| Description | Date | Identifier | |
| Query regarding payment instructions for Piston Rings received from Hepworth & Grandage Ltd. | 11th May 1939 | Box 148 \ 1 scan0130 | |
| The placement of official orders for trial piston rings, main bearings, and filters. | 11th May 1939 | Box 148 \ 1 scan0131 | |
| Letter from The Light Production Co. Ltd. proposing a design modification for pistons with raised crowns to ease foundry difficulties. | 17th May 1939 | Box 148 \ 1 scan0132 | |
| Letter from a consulting engineer enclosing Swinney's British patent for an induction system. | 18th May 1939 | Box 148 \ 1 scan0133 | |
| Patent specification for improvements to induction systems of internal combustion engines. | 26th Jul 1935 | Box 148 \ 1 scan0134 | |
| Complete specification for improvements in and relating to induction systems of internal combustion engines. | 26th Jul 1935 | Box 148 \ 1 scan0135 | |
| Patent specification for an engine induction system featuring concentric passages and movable valve elements. | 8th Jul 1936 | Box 148 \ 1 scan0136 | |
| Patent claim for an induction system for internal combustion engines. | 8th Jul 1936 | Box 148 \ 1 scan0137 | |
| Complete Specification drawing for an engine intake or carburetor system. | 19th May 1939 | Box 148 \ 1 scan0138 | |
| Requesting the shot blasting and re-cadmium plating of leaf springs. | 19th May 1939 | Box 148 \ 1 scan0139 | |
| Road spring data detailing wheel loads, spring rates, and roll ratings for a vehicle. | 19th May 1939 | Box 148 \ 1 scan0140 | |
| Table of front and rear wheel suspension movements and spring hysteresis values. | 19th Mar 1939 | Box 148 \ 1 scan0141 | |
| Letter from the Experimental Department regarding issues with piston rings and pistons. | 20th May 1939 | Box 148 \ 1 scan0142 | |
| Letter detailing piston quality issues and the status of new experimental split skirt pistons for engine testing. | 20th May 1939 | Box 148 \ 1 scan0143 | |
| Letter to The Light Production Co. Ltd. regarding foundry issues and a proposal for a tapered crown piston design. | 20th May 1939 | Box 148 \ 1 scan0144 | |
| Letter from The Light Production Co. Ltd. regarding the production of pistons and piston rings. | 23th May 1939 | Box 148 \ 1 scan0145 | |
| Letter from a supplier, The Light Production Co. Ltd., responding to a quality complaint about pistons. | 26th May 1939 | Box 148 \ 1 scan0146 | |
| Letter from The Light Production Co. Ltd. enclosing drawings for a Bentley Engine Piston Ring and Piston. | 26th May 1939 | Box 148 \ 1 scan0147 | |
| Order to cover a set of six pistons and rings. | 31th May 1939 | Box 148 \ 1 scan0148 | |
| Alterations to an Aerolite piston for production purposes. | 31th May 1939 | Box 148 \ 1 scan0149 | |
| Letter to The Light Production Co. Ltd. requesting delivery dates for experimental pistons and rings. | 31th May 1939 | Box 148 \ 1 scan0150 | |
| Letter from a patent agent regarding the preparation of a complete specification for patent application 37227/38 (Bentley Piston). | 16th May 1939 | Box 148 \ 1 scan0151 | |
| Letter regarding the lodging of an authorisation of agent, this is the second sheet of the document. | 16th May 1939 | Box 148 \ 1 scan0152 | |
| Letter from chartered patent agents requesting up-to-date drawings for a Bentley piston patent application. | 13th Jun 1939 | Box 148 \ 1 scan0153 | |
| Invoice from Light Production Co. Ltd. for pistons, rings and foundry equipment. | 24th May 1939 | Box 148 \ 1 scan0154 | |
| Letter from The Light Production Co. Ltd. regarding the delivery schedule for experimental pistons. | 2nd Jun 1939 | Box 148 \ 1 scan0155 | |
| Internal request to place an order for specific piston rings from The Light Production Co. Ltd. | 7th Jun 1939 | Box 148 \ 1 scan0156 | |
| Letter to a supplier regarding outstanding experimental pistons and ordering spare rings. | 7th Jun 1939 | Box 148 \ 1 scan0157 | |
| Letter correcting an outstanding order for experimental pistons and requesting spare rings. | 7th Jun 1939 | Box 148 \ 1 scan0158 | |
| Performance of raised crown pistons versus high power heads in Bentley engines. | 9th Jun 1939 | Box 148 \ 1 scan0159 | |
| Investigation into the effects of increasing the bump on an Aerolite raised crown piston. | 9th Jun 1939 | Box 148 \ 1 scan0160 | |
| Piston performance concerning engine detonation and oil temperature. | 9th Jun 1939 | Box 148 \ 1 scan0161 | |
| The effects of raised crown pistons on oil temperature and efficiency. | 9th Jun 1939 | Box 148 \ 1 scan0162 | |
| Blueprint graph comparing power (BHP) and BMEP against RPM for different piston types and compression ratios with a Bentley camshaft. | 1st May 1939 | Box 148 \ 1 scan0163 | |
| Graph showing ignition advance and detonation characteristics for various piston types and compression ratios using Redline petrol. | 1st May 1939 | Box 148 \ 1 scan0164 | |
| Graph of heat transfer to oil versus oil inlet temperature for various piston configurations and compression ratios. | 1st May 1939 | Box 148 \ 1 scan0165 | |
| Piston compression ratios and ordering instructions based on recent B-V engine tests. | 12th Jun 1939 | Box 148 \ 1 scan0166 | |
| Letter from The Light Production Co. Ltd. regarding the position of outstanding orders for experimental pistons. | 12th Jun 1939 | Box 148 \ 1 scan0167 | |
| Letter from The Light Production Co. Ltd. clarifying a previously incorrect advice note about pistons. | 27th Apr 1939 | Box 148 \ 1 scan0168 | |
| Changes and specifications for Bentley V production pistons. | 13th Jun 1939 | Box 148 \ 1 scan0169 | |
| Letter suggesting the deferral of the Bentley Piston Patent Application 37227/38. | 16th Jun 1939 | Box 148 \ 1 scan0170 | |
| Letter from Wellworthy Piston Rings Ltd. chasing up a request for drawings for a patent specification. | 16th Jun 1939 | Box 148 \ 1 scan0171 | |
| Acknowledgement letter from patent agents regarding the Bentley Piston patent application. | 19th Jun 1939 | Box 148 \ 1 scan0172 | |
| Cover letter to F. Blackith of Wellworthy Piston Rings Ltd, forwarding a copy of another letter. | 19th Jun 1939 | Box 148 \ 1 scan0173 | |
| Letter from a piston ring specialist regarding potential patent issues and prior claims on a special piston design. | 20th Jun 1939 | Box 148 \ 1 scan0174 | |
| Letter from Alta Car & Engineering to Wellworthy Piston Rings regarding a patent arrangement. | 6th Jun 1939 | Box 148 \ 1 scan0175 | |
| Despatch note for two sets of experimental pistons, P.451 (Aerolite) and P.461 (Split skirt), for Bentley or Wraith models. | 26th Jun 1939 | Box 148 \ 1 scan0176 | |
| Letter from The Light Production Co. Ltd. regarding a query on Bentley Production Piston specifications. | 26th Jun 1939 | Box 148 \ 1 scan0177 | |
| Letter to The Light Production Co. Ltd. discussing piston specifications and ordering additional units. | 29th Jun 1939 | Box 148 \ 1 scan0178 | |
| Request to send an official order for 14 pistons to The Light Production Co. Ltd. | 29th Jun 1939 | Box 148 \ 1 scan0179 | |
| Letter from The Light Production Co. Ltd. confirming receipt of drawings and an order for 14 pistons. | 3rd Jul 1939 | Box 148 \ 1 scan0180 | |
| Supply and stock of pistons for the Paris Depot. | 6th Jul 1939 | Box 148 \ 1 scan0181 | |
| To the Paris Depot regarding the production status of experimental raised crown pistons for the Wraith chassis. | 6th Jul 1939 | Box 148 \ 1 scan0182 | |
| Letter from The British Piston Ring Co Ltd acknowledging a request to machine 20 castings to drawing ML.1388. | 13th Jul 1939 | Box 148 \ 1 scan0183 | |
| Fitting of experimental raised crown pistons to a Wraith Chassis. | 20th Apr 1939 | Box 148 \ 1 scan0184 | |
| Letter to The Light Production Co. Ltd. confirming an order for 40 modified 'L' section rings. | 28th Jul 1939 | Box 148 \ 1 scan0185 | |
| Internal request to place an order for 40 piston rings with The Light Production Co. Ltd. | 28th Jul 1939 | Box 148 \ 1 scan0186 | |
| Fitting of experimental raised crown pistons to a Wraith chassis to increase compression. | 9th Aug 1939 | Box 148 \ 1 scan0187 | |
| Letter to The Light Production Co. Ltd. regarding the supply and modification of pistons. | 22th Aug 1939 | Box 148 \ 1 scan0188 | |
| Order for 14 pistons to be sent to The Light Production Co. Ltd. | 22th Aug 1939 | Box 148 \ 1 scan0189 | |
| Despatch request for 6 pistons to The Light Production Co. Ltd. | 22th Aug 1939 | Box 148 \ 1 scan0190 | |
| Letter to The Light Production Co. Ltd. discussing piston modifications for heat flow, taper grinding, and weight reduction. | 29th Aug 1939 | Box 148 \ 1 scan0191 | |
| Letter from chartered patent agents requesting drawings and information for a British Patent Application on a Bentley Piston. | 7th Sep 1939 | Box 148 \ 1 scan0192 | |
| Letter to Messrs. Walford & Hardman Brown regarding a Patent Application, noting further development is doubtful due to the international situation. | 9th Sep 1939 | Box 148 \ 1 scan0193 | |
| Letter from a patent agent regarding the patent application for a Bentley Piston. | 12th Sep 1939 | Box 148 \ 1 scan0194 | |
| Letter appointing Walford & Hardman Brown as patent agents for a patent application. | 1st Jan 1939 | Box 148 \ 1 scan0195 | |
| Letter to Wellworthy Ltd. discussing raised crown pistons, ignition governors, and big end bearing experiments for various engines. | 22th Sep 1939 | Box 148 \ 1 scan0196 | |
| Letter to Messrs. Walford & Hardman Brown regarding an attached copy of a letter to Mr. Blackith. | 28th Sep 1939 | Box 148 \ 1 scan0197 | |
| Letter to F. Blackith of Wellworthy Piston Rings Ltd. concerning a piston application and the use of their own patent agents. | 28th Sep 1939 | Box 148 \ 1 scan0198 | |
| Letter from a chartered patent agent regarding patent application no. 37227/38 for a 'Bentley Piston'. | 30th Sep 1939 | Box 148 \ 1 scan0199 | |
| Letter from Wellworthy Piston Rings regarding an unsuccessful Leyland test and a patent application. | 10th Oct 1939 | Box 148 \ 1 scan0200 | |
| Letter to The Light Production Co. Ltd. requesting details, a sample, and a drawing of a piston. | 12th Oct 1939 | Box 148 \ 1 scan0201 | |
| Letter to The Light Production Co. Ltd. regarding the status of modified taper grinding on an order of 14 pistons. | 4th Nov 1939 | Box 148 \ 1 scan0202 | |
| Recommending fitting flush top pistons to a 7:1 C/R head to reduce detonation. | 6th Nov 1939 | Box 148 \ 1 scan0203 | |
| Performance graph for a 3 1/2' x 5' six-cylinder petrol engine with high compression pistons. | 13th Sep 1939 | Box 148 \ 1 scan0204 | |
| Performance curves for a six-cylinder petrol engine with a Zenith carburetor, comparing standard and high compression pistons. | 13th Sep 1939 | Box 148 \ 1 scan0205 | |
| Graph showing a variable load curve for a 3½' x 5' six-cylinder petrol engine at 1500 RPM. | 13th Sep 1939 | Box 148 \ 1 scan0206 | |
| Technical drawing of a Wellworthy piston, showing dimensions and a proposed further modification. | 13th Sep 1939 | Box 148 \ 1 scan0207 | |
| Bench tests of a six-cylinder petrol engine with Wellworthy high compression pistons. | 13th Sep 1939 | Box 148 \ 1 scan0208 | |
| Engine performance tests with modified pistons, concluding that no material improvement was achieved. | 13th Nov 1939 | Box 148 \ 1 scan0209 | |
| Confirming six pistons (EW.2115) were sent to The Light Production Co. for inspection and are not required to be returned. | 13th Nov 1939 | Box 148 \ 1 scan0210 | |
| Piston ring comparison with increased cylinder lubrication to investigate cylinder bore wear. | 27th Nov 1939 | Box 148 \ 1 scan0211 | |
| Engine testing stages, analyzing oil consumption with different piston rings and lubrication setups. | 27th Nov 1939 | Box 148 \ 1 scan0212 | |
| Crankcase blowby figures, oil consumption, and a comparison of piston rings. | 27th Nov 1939 | Box 148 \ 1 scan0213 | |
| Graph comparing oil consumption for different piston and piston ring configurations. | 4th Dec 1939 | Box 148 \ 1 scan0214 | |
| Letter to The Light Production Co. Ltd. proposing a new test for a modified 'L' section piston ring to improve gas control. | 4th Dec 1939 | Box 148 \ 1 scan0215 | |
| Letter to Messrs. Hepworth & Grandage Ltd. requesting drawings and data for special piston rings. | 4th Dec 1939 | Box 148 \ 1 scan0216 | |
| Letter from The Light Production Co. Ltd. discussing modifications to a piston ring design, specifically trying an 'L' section ring. | 11th Dec 1939 | Box 148 \ 1 scan0217 | |
| Letter from The Light Production Co. Ltd. discussing a modification to a scraper ring and a forthcoming sketch. | 15th Dec 1939 | Box 148 \ 1 scan0218 | |
| Letter to The Light Production Co. Ltd. regarding a modified set-up for oil control rings. | 15th Dec 1939 | Box 148 \ 1 scan0219 | |
| Letter from The Light Production Co. Ltd. regarding a proposed piston ring arrangement. | 18th Dec 1939 | Box 148 \ 1 scan0220 | |
| Inquiry to The Light Production Co. Ltd. about the availability of special pistons with a higher crown. | 20th Dec 1939 | Box 148 \ 1 scan0221 | |
| Request to order 14 modified pistons (P.479) from The Light Production Co. Ltd. | 21th Dec 1939 | Box 148 \ 1 scan0222 | |
| Letter to The Light Production Co. Ltd. discussing piston modifications for a trial test. | 21th Dec 1939 | Box 148 \ 1 scan0223 | |
| Request to send an order to The Light Production Co. Ltd. for 21 special 'HC' Bentley pistons. | 20th Dec 1939 | Box 148 \ 1 scan0224 | |
| Letter to The Light Production Co. Ltd. enclosing drawings for a Piston and Gudgeon Pin, and inquiring about experimental pistons. | 1st Jan 1940 | Box 148 \ 1 scan0225 | |
| Letter to The Light Production Co.Ltd. regarding an order and priorities for various special pistons. | 5th Jan 1940 | Box 148 \ 1 scan0226 | |
| Page two of a letter requesting approximate delivery dates. | 8th Jan 1940 | Box 148 \ 1 scan0227 | |
| Letter to The Light Production Co. Ltd. concerning the supply and testing of 75 m/m pistons and 'L' rings. | 8th Jan 1940 | Box 148 \ 1 scan0228 | |
| Letter to The Light Production Co. Ltd. regarding the specifications and development of pistons and rings. | 8th Jan 1940 | Box 148 \ 1 scan0229 | |
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