| Description | Date | Identifier | |
| Photographic study of crankshaft vibration patterns under different balancing conditions and speeds. | 1st Dec 1931 | Box 137 \ 4 scan0405 | |
| Blueprint of a mechanical component with dimensions and load forces indicated. | 19th Dec 1931 | Box 137 \ 4 scan0406 | |
| Cover note for documents regarding a J.3. Crankshaft Damper and associated crankcase modifications. | 19th Dec 1931 | Box 137 \ 4 scan0407 | |
| Advance test of a J.S. crankshaft damper on a 20/25HP engine. | 21th Dec 1931 | Box 137 \ 4 scan0408 | |
| Alternative design for a crankshaft drum damper using rubber blocks. | 23th Dec 1931 | Box 137 \ 4 scan0409 | |
| Merits of a 4-speed gearbox over a proposed 3-speed gearbox. | 7th Feb 1919 | Box 137 \ 5 scan0001 | |
| Arguing against reverting to a 3-speed gearbox in favor of a 4-speed gearbox. | 10th Feb 1919 | Box 137 \ 5 scan0002 | |
| Merits of a 4-speed gearbox over a 3-speed for future cars. | 11th Feb 1919 | Box 137 \ 5 scan0003 | |
| Preference for a 4-speed gearbox over a 3-speed gearbox. | 12th Feb 1919 | Box 137 \ 5 scan0004 | |
| Arguing in favour of a 4-speed gearbox over a 3-speed gearbox. | 12th Feb 1919 | Box 137 \ 5 scan0005 | |
| The merits of 3-speed versus 4-speed gearboxes, considering performance, cost, and petrol consumption for a small car. | 2nd Feb 1919 | Box 137 \ 5 scan0006 | |
| Continuation page of a memo discussing the need to improve consumption due to poor quality. | 2nd Feb 1919 | Box 137 \ 5 scan0007 | |
| From Mr. Bellringer discussing overwhelming customer preference for 4-speed gearboxes over 3-speed versions. | 13th Feb 1919 | Box 137 \ 5 scan0008 | |
| Specifications for the change speed gate and side brake on the American model. | 27th Sep 1919 | Box 137 \ 5 scan0009 | |
| Use of a three-speed gearbox with central control, weighing its pros and cons against a four-speed gearbox for the 40/50 chassis. | 19th Nov 1919 | Box 137 \ 5 scan0010 | |
| Requesting blueprints be made from drawings for the 40/50 HP American Chassis gearbox. | 19th Nov 1919 | Box 137 \ 5 scan0011 | |
| Decision to use a three-speed gearbox on the American model chassis. | 17th Nov 1919 | Box 137 \ 5 scan0012 | |
| 3/19 gear box for the 40/50 HP American Chassis, discussing drawings and modifications. | 17th Nov 1919 | Box 137 \ 5 scan0013 | |
| Page continuing a list of design modifications for a vehicle's gearbox and chassis. | 17th Nov 1919 | Box 137 \ 5 scan0014 | |
| Speedometer drive for a 3/19 gear box, requesting blue prints of drawing No. LeC.1158. | 18th Nov 1919 | Box 137 \ 5 scan0015 | |
| Change in the casing thickness for the 3/19 gearbox. | 19th Nov 1919 | Box 137 \ 5 scan0016 | |
| Noting experimental numbers for American Model Chassis components. | 19th Nov 1919 | Box 137 \ 5 scan0017 | |
| Merits of three-speed versus four-speed gearboxes and driver practices. | 20th Nov 1919 | Box 137 \ 5 scan0018 | |
| Design and manufacturing strategy for gearboxes on the American chassis. | 20th Nov 1919 | Box 137 \ 5 scan0019 | |
| Page discussing setting a standard of excellence for America. | 6th Dec 1919 | Box 137 \ 5 scan0020 | |
| Drawing for a three-speed gearbox for an American chassis, noting design changes and requesting a blueprint. | 6th Dec 1919 | Box 137 \ 5 scan0021 | |
| Specifications for the first American-built chassis, recommending a three-speed gearbox. | 6th Dec 1919 | Box 137 \ 5 scan0022 | |
| Modifiable ratio for a car indicator and its manufacturing advantages. | 6th Dec 1919 | Box 137 \ 5 scan0023 | |
| Design of the American chassis, including Left Hand Steering and frame length. | 10th Dec 1919 | Box 137 \ 5 scan0024 | |
| Schemes for the reverse pinion and modifications to the 3/19 gearbox. | 22th Dec 1919 | Box 137 \ 5 scan0025 | |
| Design alterations for the front end of the 3/19 gearbox for the 40/50 HP American Chassis. | 24th Dec 1919 | Box 137 \ 5 scan0026 | |
| Design of a dynamo driving pulley and gearbox. | 24th Dec 1919 | Box 137 \ 5 scan0027 | |
| Attaching a modified drawing for a gearbox rear bracket on a 40/50 HP American chassis. | 30th Dec 1919 | Box 137 \ 5 scan0028 | |
| Drawing for a reverse pinion and gear box body. | 1st Jan 1920 | Box 137 \ 5 scan0029 | |
| Sending drawing Lec.1179 with information on the gear box and front end suspension for a 40/50 HP chassis. | 1st Jan 1920 | Box 137 \ 5 scan0030 | |
| Approved modifications to the 3/19 gear box, with reference to specific drawings. | 5th Feb 1920 | Box 137 \ 5 scan0031 | |
| Sending two schemes related to a RE 3/19 gearbox, concerning levers and a bracket. | 6th Jan 1920 | Box 137 \ 5 scan0032 | |
| Sending drawing LeC.1183 with the final particulars for the RE 3/19 gearbox arms. | 7th Jan 1920 | Box 137 \ 5 scan0033 | |
| Drawing Lec.1187 showing a Gear Glider Guide for a 3/19 Gear Box. | 10th Jan 1920 | Box 137 \ 5 scan0034 | |
| Reassembling instructions for the 3/19 gear box. | 10th Jan 1920 | Box 137 \ 5 scan0035 | |
| Request for blueprints of American Gear Box Gear Wheels for 3 experimental sets. | 1st Jan 1920 | Box 137 \ 5 scan0036 | |
| Instruction to add detail to the drawings for a Flywheel and Starter Gear Wheel, specifically how the teeth should be rounded. | 1st Jul 1920 | Box 137 \ 5 scan0037 | |
| Extract regarding the need to speed up production on new and improved chassis and engine parts. | 14th Jul 1920 | Box 137 \ 5 scan0038 | |
| Blueprints and modifications for fitting a 3/19 gearbox into a long chassis. | 20th Jul 1920 | Box 137 \ 5 scan0039 | |
| List of order numbers for various chassis and aero engines. | 24th Apr 1920 | Box 137 \ 5 scan0040 | |
| Letter from the American subsidiary recommending a change to left-hand steering. | 30th Jul 1920 | Box 137 \ 5 scan0041 | |
| Request for the production of 3 sets of gearbox components for the 40/50 HP chassis. | 20th Aug 1920 | Box 137 \ 5 scan0042 | |
| Requesting three sets of Lock Nuts for the Gear Control Lever to be made for a 40/50 HP 3/19 chassis. | 21th Aug 1920 | Box 137 \ 5 scan0043 | |
| Requesting the production of three sets of washers for a gearbox rear cover, based on drawing G:7264. | 30th Aug 1920 | Box 137 \ 5 scan0044 | |
| Request to expedite drawings for a left-hand drive 40/50 chassis with specific modifications. | 3rd Sep 1920 | Box 137 \ 5 scan0045 | |
| Extract detailing immediate and future updates to electrical systems, a new three-speed gearbox, and left-hand steering. | 1st Sep 1920 | Box 137 \ 5 scan0046 | |
| Comparing gear ratios for a proposed 3-speed gearbox against previous successful and unsuccessful cars in the Austrian Trials. | 1st Sep 1920 | Box 137 \ 5 scan0047 | |
| Comparison of gear ratios for various car models and gearbox configurations, including the Austrian Trials Cars. | 9th Sep 1920 | Box 137 \ 5 scan0048 | |
| Discussion about a new 3-speed gearbox and the increasing weight of cars. | 9th Sep 1920 | Box 137 \ 5 scan0049 | |
| Requirements for a three or four-speed gearbox in heavy cars. | 12th Oct 1920 | Box 137 \ 5 scan0050 | |
| Standardizing back axle gear ratios for heavier cars to achieve equal acceleration and hill climbing performance. | 12th Oct 1920 | Box 137 \ 5 scan0051 | |
| New chassis design, focusing on gear ratios, weight saving, and the choice between a three and four-speed gearbox. | 12th Oct 1920 | Box 137 \ 5 scan0052 | |
| Argument for using a three-speed gearbox over a four-speed, citing design complexities and prioritising engine perfection. | 12th Oct 1920 | Box 137 \ 5 scan0053 | |
| Continued discussion comparing four-speed and three-speed semi-epicyclic gear arrangements and their performance. | 12th Oct 1920 | Box 137 \ 5 scan0054 | |
| Merits of a three-speed versus a four-speed gearbox for new models, particularly concerning acceleration in traffic. | 22th Oct 1920 | Box 137 \ 5 scan0055 | |
| Engine flexibility, high speed performance, and gearing for different driving styles. | 22th Oct 1920 | Box 137 \ 5 scan0056 | |
| Fine mesh constant mesh gears for a 3/19 gear box, with drawing LeC.1296. | 28th Oct 1920 | Box 137 \ 5 scan0057 | |
| Blueprints for a modified gear box undershield for the 3/19 Gear Box on a Long Chassis. | 24th Nov 1920 | Box 137 \ 5 scan0058 | |
| Potential customer reception of left-hand drive cars and central gear change levers in a right-hand drive country. | 30th Dec 1920 | Box 137 \ 5 scan0059 | |
| Armature windings, field coils, and brush systems for various dynamos and motors. | 24th Jan 1921 | Box 137 \ 5 scan0060 | |
| Comparing American cars to a Napier, discussing driving pleasure, comfort, and central gear levers. | 8th Feb 1921 | Box 137 \ 5 scan0061 | |
| Requesting remarks in triplicate on an attached letter concerning Maag Gear. | 13th Apr 1921 | Box 137 \ 5 scan0062 | |
| Experiments and testing of Maag gears for the gearbox. | 23th Mar 1921 | Box 137 \ 5 scan0063 | |
| Letter to Mr. Claude Johnson regarding gear cutting work by Pratt & Whitney, sheet 2. | 23th Mar 1921 | Box 137 \ 5 scan0064 | |
| Inter-office letter discussing three-speed gearboxes, central gear changes, and left-hand steering for the American market. | 27th Apr 1921 | Box 137 \ 5 scan0065 | |
| Advantages of a gearbox with R.H. drive and central change, and comparing its silence to American cars. | 20th Feb 1922 | Box 137 \ 5 scan0066 | |
| Investigation into two systems of gear grinding for gearboxes, favouring the Gear Grinding Co. system over the Maag system. | 20th Feb 1922 | Box 137 \ 5 scan0067 | |
| Continuation of a letter concerning an American company. | 1st Mar 1926 | Box 137 \ 5 scan0068 | |
| Provision for friction in the new Phantom link and balance gear. | 1st Mar 1926 | Box 137 \ 5 scan0069 | |
| Question about the grinding of gearbox gears. | 19th Nov 1926 | Box 137 \ 5 scan0070 | |
| Letter regarding sketches showing the directions of rotation for shafts on the engine and gearbox for a Springfield Chassis. | 4th Nov 1927 | Box 137 \ 5 scan0071 | |
| Letter discussing a proposal from Pratt and Whitney for producing experimental oil pump gears for the Phantom engine. | 11th Nov 1927 | Box 137 \ 5 scan0072 | |
| Comments on an attached letter regarding the RRAI Gearbox. | 29th Apr 1929 | Box 137 \ 5 scan0073 | |
| Letter discussing the market and technical situation for automobile transmissions in the United States. | 17th Apr 1929 | Box 137 \ 5 scan0074 | |
| The design, performance, and construction of an experimental gearbox. | 17th Apr 1929 | Box 137 \ 5 scan0075 | |
| Design, features, and testing of a new silent gearbox. | 17th Apr 1929 | Box 137 \ 5 scan0076 | |
| Blueprint showing a cross-section of a 4-speed gearbox and its gear layout. | 17th Apr 1929 | Box 137 \ 5 scan0077 | |
| Blueprint detailing the rotational directions and helix angles of various engine components. | 11th Apr 1927 | Box 137 \ 5 scan0078 | |
| Schematic diagram of the gearbox and servo drive system, detailing gear particulars. | 11th Apr 1927 | Box 137 \ 5 scan0079 | |
| Follow-up memo requesting a reply concerning an RRAI Gearbox. | 13th May 1929 | Box 137 \ 5 scan0080 | |
| Clarifying that a previous report on American gearbox practice was purely informational. | 15th May 1929 | Box 137 \ 5 scan0081 | |
| Inter-office report on the disappointing results of the first experimental Bethune Gearbox. | 7th Nov 1929 | Box 137 \ 5 scan0082 | |
| Modifications to gears, shafts, and couplings, including material changes and gear tooth adjustments. | 6th Nov 1929 | Box 137 \ 5 scan0083 | |
| Preliminary report detailing the history and experience with the Bethune Gearbox D-3709. | 6th Nov 1929 | Box 137 \ 5 scan0084 | |
| Analysis of gearbox noise and gear changing issues, with suggestions for alternative gear materials and treatments. | 23th Oct 1929 | Box 137 \ 5 scan0085 | |
| Gearbox improvements, focusing on reducing second gear noise and enhancing the ease of shifting. | 11th Feb 1929 | Box 137 \ 5 scan0086 | |
| Graph of audibility characteristics for second speed gears, plotting vehicle speed against gear tooth contact frequency. | 11th Feb 1929 | Box 137 \ 5 scan0087 | |
| Confidential memo discussing design points and issues with a modified gearbox. | 23th Oct 1929 | Box 137 \ 5 scan0088 | |
| Confidential memo detailing the results and proposed improvements for a modified gearbox. | 25th Oct 1929 | Box 137 \ 5 scan0089 | |
| Page detailing the fitting of a side shaft on standard bearings using shims. | 29th Dec 1929 | Box 137 \ 5 scan0090 | |
| Letter discussing faults and design considerations for a herringbone gearbox. | 29th Dec 1929 | Box 137 \ 5 scan0091 | |
| Letter from Maurice Olley regarding gearbox noise and suggestions for gear helices. | 1st Sep 1929 | Box 137 \ 5 scan0092 | |
| Diagram from a Mechanics Instruction Book for a Silent-Second Transmission. | 1st Sep 1929 | Box 137 \ 5 scan0093 | |
| Cutaway diagram of a transmission selector mechanism. | 10th Sep 1930 | Box 137 \ 5 scan0094 | |
| The development of silent third and easy change gearboxes, and the potential trial of a new four-speed box. | 10th Sep 1930 | Box 137 \ 5 scan0095 | |
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