Loose Damp Capacity Delay. Sand. gravel. Dry loam. Dry clay. clay. of dipper. hours.[2] Cu. yds. Cu. yds. Cu. yds. Cu. yds. Cu.yds. 2-1/2 cu. yds. 1 Good 2,400 2,400 2,000 1,800 1,200 " 5 Poor 1,200 1,200 1,000 900 600 " 2-1/2 Avg. 1,800 1,800 1,500 1,350 900 1-3/4 cu. yds. 1 Good 1,600 1,600 1,200 1,000 800 " 5 Poor 800 800 600 500 400 " 2-1/2 Avg. 1,200 1,200 900 750 600 1 cu. yd. 1 Good 1,000 1,000 800 700 500 " 5 Poor 500 500 400 350 250 " 2-1/2 Avg. 750 750 600 525 375
[Footnote 2: The delay in hours is the time lost in moving forward and waiting for empty cars.]
+----- Loosened by explosives.---+ | Mixed | Stiff Hard clay and Loose Cemented Capacity Delay. blue clay. pan. boulders. rock. gravel. of dipper. hours.[3] Cu.yds. Cu.yds. Cu.yds. Cu.yds. Cu.yds. 2-1/2 cu. yds. 1 Good 800 600 600 600 600 " 5 Poor 400 300 300 300 300 " 2-1/2 Avg. 600 450 450 450 450 1-3/4 cu. yds. 1 Good 600 400 400 400 400 " 5 Poor 300 200 200 200 200 " 2-1/2 Avg. 450 300 300 300 300 1 cu. yd. 1 Good 400 300 300 300 300 " 5 Poor 200 150 150 150 150 " 2-1/2 Avg. 300 225 225 225 225
[Footnote 3: The delay in hours is the time lost in moving forward and waiting for empty cars.]
Loading the Material for Transportation.--The material excavated by a steam shovel is loaded on cars, wagons or carts. On railway work it is usually loaded on dump or flat cars. On other construction work small dump cars are most generally used, and sometimes wagons or carts.
Standard gage railway dump cars, Figs. 66 and 67, have nearly gone out of use. They were replaced by the center ridge flat car, Figs. 68 and 69, and it in turn has been replaced by the ordinary flat car. Dump cars are of two styles, dumping either by tipping, Fig. 66, or by means of a hinged sideboard opening on an inclined floor, Fig. 67. Both are heavy, clumsy, costly and can be used for scarcely any other purpose, often standing idle from six to eight months of the year. They dump dry materials very rapidly, but are often slow in discharging damp, tenacious materials, especially in the hinged sideboard car, whose floor slope is often not sufficient to permit the material to slip out quickly, and the material must then be pushed out, thus causing much delay. The greatest objection to these cars is that they can be used for scarcely any other purpose, on most railways for no other purpose; and there is not sufficient work for them to justify keeping the necessary number on hand for the ordinary work in this line. They were replaced by the center ridge car, Figs. 68 and 69, as above noted, which is merely an ordinary flat car with a timber 4 by 6 ins. bolted on its floor along the center line, serving as a guide for a plow, Fig. 70, drawn over it by the locomotive, thereby unloading the material. The ridge timber is slightly pointed at both ends to assist in guiding the plow onto the car as it passes from one car to another. The top edges of the ridge are sometimes protected by angle irons, as in Fig. 71, and the points by cast iron caps, Fig. 72. By taking off the center ridge this car can readily be restored to general service after completing the steam shovel work. The center dump car, shown in Fig. 73, is used only for gravel ballasting where the material is wanted delivered between the rails.