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Translated by AltaVista,
June 14, 2004. Posted here for historic archive purposes.
normally, while following the plans and by preserving materials indicated, that should function of the first blow! if it is not the case at the time of the first startup, try to create a difference in important temperature between the two plates for example, you can place your
engine at the top of a very hot water container and have the cubes of ice on
the higher plate, then to gently launch the wheel to the hand in a direction
and the other - indeed the direction of rotation depends on dephasing of
approximately 90° that you regulated between the piston and the deplacor (a
very stupid indication, but perhaps not useless, these small engines, not more
than those of the cars, do not start all alone: they should obligatorily be
launched to the hand!) that can come from: to check the sealing, you can for
example, after having disconnected the rod from the operating piston, to
ensure you that on a moderated heat source, the membrane is raised and dropped
of it even when you move the deplacor from one plate to another.
UN average a little more "scientific" consists in making a pressure gauge with water simplified with 1 m of hose connection silicone (Ψ 2 mm int - stores of model making) without applying heat source, by again connecting the rod of the operating piston and while turning the wheel to the hand, one can see the liquid moving few cm on both sides point of balance (1 cm of difference between the levels corresponds to a pressure from approximately 1 gf/cm2) if one stops the wheel with the PMH (operating piston in high position), the difference between the levels is with its maximum, and one can then check the sealing of the engine by observing time that the pressure gauge puts to turn over to the point of balance (pressure = 0) according to the sealing of the engine, the duration can vary few seconds at several minutes, but so that it functions, it is necessary that this return to balance is rather definitely higher than the duration of a revolution: for an engine likely to turn to 60 rpm, count between 5 and 10 seconds - frictions: the power provided by this type of engine being very low (15 MW converted into mechanical energy on the 1.2) it is necessary that frictions are as reduced as possible on the level of the slide and the stages. UN test simple consists in disconnecting all the rods and with launching the wheel to the hand: CD must turn around fifty of turns before stopping, whether it is equipped with bearings or balls of glass. if you use stages in glass shots, it is very important to use an axis out of piano wire of Ψ 0,8 mm - if you use an axis made in another material, or it will not be rigid enough, or you will have to increase his Ψ and the forces of friction will be too high. if you assembled the axis of the wheel on bearings, the axis can have in this case a more important section - but I however advise you to continue to use piano wire Ψ 0,8 mm and glass shots for the vertical guides of the deplacor - this device, once oiled, ensures a good sealing and reduced frictions. -
dephasing: very important, did you strictly respect the dephasing of 90° between the movement of the deplacor and that of the operating piston? It is true that to support the couple or the number of revolutions, one can exploit this value a little, but for the first tests preserve 90°. - spacers (only for the engines of the series 3.x): the plates of the series 3.x, carried out in aluminum sheets of 0.8 mm are not rigid enough by themselves - if one omits to install the two spacers indicated, with the place that it is the operating piston which moves, in fact the plates become deformed few 1/10 of mm, and of course, the engine does not turn...
it is not very complicated: it is necessary to manufacture the form that one wishes to obtain in wood or resin of carriage-builder (photo on the right), then to stick it on a sheet of paperboard or plywood, and finally to bore it small holes of Ψ 1 mm Ensuite, while maintaining the membrane in position (with adhesive), one heats it at good temperature with a thermal gun when it is rather hot, the small folds of surface disappear, and it is then enough to aspire by below (with a vacuum cleaner) and to let cool the whole continuously to aspire Sur the photograph of right-hand side, the black rectangles are pastilles of adhesive doubles face which are used to maintain the membrane in position - they present the defect to function only one or twice, also it should be reloaded with adhesive repositionnable between each operation ttentionhas, this method is valid only with vinyl membranes (pieces taken in disposable gloves), and forms it represented is not appropriate that for transparent packing of films 24 X 36 (... and at all with the black cases with gray stoppers...)
Uanother method, which
dephasing with 90° authorizes, it is to balance separately, and by groping,
the two moving elements: while placing the operating piston with the PMH or
PMB, the big end of the deplacor is on a horizontal axis passing by the axis
of the wheel and involves it to the bottom - it is then enough to place at
opposite small mass which balances it in this position - and one starts
again the manipulation for the rod engine... C' is besides a good means of checking of the first method, but it is necessary of course that the wheel turns very freely...
JE proceeds like that: I disconnect the big end and I check that under the weight of the rod, the piston and the membrane, the axis of the big end goes down from approximately 1 mm under that of the crank with the PMB - then I turn over Stirling of 180°, I make swivel the crank so that it positions with the PMH, and I control that the axis of the big end is 1 mm under the axis of the crank ... I do not know if I were very clearly...;o) then to summarize: the free clearance of the membrane must be higher 2 mm than the travel of the crank.
See also
Page posted by Sterling
D. Allan, June 14, 2004 |
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