FIRST SPEED, When the accelerator pedal is
SUMMARY
depressed to the first speed contact MS-1 closes,
You should now know about the major deck
the direction handle is placed in the forward
equipment that is installed for winching operations,
position, the F contactor picks up, and the drive
anchoring the ship, elevator operations, and
motor is energized.
replenishment at sea. If you do not understand the
sequence of operation of this equipment, before
SECOND SPEED. The pedal is depressed to the
continuing on, review these sections. Extensive
second speed point to close contact MS-2, a
step-by-step operational methods were described, and it
positive voltage appears at TDR-1, SS-1 anode,
is essential that you know how to operate, troubleshoot,
and TDR-2 on the static timer. The positive
and repair this equipment properly. Having learned this
voltage appears at these points because of the
information thoroughly, you should be able to maintain
low-resistance path through the 1A coil. The very
the equipment in a reliable condition.
small currents needed to operate the time-delay
circuitry is about 1/100 of that needed to operate
ELECTROHYDRAULIC
the coil; therefore, only a small voltage is
STEERING GEAR
dropped across the coil. Now TDR-1 cannot
operate until a positive voltage also appears from
Ships have been in use almost as long as man has
either ARB or the plug. A positive voltage could
been actively exploring the earth and defending his
only come from ARB when the brake pedal is
territory. In that time, ship's steering has evolved from
depressed. However, a small positive voltage
a simple rudder of wood attached to the stem of the ship
comes through the plugging section due to the
to today's modern electrohydraulic systems.
voltage developed across the armature of the
The modern or industrial era saw steering systems
drive motor. Now TDR-1 does operate, fires
evolve in definite stages from steam driven to
SS-1, and picks up 1A coil, which provides the
electromechanical and finally the electrohydraulic
second speed.
systems of today. Electrohydraulic steering gear was
THIRD SPEED. The pedal is depressed to the
developed to meet the power requirements of naval
third speed point to close MS-3, and a positive
vessels having large displacements and high speeds with
voltage appears at TDR-2 and SS-2. Since 1A has
attendant increase in rudder torques.
already picked up, a negative voltage is at the top
The steering gear is one of the most vital auxiliaries
input to TDR-2; and after a time delay, SS-2
aboard ship. It must be dependable and have sufficient
operates and 2A coil picks up, which provides the
capacity for maximum maneuverability. The ship
third speed. Now the 2A interlock leading to
steering control system for the modem ships is an
contact MS-4 closes, providing a positive voltage
integrated group of electrical, mechanical, and
to the left of contact MS-4 to ready the control of
hydraulic subsystems, equipment, and components
the fourth speed.
interconnected to provide rapid and flexible control of
FOURTH SPEED. The pedal is depressed to the
the ship's course and maneuverability under all
conditions of ship readiness. The ship is equipped with
fourth speed point to close contact MS-4 and to
two separate steering gear systems--one for each
open contact MS-2, which de-energizes relay
rudder. The steering control system coordinates
1A. In a manner similar to the previous steps, the
operation of the steering gear system as rudder
auxiliary static timer gives a time delay to the
commands constantly vary.
pickup of 4A. After 4A energizes, both normally
open 4A interlock contacts close. One shorts out
The ship steering control system provides steering
the auxiliary static timer and turns it off. The
control from a fixed station in the pilot house, from
other interlock lets coil 3A pick up to shunt the
either bridge wing using portable steering equipment, or
field. However, relay 1A has opened; therefore,
from the aft emergency steering station in the steering
afield is still present. The 4A coil picks up before
gear room.
the 3A coil so that any arc that might be present
CONSTRUCTION
when the normally closed 4A contacts open will
The movement of the two rudders is controlled by
be extinguished before 3A coil picks up.
two mechanically independent steering gears located in
Otherwise, a direct short may occur. This
the steering gear room (fig. 5-39). Each steering gear is
provides the fourth speed.
5-58
