| Description | Date | Identifier | |
| Flywheel deflection test results for a 20 HP engine, including a table of loads and deflection measurements. | 24th Oct 1930 | Box 137 \ 4 scan0105 | |
| Issues with engine roughness and body 'booming' in the 20 HP and 40/50 models, and a proposed testing scheme. | 4th Nov 1930 | Box 137 \ 4 scan0106 | |
| Solutions for vibrations in a 25 HP engine, proposing tests on counter-weights and a unified crankcase-block casting. | 5th Nov 1930 | Box 137 \ 4 scan0107 | |
| Experiments investigating the cause of vibrations in a 25 HP engine. | 5th Nov 1930 | Box 137 \ 4 scan0108 | |
| Analysis of engine and flywheel vibrations, diagnosing the cause as crankcase vibration. | 5th Nov 1930 | Box 137 \ 4 scan0109 | |
| Page discussing the 'long couples' that exist in a six-cylinder crankshaft. | 5th Nov 1930 | Box 137 \ 4 scan0110 | |
| Test data for flywheel vibrations on a 25 HP engine, showing crank deflection under load. | 6th Nov 1930 | Box 137 \ 4 scan0111 | |
| Test data sheet showing crank deflection measurements under different loads. | 6th Nov 1930 | Box 137 \ 4 scan0112 | |
| Blueprint of a lever mechanism with dimensional measurements. | 7th Nov 1930 | Box 137 \ 4 scan0113 | |
| Experiments to eliminate a 'boom' noise in Phantom II cars at 60 M.P.H. | 10th Nov 1930 | Box 137 \ 4 scan0114 | |
| Test report detailing modifications to engine mountings, including a Y bracket and rubber feet, to reduce noise and vibration. | 10th Nov 1930 | Box 137 \ 4 scan0115 | |
| Test report on diagnosing a 'boom' noise by modifying the exhaust and concluding that vibration is the likely cause. | 10th Nov 1930 | Box 137 \ 4 scan0116 | |
| Tests to eliminate engine vibrations and booms in the 20/25 HP car model. | 21th Nov 1930 | Box 137 \ 4 scan0117 | |
| Report proposing to standardise Cotton 'A' fabrics for torque reaction dampers on 20/25 HP cars. | 21th Nov 1934 | Box 137 \ 4 scan0118 | |
| Blueprint diagram of a torque reaction damper for a 20/25 HP model. | 21th Nov 1930 | Box 137 \ 4 scan0119 | |
| Experiments investigating vibrations in a 25 HP engine. | 21th Nov 1930 | Box 137 \ 4 scan0120 | |
| Analysis of vibration experiments on a 25 HP engine, focusing on the flywheel, crankcase, and crankshaft. | 21th Nov 1930 | Box 137 \ 4 scan0121 | |
| The measurement of angular distortion in a crankcase bearing housing to assess rigidity and design. | 21th Nov 1930 | Box 137 \ 4 scan0122 | |
| Blueprint showing designs for a 25 HP No. 6 Bearing and a Flywheel. | 21th Nov 1930 | Box 137 \ 4 scan0123 | |
| Graph plotting deflections for a 25 HP crankcase and flywheel under load. | 26th Nov 1930 | Box 137 \ 4 scan0124 | |
| Car body 'booming' and vibrations from the engine and road. | 26th Nov 1930 | Box 137 \ 4 scan0125 | |
| Tests for 25 HP high-speed engine roughness, focusing on the flywheel and bearings. | 23th Nov 1930 | Box 137 \ 4 scan0126 | |
| Blueprint diagram for a tail bearing for a 25 HP flywheel. | 1st Dec 1930 | Box 137 \ 4 scan0127 | |
| Proposed 'interlaced' 6-throw crankshaft design for 6 and 12-cylinder engines. | 1st Dec 1930 | Box 137 \ 4 scan0128 | |
| Redesign of the 40/50 model's engine suspension to solve a 'booming' issue. | 4th Dec 1930 | Box 137 \ 4 scan0129 | |
| Report comparing boom and vibration issues between vehicles 17-G4 and 12-G4. | 1st Dec 1930 | Box 137 \ 4 scan0130 | |
| Vibration tests conducted on the 18-G4 (C.7 Unit) with and without torque reaction dampers. | 1st Dec 1930 | Box 137 \ 4 scan0131 | |
| Experiments to reduce vibrations on a 25-HP engine using different flywheels and bearings. | 8th Dec 1930 | Box 137 \ 4 scan0132 | |
| Stationary dynamometer tests on a 25 HP model to investigate and separate exhaust boom from engine vibration. | 8th Dec 1930 | Box 137 \ 4 scan0133 | |
| Investigation into the cause of engine and exhaust booms on a 25 HP engine (Japan Engine 1V-G6). | 3rd Dec 1930 | Box 137 \ 4 scan0134 | |
| Analysis of exhaust system configurations and silencers to mitigate engine booms. | 9th Dec 1930 | Box 137 \ 4 scan0135 | |
| Arranging a visit to Derby to inspect work on engine balancing and mounting. | 15th Dec 1930 | Box 137 \ 4 scan0136 | |
| Postponing the 14-EX demonstration regarding 40/50 Booms until after Christmas. | 15th Dec 1930 | Box 137 \ 4 scan0137 | |
| Engine boom issues in 40/50 & 25 HP models, detailing tests with balanced crankshafts and new engine mountings. | 16th Dec 1930 | Box 137 \ 4 scan0138 | |
| Short memo postponing a visit to the works until after Christmas to discuss another point. | 16th Dec 1930 | Box 137 \ 4 scan0139 | |
| Experiments on a new engine mounting for the 40/50 & 25 HP models to reduce a 60 mph 'boom'. | 17th Dec 1930 | Box 137 \ 4 scan0140 | |
| Engine mounting schemes and efforts to eliminate engine boom in 40/50 & 25 HP models. | 18th Dec 1930 | Box 137 \ 4 scan0141 | |
| Fitting car GLN-60 with experimental parts to demonstrate improvements in booming and gain mileage. | 18th Dec 1930 | Box 137 \ 4 scan0142 | |
| Requesting a drawing for a new torque reaction damper part for standardisation. | 18th Dec 1930 | Box 137 \ 4 scan0143 | |
| Engine balancing, crankshaft stiffness, and vibration reduction for 25HP and 45HP engines. | 20th Dec 1930 | Box 137 \ 4 scan0144 | |
| Urgent improvements for the 25HP and 45HP models, focusing on crankshaft balancing, suspension, and clutch design. | 23th Dec 1930 | Box 137 \ 4 scan0145 | |
| Efforts and departmental collaboration to resolve the issue of 'booming' noise in car bodies. | 23th Dec 1930 | Box 137 \ 4 scan0146 | |
| Technical memorandum discussing the design and balancing of a 25HP and 45HP crankshaft. | 23th Dec 1930 | Box 137 \ 4 scan0147 | |
| Engine design focusing on crankshaft balancing, counterweights, and flywheel modifications to achieve smoother performance. | 24th Dec 1930 | Box 137 \ 4 scan0148 | |
| Experiments investigating flywheel vibrations in a 25 HP engine. | 24th Dec 1930 | Box 137 \ 4 scan0149 | |
| Series of five photographs showing the distortion of a rotating object at various speeds. | 24th Dec 1930 | Box 137 \ 4 scan0150 | |
| Photographic series documenting pattern changes at different numerical intervals, possibly RPMs. | 24th Dec 1930 | Box 137 \ 4 scan0151 | |
| Blueprint detailing the optical measurement of flywheel vibrations. | 24th Dec 1930 | Box 137 \ 4 scan0152 | |
| Problem of 'booming' in finished cars and proposed improvements. | 24th Dec 1930 | Box 137 \ 4 scan0153 | |
| Solutions for engine vibrations and 'booming' in car bodies for 25HP and 45HP models. | 26th Dec 1930 | Box 137 \ 4 scan0154 | |
| Delay in the scheme for 40/50 Engine Booms. | 31th Dec 1930 | Box 137 \ 4 scan0155 | |
| Measurement of flywheel vibrations on the 40/50 engine using optical apparatus. | 7th Jan 1931 | Box 137 \ 4 scan0156 | |
| Photographic record of three numbered test samples showing spray or deposit patterns. | 7th Jan 1931 | Box 137 \ 4 scan0157 | |
| Blueprint diagram illustrating the bending moment on a motion shaft due to flywheel tilt. | 8th Jan 1931 | Box 137 \ 4 scan0158 | |
| Battery box vibration tests on the Phantom II chassis, comparing cantilever and continuous cross-member supports. | 8th Jan 1931 | Box 137 \ 4 scan0159 | |
| Diagram illustrating the setup for the measurement of battery vibrations using a cantilever and steam indicator. | 8th Jan 1931 | Box 137 \ 4 scan0160 | |
| Test report showing the movement of a cantilever battery box support at various drum speeds. | 8th Jan 1931 | Box 137 \ 4 scan0161 | |
| Series of waveform measurements for a continuous battery box support at various speeds, indicating critical axle speed tramping at 30 MPH. | 9th Jan 1931 | Box 137 \ 4 scan0162 | |
| Test report on the torsional period, engine RPM, and speedometer accuracy for the 20-EX model. | 9th Jan 1931 | Box 137 \ 4 scan0163 | |
| Engine vibrations, a 'boom' issue on the 40/50 engine, and the effects of connecting rod lengths. | 9th Jan 1931 | Box 137 \ 4 scan0164 | |
| Connecting rod length and engine vibration for the improved 25HP model. | 11th Jan 1931 | Box 137 \ 4 scan0165 | |
| Engine rod lengths and related specifications in a table format. | 12th Jan 1934 | Box 137 \ 4 scan0166 | |
| Modifications to engine mounting to improve smoothness and suggesting a redesign of the 'Diamond' mounting. | 12th Jan 1934 | Box 137 \ 4 scan0167 | |
| On tests comparing a standard flywheel with a new lightened and strengthened version for a 25 HP model. | 12th Jan 1931 | Box 137 \ 4 scan0168 | |
| Graph comparing the deflection vs load characteristics of a standard and a lightened 25 HP clutch. | 13th Jan 1931 | Box 137 \ 4 scan0169 | |
| 25 HP engine vibrations, specifically the behaviour of a lightened flywheel with different bearing configurations. | 13th Jan 1931 | Box 137 \ 4 scan0170 | |
| Study of W.W. Flywheel vibration patterns with and without a tail bearing at various RPMs. | 13th Jan 1931 | Box 137 \ 4 scan0171 | |
| Cross-sectional drawing of a mirror holder and tail bearing for a 25 HP flywheel. | 13th Jan 1931 | Box 137 \ 4 scan0172 | |
| Re-design of the engine mounting for the improved 25HP chassis. | 13th Jan 1931 | Box 137 \ 4 scan0173 | |
| Test report detailing crank pin dimensions, top torsional period, top speed, and speedometer checks. | 15th Jan 1931 | Box 137 \ 4 scan0174 | |
| Flywheel vibrations for P.2. and Japan models, exploring potential solutions for crankshaft and bearing configurations. | 17th Jan 1931 | Box 137 \ 4 scan0175 | |
| The failure of a low inertia slipper wheel during crankshaft critical speed testing. | 21th Jan 1931 | Box 137 \ 4 scan0176 | |
| Blueprint showing two views of a P.II. Low Inertia Crankshaft Damper. | 21th Jan 1931 | Box 137 \ 4 scan0177 | |
| Design improvements and simplifications for the Japan Engine, focusing on crankshafts, bearings, and mounting. | 21th Jan 1931 | Box 137 \ 4 scan0178 | |
| Diagram of a starter handle shaft tube location and a telegram from Royce regarding design simplification. | 21th Jan 1931 | Box 137 \ 4 scan0179 | |
| Vibrations in Phantom II cars and proposed modifications to fix them. | 22th Jan 1931 | Box 137 \ 4 scan0180 | |
| Telegram from Royce detailing engine modifications for the Phantom model. | 26th Jan 1931 | Box 137 \ 4 scan0181 | |
| Design of timing gears and a double rear bearing to address flywheel vibration. | 26th Jan 1931 | Box 137 \ 4 scan0182 | |
| Sketches comparing four different designs for a journal and flywheel flange. | 27th Jan 1931 | Box 137 \ 4 scan0183 | |
| Engine roughness caused by inertia torque and local out-of-balance issues in 6 and 8 cylinder engines. | 27th Jan 1931 | Box 137 \ 4 scan0184 | |
| Experimental double rear crank bearing for test on a 20/25 engine. | 27th Jan 1931 | Box 137 \ 4 scan0185 | |
| Failure of a crankshaft damper disc and proposing design modifications for the low inertia slipper wheel. | 28th Jan 1931 | Box 137 \ 4 scan0186 | |
| Summary of a letter discussing engine design schemes, vibrations, and suggestions for future engine development. | 29th Jan 1931 | Box 137 \ 4 scan0187 | |
| Analysis of engine and crankshaft vibrations, their causes, and potential solutions for various car models. | 29th Jan 1931 | Box 137 \ 4 scan0188 | |
| Engine modifications to address issues with overhanging weight, high revs, bearing loads, and steering troubles. | 1st Feb 1931 | Box 137 \ 4 scan0189 | |
| Analysis of a low inertia slipper wheel failure, discussing torsional vibrations, engine testing, and potential solutions. | 1st Feb 1931 | Box 137 \ 4 scan0190 | |
| Issues with flywheel vibration in an engine and potential solutions. | 2nd Mar 1931 | Box 137 \ 4 scan0191 | |
| Confidential memo discussing the performance of the Bentley 8 litre and its threat to the Phantom II model. | 1st Feb 1931 | Box 137 \ 4 scan0192 | |
| Feasibility of producing a 12-cylinder car for the 1931 Show, considering competitor models and existing company commitments. | 5th Feb 1931 | Box 137 \ 4 scan0193 | |
| Confidential memo discussing the purchase of a competitor's car, gearbox issues, and performance comparisons. | 5th Feb 1931 | Box 137 \ 4 scan0194 | |
| Confidential memo from A.F. Sidgreaves regretting Bentley's success and emphasizing the importance of testing competitors' cars. | 5th Feb 1931 | Box 137 \ 4 scan0195 | |
| Technical memo discussing engine flywheel vibrations and potential solutions. | 6th Feb 1931 | Box 137 \ 4 scan0196 | |
| Engine vibration, balance weights, and potential design improvements by modifying pins and webs. | 6th Feb 1931 | Box 137 \ 4 scan0197 | |
| Report discussing 12-cylinder engine design, crankshafts, and vibration issues. | 9th Feb 1931 | Box 137 \ 4 scan0198 | |
| Vibrations and booming issues in Phantom II and 25 HP models. | 9th Feb 1931 | Box 137 \ 4 scan0199 | |
| Tests and modifications to address engine and torque reaction vibrations, specifically 'booms'. | 9th Feb 1931 | Box 137 \ 4 scan0200 | |
| Technical report on engine vibrations, propeller shaft issues, and flywheel wobble in 20 HP and 25 HP models. | 9th Feb 1931 | Box 137 \ 4 scan0201 | |
| Mathematical investigations into the benefits of heavy crankshafts and stiff crankcases for the 25 HP engine. | 11th Feb 1931 | Box 137 \ 4 scan0202 | |
| Photographic study of flywheel vibration patterns at various speeds and configurations. | 11th Feb 1931 | Box 137 \ 4 scan0203 | |
| Tests conducted on 25 HP flywheel vibrations. | 11th Feb 1931 | Box 137 \ 4 scan0204 | |
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