Jib cranes can be subdivided into fixed cranes and portable cranes; in the former the central post or pivot is firmly fixed in a permanent position, while in the latter the whole crane is mounted on wheels, so that it may be transported from place to place.
Here the crane-post is extended into a long mast and is furnished with pivots at the top and bottom; the mast is supported by two " back ties," and these are connected to the socket of the bottom pivot by the " sleepers."
This hook swings on the pivot B, and has an arm which extends backwards, practically at right angles with the working face of the hook, FIG.
The compass needle is a little steel magnet balanced upon a pivot; one end of the needle, which always bears a distinguishing mark, points approximately, but not in general exactly, to the north,' the vertical plane through the direction of the needle being termed the magnetic meridian.
3 From the first he recognized that his chief duty was to drive the Turks from Europe, or, at least, keep them out of Hungary, and this noble ambition was the pivot of his whole policy.
It was probably in Paris, the chief intellectual centre of his time, that Neckam heard how a ship, among its other stores, must have a needle placed above a magnet (the De utensilibus assumes a needle mounted on a pivot), which needle would revolve until its point looked north, and thus guide sailors in murky weather or on starless nights.
It is named the antifriction curve, since a pivot and step having the form of the surface generated by revolving the curve about its vertical axis wear away equally (see MECHANICS: Applied).
The cavalry of his left wing stood fast, west of Doon Hill, as a pivot of manoeuvre, the northern face of Doon (where the ground rises from the burn at an average slope of fifteen degrees and is even steeper near the summit) he left unoccupied.
The fortress was strengthened by a circle of detached forts, which, after 1870, were modified and completed by the Germans, who treated the fortress as the principal pivot of offensive operations against France.
When the rays of the sun or a candle, or dark radiation from a warm body, are incident on the vanes, the dark side of each vane is repelled more than the bright side, and thus the vanes are set into rotation with accelerated speed, which becomes uniform when the forces produced by the radiation are balanced by the friction of the pivot and of the residual air in the globe.
The important part played by the residual air in the globe had also been deduced by Osborne Reynolds from observing that on turning off the light, the vanes came to rest very much sooner than the friction of the pivot alone would account for; in fact, the rapid subsidence is an illustration of Maxwell's great theoretical discovery that viscosity in a gas (as also diffusion both of heat and of the gas itself) is sensibly independent of the density.
The pivot of this part is the logical principle of contradiction.
The: bridge is carried on a circular base plate with a central pivot and a circular track for a live ring and conical rollers.
A circular revolving platform rests on the pivot and rollers.
Proposed to make the Cossacks the pivot of his foreign policy and his domestic reforms. His far-reaching plans were based upon two facts, the absolute devotion of the Zaporozhians to himself personally, and the knowledge, secretly conveyed to him by Stanislaus Koniecpolski, that the whole of the Ukraine was in a ferment.
The whole of the Southern army in the west swung round on its left wing as the pivot, and Buell only just reached Louisville before his opponent.
This is the pivot date of St Paul's later life, but unfortunately two schools of critics date it as differently as A.D.
To obviate this the cunning workman devised a circular table, turning on a pivot, with seats affixed, at which the guests sat the one half in turn within, the other without, the hall "man against man."
C, aluminium cap with sapphire centre; N, N', needles; P, pivot stem with pivot.
4 shows the mounting of a Thomson card on its pivot, which in common with the pivots of most other compasses is made of brass, tipped with osmium-iridium, which although very hard can be sharply pointed and does not corrode.
Great steadiness of card under severe shocks and vibrations, combined with a minimum of friction in the cap and pivot, is obtained with this compass.
That when the compass is placed in the binnacle the line joining the pivot and the lubber's point be parallel to the keel of the vessel.
Several important points were gained in the latter: the quadrantal deviation could be finally corrected for all latitudes; frictional error at the cap and pivot was reduced to a minimum, the average weight of the card being 200 grains; the long free vibrational period of the card was found to be favourable to its steadiness when the vessel was rolling.
He speaks there of a needle carried on board ship which, being placed on a pivot, and allowed to take its own position of repose, shows mariners their course when the polar star is hidden.
Da Buti, the Dante commentator, in 1380 says the sailors use a compass at the middle of which is pivoted a wheel of light paper to turn on its pivot, on which wheel the needle is fixed and the star (wind-rose) painted.
In this house the principal part of the roof is a fixture, ventilation being provided for by small lifting sashes against the back wall, and by the upright front sashes being hung on a pivot so as to swing outwards on the lower side.
The eye end of the telescope tube is removed - a counterpoise to the object end being substituted in its place - and a prism is inserted at the intersection of the visual axis with the transit axis, so that the rays from the object-glass may be reflected through one of the tubes of the transit axis to an eye-piece in the pivot of this tube.
The pivot of the foreign policy of Christian III.
(C) The declination axis is mounted on the prolongation of the upper pivot of the polar axis; the telescope is placed at one end of the declination axis and counterpoised by a weight at the other end.
(D) The declination axis is mounted on a forked piece or other similar contrivance attached to a prolongation of the upper pivot of the polar axis; the telescope is mounted between the pivots of the declination axis.
(E) The eye-piece of the telescope is placed in the pivot of the polar axis; a portion or the whole of the axis of the telescope tube coincides with the polar axis.
Mountings of types A and B - that is, with a long polar axis supported at both ends - are often called the" English mounting,"and type C, in which the declination axis is placed on the extension of the upper pivot of the polar axis, is called the" German mounting,"from the first employment of type C by Fraunhofer.
If now a wheel W is forced up against q with a pressure equal to the weight of the moving part of the instrument, the whole weight of the moving part would rest upon W in unstable equilibrium; or if a pressure R, less than W, is employed, we have the end friction on the lower bearing removed to an extent = R sin 4),4), and the friction on the bearings of the upper pivot removed to the extent of F cos 4), - where 4 is the latitude of the place.
The drawbacks to this plan are (1) the necessarily large size of the upper pivot (viz.
The diameter of the tube) and of the lower pivot (which must be perforated by a hole at least equal in diameter to the photographic field of the telescope), conditions which involve very refined arrangements for relief of friction, and (2)ythe less comfortable attitude of looking upward instead of downward.
One pivot of the polar axis is attached to the lower end of this box, and a strong hollow metal cone, terminating in the other pivot, forms the upper part of the polar axis.
Regarding evil simply as privation, Eckhart does not make it the pivot of his thought, as was afterwards done by Boehme; but his notion of the Godhead as a dark and formless essence is a favourite thesis of theosophy.
It consisted simply of a light metallic needle balanced on a pivot like a compass needle.
Friction of Pivots and Collars.When a shaft is acted upon b a force tending toshift it lengthways, that force must be balanced by the reaction of a bearing against a pivot at the end of the shaft; or, if that be impossible, against one or more collars, or rings projecting from the body of the shaft.
The flat pivot is a cylinder of steel having a plane circular end as a rubbing surface.
And, introducing this value into equation 59, the moment of friction of tile flat pivot is found to be affNr (61)
129) be the axis of a pivot, and let RPC be a portion of a curve such that at any point P the secant of the obliquity to the normal of the curve of a line parallel to the axis is inversely proportional to the ordinate PY, to which the velocity of P is proportional.
This curve, bein~ an asymptote to its axis, is capable of being indefinitely proloi~ged towards X; but in designing pivots it should stop before the angle PTY becomes less than the angle of repose of the rubbing surfaces, otherwise the pivot will be liable to stick in its bearing.
The moment of friction of Schieles anti-friction pivot, as it is called, is equal to that of a cylindrical journal of the radius OR=PT the constant tangent, under the same pressure.
Records of experiments on the friction of a pivot bearing will be found in the Proc. Inst.
And between 74° o' and 83° o' E., and may be said to consist of two large detached tracts of country which, with Jhansi as a pivot, spread outwards east and west into the peninsula, reaching northward to within some 30 m.
This power is acquired by a very massive lever, moving on a pivot bolt in the top of the near side of the staple, and passing across the press to the further side of the frame, at which end the power is applied through the coupling-bar by a bar-handle working from the near side.
Thus the pivot of the Haldane system is the organization of the Territorial Force as a completely self-contained army.
On the 27th the Bulgarian wheel began, but instead of its being carried out on a fixed pivot, the pivot itself was allowed to advance eastward, so that, instead of presenting a united line, the Bulgarians formed a loose echelon, left in advance, which led to successive instead of simultaneous engagements.
Nevertheless, at this same time (June 1834) Lord Palmerston wrote that " Paris is the pivot of my foreign policy."