The heating of journals and reciprocating parts of an engine may be attributed to the following causes:
Improper proportions and fitting, unsuitable material, want of homogeneity between the metals of which the journals and bearings are composed, the revolving or reciprocating parts not being in line, the boxes being keyed up too tight, sand or grit getting into the journals, improper lubricating, etc. The last mentioned cause is very complicated, as the conditions of weight of load, area of surface subject to pressure, velocity of movement, etc., must be taken into consideration.
To remedy the heating of journals which is caused by the revolving or reciprocating parts not being in line, the engine or shaft must be put in line.
When caused by the boxes or bearings being too tight, they must be loosened a very little at a time until bearings run cool. Apply plenty of good oil.
Clean the boxes and journals thoroughly, and see that the oil holes are not stopped up; also see that the oil-cups are clean, to assure of the oil getting to the bearings freely.
Oiling frequently, using a little oil at a time, gives the best results and is the most economical.
When the piston or valve rod of an engine or pump needs re-packing, take off the stuffing box gland, remove all the old packing carefully, and replace with new.
If a patent packing is used, it should be cut in suitable lengths diagonally across the packing, making the angle of one end opposite from that of the other, so that when ends are brought together they will make a splice joint. The joint of each ring of this packing should be placed at opposite sides of the rod, and the stuffing box filled, the gland replaced and screwed up just tight enough to stop leakage. If hemp packing is used, take about the amount required and pick it to pieces, removing all sticks, lumps or hard substances. Then twist it into three compact cords, saturate well with oil or tallow, and braid the cords together tightly. Then wind this braid around the rod until stuffing box is full, replace the stuffing box gland, and screw up as before described.
Care should be taken not to screw the packing in stuffing boxes too tight, as it not only increases the friction on the rod and diminishes the power of the engine, but will have a tendency to flute the rod. If the rod is once fluted, it will be very difficult to stop leakage at this joint.