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When a main shaft is belted to the engine and to a countershaft, as shown in Fig. 9, the pulley A1 gets all the load of main and countershafts. In the arrangement shown in Fig. 10 point 1 gets A's load and 2 gets B's load and is the better arrangement.
Fig. 9——Fig. 10.
Where a machine is situated close to one of the columns or timber uprights of the building it is very customary to carry the belt shifter device upon the column, as in Fig. 11. The sudden stoppage of a machine seldom does any damage, whereas an unexpected starting may cause irreparable damage and often even endanger the limb and life of the machine operative.
Fig. 11.
To avoid the possibility of some passing person brushing up against the shifting lever and thus starting the machine, the tight and loose pulleys of the countershaft should be so placed that when A is exposed—that is, away from the column—its accidental shifting shall stop the machine. Fig 12 makes this point clear.
Fig. 12.
This arrangement is often used to save a collar (at A). The oil runs out between the loose pulley and the bearing, especially if the latter be a split bearing; the loose pulley, instead of being totally free when the belt is on the tight pulley, acts more or less, in proportion to the end play of the shaft, as a buffer between the tight pulley and the bearing; finally, the tight pulley is deprived of the support (which, when under load, it can use to good advantage) a nearer proximity to the hanger would give it.