157. T lever valve motion, used in rock drills, some forms of steam engines, &c.
158. Four-bolt camplate, used for screwing dies, locks for fireproof safes, &c.
159. Slot, cam, and lever motion.
160. Barrel motion for musical instruments, looms, &c., in which the barrel is provided with pins or staples to lift the respective levers.
Larger plate.
161. Drum with spiral vanes of long pitch, operated by a revolving arm on a shaft at right angles to the cam shaft, used for intermittent circular motion.
162. Volute and lever.
163. Double screw, for converting circular into reciprocating motion; has a right and left hand screw thread, and a shuttle attached to the lever end shaped to fit the thread, and capable of swivelling to turn the angle for reversing.
164. Eccentric ring and roller motion, for converting circular into reciprocating motion.
165. Triangular cam. Gives three reciprocations to the sliding bar in one revolution of the cam.
166. Fan for giving motion to several rods or arms at one time, used for organ composition pedal movement, &c.
167. Crossed lever motion with inclined contact surfaces, the levers being at right angles to one another.
Section 10.—CRANK AND ECCENTRIC GEAR.
168. Bent crank of round section; retains the fibre and strength of the metal.
169. Square forged crank. The crank arm is usually forged solid and the slot cut out by machine.
170. Built-up crank. There are other methods of building them. See Mechanical World, December 1885. See also No. 182.
171. Single crank, usually of wrought iron, but often made with cast-iron arm.
172. Disc crank. This form is generally adopted when cast iron is employed, and the counterbalance weight cast upon it, to balance the connecting rod, &c.
173. Counterbalanced single or double crank.
174 & 175. Two forms of crank pin eccentrics; sometimes used to drive the slide valve instead of the ordinary sheave and strap, as No. 183.
176. Crank pin set in a boss formed on the driving wheel.
177. Double rod crank.
178, 179, & 181. Hand cranks. These should always be fitted with a loose ferrule of wood for the hand if possible, as much power is lost by the slipping of the hand to change its grip as the crank revolves.
180. Solid three-throw crank shaft, turned out of a solid forging.
Larger plate.
182. Built crank. Several modifications of this are in use for large marine shafts.
183. Solid sheave eccentric.
184 & 185. Split sheave eccentrics.
Large eccentrics cause great loss from friction, unless provided with friction rollers in the sheave; but are sometimes used to avoid an additional crank in shaft.
186. Eccentric motion for multiplying travel of eccentric by leverage.
187. Crank motion to turn an angle instead of bevil gear and shaft, the cranks being of the form of Nos. 174 or 175.
188. Shifting or variable throw eccentric. The sheave is slotted to fit the shaft, and its throw is governed by a disc having a spiral slot and locking bolt.
189. Another form of shifting eccentric. The sliding block is arranged to lock in any part of the slot in the sheave.
190. Another form of shifting eccentric, in which the sheave is loose on an eccentric boss cast with the worm wheel, and is revolved by the worm, the bearings of which are fixed to the sheave.
See also Nos. 606, 712, 720, 728, 729.
See also Sections 40 and 79.
Section 11.—CHAINS AND LINKS.
For Hooks, Swivels, &c., see Section 43.
191. Ordinary long or short link chain. It is sometimes made to exact pitch to fit a snug or sprocket wheel. See Nos. 1250 & 1251.
192. Stud link chain.
193. Flat chain for use on flat rim double-flanged pulley.
194. Square link pitched chain for sprocket wheel.
195. Stamped link pitched chain and special sprocket wheel.
196. Ordinary pitched link chain. Links drilled to templet.
197 & 198. Pitched chains to drive wheels with ordinary and special teeth.
199. Another form of square link chain.
200. Stamped link chain, for light purposes.
201 & 202. Long link flat suspension chains.
203. Gib and cotter attachment for long link flat suspension chains.
Larger plate.
204 & 205. Drive chains. See Ewart’s patent, No. 2752–76, and others. These chains are replacing belts for many purposes, as they give a positive drive, do not stretch so much, and last longer, besides which they are easily detached at any point, and a damaged link can be readily replaced.
206 & 207. Thrust chains, with friction rollers at each junction, used in hydraulic multiplying cylinder gear in some cases.
208. Ewart and Dodge’s patent chain, with renewable seatings between the links.
Section 12.—CARRIAGES AND CARS.
The design and details of these must always be suited to circumstances. We only propose here to indicate the various types of under-framing and wheels in use, and to give sketch sections of bodies or cars for different purposes.
UNDER-FRAMES.
209. Two-wheel suspension car for single rail or wire rope, used commonly on some kinds of cranes. See