TM 5-850-1
tween steel plate and rubber; and high initial cost for
two major types, rubber-in-compression and rubber-
general cargo berths.
inshear.
(3) Lord flexible fender. This system (fig 9-
(1) Rubber-in-compression.
This fender
consists of a series of rubber cylindrical or rectangular
between two end steel plates. It can be installed on
tubes installed behind standard fender piles or behind
open or bulkhead-type piers, dolphins, or incorporated
hungtype fenders. The tubes may be compressed in
with standard pile or hung fender systems. Impact
axial or radial directions. Typical arrangements of
energy is absorbed by bending (buckling) the
rubber fenders in radial compression are shown in
compression of the arch-shaped column. When an
impact force is applied, it builds up a relatively high load
compression of the rubber.
Absorption capacity
with small deflection, buckles at still smaller deflections,
depends on the size of the buffer and on maximum
and maintains a virtually constant load over the range of
deflection.
Loaddeflection and energy-absorption
buckling deflection (fig. 9-13).
characteristics of various rubber fenders are illustrated
(a) Advantages. The advantages are
in figures 9-7, 9-8, and 9-9. In design, a proper bearing
timberframe is required for transmission impact force
high
energy-absorption
and
low
terminal-load
from ship to pier. Draped rubber tubes hanging from
characteristics.
(b) Disadvantages. The disadvantages
solid wharf bulkheads may be used as a rubber-in-
compression system. The energy-absorption capacity of
include possible destruction of bond between steel
such a system can be varied by using the tubes in single
plates and rubber plus possible fatigue problems.
(4) Rubber-in-torsion fender. This fender is a
or double layers, or by varying tube size. The energy
absorption of a cylindrical tube is nearly directly
rubber and steel combination fabricated in cone-shaped,
proportional to the ship's force until the deflection equals
compact bumper form, molded into a specially cast steel
approximately one-half the external diameter. After
frame, and bonded to the steel. It absorbs energy by
that, the force increases much more rapidly than the
torsion, compression, shear, and tension, but most
absorption of energy. Consequently, a large enough
energy is absorbed by compression (fig 9-14).
(a) Advantage. The advantage is being
fender should be used so that the energy of the berthing
ship will be absorbed without requiring a deflection of
capable of resisting the impact load from all directions.
(b) Disadvantages. The disadvantages
such magnitude that it results in a disproportionate
increase in force.
are possible destruction of the bond between steel
(a) Advantages.
The advantages
casting and rubber and possible fatigue problems.
(5) Pneumatic fender. Pneumatic fenders are
include simplicity and adaptability plus effectiveness at
reasonable cost.
pressurized, airtight rubber devices designed to absorb
(b) Disadvantages. The disadvantages
impact energy by the compression of air inside a rubber
are: high concentrated loading may result; frictional
envelope. Table 9-1 lists pneumatic-fenders that have
force may be developed if rubber fenders contact ship
been used by the US Armed Forces. These pneumatic
hull directly; and initial cost is higher than standard pile
fenders are not applicable to fixed dock-fender systems
system without resilient units.
but are feasible for use as ship fenders or shock
(2) Rubber-in-shear. This consists of a series
absorbers on floating fender systems. A proven fender
of rubber pads bonded between steel plates to form a
of this type is the pneumatic tire-wheel fender, which
series of rubber sandwiches mounted firmly as buffers
consists of pneumatic tires and wheels capable of
between a pile-fender system and a pier. Two types of
rotating freely around a fixed or floating axis. The fixed
mounting units are available: the standard unit (fig. 9-
unit is designed for incorporation in concrete bulkheads.
The floating unit may consist of two to five tires.
100 percent more energy. Load-deflection and energy-
Energy-absorption capacity and resistance load depend
absorption characteristics of Raykin rubber-inshear
on the size and number of tires used and on the initial
buffers are shown in figure 9-11.
air pressure when inflated. Load-deflection and energy-
(a) Advantages.
The advantages
absorption characteristics are shown in table 9-2. The
include: capability of cushioning berthing impact from
Yokohama pneumatic rubber fender, which utilizes the
lateral, longitudinal, and vertical directions; most
compression elasticity of air, is shown in figures 9-15, 9-
suitable for dock-corner protection; high energy-
absorption capacity for serving large ships of relatively
layer, a reinforcement synthetic cord layer, and an
uniform size; and favorable initial cost for very heavy
interior rubber layer. To facilitate handling, the fender is
duty piers.
slung in a wire rope net. The internal working pressure
(b) Disadvantages. The disadvantages
of these units is 7 pounds per square inch.
(a) Advantages. The advantages are
are: Raykin buffers are too stiff for small vessels and
for moored ships subject to wave and surge action; steel
that this fender is suitable for both berthed and moored
plates subject to corrosion; problem with bond be-
ships
9-2
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