necessary to provide against the extra strain imposed by the actual weight of the ropes. by strengthened shafts and bearings

should the distance prove too great for one span, rather thin merely sustaining the ropes mid-way, it is far better economy to di ideyan I drive forward from intermediate pulleys.

Centre distances in ordinary mill driving seldom exceed yo feet, and these are usually fixed in an oblique direction.

In cases where sustaining pulleys are found necessary it is always advisable to so distribute them along the drive that the intervals between the centres shall not be equal.

The tunnel drive at a large timber works in Scotland represents one of the best examples of this class of driving known to us, and well explains the reason for such unequalities. The centre distances in this instance read as follows:-From fly wheel to pulley deflecting ropes into the tunnel 16 feet, from this to the first set of sustaining pulleys 15 feet 6 inches, between these and the second set, 29 feet; and from the second set to the driven pulley at the far end of the tunnel, 22 feet. The oscillations due to starting the engines or the sudden removal of the entire load of 225 horse power, are thus anticipated and the possibility of synchonization along the whole track is entirely obviated by altering the length of the beat, and breaking up the rhymth, to such an extent that the initial wave-like movements quickly diminish to mere rippling disturbances.

It being scarcely possible to cover all the varied conditions which may rightly come under the head of angular driving. that is, when ropes require to be turned aside from the straight

driving path. One or two illustrations may point the way to the solution of similar problems.

Good examples of right angled driving with shafts on the same plane are shown by Figures 25 and 26. In both cases it will be observed the tight sides of the ropes are deflected by the guide fixed at a suitable angle, while the slack is directed by the one having the horizontal axis, either from above or below.

The sketch of scutching room fan drive shows probably the best means of getting over the difficulty when driving and driven pulleys are not upon the same plane and gives a good definition of the guidance required, although only one rope is necessary for this class of work. The same method applies to rope driven ring frames and other light machinery.

GUIDE PULLEYS.

Seeing that the hurt to ropes is due more to the bending

action which takes place immediately it touches the periphery however limited the contact, guide pulleys should never be allowed to come below the regulation thirty rope diameters. Small pulleys may in most cases be held responsible for failures in this class of driving.

The disintegrator drive shows how shafts may be made to revolve in opposite directions, one inside the other, by ropes from a driving pulley on line shaft round the two driven pulleys and over a sliding tension actuated by a screw.

When shafts are only slightly out of alignment, ropes will direct

Another method of transmitting power to buildings which may not run parallel with main driving arrangements, is by means of a specially constructed universal coupling. This has been successfully carried out at a works near Birmingham, where the shafts are nine degrees out of line. The coupling works so smoothly that vibration can scarcely be detected. Unfortunately the arrangement is in too cramped a position to be successfully photographed.

FIGURE 30.- FAN DRIVING IN SCUTCHING ROOM.