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.

[Illustration: Fig. 4.

PLAN AND ELEVATION OF 10,000,000-LB. VERTICAL COMPRESSION
TESTING MACHINE]

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.