CLUTCHES AND COUPLINGS. The Bill Friction-Mich Pulley is shown in Fig. I. The pulley is cast with a rim projecting from the arms, inside of and concentric with the or dinary rim, which rim is gripped on both sides by wooden blocks. These are moved by a com bination of toggles, whose action is shown in the sectional view.
The Liok-Bell Engiwering Co.'s Disk is shown in Fig. 2: figure showing the clutch in engagement, and figure disengaged. It consists of a plate-center pulley, con taining beneath its rim on one side the toggle-lever mechanism, and on the other the clamping-plate, embracing a disk which is provided with projecting hard-wood plugs. This disk is loosely interlocked with square jaws on the hub of the pulley, wheel, or coupling.
The Brod; b'rielion-Cluleh, a portion of which is shown in the sectional view (Pig. :O. has a rim which is grasped on the inner mid out er sides by the clench members, which are shod with seasoned maple. The radial motion of the jaws or clutch mcmliers is produced by the sliding piece (seen to the right of the policy) being pushed townrd the elnteh or pulley. giving motion to angled levers, which force the upper or outer jaws in wardly anal the inner jaws outwardly, until they grip tinnily both sides of the rim. Moving the sliding piece away from the clutch, in the position shown in cut, disengages the jaws or frictional surfaces.
The Weston Safety Ratchet, as applied to crabs, winches, and similar hoisting apparatus, is shown in Fig 4. The principle is based upon the combined use of a friction-clutch with a ratchet wheel and pawl in such a manner that the action of the weight tightens the clutch and pi-events all possibility of accidental release. The reverse motion of the handle releases the clutch and permits the load to follow, but any variation in the speed of the crank-motion is followed by a corresponding variation in the barrel movement, and when the motion of the crank is stopped, either in tentionally or accidentally, the barrel also stops. Referring to the cut, D i6 a section of a spur-pinion suitable to be used in connection with any light train of gearing. At C is a ratchet-wheel with which
a pawl engages, and which can thus only revolve freely in one direction. Between the pinion D and the ratchet-wheel C are several friction disks, the alternate ones being connected with pinion and ratchet-wheel, and giving enough friction surface to hold the two parts firmly together as a unit when they are forced into close frictional contact. Both pillion and ratchet-wheel are loose upon the shaft A, and are placed between two collars. One collar, B. is pinned fast to the shaft, and is a plain collar. The other collar, E, has a helix formed upon its side, and there is a corresponding helix upon the hub of the pM ion upon that side. This collar E is also pinned fast to the shaft, so that there is but slight play between the parts, just enough to permit the engagement or release of the friction-disks. When the shaft, A, carrying with it the collar E, is revolved, the top moving toward the observer, the helix on the collar acts as a circular wedge upon the helix on the pinion-hub, and forces the fric tion-disks tightly together, and also tightens the whole series upon the shaft; a.nd any motion given to the shaft A is transmitted through the pinion D, just as if it were keyed fast. The same action takes place when the load attempts to rotate the pinion backward. When it is desired to lower the load, the shaft A is turned backward. The ratchet-wheel can not revolve in that direction, as it is held by the pawl, and, as the pillion is held by the friction-disks, the shaft alone is turned. carrying with it the collar E. This motion releases the wedge action of the helix, and reduces the pressure upon the disks, and hence the load can now pull the pinion backward, the alternate disks slipping unon each other. Any tendency for the load. to turn the pinion faster than the shaft and collar once creates an increase in the friction between the disks. and so t ha pillion can not run down any faster than the motion of the crank and shalt, and, if the crank is for any reason let go, the friction-disks will at once tighten and hold the load.