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Post by fostergp6nhp on Apr 25, 2012 18:44:07 GMT
In the 1st pic it looks like the description card on the table in front of the driving wheels says 3 1/2" gauge.
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Post by Laurie_B on Apr 25, 2012 19:15:05 GMT
Glad you liked the photos,Reg.I seem to recall that the parts in front of the loco were from the cam box.Amazing pieces of work.
The first photo is of the 3-1/2" gauge loco.
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Post by Nigel Bennett on Apr 26, 2012 11:42:22 GMT
I recall seeing Reg's Class 5 run at Blackgates some years ago, when it was still owned by Denis. The cambox covers then were in Perspex so you could see the gubbins inside. Fascinating! A pal of Denis' reckoned you needed to be able to build a watch wearing boxing gloves to build Caprotti gear in 3.1/2"G...
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Andrew C
Part of the e-furniture
Posts: 447
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Post by Andrew C on Apr 27, 2012 7:22:13 GMT
Yes, the Class 5 is alive and well. I gave it a run at the Tyneside track a couple of months ago. I'm now in the process of building a new brass tender body to replace the rusted out zintec one. Reg We are going to have to persuade Reg to take a deep breath and remove the cover from one of the cam boxes and stick his camera lens in ;D ;D ;D ;D Just thinking of my next project I asume the LMS 5's that were fitted had the same type of cam box? Andrew |
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hudson
Involved Member
Posts: 92
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Post by hudson on Apr 27, 2012 16:42:54 GMT
A good information about the Caprotti valve gear is contained in
the book
Locomotive Maintenance and Operation
by R.E. Brinkworth, A.M.I.Loco.E.
published by Thacker, Spink & Co (1933), Ltd.
in 1938, Calcutta.
The pages are 240 - 279 with several foldouts,but only the drive
from a gearbox on the centre of the main drive axle is shown.But
I think it would
not be to difficult to design an own variant of the
gearbox used on the outside of say 71000 Duke of Gloucester.
Best regards,
hudson
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Post by greenbat on Apr 27, 2012 19:36:39 GMT
I bought Martin Evans book, and I have to say it wasn't what I'd hoped on Caprotti. The rest of it is very in depth and interesting in its own right, but the Caprotti section seemed to stop just before the end. I think I've got the general idea though, clever chaps these italians. One day I'd love to have a go at one of the poppet valve gears, though I've got plenty of other things to do first.
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Andrew C
Part of the e-furniture
Posts: 447
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Post by Andrew C on Apr 27, 2012 21:28:07 GMT
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Post by loco112 on Apr 24, 2013 4:31:14 GMT
Peterseager, those Caprotti illustrations are really good. I have the Caprotti gearbox drawing that was included in the SAR 16DA blueprint set, and am hoping to get the full set for the IRCA #152 ™ (Baldwin, 1928, C/N 60588 #152 8/1928, C/N 60589 #153 8/1928, both 3' gauge). Both the IRCA and SAR locomotives appear to use the very same gearbox as that shown in your postings. I'd like to find everything that is available for the Caprotti gear in preparation for a miniature replica build project of the IRCA Baldwin locomotive. Baldwin issued a "Caprotti Poppet Valve Gear" booklet in the 1920's that I'm hoping to find a copy of. Other references might be; the 5AT Society, the National Rail Museum of York, (I have not yet contacted either). Henschel built; Indian ZF class 2-6-2T No.76, so if there is a modern Henschel archive it might be of some help. This link explains the developments and modifications made to the original Caprotti gear to from what we now term the British Caprotti gear; www.71000trust.com/caprotti.html |
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Post by Deleted on Apr 24, 2013 12:25:57 GMT
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Post by englishlivesteam on Apr 25, 2013 0:09:33 GMT
I found this 7.25" Britannia with Caprotti valve gear as a feature model from Christchurch New Zealand built by Ian Fanshawe. There are a few short videos at the bottom of the page showing the valve gear. csmee.org.nz/ |
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Post by Deleted on Apr 25, 2013 0:23:39 GMT
I found this 7.25" Britannia with Caprotti valve gear as a feature model from Christchurch New Zealand built by Ian Fanshawe. There are a few short videos at the bottom of the page showing the valve gear. csmee.org.nz/--------------------------------------------------------------------- What a beauty !!.. Interesting also to watch the video of his cambox in operation, then compare with the second link I supplied earlier of the full size = almost identical and just as fascinating to watch..... I'm Brunswick Green with envy ;D ;D |
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Post by Deleted on Apr 25, 2013 0:30:08 GMT
Just as an aside, but we could see a sequel film to Captain Corelli's Mandolin in the form of Captain Caprotti's Valve Gear ??----- You're right, perhaps not !!
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Post by ilvaporista on Apr 25, 2013 6:20:17 GMT
Almost off topic... but... Here is a picture of Caprotti valve gear as fitted to an Italian narrow gauge loco, this was derived from the R301/2 class. Gauge is 950mm (another long story why it was not the normal 1m!). This loco is currently under sub contract overhaul and I was lucky enough to be invited to see it a couple of weeks ago. Attachments:
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Post by ettingtonliam on Apr 25, 2013 8:53:08 GMT
Hi
The second volume of Eric Langridge's autobigraphy 'Under 10 CMEs' has a good cross section of 71000's cylinder showing the valves, but unfortunatlely no details of the cams. There are also several photos of the drive mechanism for 71000 and Class 5s.
Richard
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Post by englishlivesteam on May 1, 2013 20:52:13 GMT
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Post by masahiraoka on Aug 20, 2013 6:09:59 GMT
Yes Denis Evans' 3 1/2 inch gauge Duke of Gloucester is alive and well Down Under as indicated by Reg. The following gives a detailed description of the locomotive. in a separate post I'll detail what I know of Denis' life and career in model engineering.
Regards Martyn
DENIS EVANS’ 3½ INCH GAUGE B.R. CLASS 8 'DUKE OF GLOUCESTER’
Denis Evans’ ‘Class 8’ BR Pacific, Duke of Gloucester, is a museum quality working 1:16 scale replica of the full size locomotive. The scale Duke includes essentially all the components and systems of the full size locomotive and these are designed, built and operate exactly as per full size except where nature can’t be scaled such as the configuration and sizes of the fire tubes within the boiler. The care taken and attention to detail in this locomotive are such that it won the Model Engineer magazine Gold medal and Crebbin Memorial Trophy when the locomotive was first exhibited in 1992.
The outstanding feature of the scale locomotive is difficult to see ie. the fully working replication of the Caprotti / Daniels cam actuated poppet valve gear. At present, whilst the locomotive is on static display, the LHS cambox has a clear plastic top cover plate so that the cam gear can be seen working if the locomotive is pushed along its’ display track. The Duke has been clearly been steamed at least once as unburnt coal remains in the grate and ash in the smokebox. Unless noted below, all dimensions of the elements of Denis’ Duke are correctly scaled at 1:16. The Duke is 52½ inches long, 6¾ inches wide and 9¾ inches high. The locomotive is painted in the BR Brunswick green livery as of 1954 including detailed lining out.
Chassis includes: frames and bracing elements as per full size design, 4⅝ inch diameter driving wheels, working leaf springs, bogie with working leaf springs and coil spring centering, and pony truck coil springs and coil spring centering. Three cylinders; 1⅛ inch diameter x 1¾ inch stroke with steam operated drain cocks and pressure relief valves giving a tractive effort of 40 lbf (at 70% efficiency). Steam supply is controlled by three sets of Caprotti / Daniels cam operated poppet valve gear, the outside camboxes driven by worm drives on the return crank on each centre diving wheel, the centre cambox being driven by an off-take coming through the front of the LHS cambox as per the full size Duke. Poppet valves; inlet 25/64 inch diameter and exhaust 7/16 inch diameter. Reversing gear drive is via a shaft from the LHS side of the cab to a gear box mounted above the guide bar splitting to drive the reversing mechanism in the centre and RH camboxes. Working steam brake gear, cylinder located between the rear pair of driving axles.
Boiler: design pressure 80? lb/sq in., two safety valves, 4 x ¾? inch superheater tubes, 16 x ⅜ inch fire tubes, combustion chamber 3½ inches long with no water tubes, radiant type superheaters with the elements extending half way to the back of the firebox. The grate includes a working rocking grate split into two halves lengthwise as per the full size Duke. Ashpan has working air supply damper doors operated by two hand wheels in the RHS of the cab. The ashpan also incorporates the bottom doors for emptying the ash operated by working, locking actuators located on the LHS of the ashpan. It appears that Denis, instead of making the damper openings to the sizes of the original drawings, made them to the as-originally-built full size openings which during restoration were found to be too small.
Backhead and Cab includes, (unless otherwise stated all these elements are fully operating and in the same configuration and position as on the full size Duke):-
• Steam manifold shut-off valve hand wheel (on the top centre of the blackhead)
• Two boiler water level sight glasses both with top and bottom linked boiler isolating valves and blow down valves.
• Live steam injector steam supply valve hand wheel (RH edge of the backhead – lower of pair).
• Exhaust steam injector steam supply valve hand wheel (RH of the backhead – upper of pair).
• Ashpan front dampers hand wheel (lower RHS front of the cab - upper of the pair)
• Ashpan rear damper hand wheel (lower RHS front of the cab - lower of the pair)
• Two injector water supply valve handles (both hinged rods – rising from RH rear cab floor)
• Boiler Pressure gauge graduated to 120 lb/sq in. (RHS of the backhead)
• Vacuum? gauge graduated to 30 lb/sq in. (above the driver)
• Regulator long handle (on the backhead immediately above the driver)
• Steam Brake valve – (on the backhead above the pedestal)
• Whistle operating handle – dummy (on backhead above driver)
• Reversing Gear mechanism with working indicator drum (large hand wheel in front of the driver)
• Blower valve with hand wheel (on top front of the pedestal to the right of the driver)
• Sanding valve with handle (dummy?) (on bottom front of the pedestal to the right of the driver)
• Vacuum brake valve with handle (on the top of the pedestal to the right of the driver)
• Vacuum brake ejector duplex valve hand wheel (below) and handle (above) - (above the reverser)
• Cylinder drain cocks steam valve lever (on the LH cab wall beside the driver)
• Pair of ashpan rocking grate operating sockets under flaps in the floor in front of the fire door
The steam manifold on top of the firebox in front of the cab includes a boiler isolating valve operated by a round handle located at the very top centre of the backhead. The manifold has six off takes (vs seven on the full size locomotive) supplying; two injectors, boiler pressure gauge, ejector steam valve, coal pusher operating valve, and cylinder drain cock actuating valve. The one manifold off take that is missing compared with full size is to the carriage warming valve. On the LHS of the firebox there are; the vacuum brake ejector duplex valve above the running board and the steam valve for the steam operated cylinder drain cocks below the running board. There are two feed water injectors; live steam on the LHS and exhaust? steam on the RHS, each mounted below the firebox fed by adjacent water supply valves under the cab floor. Steam for the injectors comes from separate supplies from the manifold through valves mounted on the outside RHS of the firebox in front of the cab. The feed water is fed into the boiler through clacks mounted on top at the front of the boiler. There is no mechanical feed pump.
As Denis was building his 3½ inch gauge Duke during the late 1970’s and 1980’s, his design of the smokebox was as per the original BR design ie. before the modifications made to the full size Duke in the late 1980’s during restoration. Thus the smokebox incorporates a parallel sided double chimney (ie. no choke) ¾ inches in diameter with bell bottom petticoat. This diameter of chimney is the scale equivalent of the originally designed 12 inch choke, which during restoration of the full size Duke, was found to be too narrow. The full size rebuilt chimney has a choke 15 inches in diameter (as per the LNER ‘A2’) or 15/16 inches at 1:16 scale giving a choke area 56% larger than that originally designed. The double blast pipe has nozzles ¼ inch diameter again corresponding to the original full size design of 4 inches whereas on restoration the diameter of the nozzles was opened out to 5 inches, increasing nozzle area by 56%. Each blast nozzle is fitted with an integrated blower. The scale Duke does not include the Kylchap blast pipe as fitted to the full size locomotive during restoration. The steam supply pipes from the super heater header to the cylinders are of a relatively large correctly scaled diameter of 7/16 inches and are curved to maximum radius possible with the confines of the smokebox.
The vacuum brake ejector, mounted on the LH outside of the smokebox, exhausts into the rear chimney. The poppet valve regulator is mounted in the smokebox as per full size including BR ‘Class 7’ Pacific practice. There is no snifting valve in the smokebox so one assumes that Denis was faithful to the original Daniels design of the poppet valves ie. he used saturated steam from a pilot valve in the regulator to close the valves rather than springs as in the original Caprotti design. This feature meant that when coasting with the regulator closed, the poppet valves dropped open under the effect of gravity thereby creating an “open circuit” between the inlet and exhaust valves and bypassing the cylinders creating the perfect bypass without the need for a snifting valve.
There are two steam oil mechanical pumps as per full size, one mounted each side between the running board and the guide bars each driven by a link from the outside camboxes. Each oil pump has three off-takes; LH pump feeds the left and centre guides bars and left cylinder, and the RH pump feeds the RH guide bars and RH and centre cylinders. A dummy whistle is mounted in the correct location on the front RHS of the smokebox, and dummy sand box fillers, boxes, plumbing and gear at rail level are also fitted.
Tender: framing and tank design as per full size, working leaf springs, working water scoop with mechanism actuated by handle mounted on the LHS of the tender front plate, working steam or hand operated brakes actuated either by the cylinder mounted in front of the front axle or the handle on the RHS of the tender front plate. Working steam operated coal pusher operated by a handle on the RHS of the tender which is connected to the valve itself at the top rear of the tender by mean of a long control rod just below the top RHS lip of the coal bunker with the steam supplied through a pipe running under the tender. Feed water is drawn through working filter boxes mounted one each side outside the frames, below the tank and between the forward two axles. An emergency hand pump is located in the rear of the tank.
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Post by masahiraoka on Oct 11, 2014 10:21:06 GMT
This is long shot
Does anyone out there (that is apart from the 71000 Trust and Denis Evans' family) have any of the Associated Locomotive Equipment (ALE) drawings for the British Caprotti valve gear?
Naturally the 71000 Trust has lots and clearly enough to maintain the full size Duke but even they are missing some of the original drawings. Denis Evans' family has quite a number though not nearly as many as the Trust but have nevertheless they been able to contribute more than a dozen to the Trust that the Trust did not already possess.
Unfortunately the NRM has no drawings from ALE at all hence this fishing expedition to try and help the Trust
regards Martyn
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Post by fostergp6nhp on Oct 11, 2014 13:01:38 GMT
What have the owners of the full size Std 5 caprotti got?
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Post by masahiraoka on Oct 11, 2014 17:45:46 GMT
Good suggestion, thanks, I'll contact the Midland Railway.
i'd forgotten that a full size Caprotti Black 5 had been preserved
is anyone a member of the Midland Railway who could introduce me to the appropriate person?
martyn
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Post by odc on Oct 16, 2014 18:00:06 GMT
The 7 1/4 and 5'' engines made an appearence at the society stand for the full sized Duke at the Great Central Railway a couple of weeks ago. The 7 1/4 engines overhaul is apparently proceeding well. Photographs of them, including views inside the cambox start with this www.flickr.com/photos/owenchapman/15331325297/in/set-72157648705939785 The whole albam mostly includes the big engines running that day |
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