| Description | Date | Identifier | |
| Secret memo discussing arrangements for vehicle testing, including a 20/25 model, a Spectre, and a Vauxhall, to evaluate suspension characteristics. | 7th Mar 1935 | Box 136 \ 4 scan0116 | |
| Requesting power loss tests on a Wilson Gearbox removed from vehicle 18-G-IV. | 10th Apr 1935 | Box 136 \ 4 scan0117 | |
| French language article discussing Cotal electro-mechanical, Wilson, and Maybach gearboxes with diagrams. | 25th Apr 1935 | Box 136 \ 4 scan0118 | |
| Letter from The S.U. Company acknowledging the return of a Balor Gear box in good condition. | 11th May 1935 | Box 136 \ 4 scan0119 | |
| Letter to Mr. Flower of The S.U. Company regarding the Balor Gear Box, declining its current use but expressing interest in future developments. | 22th May 1935 | Box 136 \ 4 scan0120 | |
| Competitor's gearbox and proposing a pump-powered system for remote control gear changes. | 18th May 1936 | Box 136 \ 4 scan0121 | |
| Letter from The British Thomson-Houston Company Ltd regarding a report on a gear after laboratory examination. | 21th Nov 1936 | Box 136 \ 4 scan0122 | |
| Specifications for Ford Steel, including its supplier, composition, and heat treatment process for gears. | 18th Dec 1936 | Box 136 \ 4 scan0123 | |
| Visit to Hughes Johnson to investigate the high cost of stampings for gearbox levers. | 14th Jan 1937 | Box 136 \ 4 scan0124 | |
| Cost savings and manufacturing modifications for a reverse drag link on the Bentley servo. | 14th Jan 1937 | Box 136 \ 4 scan0125 | |
| Requesting the standardization of thrust races in test bed gear box units. | 13th Jan 1937 | Box 136 \ 4 scan0126 | |
| Letter from the Experimental Department to Mr. A. Alltree about his synchromesh gear change method. | 10th Feb 1937 | Box 136 \ 4 scan0127 | |
| Letter to the editor of 'The Motor' magazine, requesting to forward an enclosed letter to a Mr. A. Alltree regarding his gearbox. | 10th Feb 1937 | Box 136 \ 4 scan0128 | |
| Letter from an external party responding to an enquiry about a preselector gear control mechanism and its potential applications. | 12th Feb 1937 | Box 136 \ 4 scan0129 | |
| Article from 'The Motor' magazine about a novel semi-automatic clutch-pedal gear change mechanism with synchromesh. | 9th Feb 1937 | Box 136 \ 4 scan0130 | |
| Article discussing the Pneugrippa process for improving tyre grip and mileage. | 9th Feb 1937 | Box 136 \ 4 scan0131 | |
| Description of a novel clutch-pedal gear change mechanism. | 9th Feb 1937 | Box 136 \ 4 scan0132 | |
| Description of the gear disengagement, engagement, and the self-change spring mechanism. | 9th Feb 1937 | Box 136 \ 4 scan0133 | |
| With diagrams describing the cam and peg mechanism for a gearbox. | 9th Feb 1937 | Box 136 \ 4 scan0134 | |
| Description of gear lock mechanisms and an automatic gear selection feature for quick getaways. | 9th Feb 1937 | Box 136 \ 4 scan0135 | |
| Page detailing the operation and benefits of a preselector gearbox and potential future developments. | 9th Feb 1937 | Box 136 \ 4 scan0136 | |
| Comparison between Synchromesh and Epicyclic gears. | 9th Feb 1937 | Box 136 \ 4 scan0137 | |
| Technical drawing and description of a 2-speed unit preselector self-changing control for synchro-mesh gears. | 16th Feb 1937 | Box 136 \ 4 scan0138 | |
| Follow-up letter discussing patent specifications for a preselector semi-automatic gearbox and an alternative clutch mechanism. | 16th Feb 1937 | Box 136 \ 4 scan0139 | |
| Letter from a consulting engineer regarding US and British patents for a gear shift lock. | 12th Feb 1937 | Box 136 \ 4 scan0140 | |
| Letter from W.W. Constantine to L.H. Grylls regarding a gear shift lock developed by Fiat. | 12th Feb 1937 | Box 136 \ 4 scan0141 | |
| Patent diagram sheet for a gear shift lock mechanism. | 14th Feb 1933 | Box 136 \ 4 scan0142 | |
| Patent drawing for a gear shift lock mechanism. | 14th Feb 1933 | Box 136 \ 4 scan0143 | |
| Patent document for a Gear Shift Lock mechanism. | 14th Feb 1933 | Box 136 \ 4 scan0144 | |
| Patent diagram illustrating a gear shift lock mechanism. | 14th Feb 1933 | Box 136 \ 4 scan0145 | |
| United States Patent for a gear shift lock mechanism, assigned to General Motors. | 14th Feb 1933 | Box 136 \ 4 scan0146 | |
| Page from a patent application describing a change-speed transmission mechanism. | 14th Feb 1933 | Box 136 \ 4 scan0147 | |
| Detailed description of a gear selection and locking mechanism, likely from a patent application. | 14th Feb 1933 | Box 136 \ 4 scan0148 | |
| Detailed description of a change speed transmission mechanism. | 14th Feb 1933 | Box 136 \ 4 scan0149 | |
| Patent document detailing the claims and operation of a change speed transmission system. | 21th Mar 1931 | Box 136 \ 4 scan0150 | |
| Patent specification for improvements to a control mechanism with reference to gear boxes. | 21th Mar 1931 | Box 136 \ 4 scan0151 | |
| Patent specification document for improvements to gearbox control mechanisms. | 21th Mar 1930 | Box 136 \ 4 scan0152 | |
| Patent application describing a control mechanism for gearboxes with seven distinct claims. | 18th Jan 1932 | Box 136 \ 4 scan0153 | |
| Patent specification for a preselector self-selecting gear control mechanism. | 7th Jul 1934 | Box 136 \ 4 scan0154 | |
| Patent specification detailing improvements in and relating to change-speed gear control. | 7th Jul 1934 | Box 136 \ 4 scan0155 | |
| Patent specification for a change-speed gear control mechanism. | 6th Jul 1935 | Box 136 \ 4 scan0156 | |
| Page of claims from a patent specification regarding a change-speed gear control system. | 6th Jul 1935 | Box 136 \ 4 scan0157 | |
| Complete specification drawing sheet detailing various mechanical components and assemblies. | 6th Jul 1935 | Box 136 \ 4 scan0158 | |
| Complete specification document sheet showing various mechanical linkage and governor mechanisms. | 21th Oct 1932 | Box 136 \ 4 scan0159 | |
| Patent specification for improvements in change-speed gearing, specifically for preselector semi-automatic control for synchromesh gears. | 21th Oct 1932 | Box 136 \ 4 scan0160 | |
| Provisional specification detailing improvements to change-speed gearing mechanisms. | 20th Oct 1932 | Box 136 \ 4 scan0161 | |
| Specification for an invention relating to improvements in change-speed gearing mechanisms. | 1st Nov 1932 | Box 136 \ 4 scan0162 | |
| Patent specification document detailing the claims and mechanisms for a change-speed gearing system. | 6th Jun 1933 | Box 136 \ 4 scan0163 | |
| Complete specification drawing with six figures illustrating a mechanical linkage and cam system. | 6th Jun 1933 | Box 136 \ 4 scan0164 | |
| Complete specification drawing of engine components, possibly related to a valve operating mechanism and crankshaft. | 6th Jun 1933 | Box 136 \ 4 scan0165 | |
| Complete specification drawings of various mechanical cam and lever arrangements. | 17th Feb 1937 | Box 136 \ 4 scan0166 | |
| Letter from the Experimental Department regarding a patent specification for a gear shaft lock. | 17th Feb 1937 | Box 136 \ 4 scan0167 | |
| Specifications for a universal gearbox for Bentley III, Phantom, and Wraith models. | 16th Jul 1937 | Box 136 \ 4 scan0168 | |
| New gearbox design, including its actuation, shaft, and casing, with comparisons to the Phantom III and Wraith models. | 16th Jul 1937 | Box 136 \ 4 scan0169 | |
| Note detailing modifications to the drive shaft, speedometer gears, and rear rubber mountings. | 26th Aug 1937 | Box 136 \ 4 scan0170 | |
| The Spigot Bearing for the Universal Gear Box and a related quotation from Hoffmanns. | 26th Aug 1937 | Box 136 \ 4 scan0171 | |
| Blueprint for a spigot bearing for a universal gearbox, for Bentley III, Phantom, and Wraith models. | 27th Aug 1937 | Box 136 \ 4 scan0172 | |
| Change from chromium plated and engraved speed gates to dull nickel plated gates without lettering, and the addition of a leather cover. | 27th Aug 1937 | Box 136 \ 4 scan0173 | |
| Springs in the universal gearbox, comparing Buick and Vauxhall synchromesh systems. | 2nd Sep 1937 | Box 136 \ 4 scan0174 | |
| Continued note on reducing stress in springs by tapering them to increase flexibility. | 2nd Sep 1937 | Box 136 \ 4 scan0175 | |
| Changes to the change speed gate for all chassis, including plating and model adoption. | 3rd Sep 1937 | Box 136 \ 4 scan0176 | |
| On reverting to bronze cones for gearboxes after cast iron failures, and continuing to test alternative materials. | 8th Sep 1937 | Box 136 \ 4 scan0177 | |
| The discontinuation of chromium plating and engraving on change speed gates for specific chassis. | 16th Sep 1937 | Box 136 \ 4 scan0178 | |
| Modifications to the universal gearbox pattern to accommodate a larger universal joint. | 16th Sep 1937 | Box 136 \ 4 scan0179 | |
| Modifications to a 2nd speed Buick type coupling for a Universal Gearbox being tested on a Phantom III. | 29th Sep 1937 | Box 136 \ 4 scan0180 | |
| Request to fit a gearbox with 3 plates and a non-positive synchromesh to vehicle 22.G.V. | 30th Sep 1937 | Box 136 \ 4 scan0181 | |
| Request to obtain two new departure Radax type bearings from Delco-Remy & Hyatt. | 11th Oct 1937 | Box 136 \ 4 scan0182 | |
| Order for New Departure Radax Type Bearings which are no longer required. | 18th Oct 1937 | Box 136 \ 4 scan0183 | |
| Letter to Messrs. Delco-Remy & Hyatt Ltd. regarding the cancellation of an order for No.30307 bearings. | 18th Oct 1937 | Box 136 \ 4 scan0184 | |
| Quotation from Delco-Remy & Hyatt Ltd. for New Departure Radax type bearings. | 15th Oct 1937 | Box 136 \ 4 scan0185 | |
| Letter proposing an alternative design for a semi-automatic synchromesh gear preselector control. | 26th Oct 1937 | Box 136 \ 4 scan0186 | |
| Semi-automatic gear control mechanism. | 26th Oct 1937 | Box 136 \ 4 scan0187 | |
| Description of the gear change mechanism, focusing on clutch operation, cam, peg, gear lock, and coupling pawls. | 26th Oct 1937 | Box 136 \ 4 scan0188 | |
| Description of the self-selection gear mechanism for easier and safer acceleration during a getaway. | 1st Oct 1937 | Box 136 \ 4 scan0189 | |
| Blueprint detailing the mechanism of a preselector self-changing gear control system for synchromesh gears. | 1st Oct 1937 | Box 136 \ 4 scan0190 | |
| Blueprint for a modification to the Universal Gearbox 2nd speed coupling. | 1st Nov 1937 | Box 136 \ 4 scan0191 | |
| Instruction to incorporate a 2nd speed Buick type coupling modification into universal gearboxes. | 2nd Nov 1937 | Box 136 \ 4 scan0192 | |
| Patent specification for improvements in change speed gears. | 27th Dec 1934 | Box 136 \ 4 scan0193 | |
| Detailed description of a change-over coupling mechanism and synchronizing brake for a multi-speed gearbox. | 22th Dec 1934 | Box 136 \ 4 scan0194 | |
| Patent specification detailing claims for a change-speed gearing system for motor vehicles. | 22th Dec 1934 | Box 136 \ 4 scan0195 | |
| Complete specification drawing of a mechanical assembly with multiple figures. | 9th Nov 1937 | Box 136 \ 4 scan0196 | |
| Cone assembly tests for a universal gearbox synchro-mesh. | 9th Nov 1937 | Box 136 \ 4 scan0197 | |
| The assembly methods and testing for cones and gears, comparing pressure and shrinkage processes. | 9th Nov 1937 | Box 136 \ 4 scan0198 | |
| Test report for a universal gearbox synchro-mesh cone, including a diagram of surface wear and performance data tables. | 1st Jan 1938 | Box 136 \ 4 scan0199 | |
| Bush seizure failure in a Bentley's overdrive gearbox, attributing it to a hardened steel bush and planning to revert to a bronze one. | 1st Jan 1938 | Box 136 \ 4 scan0200 | |
| Advising on the initial running of Over-Drive Gearbox No.15.HS with Hi-press oil to avoid seizure. | 4th Jan 1938 | Box 136 \ 4 scan0201 | |
| Modification to the revised universal gearbox for B.111, B.50, and Wraith models. | 18th Jan 1938 | Box 136 \ 4 scan0202 | |
| Recording the experiences and results of testing steel versus bronze bushes in synchromesh gearboxes. | 19th Jan 1938 | Box 136 \ 4 scan0203 | |
| Issue with free pinions in gearboxes for the Wraith model. | 19th Jan 1938 | Box 136 \ 4 scan0204 | |
| Letter to Kennings Ltd. requesting a trial run on a 16.HP. Riley with an over-drive gearbox. | 2nd Feb 1938 | Box 136 \ 4 scan0205 | |
| Secret memo discussing experimental mileage, discovery of troubles, and the fitting of steel bushes. | 9th Feb 1938 | Box 136 \ 4 scan0206 | |
| Short run of a 16 HP Riley to evaluate its overdrive gearbox. | 11th Feb 1938 | Box 136 \ 4 scan0207 | |
| Auto-Static brake as a preferable arrangement to a scotch in the brake system. | 14th Feb 1938 | Box 136 \ 4 scan0208 | |
| Letter from British Timken Limited offering a trial set of ball races for gear boxes. | 14th Feb 1938 | Box 136 \ 4 scan0209 | |
| Price list and specification sheet for Timken single row cylindrical roller bearings, medium series in inch and metric sizes. | 14th Feb 1938 | Box 136 \ 4 scan0210 | |
| Specification sheet for Deep Groove, Single Row Ball Bearings, divided into Light and Medium series with both Inch and Metric dimensions. | 22th Feb 1938 | Box 136 \ 4 scan0211 | |
| Experimental fitting of a vacuum-operated servo for the change speed lever. | 22th Feb 1938 | Box 136 \ 4 scan0212 | |
| Letter regarding the return of noisy gearbox bearings for re-burnishing after running for 20,000 miles. | 3rd Mar 1938 | Box 136 \ 4 scan0213 | |
| Accompanying blueprints for a Wraith gearbox casing, detailing its components and referencing related part drawings. | 17th Mar 1938 | Box 136 \ 4 scan0214 | |
| Modification to rubber buffers for a gearbox tie rod. | 20th Apr 1938 | Box 136 \ 4 scan0215 | |
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