...Railway artillery - Personal Page of GENE SLOVER

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axles, and the ratio of gearing is from 100 to 132 turns of the handle
to one revolution of the wheel. The mount can be moved at the
rate of from 3 to 5 feet per minute. With the mounts hadng rolling
recoil, the length of recoil is considerably greater and a gasolinedriven
winch, mounted on the front truck or span bolster and taking
up a cable fastened to the track ahead, is preferred for returning
the mount to its firing position. For this sort of movement, experience
has shown that the rolling friction is much greater than is
ordinarily assumed for railway work. The traotive effort on 8. level
track with the American 16-inch howitzer ran up to 50 pounds per
ton. On the heaviest sliding mounts electrical translating mechanism
is provided. This is very convenient, of course, but requires a
power plant and complicates the design and accessory equipment.
Manpower is always available and is reliable. Electrical equipment
has the bad habit of failing when it is needed most.
413. ELEVATING MECHANISM.-Elevating mechanisms are so
diverse in type, and the speed of operation of the piece is so largely
dependent on them that a somewhat lengthy consideration is felt
to be justified. First the requirements of the mechanism will be
discussed, and then their practical embodiment will be described.
414. The requirements of an elevating mechanism are that it
shall:
(a) Afford proper extent of elevation.
(b) Give proper ratio of handwheel to gun movement.
(c) Be sufficiently strong to withstand shocks of fire.
(d) Be efficient enough to allow operation at the required
speed with the power available.
(8) Be.simple in construction and easily maintained.
415. In regard to extent of elevation, (a) above, ideas have been
modified considerably by the experience of the European War. For
howitzers, a maximum. elevation of 65 degrees is required to give
the desired plunging fire. For guns there may be objectives at long
ranges of such size that the high dispersion incident to fire at maximum
range is not disadvantageous. Therefore the mount should
always allow sufficient elevation for the gun to attain this maximum
range. . For medium caliber guns at medium velocities, this app'roximates
the theoretical 45 degrees. For large guns and high muzzle
velocities, however, the decreased air resistance at high altitudes
so far increases the range that the maximum appears to be attained
at from 50 to 55 degrees. The long range 21O-millimeter German
gun which operated at a muzzle velooity of 1,500-1,600 meters per
second, was fired at an angle of at least 55 degrees. The French
220-millimeter gun will be mounted' with provision for an elevation
of 55 degrees.
Digitized by Coogle