| Description | Date | Identifier | |
| Progress with an oil plunger scheme and piston castings to cure engine knock. | 9th Oct 1919 | Box 35 \ 2 scan 150 | |
| Use of a clearance hole for a locking set screw on pistons for the 40/50 chassis to prevent deformation. | 9th Oct 1919 | Box 35 \ 2 scan 151 | |
| Method for determining the position of piston knock using a stroboscopic telephone. | 11th Oct 1919 | Box 35 \ 2 scan 152 | |
| Tests to resolve piston knock issues using oil pressure and a modified relief valve. | 17th Oct 1919 | Box 35 \ 2 scan 153 | |
| Engine testing to address piston knock by adjusting oil pressure and piston design. | 17th Oct 1919 | Box 35 \ 2 scan 154 | |
| Testing split pistons, their clearances, and difficulties diagnosing engine knock using a stroboscopic telephone. | 17th Oct 1919 | Box 35 \ 2 scan 155 | |
| Investigation into piston knocks where dismantled engines showed pistons exceeding the maximum clearance limit. | 22th Oct 1919 | Box 35 \ 2 scan 156 | |
| Recommending new standard instructions for the fitting of gudgeon pins to prevent distortion. | 23th Oct 1919 | Box 35 \ 2 scan 157 | |
| Benefits of grooving pistons to improve lubrication and recommending it become a standard practice. | 23th Oct 1919 | Box 35 \ 2 scan 158 | |
| Confirmation of a telegram regarding the effect of short connecting rods on reaction vibrations. | 29th Oct 1919 | Box 35 \ 2 scan 159 | |
| Typed copy of a wire to Claude Johnson regarding chassis modifications and engine compression choices. | 30th Oct 1919 | Box 35 \ 2 scan 160 | |
| To Mr. Royce recommending the adoption of aluminium pistons, citing their successful use and weight-saving benefits. | 1st Jul 1915 | Box 35 \ 2 scan 161 | |
| Origin of aluminium pistons, attributing the idea to Mr. Bentley over Commander Briggs. | 4th Nov 1919 | Box 35 \ 2 scan 162 | |
| Issue with gudgeon pin locking screws protruding in pistons for the 40/50 chassis. | 1st Nov 1919 | Box 35 \ 2 scan 163 | |
| The need for higher range oil pressure gauges due to increased engine lubrication. | 14th Nov 1919 | Box 35 \ 2 scan 164 | |
| Confirmation of a telegram regarding testing piston pin locking screws. | 14th Nov 1919 | Box 35 \ 2 scan 165 | |
| Requesting review and signature on a standardisation sheet for an experiment on short connecting rods. | 17th Nov 1919 | Box 35 \ 2 scan 166 | |
| Distributing standardisation sheets for short connecting rods. | 21th Nov 1919 | Box 35 \ 2 scan 167 | |
| Failure of locking screws for the gudgeon pin and recommending reverting to a previous design. | 24th Nov 1919 | Box 35 \ 2 scan 168 | |
| Telegram from Royce regarding a test on piston pin locking screws. | 26th Nov 1919 | Box 35 \ 2 scan 169 | |
| Technical memorandum discussing the performance, faults, and potential improvements of split type pistons. | 12th Dec 1919 | Box 35 \ 2 scan 170 | |
| Overcoming piston knock, the production delays caused by a Moulders' strike, and the consideration of cast iron pistons. | 12th Dec 1919 | Box 35 \ 2 scan 171 | |
| Abandoning cast iron pistons due to seizure risk, comparing them with aluminium pistons on weight, expansion and engine silence. | 12th Dec 1919 | Box 35 \ 2 scan 172 | |
| The reliability of aluminium pistons versus cast iron, noting disintegration issues experienced by Crossley Co. and Rover Co. | 12th Dec 1919 | Box 35 \ 2 scan 173 | |
| Copy of a telegram from Mr. Royce discussing piston design choices for mass production. | 19th Dec 1919 | Box 35 \ 2 scan 174 | |
| Testing of various piston materials and designs, such as aluminium, cast iron, and Zephyr split types. | 22th Dec 1919 | Box 35 \ 2 scan 175 | |
| Typed letter discussing modifications to piston design, including the use of springs and scraper rings. | 22th Dec 1919 | Box 35 \ 2 scan 176 | |
| Piston design, comparing it to the Bentley type, and experiments with split aluminium pistons. | 29th Dec 1919 | Box 35 \ 2 scan 177 | |
| Piston experiments, detailing tests on cast iron and plunger types and addressing issues like flexibility and oil leakage. | 29th Dec 1919 | Box 35 \ 2 scan 178 | |
| Sending a sample of successful E.4237 cast iron pistons to West Wittering. | 31th Dec 1919 | Box 35 \ 2 scan 179 | |
| Piston testing, specifically addressing over-oiling and knocking issues on a 10,000-mile test car. | 1st Jan 1920 | Box 35 \ 2 scan 180 | |
| Piston wear, lubrication, and testing for the 10,000-mile test car. | 1st Jan 1920 | Box 35 \ 2 scan 181 | |
| Note on oil leakage past the piston ram and the function and limitations of scraper rings. | 1st Jan 1920 | Box 35 \ 2 scan 182 | |
| Development of new piston designs for a 10,000-mile test, comparing plunger and Recardo types. | 3rd Jan 1920 | Box 35 \ 2 scan 183 | |
| Piston technology, comparing Ricardo's aluminium pistons to older cast iron ones. | 3rd Jan 1920 | Box 35 \ 2 scan 184 | |
| Technical memorandum critiquing a supplied cast iron piston and proposing an alternative trunk type design. | 1st Jan 1920 | Box 35 \ 2 scan 185 | |
| Testing Ricardo pistons in aluminium and cast iron, comparing the Zephyr and Ricardo types. | 1st Jan 1920 | Box 35 \ 2 scan 186 | |
| Reported disintegration of aluminium pistons with a die-cast aluminium founder. | 8th Jan 1920 | Box 35 \ 2 scan 187 | |
| Instruction to forward a sample Crossley Piston upon its arrival. | 8th Jan 1920 | Box 35 \ 2 scan 188 | |
| Faults with aluminium pistons, specifically loud knocking and carbon deposits. | 15th Jan 1920 | Box 35 \ 2 scan 189 | |
| Piston carbon build-up and knocking issues on vehicle 49-GB. | 15th Jan 1920 | Box 35 \ 2 scan 190 | |
| Recommendation to adopt an improved design of split aluminium piston and comparison with cast iron pistons. | 17th Jan 1920 | Box 35 \ 2 scan 191 | |
| Comparative testing of cast iron versus aluminium pistons in specific trial cars. | 17th Jan 1920 | Box 35 \ 2 scan 192 | |
| Potential causes for trouble with aluminium pistons on the 49-GB car engine, such as carbon deposits or expansion. | 15th Jan 1920 | Box 35 \ 2 scan 193 | |
| Piston performance, carbon deposits from different lubricating oils, and potential remedies. | 20th Jan 1920 | Box 35 \ 2 scan 194 | |
| Potential seizing issue with the Crossley piston due to its 'desaxé' (offset) pin design. | 27th Jan 1920 | Box 35 \ 2 scan 195 | |
| Engine performance test data for aluminium pistons using 50% Benzol fuel with the cut-out closed. | 3rd Feb 1920 | Box 35 \ 2 scan 196 | |
| The location of a missing model of a Slipper Type Piston. | 5th Feb 1920 | Box 35 \ 2 scan 197 | |
| Gas leakage issues with non-gas-retaining split type pistons causing noise and fumes. | 6th Feb 1920 | Box 35 \ 2 scan 198 | |
| Test history report on the disappointing performance of the T2 motor, discussing its issues and future prospects. | 8th Jul 1938 | Box 35 \ 2 scan 199 | |
| Cases of piston rattles, tests conducted to resolve the issue, and subsequent recommendations. | 13th Feb 1920 | Box 35 \ 2 scan 200 | |
| Resolving piston rattles by adjusting piston ring position, referencing pre-war designs and lubrication. | 1st Jun 1919 | Box 35 \ 2 scan 201 | |
| Complaint detailing the causes of fumes entering covered car bodies and requesting a cure for current and post-war models. | 24th Feb 1920 | Box 35 \ 2 scan 202 | |
| Adoption of split aluminium pistons and troubleshooting an engine knock. | 26th Feb 1920 | Box 35 \ 2 scan 203 | |
| Telegram from Mr. Royce detailing a solution for piston tightness due to carbon deposits. | 15th Mar 1920 | Box 35 \ 2 scan 204 | |
| Cause of and solution for piston rattles. | 16th Mar 1920 | Box 35 \ 2 scan 205 | |
| Urgent modification of pistons by fitting extra rings, referencing pre-war practices. | 18th Mar 1920 | Box 35 \ 2 scan 206 | |
| Confirmation of a telegram regarding engine piston modifications to resolve rattles caused by carbon deposits. | 16th Mar 1920 | Box 35 \ 2 scan 207 | |
| Piston rattles, binding issues, and the modification of adding rings to solve the problem. | 18th Mar 1920 | Box 35 \ 2 scan 208 | |
| Rattling pistons, the potential for engine seizure, and the need for an immediate conference to determine a solution. | 18th Mar 1920 | Box 35 \ 2 scan 209 | |
| Summary of a conference discussing the causes and observations of piston rattles in engines. | 23th Mar 1920 | Box 35 \ 2 scan 210 | |
| Internal memorandum discussing piston rattles, experiments with increased clearances, and the performance of different piston types and lubricating oils. | 31th Jan 1930 | Box 35 \ 2 scan 211 | |
| Piston rattle faults, decarbonisation, and recommendations against immediate modifications to engines. | 31th Jan 1930 | Box 35 \ 2 scan 212 | |
| Implementation of modifications, specifically increased clearance for split pistons. | 23th Mar 1920 | Box 35 \ 2 scan 213 | |
| Cause and potential cure for an elusive engine knock related to gudgeon pin lubrication. | 25th Mar 1920 | Box 35 \ 2 scan 214 | |
| Extract detailing four urgent design issues causing production delays, related to the starter, steering, pistons, and dynamo. | 26th Mar 1920 | Box 35 \ 2 scan 215 | |
| Confirming that an 'elusive knock' is caused by the gudgeon pin, and outlining a discussion with Mr. Royce on potential solutions. | 27th Mar 1920 | Box 35 \ 2 scan 216 | |
| Diagnosing 'elusive knocks' as gudgeon pin knock and discussing potential solutions with Mr. Royce. | 27th Mar 1920 | Box 35 \ 2 scan 217 | |
| Design and testing of aluminium pistons for car engines, including ring configuration and split piston design. | 29th Mar 1920 | Box 35 \ 2 scan 218 | |
| Test results table showing compression and permanent set data for a solid type piston under various weights. | 29th Mar 1920 | Box 35 \ 2 scan 219 | |
| Table of weight, compression, and permanent set measurements for a solid type piston. | 12th Apr 1920 | Box 35 \ 2 scan 220 | |
| Comparative wear on cylinder bores caused by aluminium versus cast iron pistons. | 12th Apr 1920 | Box 35 \ 2 scan 221 | |
| Continued discussion on the issues and relative merits of cast iron versus aluminium pistons. | 12th Apr 1920 | Box 35 \ 2 scan 222 | |
| Piston troubles, comparing aluminium with cast iron pistons and discussing knock issues. | 12th Apr 1920 | Box 35 \ 2 scan 223 | |
| Technical report discussing piston clearances, internal strains, and gas leakage issues. | 12th Apr 1920 | Box 35 \ 2 scan 224 | |
| Analysis of piston ring performance concerning gas leakage, crankcase vapor, and piston materials. | 12th Apr 1920 | Box 35 \ 2 scan 225 | |
| Comparison of horsepower for a standard engine using cast iron versus aluminium pistons, and a second test showing horsepower with varying numbers of rings on aluminium pistons. | 12th Apr 1920 | Box 35 \ 2 scan 226 | |
| The findings regarding engine piston rattles following tests. | 14th Apr 1920 | Box 35 \ 2 scan 227 | |
| Agreeing to the immediate issue of a Standardisation Sheet for a modification, based on a report by Mr. Hives. | 20th Apr 1920 | Box 35 \ 2 scan 228 | |
| Piston rattles caused by carbon build-up and a proposal for a new six-ring piston design. | 20th Apr 1920 | Box 35 \ 2 scan 229 | |
| Inconsistency of using 1/8' liners under cylinders for new high and low compression pistons. | 9th Jun 1920 | Box 35 \ 2 scan 230 | |
| Use of liners for chassis pistons. | 11th Jun 1920 | Box 35 \ 2 scan 231 | |
| Chassis pistons and liners, discussing low compression configurations and engine vibrations. | 11th Jun 1920 | Box 35 \ 2 scan 232 | |
| Use of a cylinder liner for modifying engine compression between high and low compression pistons. | 14th Jun 1920 | Box 35 \ 2 scan 233 | |
| Decision to abolish the liner used in low compression pistons for early postwar cars to reduce compression. | 16th Jun 1920 | Box 35 \ 2 scan 234 | |
| Confirming the decision to alter pistons for a low compression engine instead of using a liner. | 25th Jun 1920 | Box 35 \ 2 scan 235 | |
| Testing of a full floating piston pin design to eliminate engine knock for the 40/50 HP chassis. | 18th Sep 1920 | Box 35 \ 2 scan 236 | |
| Solution to fix elusive gudgeon pin knocks at low engine speeds. | 27th Sep 1920 | Box 35 \ 2 scan 237 | |
| Experimental solutions for engine knocking, including expanding gudgeon pins and tapered wedges. | 27th Sep 1920 | Box 35 \ 2 scan 238 | |
| Seeking Mr. Royce's agreement on methods to resolve customer complaints. | 27th Sep 1920 | Box 35 \ 2 scan 239 | |
| Measured wear on six pistons from a Shop Car. | 27th Oct 1920 | Box 35 \ 2 scan 240 | |
| Letter to Allen & Simmonds Ltd. requesting samples of recommended piston rings for motor car engines. | 28th Oct 1920 | Box 35 \ 2 scan 241 | |
| The wear analysis of aluminium pistons from a Shop Car after 33,000 miles. | 28th Oct 1920 | Box 35 \ 2 scan 242 | |
| Wear on aluminium pistons and cylinders, exploring the effects of different lubricating oils and piston ring configurations. | 1st Nov 1920 | Box 35 \ 2 scan 243 | |
| Pistons and rings from Allen and Simmonds Ltd., recommending a test of their product to improve gas-tightness. | 5th Nov 1920 | Box 35 \ 2 scan 244 | |
| Friction tests for thin and thick leaf cantilever springs under different conditions. | 6th Nov 1920 | Box 35 \ 2 scan 245 | |
| Friction tests on thin and thick leaf springs, comparing greased springs with those using Ferodo interleaving material, and the effects of clipping. | 1st Nov 1920 | Box 35 \ 2 scan 246 | |
| Continued memo discussing the application of friction in leaves and shock absorbers. | 6th Nov 1920 | Box 35 \ 2 scan 247 | |
| Graph comparing friction in different types of cantilever springs under greased and rusty conditions. | 5th Nov 1920 | Box 35 \ 2 scan 248 | |
| Cover page with handwritten reference numbers and a company ink stamp. | 9th Nov 1920 | Box 35 \ 2 scan 249 | |
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