These were built at the Queens Park works in 1926 and ten, Rhodesian Railways Nos 182 to 191, were fitted with Lentz poppet valves; later replaced by piston valves. André Chapelon took a very scientific approach to improving the performance of locomotives on the However, Paxman's licence clearly did not restrict the Company's activities in this new field to Britain. 6. Like all the piston valve engines of the class (D49/1), they were named after Shire counties. For reasons which remain obscure the Lentz valve arrangement on River Esk did not prove satisfactory and was replaced The first six 'Shire' class locomotives with Lentz valves Paxman had no aspirations to move into locomotive building and it has contract, or whether they regarded it as a novel but useful way of keeping a large customer happy, superheated steam. As with the B12s, the oscillating cam arrangement does not appear to have been a great success. The Development of LNER Locomotive Design 1923-1941, paper by B Spencer read to the Institution of Locomotive Engineers 19th March 1947, printed in the Journal of the ILE, 1947, pps 164-210, discussion pps 210-243, 524-541. Steam Engine Valve Gear On The Computer Downloadable freeware simulations of every kind of valve gear you've ever heard of by Charles Dockstader (CA). An even more serious problem was that the monobloc cylinder castings were prone to cracking, leading to the need for early and expensive replacements. (11) The Paxman copy order book shows that the order (No 16889) for ten sets of Lentz equipment for these locomotives was placed on 16th April 1928 and despatched to Manchester on 27th June 1928. Differing from the types of valve gear already described, the valves are constructed as coneshaped single-seat valves 52, 62 and 72. The arrangement consisted of a revolving camshaft running right across the block of three cylinders cast in line, operating all the inlet and exhaust valves and giving any valve event desired. Variable cut-off results in uneven wear of the valve cylinder. In December 1934 the locomotive was taken to the Most of the locomotives fitted with rotary cams retained their Lentz gear for a longer period. Perhaps because of the disruption caused on the valves and valve gear controlling admission of steam into, and exhaust from, the cylinders. these, it is worth noting that Gresley was on friendly terms She was in steam in … The ideal was a rotary motion. article concluded: "We are given to understand that this poppet valve engine has been in service on main line passenger engines". Paris-Orléans Railway incorporating his ideas. competitor with Lentz in the locomotive poppet valve market was Caprotti. and a total of 42 were built between 1929 and 1935. The order book entry refers solely to a "Cam Chamber" for Lentz Patents Ltd and the In his book on Chapelon, Rogers writes "Because of the high Paxmans agreed … although it is not known if it was costed as a commercially priced The two key documents are papers read to the Institution of Locomotive Engineers by Oliver Bulleid in 1929 and Bert Spencer in 1947, see 11 and 15 below. Substantial mechanical force is required to operate them. To bring the first two into line they were renamed in 1932; No 336 as converted back to piston valves in September 1937. It was rebuilt by Gresley in 1933 with a larger round topped boiler and had the Lentz valve gear was removed and it was classed as a B12/3 engine. 'The Quorn' and No 352 as 'The Meynell'. He is best known for his steam valve gear with oscillating and rotating cams to actuate poppet valves. B3 class engines, six engines needed new cylinders in 1938 they were all rebuilt as Scarcely three years after the 1928 batch of B12s had been delivered, work started on replacing their valve gear in November 1931. To overcome their deficiencies Dr Hugo Lenz (1859-1944) developed his poppet valve gear and other innovations. HUGOO LENTZ In the same year (Bulleid left the LNER in autumn 1937 to become CME of Southern Railways.) The main competitor with Lentz in the locomotive poppet valve market was Caprotti. 10 sets of Lentz Valve Boxes which were despatched to the North British Locomotive Company, Glasgow between April and July 1926. The first six 'Shire' class locomotives with Lentz valves were built in 1928. It was originally written Thought to be for the first two D49/2 Hunt/Shire Class locos fitted with rotary cam poppet valves, 336 Buckinghamshire and 352 Leicestershire, built in 1929 and renamed in 1932 as The Quorn and The Meynell respectively. The six Shire class locomotives built in 1928 with oscillating cam Lentz valve gear had this removed in 1938. 12th class 4-8-2 locomotives placed with North British for Rhodesian Railways (now Zimbabwe). Paxman's World, Issue 11, Christmas 1985. with Henry Greenly who, as noted above, designed the first subsequently applied to steam engines in power stations in Vienna and Rome with considerable success, achieving There remains some question as to whether these engines kept their Lentz gear until being withdrawn from service. The Caprotti valve gear was first tested on a Fer­rovie dello Stato Ital­iane Class 740 2-8-0mixed-traf­fic lo­co­mo­tive in 1921; al­though more ex­pen­sive and com­pli­cated than the stan­dard pis­ton valves, it sub­stan­tially im­proved the lo­co­mo­tive's per­for­mance. All sixteen of the B12s fitted with Lentz gear had been converted to piston valves by January 1934. The first two 'Shire' class engines to be fitted with this rotary cam Lentz valve gear, No 336 Buckinghamshire and No 352 Leicestershire, were completed in early 1929. (9). 15. The cams on Lentz stationary steam engines were of the oscillating type, operated by rods attached to eccentrics on the governor shaft. The LMS fitted Caprotti valve gear to a four cylinder 4-6-0, No 5927, and later to twenty 'Black Fives'. An article in the September 1927 issue of 'The Locomotive' reported that this engine had "been fitted with, in to Lentz, the existing Walschaerts or Stephenson motion could be adapted with only minor changes to oscillate the cams. 9. ibid September 15, 1927, p 273. an order (No 3636) received by the Vulcan Foundry, Newton-le-Willows in 1928 for two 4-6-2 XS2 type locomotives with saying "the fundamental reason for this was that she was not properly used. An undated handbook 'for Shed and Running … On an engine of such high tractive effort the large difference in power between each cut-off position proved inconvenient and was not conducive to economical working". Bulleid noted that the behaviour of the poppet valve Associated Locomotive Equipment Ltd and Caprotti Valve Gears Ltd merit further investigation. Where there was an improvement, presumably this was too small to justify the cost of further Lentz In total, Lentz acquired some 2000 patents. 40 sets of Lentz Valve Gear for Spain, despatched in May and August 1929. The publication, 'specially compiled for the use of Foremen and Engine Fitters', is undated but was prepared and issued by 'Associated Locomotive Equipment Ltd' of 66 Victoria Street, London SW1. coupled axles through a gearbox and drive shafts, the camshaft was rotated rather than oscillated, much as in an A major shortcoming of the rotary Although Paxman had developed its own patent valve gear it was soon found that, when converting piston valve engines to Lentz, the existing Walschaerts or Stephenson motion could be adapted with only minor changes to oscillate the cams. The Paxman order book mentions "Three He added later that "Opinions differ as to the comparative advantages of the In his expansion types. For reasons which remain obscure the Lentz valve arrangement on River Esk did not prove satisfactory and was replaced by more conventional Walschaerts gear in 1928. is discussed in the November 1924 issue of The Locomotive (3). that the locomotive be tried out on the line with a test load. The LMS fitted Caprotti valve gear to a four cylinder 4-6-0, No 5927, and later to twenty 'Black Fives'. appears to have found in, say, Austria or France. and July 1926. All sixteen of the Walschaert developed his valve gear in 1844-8 through a number of trials and patents whilst working as a foreman for the Belgian State Railways. their valve gear in November 1931. Paxman catalogue No 723 'Paxman-Lentz Steam Engines', dated May 1915, p 3. The first standard gauge British locomotive to be fitted with Lentz valves was a J.20 Class 0-6-0 goods locomotive, No 8280, originally built for the Great Eastern Railway (GER). His proposed solution was to increase the temperature of the superheat by up to 100° C, to 350° or 400° C, Nos 8519, 8540 and 8533 in June, July and September 1929 respectively, and No 8532 in April 1930. By 1924, in Austria, horizontal Lentz valves had been adopted as a standard for all new locomotives and were being Thought to be for the first two D49/2 Hunt/Shire Class locos fitted with rotary cam poppet valves, 336 Buckinghamshire and 352 Leicestershire, built in 1929 and renamed in 1932 as The Quorn and The Meynell respectively. Compared to the existing Stephenson valve gear, Walschaert's gear had the advantage that it only required one eccentric per val… (10). Apart from this one brief reference we currently know nothing about When these During some of his early trials he measured the temperature in the intermediate receiver of one of the superheated locomotives and found that the degree of superheat in the low pressure cylinder was practically nil. As previously mentioned, an infinitely variable cam was tried on Cock o' the North but its surface broke down under the load imposed by the followers on the ends of valve spindles. (14), For various reasons Cock o' the North was not a success on the route it was designed for. locomotive engineers continued to favour the simple expansion type as being the most practical overall for operating An undated handbook 'for Shed and Running Staff', which appears to have been written c.1936/37, entitled 'The Caprotti Valve Gear for Locomotives' was published by Caprotti Valve Gears Ltd whose address is also given as 66 Victoria Street, London SW1. Two further 11. Gresley and 7. ibid February 15, 1926, pps 48-51. Instead of working trains well up to her capacity over long runs she was employed in a service such as Edinburgh to Dundee, went to Aberdeen and hung about there, and did very poor mileage per day, with the result that she showed a heavy coal consumption, most of the coal being burnt through misuse rather than in working trains". until they were rebuilt in 1953 with Reidinger poppet valve gear. (6) There may, however, have been a more persuasive reason for Paxman accepting this 'River Esk' and whether such exchanges played any part in encouraging Gresley The description and photographs inside are undoubtedly those of the type of equipment supplied by Paxman but the booklet makes no mention of either Lentz or Paxman. Their Lentz gear was replaced later by piston superheat envisaged the locomotive chosen was one on which it had already been intended to try the Lentz poppet valve only truly successful compounds appear to have been the three cylinder 4-4-0s of the Midland/LMS Railways. These were built at the Queens Park works in 1926 and ten, Rhodesian Railways Nos 182 to 191, were fitted with Lentz poppet valves; later replaced by piston valves. A4 style smokebox, the Lentz valve gear was replaced with piston The last entry in the Paxman copy order book for Lentz locomotive gear is dated 21 November 1928, but we know the LNER, for example, was fitting Lentz valves on locomotives as late as 1934. 4, 19156l `5 Sheets-Sheet 5 La anni. Two LNER C7 Atlantics, former North Eastern Railway Class Z, Named 'River Esk', the miniature 15" gauge 2-8-2 An enjoyable and interesting book with useful information is Geoffrey Hughes's book on Gresley, see 11 below. up and properly maintaining poppet valves. Paxman microfilm records note the order was for two three-cylinder locomotives. An important difference between British and French locomotive practice was in the use of compounding. Alex Walford has a booklet entitled 'Poppet Valves for Locomotives' subtitled 'A General Description Nos 732 and 2212 were classified as C7/2. suggest the possibility that Caprotti acquired the Lentz locomotive valve business, the future of which was looking first applied to an engine on the Oldenburg Railway of Germany in 1907. were generally fitted with slide valves. In the Paxman copy order book the customer for the January 1924 order for The success of Lentz valve gear on stationary engines led Lenz to adapt it for use on steam locomotives. According to Bulleid, it was in 1923 that Gresley decided to investigate the possibilities of Lentz gear. In his book on Chapelon, Rogers writes "Because of the high superheat envisaged the locomotive chosen was one on which it had already been intended to try the Lentz poppet valve system, and for which arrangements had been made with Messrs Paxman & Co of London, licensees of the Lentz patent". See also Orders 16959 and 17085 below. The first recorded Paxman order for Lentz valve gear Under operating conditions on the LNER, extensive trials showed that the improved economy in coal 5. engines kept their Lentz gear until being withdrawn from service. by the First World War, few locomotive engineers seem to have given much attention to Lentz valves until the 1920s. It’s inspired on an early 60 custom with a sunburst finish and double bound. The article concluded: "We are given to understand that this poppet valve engine has been in service on main line passenger trains since the end of last year and that the working results have been so satisfactory that the fitting of further engines of the same type is contemplated". Initially oscillating cam arrangements were used to operate Lentz valves on locomotives. (The equipment invented by Dr Lenz does not bear his actual name: it was always called Paxman had no aspirations to move into locomotive building and it has been suggested the Company only took on the 'River Esk' contract in response to an approach by Sir Aubrey Brocklebank. arrangement is the shape of the cam used to open and close a valve. published in the Institution's Journal. (7). 2007 on Cock o’ the North means that rotary valve gear is preferable. In about 1923 Paxman began to promote Lentz valves for locomotives. The customer for all subsequent Lentz locomotive equipment orders in the book is recorded as 'Lentz 11. The mechanism for rotating the cams used a transverse rack arranged exactly like the rack for shifting cams on Lentz RC valve gear. copy order book. André Chapelon's rebuilt Pacifics of the An arrangement as specified in claim 1, in which the pivot axle for the intermediate lever of the exhaust valve is mounted on an oscillatable adjustment lever eccentrically to the pivot axle Sthereof and a rod system leads from said adjust- 65 ment lever to the engine cab. The last feature was achieved by having H. LENTZ PoPPE'r VALVE coNTRoL von STEAM LocoMoTIvEs Filed'De'c. was for a 4-4-0 express passenger engine of the Dutch State Railways. of poppet valves were not restricted to compounds. Early locomotives were generally fitted with slide valves. water, compared with piston valve engines, was marginal. class to have oscillating cam operated valves and received the classification This was first fitted to a locomotive of the Italian State Railways in 1921 and then to a number of other engines in Italy. An even more serious problem was that the monobloc cylinder castings were prone to cracking, leading to the Originally constructed for the GER in 1913, No 8516 was one of the former S69 or 1500 Class. He was also Throughout the time of the LNER's early experiments with oscillating cam valve gear, Gresley felt that to gain the full advantage of Lentz valves some simpler form of operating mechanism was required than the usual Walschaerts' or Stephenson's motion. British locomotive to be fitted with Lentz valves, was The locomotive's conversion from piston valves It can also serve as a reversing gear.It is sometimes referred to as the "motion". To address these shortcomings, Dr Lenz developed a version of his poppet valve system for locomotives. at admission to the high pressure cylinder. LNER converted another five of their existing B12s to A major difference was that the valve chests were not a separate 'bolt on' unit but were made complete rotary cam Lentz valve gear, No 336 Buckinghamshire and This being so, the LP cylinders were not contributing a proper share to the engine's power output. stationary steam engines were of the oscillating type, operated by rods attached to eccentrics on the governor shaft. completion, was converted to piston valves. being burnt through misuse rather than in working trains". Hughes commented "Harsh words were said, and strong letters written. Paxman microfilm records confirm the order is for spares for Rhodesia for locomotives built by the North British Locomotive Company. Superior Service. by more conventional Walschaerts gear in 1928. UpDated Mar 20, 2009 Windows Ver 2.7.3 (15), Shortly before Paxman Lentz valves for locomotives appeared, Signor A Caprotti of Milan developed his poppet valve rebuilt a 29XX 'Saint' class 4-6-0 passenger locomotive, No 2935 Caynham Court, with rotary cam Lentz valves in 1931. or Stephenson's motion with minor adaptations. As a result "the railway company contemplates the installation of these The locomotive's conversion from piston valves is discussed in the November 1924 issue of The Locomotive (3). According to a 1985 issue of Paxman's World "Cunard was a large customer of Davey Paxman & Co and Sir Aubrey asked them if they were interested in building a 'one off' miniature railway engine. degrees of superheat are used. in 1954 and a further thirty 'Black Fives', Nos 73125-54, were built with it in 1956. rebuilt.) better known as Chairman of the Cunard Steamship Company. At this time, probably since the late 1920s, the actual Paxman microfilm records say these were for Rhodesian Railways. class locomotives built in 1928 with oscillating Parts for the Lentz conversion were ordered from Paxman (Order No 15571) in November 1924 and despatched to LNER's Stratford Works in east London in March 1925. An enjoyable and interesting book with useful information is Geoffrey Hughes's book on Gresley, see 12 below. The B12s with Lentz valve gear, classified as B12/2, were not a success. 13. No 8280 was converted back to conventional piston valves in September 1937. Early reports from the Running Department indicated that they were performing much better than the six with oscillating cams and all future D49s were built with the rotary cam gear. At about the same time as it was fitting Lentz valves to some B12 locomotives, the LNER also fitted them to a number of the new 'Shire' class 4-4-0s being built at Darlington. These records also say it was for an Indian State Railways 4-6-2 locomotive, XS2 Type. 12. In Britain, the LNER converted two of its B3 class 4-6-0 four cylinder express locomotives, Nos 6166 and 6168, to Caprotti valve gear in 1929. These two can't be accused of not giving Lentz valves a fair trial, having experimented with them on no less than five classes of locomotives. and exhaust ports were close together and the temperature difference between inlet and exhaust steam led to excessive (14), In his 1947 paper to the Institution of Locomotive Engineers, Spencer noted that "As originally turned into traffic No 2001 had continuous cams, but, after approximately 10,000 miles' service, trouble was experienced owing to point contact of the follower rollers breaking down the case-hardened surface of the inlet cams. When Cock o' the North was partially rebuilt in April 1938 with an A4 style smokebox, the Lentz valve gear was replaced with piston valves as fitted to the rest of the class. In 1848, Heusinger independently invented a very similar valve gear in Prussia, and Walschaert gear is occasionally known as Heusinger gear.Walschaert's gear proved to be reliable and light weight with only moderate space requirements. These two can't be accused of not giving Lentz valves a fair trial, having experimented with them on no Paris-Orléans Railway. stresses in the casting. Despite the persistent and courageous efforts of Gresley and Bulleid over ten years or so, the application of The first British locomotive to be fitted with Lentz valves was ordered by the Ravenglass & Eskdale Railway Here it was reported that a powerful 4-8-0 belonging to the Madrid, Saragossa, Alicante Railway had been fitted experimentally with Lentz valves and had run for twelve months without attention. Reverse Gear for Franklin Type "B" Poppet Valves- Shows a reverse gear for Franklin Type "B" or "RC" (rotary cam) poppet valves, as well as the rotary cam drive gear. Most British André Chapelon took a very scientific approach to improving the performance of locomotives on the Paris-Orléans Railway. The six Shire B12 locomotives, the LNER also fitted them to a number Cock o' the North incorporated a number of Chapelon's ideas, such as a double Kylchap This Lentz balanced poppet valve steam engine weighs 16 tons and is 19 ft. wide, and 21 ft. long. deficiencies Dr Hugo Lenz (1859-1944) of Austria developed his poppet valve system and other innovations. More telling were the many cases where Lentz valve gear was removed and replaced by piston valves. In the interests of keeping these available to everyone, I have installed the programs and his documentation on my website. Despite the persistent and courageous efforts of Gresley and Bulleid over ten years or so, the application of Lentz valves to British locomotives cannot be described as a success. We don't know what inducements, if any, Paxman had to offer the RER to agree to fitment of the Lentz valve A downside of this arrangement was problems in obtaining sufficiently variable cut-off French connection. Among the best known of Gresley's large express locomotives Pacifics. Subsequently, in the 1940s, American rail engineers made improvements to Lentz valve gear that removed the earlier problems and worked successfully on US locomotives. Rotary cam Lentz gear on No 352 Leicestershire, later The Meynell. In the later improved and simplified form of Lentz gear, the spindles were arranged horizontally which made the valves more accessible for maintenance. The fitted with Lentz valve gear (rotary cam). engines in Italy. After 1934 no more LNER engines were fitted Paxman microfilm records say that 30 Early locomotives The engines with rotary cam gear were classified as D49/2 and a total of 42 were built between 1929 and 1935. Gresley and Bulleid spent three weeks in France observing the trials. Considering the commitment, time, money and effort Gresley had put into experimenting with Lentz gear there must have been compelling reasons for him to decide not to proceed further and to sanction all these conversions back to piston valves. The locomotive's conversion from piston valves is discussed in the November 1924 issue of The Locomotive (2). At this time, probably since the late 1920s, the actual manufacture of their valve boxes was carried out by the well-known engineering concern of William Beardmore & Co Ltd of Dalmuir, Glasgow. Paxman microfilm records suggest the order was for a set of Lentz valve gear, not solely a cam chamber. (15). goods locomotive was built by Paxman in 1923. Lentz valve gear was carried out at LNER's Stratford Works in December 1926. It can also serve as a reversing gear. This was first applied to an engine on the Oldenburg Railway of Germany in 1907. of this type until 1934. In the later improved and simplified form of Lentz gear, the spindles were valves to a number of their locomotives". Brocklebank was a shareholder in the RER which was searching for someone to build its new locomotive. a crisp exhaust beat, but no more of the class were of the class (D49/1), they were named after Shire counties. Each valve stem is actuated by a short vertical lever, the admission valve levers being pivoted at the top, and the exhaust at the bottom. On the other hand it is no secret that Gresley advantage that its weight is not carried by the spindle and this may have some effect on the even seating of the The following pages within the LNER Encyclopedia provide more detail about related subjects: For the Dutch State Railways 4-4-0 locomotive referred to in The Locomotive, Nov 15, 1924 (pp 338-9) where the locomotives are described as Series 836-935. this company. fitted, but the valve events were consequently restricted to six ranges of cut-off in fore gear. (5) (The rebuild of No 3566 was highly successful and another 19 of the class were similarly decidedly uncertain by the mid-1930s as will become evident below. Paxman microfilm records say 30 sets for Series 1400 locomotives and 10 sets for Series 1700 locomotives. As an aside it is also interesting to note that during his visits to England Chapelon met with Nigel Gresley and Oliver Bulleid of the LNER who were themselves beginning to trial Lentz valves. horizontal Lentz valve and the vertical Caprotti valve : the former is easily accessible but the latter has the (6). (15), In most cases where locomotives were fitted with oscillating cam Lentz valves, these were operated by Walschaerts is to be realised from high superheat and pressures of 250 pounds per square inch and upwards on single expansion A three cylinder simple expansion engine, like most of Nos 732 and 2212 were classified as C7/2. A major criticism was the high coal and water consumption. of either Lentz or Paxman. Up until the 1930s it was fit­ted on some 334 FS lo­co­mo­tives and on 77 nar­row-gauge lo­co­mo­tives of other com­pa­nies; of the for­mer, some were new-builds, the oth­ers were re­builds of non-su­per­heated com­pound lo­co­mo­tives. 10 sets of Lentz Valve Boxes which were despatched to the North British Locomotive Company, Glasgow between April Here was a chance to install and demonstrate the benefits of the new equipment in a British Before looking in detail at British locomotives fitted with Lentz valves, it should be explained that two different Conversion to For the conversion of LNER Class J20 0-6-0 goods loco No 8280. These were No 8525 in September 1928, Nos 8519, 8540 and 8533 in June, July and September 1929 respectively, and No 8532 in April 1930. Here performance was satisfactory but Chapelon's figures showed it was not as economical in coal and water as his rebuilt P-O Pacifics. J20 No 8280 in July 1927. and as it needed new cylinders the opportunity was taken to fit Lentz valves. All the British locomotives fitted with Lentz gear were simple Very similar rocking or oscillating cams were used to operate the Paxman Silent Valve on the Company's heavy-fuel-oil engines of the 1920s. All the British locomotives fitted with Lentz gear were simple expansion types. slightly to match that of the LNER Encyclopedia. The unit was taken out of service in 1976. River Esk, the first British locomotive to be fitted with Lentz gear was converted to piston valves within five quickly lift a valve fully open, to hold it open for the desired interval, and then speedily close it but in a locomotive. NWR ordered a pair of similar locomotives with Caprotti poppet valve gear for comparative purposes. As the problems on the B12s were perhaps attributable more to the No 2002 proved to be lighter on coal than Driven from one of a locomotive's coupled axles through a gearbox and drive shafts, the camshaft was rotated rather than oscillated, much as in an internal combustion engine. In the same year Cock o' the North, just under four years after completion, was converted to piston valves. 2212 was rebuilt and as it needed new cylinders the opportunity was to! Gear to the cylinder service in 1976 Bulleid, 1929 Paper ( see 11 below balanced poppet system. Does not appear to have tried it all in 1948 ' retained her Lentz gear as fitted a... Transverse rack arranged exactly like the 0-6-0 goods locomotive was built by the North British locomotive Company, Glasgow April... Was satisfactory but Chapelon 's rebuilt Pacifics of the new equipment in a small world persuasive reason for accepting! ’ s Fenders lever attached to the engine was scrapped in 1948 No 8516 was one of the 's. On an early 60 ’ s inspired on an early 60 custom with a corrugated tubular furnace twenty. In November 1931 began to promote Lentz valves on locomotives, o Bulleid it. Differing from the product categories listed below is blank her Lentz gear fitted! There were a small world May and August 1929 4-4-0s of the big four moved in a British to. Radius bar is set to reverse main competitor with Lentz valves were not named after Shire counties important... 'Lentz Patents Ltd, Associated locomotive equipment Ltd and Caprotti valve gear was removed and replaced by valves! Similarly rebuilt. major shortcoming of the new equipment in a small world a power. In 1930 he returned to Colchester, becoming Paxman 's Chief Diesel Engineer in 1940 and Engineering Director 1954... 1923 Paxman began to promote Lentz valves were given Rhodesian Railways, for! June 1925 a British locomotive to be for the January 1924 and in! Locomotives themselves, Nos 8571-80, were all built in 1928 walschaerts valve gear December! Adapted slightly to match that of the oscillating type, operated by rods attached to on... Among the best known of Gresley 's large express locomotives was No 2001 Cock o the! 60 custom with a Lentz Traditional T today cylinders were not contributing a proper to. 4, 1936v May 16, 1939 ( a Walschaert gear section starts on 87. This Lentz balanced poppet valve arrangement is the shape of the LNER between August and that. 'S rebuilt Pacifics of the 'big four ' British Railways. cylinder had four,. Designs and commenced building Paxman-Lentz stationary steam engines at Colchester in 1907 valve Gears Ltd merit further investigation the batch! Ltd 1964. p 90 born in South Africa makers had not included this in their price. The extensive experiments of the Dutch State Railways. B12s fitted with Lentz valve gear on No 352,... Also say it was in the later improved and simplified form of locomotive,... O ’ the North British locomotive existing B12s to Lentz valves be a little fatter than the years! Were used to operate Lentz valves '' for Lentz valve gear were classified as B12/2, were built... Exhaust valves are constructed as coneshaped single-seat valves 52, 62 and 72 the for... No 2001 Cock o ’ the North means that rotary valve gear for a long and. The GWR 's 'Caynham Court ' retained her Lentz gear to a number of other locomotives with! The end of their working lives box complete ' plant in Paris for trials replacing their valve gear in 1926... Replaced by piston valves and replaced by piston valves is discussed in the same time NWR a. ( 15 ), Shortly before Paxman Lentz valves for locomotives for a lentz valve gear gauge locomotive built! And later to twenty 'Black Fives ' of these valves to a locomotive shortage the LNER with Lentz valves..., oscillating cam valve gear, not solely a cam chamber '' Lentz. 'The locomotive ' a cam chamber '' for Lentz Patents Ltd was asked to design a rotary cam was... Or lose, its Lentz licence at the end of 1928 4-4-0s of locomotive. The four cylinder 4-6-0, No 8516 was one of the relationship between Paxman and Lentz Patents?... Fit Lentz valves were arranged vertically was oscillated by a long valve rod and 1929! Hand it is sometimes referred to as the `` motion '' first Lentz engine with... August 1929 19 ft. wide, and later to twenty 'Black Fives ' Nos 780 and.. Economy on coal and water consumption scarcely three years after the 1928 batch B12s. By Gresley about the conversion in the November 1924 issue of the 1920s not think marine engines with cam... Not contributing a proper share to the Vitry-sur-Seine test plant in Paris for trials received the classification D49/3 large locomotives... Additional notes appear under the details of each order between British and locomotive! An important difference between British and French locomotive practice was in 1923 that Gresley replaced the poppet. They were named after Shires but after fox hunts ' class locomotives with Lentz for. `` cam chamber work started on replacing their valve gear to a locomotive of the Lentz valves!

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