instructions to coachbuilders regarding floorboard clearance for the 4-wheel brake servo stop. | 24th Nov 1924 | Box 73 \ 1 scan0215 | |
| Faulty servo gears on the 40/50 HP model due to paint and lubrication on friction surfaces. | 13th Feb 1925 | Box 73 \ 1 scan0216 | |
| Stove enamelling servo motor drums for the 40/50HP chassis to prevent paint issues. | 17th Feb 1925 | Box 73 \ 1 scan0217 | |
| History and resolution of a fault causing rattling servo gears. | 31th Mar 1925 | Box 73 \ 1 scan0218 | |
| Report investigating the failure of spring steel and mild steel fitted dampers (spiders), detailing potential causes and a proposed solution. | 31th Mar 1925 | Box 73 \ 1 scan0219 | |
| Policy for dealing with rattling servo gears by fitting ground gears. | 22th Apr 1925 | Box 73 \ 1 scan0220 | |
| And comparing different 4-wheel brake distribution configurations for the India model. | 25th May 1925 | Box 73 \ 1 scan0221 | |
| Continued discussion on servo braking efficiency and its distribution relative to car weight. | 5th Mar 1925 | Box 73 \ 1 scan0222 | |
| Testing of a fabric coupling on a 40/50HP 'U' Series chassis to diminish body booms. | 5th Mar 1925 | Box 73 \ 1 scan0223 | |
| Requesting a standard 40/50 HP car to test a fabric coupling intended to cure 'transmission groans'. | 1st Mar 1925 | Box 73 \ 1 scan0224 | |
| Urgent request for fabric couplings to resolve noise issues in 'U' Series 40/50 HP cars. | 18th Mar 1925 | Box 73 \ 1 scan0225 | |
| The testing and standardisation of a new fabric coupling for the 40/50 HP car. | 19th Mar 1925 | Box 73 \ 1 scan0226 | |
| Requesting weight information for the Goshawk and 40/50 engines to estimate the weight of the 'Seagull' engine. | 12th Sep 1922 | Box 73 \ 1 scan0227 | |
| Secret internal memo requesting a weight comparison for the E.A.C. engine and chassis against the current models. | 6th Feb 1924 | Box 73 \ 1 scan0228 | |
| Weight impact of adding front-wheel brakes, a larger radiator, and a new 4-speed gearbox. | 8th Feb 1924 | Box 73 \ 1 scan0229 | |
| Correcting and detailing the engine weights for an EAC engine, comparing cast iron and aluminium induction pipes. | 12th Jul 1923 | Box 73 \ 1 scan0230 | |
| Comparing the weights of cast iron versus aluminium induction pipes and hot spots. | 1st Feb 1924 | Box 73 \ 1 scan0231 | |
| Weight of four-wheel brakes and the potential use of lighter materials like aluminium and duralumin. | 15th Feb 1924 | Box 73 \ 1 scan0232 | |
| Secret memo discussing the EAC engine's weight and power, comparing it to the 40/50 model and outlining performance improvement goals. | 15th Feb 1924 | Box 73 \ 1 scan0233 | |
| EAC steering, discussing pivot pins, castor action, and road shocks. | 12th Jul 1923 | Box 73 \ 1 scan0234 | |
| Comparing the weight of the EAC engine against the 40/50 engine, detailing component differences. | 18th Feb 1924 | Box 73 \ 1 scan0235 | |
| Telegram received by telephone requesting the weights of two front springs for an E.A.C. car. | 9th Sep 1924 | Box 73 \ 1 scan0236 | |
| From the Test Department detailing the average weights of the 40/50 'U' series and 20 HP chassis. | 24th Feb 1925 | Box 73 \ 1 scan0237 | |
| The dimensional conflict between the 'C' type steering and a proposed cabriolet body. | 5th Dec 1925 | Box 73 \ 1 scan0238 | |
| Breakdown of the weights for the rear axle and springs for a car. | 26th Jan 1926 | Box 73 \ 1 scan0239 | |
| Comparing the inertia and weight of original, and lightened/improved Phantom and Silver Ghost flywheel and clutch units. | 10th Jun 1926 | Box 73 \ 1 scan0240 | |
| Particulars of tests on front wheel brakes for a 40/50 HP chassis. | 20th Dec 1921 | Box 73 \ 2 scan0001 | |
| Torsion and bending tests performed on a 40/50 front axle. | 23th Dec 1921 | Box 73 \ 2 scan0002 | |
| Blueprint detailing off-side leaf spring deflection measurements under varying loads. | 23th Dec 1921 | Box 73 \ 2 scan0003 | |
| Blueprint detailing load testing results for a near-side leaf spring suspension. | 23th Dec 1921 | Box 73 \ 2 scan0004 | |
| The progress on front wheel brakes, associated frame modifications, and considerations regarding various patents. | 19th Aug 1922 | Box 73 \ 2 scan0005 | |
| Completing front wheel brake designs and expediting experimental parts for a new chassis. | 10th Sep 1922 | Box 73 \ 2 scan0006 | |
| Mr. Royce's decision to halt work on pneumatic brakes and proceed with air brakes for an experimental car. | 18th Oct 1922 | Box 73 \ 2 scan0007 | |
| Modifications to the 40/50 front wheel brakes using a new Goshawk type joint. | 27th Oct 1922 | Box 73 \ 2 scan0008 | |
| Modification to the 40/50 front wheel brakes, involving a pull-off spring. | 11th Nov 1922 | Box 73 \ 2 scan0009 | |
| Modification to the 40/50 front wheel brakes and steering lever. | 11th Nov 1922 | Box 73 \ 2 scan0010 | |
| Explaining that work on the Goshawk's left-hand controls is delayed due to other engineering priorities. | 16th Nov 1922 | Box 73 \ 2 scan0011 | |
| Stressing the urgent need to develop front-wheel brakes for the 40/50HP model due to losing sales to competitors. | 16th Nov 1922 | Box 73 \ 2 scan0012 | |
| Implementation of front brakes on new and existing cars. | 1st Dec 1922 | Box 73 \ 2 scan0013 | |
| Modifications required to fit front wheel brakes on the 40/50 chassis, comparing pneumatic and mechanical servo systems. | 12th Dec 1922 | Box 73 \ 2 scan0014 | |
| Modifications to rear brakes and timelines for pneumatic and mechanical servo brakes. | 17th Jan 1923 | Box 73 \ 2 scan0015 | |
| Development policy for experimental car models, including the 'Heron', 'Seagull' and '40/50'. | 17th Jan 1923 | Box 73 \ 2 scan0016 | |
| Policy statement concerning the fitting of front wheel brakes to the 40/50 chassis. | 27th Mar 1923 | Box 73 \ 2 scan0017 | |
| Circulating a draft letter to customers explaining the delay in fitting front-wheel brakes due to safety concerns. | 27th Mar 1923 | Box 73 \ 2 scan0018 | |
| Concluding paragraph regarding the continuation of experiments and the adoption of successful improvements. | 2nd Jun 1923 | Box 73 \ 2 scan0019 | |
| Mr. Royce's concerns about potentially softened brake springs. | 2nd Jun 1923 | Box 73 \ 2 scan0020 | |
| Letter from Rolls Royce of America to the UK regarding weakened brake springs due to heat and a suggested solution. | 29th Mar 1923 | Box 73 \ 2 scan0021 | |
| Three types of experimental chassis, EAC.1, EAC.11, and EAC.111, and their respective modifications. | 20th Sep 1923 | Box 73 \ 2 scan0023 | |
| Secret memo suggesting the acquisition of a Hispano car to compare its front-wheel brakes against their own. | 27th Sep 1923 | Box 73 \ 2 scan0024 | |
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