| 释义 |
▪ I. piston, n.|ˈpɪstən|
[a. F. piston (1647 Pascal, in Littré), ad. It. pistone piston, variant of pestone great pestle, rammer, augm. from stem pest- in pestello pestle: cf. It. pestāre:—late L. pistāre, freq. of pinsĕre, pist- to pound, beat. Cf. OF. peston = pilon pestle, stamper.]
1. A mechanical contrivance, consisting of a disk or short cylinder of wood, iron, or other solid substance, which fits closely within a hollow cylinder or tube, and can be driven with a reciprocating motion up and down the tube, or backwards and forwards in it; on one side it is attached to a rod (piston-rod) by which it imparts motion to machinery (e.g. in a steam-engine), or by which motion is imparted to it (e.g. in a pump).
1704J. Harris Lex. Techn. D ij (s.v. Air pump), Each time the Piston or Sucker of the Pump is drawn back, the Air in the Receiver must expand it self so as in some measure to fill up the Cavity of the Pump left vacant by the Piston, as well as the Receiver it self. 1712J. James tr. Le Biond's Gardening 192 Piston is the short Cilinder..which is moved up and down in the Barrel of the Pump. 1786Rees Chambers' Cycl. s.v. Steam-engine, A large barrel or cylinder..and in this a piston well leathered. 1827Faraday Chem. Manip. xv. 341 A small piston rendered air-tight by tow and tallow. 1842Brande Dict. Sc., etc. s.v., Two sorts of pistons are used..: one hollow, with a valve, used in the sucking pump; and the other solid, which is employed in the forcing pump. 1867W. W. Smyth Coal & Coal-mining 210 Horizontally-working pistons in prismatic chambers were erected in 1828 by M. Brisco, near Charleroi.
2. a. In the cornet and other wind-instruments: A sliding valve which moves in a cylinder like a piston, used for increasing the effective length of the air-passage and thus lowering the pitch of the note. Hence cornet-à-piston.
1876tr. Blaserna's Sound i. 20 By opening a communication with the external air..by means of pistons in the cornet.
b. A pneumatic thumb-knob in an organ, which is pushed in like a piston, and has the effect of combining a number of stops.
1890in Cent. Dict.
3. Zool. A central retractile part in the suckers on the arms of a cuttle-fish or other cephalopod, which acts like the piston of an air-pump in producing a vacuum.
1871T. R. Jones Anim. Kingd. (ed. 4) 605 A deep cavity..at the bottom of which is placed a prominent piston..that may be retracted by muscular fibres.
4. attrib. and Comb., as piston-plunger, piston power, piston speed; piston-like adj.; piston bellows, bellows in which the draught is supplied by the action of a piston; piston corer or core sampler, a core sampler consisting of a long weighted cylinder containing at its lower end a piston attached to the lowering cable, devised so that when the cylinder enters the bottom sediments under its own weight the descent of the piston is arrested, and the resulting partial vacuum inside the cylinder causes the pressure of the water to be effective in forcing it into the bottom; piston drill, a percussion drill in which the bit is attached to the rod of a piston; piston engine, a reciprocating engine, esp. an aircraft engine in which the airscrew is driven by the reciprocating action of pistons; hence piston-engined a., powered by this kind of engine; piston-head, the disc or cylindrical part of a piston, which slides in the tube, as distinguished from the piston-rod; piston-knob = 2 b; piston-packing, (a) any material used for filling the space between the piston-head and the cylinder in which it works, so as to make it steam-tight, air-tight, or water-tight; (b) a mechanical device for packing pistons; pistonphone Acoustics, a device for producing known sound pressures by means of a vibrating piston whose motion is precisely measured, used mainly for calibrating microphones; piston pin, a pin which secures a piston to its connecting rod in an internal-combustion engine; piston-pump, a pump having a piston; piston ring, a metal ring fitted on a piston to seal the gap between the piston and the cylinder wall; piston-rod (see 1); piston slap, rocking of a loosely fitting piston against the cylinder wall, or the noise resulting from this; piston-sleeve, a hollow cylinder or trunk moving longitudinally with the piston-head in a trunk-engine, and taking the place of the cross-head; piston-spring, a spring connected with a piston-head, and forming, or having the effect of, a packing (Knight Dict. Mech. 1875); piston-valve, (a) a valve in a piston, as in that of a pump; (b) a valve formed by a small piston sliding backwards and forwards in a tube, for admitting steam into, or exhausting it from, the cylinder of a steam-engine; piston-wheel, (a) a wheel or rotating disk carrying at its outer margin one or more pistons; (b) in a chain-pump, a wheel carrying an endless chain bearing pistons or disks working in a tube or barrel; piston-whistle, a whistle in which the pitch of the sound is varied by means of a piston sliding in the tube.
a1877Knight Dict. Mech. II. 1717/1 A *piston-bellows, formed by boring out the trunks of trees, used by the natives of Madagascar for smelting..iron.
1947B. Kullenberg in Svenska Hydrogr.-Biol. Komm. Skrifter (Ser. 3: Hydrogr.). I. ii. 12 The *piston core sampler..has been based on a method to procure samples for ground investigations, developed by the Geotechnical Department of the Swedish State Railways. 1956Piston core-sampler [see core n.1 4]. 1959H. Barnes Oceanogr. & Marine Biol. i. 67 In Kullenberg's *piston corer the hydrostatic pressure at great depths is utilized to overcome..friction and to allow very long undisturbed cores to be taken. 1976New Scientist 9 Dec. 576/2 The oceanographers' piston corers that were beginning to recover cores, or columns of mud, from the floor of the deep ocean.
[1901M. M. Kirkman Locomotive Appliances 475 (caption) Piston air drill for drilling, reaming and tapping on locomotive work.] 1919R. Peele Compressed Air Plant for Mines (ed. 3) xx. 306 At a large group of mines on the Rand, the complete repair cost of standard *piston drills..averaged $42.00 per 52 shifts. 1967K. McGregor Drilling of Rock i. 12, 1860–70..; a commercial piston drill was patented by Burleigh in America. Ibid. 13 From these [drop drills] developed..the pneumatic piston drill... These machines were finally obsolete in the early 1920's.
1907Engineering 21 June 829/2 If the turbine requires a screw which is necessarily less efficient than that of the *piston engine, it is the fault of the turbine system. Ibid., Ordinary reciprocating, or, to use a shorter word, piston, engines. 1943G. G. Smith Gas Turbines & Jet Propulsion (ed. 2) vii. 54 Even if free-flying piston engine and compressor units were employed these handicaps would remain. 1960C. H. Gibbs-Smith Aeroplane xvi. 126 The piston engine reached its apogee in the post-war period with such examples as the Pratt & Whitney 28-cylinder 3,500 h.p. radial. 1971P. J. McMahon Aircraft Propulsion xi. 311 Mechanical losses in piston engines are high, being up to 25% of the indicated power.
1948Jrnl. R. Aeronaut. Soc. LII. 591/1 The Airspeed Ambassador may be taken as representing the most advanced *piston-engined commercial aeroplane of its size yet in prospect. 1974E. Ambler Dr. Frigo i. 56 For most of those critical three days I was..in piston-engined planes missing connecting flights. 1979Daily Tel. 1 Dec. 10/6 Their departure..coincides with the paying off of the Navy's only remaining steam reciprocating, or piston-engined, ship.
1875Knight Dict. Mech., *Piston-head, that portion which fits into and reciprocates in the cylinder. 1888Hasluck Model Engin. Handybk. (1900) 51 The piston-head is in two parts..; one must have a taper hole bored to fit the rod.
1902Academy 9 Aug. 159/2 Defoe's *piston-like pen.
1875Knight Dict. Mech., *Piston-packing, a material for preventing the leakage of steam between the piston-head and the cylinder in which it works.
1922E. Wente in Physical Rev. XIX. 343 (caption) Use of *pistonphone for calibrating an electrostatic transmitter. Ibid. 500 The open-circuit voltage of the transmitter per unit of pressure has been measured with the piston-phone for the frequency range of 10 to 200 cycles per second. 1965C. A. Taylor Physics Mus. Sounds vi. 100 The pistonphone..appears to be used only for scientific work at very low frequencies. It consists..of a piston driven by a rotating cam which permits the generation of sinusoidal variations in pressure of accurately-controlled form. 1972Where Dec. 336/3 Our tests were done with a B and K portable octave band analyser, which was calibrated before and after each occasion with a pistonphone.
1897F. Grover Pract. Treat. Mod. Gas & Oil Engines xvii. 175 The pressure on the *piston pin may be much more than upon the crank pin. 1910W. A. Tookey tr. Mathot's Construction & Working of Internal Combustion Engines xiii. 375 The piston pin is made of the best quality mild steel. 1967J. L. & G. H. F. Nayler Dict. Mech. Engin. 176 Gudgeon pin... Also called ‘piston pin’.
1797Monthly Mag. III. 464 The *piston-plunger is worked by a toothed segment-wheel.
1899Daily News 7 Dec. 3/5 These solid slabs of metal are forced by..‘*piston-power through a series of holes.’
1867N. P. Burgh Mod. Marine Engin. vi. 277/2 The adoption of ‘springs’ behind the ‘*piston ring’ is now becoming general. 1936Discovery Feb. 39/1 Steam leaking past the piston rings of the high-pressure cylinders. 1971J. H. Haynes Mini Owner's Workshop Man. i. 30/1 To remove the piston rings, slide them carefully over the top of the piston, taking care not to scratch the aluminium alloy. 1976L. Deighton Twinkle, Twinkle Little Spy x. 97 The running repairs I do myself... Last month I changed the piston rings.
1786Rees Chambers' Cycl. s.v., Steam-engine, The *piston-rod, which is truly cylindrical, moves up and down through that hole. 1830Herschel Stud. Nat. Phil. ii. vii. 194 The power which alternately raised and depressed the piston-rod of the engine. 1895Model Steam Engine 39 Small holes should be drilled in the top of the bearings, piston-rod guide, eccentric-band, and crank-pin end of connecting rod for admitting oil.
1916P. M. Heldt Gasoline Automobile (ed. 4) I. vii. 163 To obviate..*piston slap when starting, it is well to make the piston comparatively long. 1962Which? Car Suppl. Jan. 32/2 A worrying piston-slap rattle from the engine. 1968Practical Motorist Dec. 459/1 Piston slap, a characteristic metallic slapping sound within the cylinders caused by slight rocking motion of an ill-fitting or worn piston.
1815J. Smith Panorama Sc. & Art II. 6 To improve the air-pump, Smeaton..covered the top of the barrel..by which contrivance he took off the pressure of the atmosphere from the *piston-valve. 1875Knight Dict. Mech., Piston-valve, a valve consisting of a circular disk, which reciprocates in a cylindrical chamber.
▪ II. ˈpiston, v.
[f. the n.]
intr. To move like a piston. Occas. trans., to direct, throw with a piston-like movement.
1930R. Campbell Adamastor 80 Down the stage the dance..Tarantulates in scarlet tights For flashing arms to piston. 1940Dylan Thomas Portrait of Artist as Young Dog 52 The small boy in his invisible engine..kicked the dog's plate at the washhouse stop, and puffed and pistoned slower and slower while the servant girl lowered the pole. 1958Spectator 15 Aug. 219/3 Thin grey knees piston over the beach. 1976‘E. McBain’ Guns (1977) v. 118 He..pistoned a short hand punch to her shoulder. |