sb. Also 6 sprokett, 6, 9 sproket. [Of obscure origin.]
1. Carp. and Build. A triangular piece of timber used in framing, esp. one fastened on the foot of a rafter in order to raise the level of the eaves.
1536. MS. Acc. St. John’s Hosp., Canterb., To Nycoles & Horton for makyng sprokettis & a grunsyll att Arnoldes, ij d.
1593. MS. Churchw. Acc. St. Andrew’s, Canterb., For setting vp a forme, nayles and sproketes, xiij d.
1703. [R. Neve], City & C. Purchaser, 121. A Coving-cornish … has a great Casement, or Hollow in it, which is commonly Lathed and Plaister’d upon Compass, Sprockets, or Brackets.
1880. Leaning, Quantity Survey., 61. Sprockets.—State what size two are cut out of.
2. A projection (either forked or simple) from the rim of a wheel, engaging with the links of a chain.
1750. Blanckley, Naval Expos., 126. Sprockets are made not unlike a large Horse Shoe, drove into the Wheel, and the Chain works on them.
1875. Knight, Dict. Mech., 522/1. The sprockets on the wheel are adapted to receive the links of the chain successively. Ibid., 2292/2. The sprockets may be forked, and thus made to partially embrace the links of the chain.
1897. C. T. C. Monthly Gaz., Jan., 21. A roller-chain passing over ordinary sprockets.
b. attrib. in sprocket-wheel.
1769. Falconer, Dict. Marine (1780), s.v. Pump, The sprocket-wheels, employed to wind it up from the ship’s bottom.
1792. J. Townsend, Journ. Spain, I. 170. It [the noria] consists of a band or girdle passing over a sprocket wheel.
1846. A. Young, Naut. Dict., 239. Above the upper extremities of these tubes there is fixed a sproket-wheel worked by crank-handles.
c. 1860. H. Stuart, Seaman’s Catech., 54. It is rove round the sprocket-wheel of the capstan.
1896. Westm. Gaz., 21 Nov., 7/2. The chain, instead of acting direct on the driving wheel, passes from the sprocket wheel to another at the back of the saddle.
c. ellipt. A sprocket-wheel, esp. that of a cycle.
1886. J. M. Caulfeild, Seamanship Notes, 3. Parts of the Capstan. Drum head, barrel, sprocket.
1893. Fortn. Rev., No. 314. 241. The elliptical sprocket, or lower chain-wheel, has caused much discussion.
attrib. 1897. Outing, XXX. 277/2. A wheel, from handle-bar to sprocket-chain. Ibid., 370/2. A sprocket-lock, which was guaranteed to prevent any sprocket from revolving. Ibid., 371/1. I snapped in its place my sprocket-guard.
3. Naut. One of the teeth of a pawl-rim.
1903. Speaker, 7 Feb., 452/1. The Hermione capstans are of the dangerous, old-fashioned type, fitted with the antiquated ‘pawls and sprockets’ that were in use in Howe’s time.
1906. Temple Bar, Jan., 59. The little iron pawls … begin to click and clatter, as they pass over their sprockets.
Hence Sprocketed a., furnished with sprockets.
1895. Queenslander, 7 Dec., 1071/1. The chain runs on and engages sprocketed wheels.
