TRUCKS MADE OF CONCRETE.

Digger (Invercargill RSA), Issue 39, 10 December 1920, Page 15

TRUCKS MADE OF CONCRETE.

The heginning of- practical plans for the manufacture of reinforced concreke freight cars dates from 1909, when . a patent for such a car was granted to Joseph B. Strauss, of Chicago. On account of the war, construction of a trial car was delayed ; and it was but recently that the first car, of the gondola type, was completed by a Chicago company and tested under service conditions. Not only in the material used, hut in i'ts design and the details of construction, it represents an interesting departui-e from usual methods. The basic feature of the design, the "Scientific American" • explains, is a steel skeleton body forming the outer boundary of the car, and mounted upon a steel underframe. The concrete walls and fioor are contained within this frame, and, together with the frame and floor reinforcement, are connected to and interlocked with the underframe. The steel frame forms the finishing and pi'otective edges, thus entirely shielding the concrete, and also serving as a complete system of stress-bearing members. In the construction of the test car the "cement gun" was used. The forms were placed on the outside of the car, and the cement was shot against them from within. The outside of the car, that is the surface against the forms, was given a smooth. finish, but the interior was left much- as it came from the gun. Tests of the completed car, both empty and loaded, demonstrated its practicability for rough service. In the test without load it withstood extremely rough handling in switching, and came thiough without injury. Subsequently the car was loaded with 55 tons (10 per cent. overload) of sand and turned over to a switching crew for service handling. It withstood this test also without injury. Otiier merits are claimed for the concrete . car. It will not need painting, and will practically eliminate maintenance charges. Its life will be much longer than that of the wooden" car.