The weighing device consists of a set of standard Olsen levers for weighing one-eightieth of the total load on the main cylinder. This reduction is effected through the medium of a piston and a diaphragm. The main cylinder has a diameter of 50 in., and the smaller one, a diameter of 5 9/16 in. The weighing beam is balanced by an automatically-operated poise weight, and is provided with a device for applying successive counterweights of 1,000,000 lb. each. Each division on the dial is equivalent to a 100-lb. load, and smaller subdivisions are made possible by an additional needle-beam.
The power is applied by a 15-h.p., 220-volt, variable-speed motor operating a triple-plunger pump, the gearing operating the upper head being driven by the same motor. The extreme length of the main screws necessitates splicing, which is accomplished as follows:
In the center of the screws, at the splice, is a 3-in. threaded pin for centering the upper and lower screws; this splice is strengthened by sleeve nuts, split to facilitate their removal whenever it is necessary to lower the upper head; after the head has passed the splice, the sleeve nuts are replaced.
In order to maintain a constant load, a needle-valve has been provided, which, when the pump is operated at its lowest speed, will allow a sufficient quantity of oil to flow into the main cylinder to equalize whatever leakage there may be. The main cylinder has a vertical movement of 24 in. The speed of the machine, for the purpose of adjustment, using the gearing attached to the upper head, is 10 in. per
min. The speed for applying loads, controlled by the variable-speed motor driving the pump, varies from a minimum of at least 1/60 in. per min. to a maximum of at least ½ in. per min. The machine has a guaranteed accuracy of at least one-third of 1%, for any load of more than 100,000 lb., up to its capacity.
The castings for the base and the top head weigh approximately 48,000 lb. each. Each main screw weighs more than 40,000 lb., the lower platform weighing about 25,000 lb., and the main cylinder, 16,000 lb. The top of the machine will be about 70 ft. above the top
of the floor, and the concrete foundation, upon which it rests, is about 8 ft. below the floor line.
Concrete and Cement Investigations.—The investigations relating to concrete include the examination of the deposits of sand, gravel, stone, etc., in the field, the collection of representative samples, and the shipment of these samples to the laboratory for analysis and test. These tests are conducted in connection with the investigation of cement mortars, made from a typical Portland cement prepared by thoroughly mixing a number of brands, each of which must meet the following requirements:
Specific gravity, not less than 3.10;