Fig. 53.—Allen Paper Car Wheel.
Steel tires have the advantage that when they become worn their treads and flanges may be turned off anew, whereas chilled cast-iron wheels are so hard that it is almost impossible to cut them with any turning tool. For this reason machines have been constructed for grinding the tread with a rapidly revolving emery-wheel. In these the cast-iron wheel is made to turn slowly, whereas the emery-wheel revolves very rapidly. The emery-wheel is then brought close to the cast-iron wheel, so that as they revolve the projections on the latter are cut away, and the tread is thus reduced to a true circular form. These machines are much used for "truing-up" wheels which have been made flat by sliding, owing to the brakes being set too hard.
It would require a separate article to give even a brief description of the different kinds of cars which are now used. The following list could be increased considerably if all the different varieties were included.
Baggage-car,
Boarding-car,
Box-car,
Buffet-car,
Caboose or
conductor's car,
Cattle- or stock-car,
Coal-car,
Derrick-car,
Drawing-room car,
Drop-bottom car,
Dump-car,
Express-car,
Flat or platform car,
Gondola-car,
Hand-car,
Hay-car,
Hopper-bottom car,
Horse-car,
Hotel-car,
Inspection-car,
Lodging-car,
Mail-car,
Milk-car,
Oil-car,
Ore-car,
Palace-car,
Passenger-car,
Post-office car,
Push-car,
Postal-car,
Refrigerator-car,
Restaurant-car,
Sleeping-car,
Sweeping-car,
Tank-car,
Tip-car,
Tool or wrecking car,
Three-wheeled
hand-car.
The following table gives the size, weight, and price of cars at the present time. The length given is the length over the bodies not including the platforms.
| Length, feet. | Weight, lbs. | Price. | |
| Flat-car | 34 | 16,000 to 19,000 | $380 |
| Box-car | 34 | 22,000 to 27,000 | $550 |
| Refrigerator-car | 30 to 34 | 28,000 to 34,000 | $800 to $1,100 |
| Passenger-car | 50 to 52 | 45,000 to 60,000 | $4,400 to $5,000 |
| Drawing-room car | 50 to 65 | 70,000 to 80,000 | $10,000 to $20,000 |
| Sleeping-car | 50 to 70 | 60,000 to 90,000 | $12,000 to $20,000 |
| Street-car | 16 | 5,000 to 6,000 | $800 to $1,200 |
