(Material courtesy of A.N.T.A. publications, edited html extracts Ranger Hope © 2008,)
Cable and Mechanical Steering
A basic tension cable steering system is shown in Figure 59. Different cable arrangements are common.
Cable steering for modern outboards usually use a semi-rigid push-pull cable inside a sheath.
A gear arrangement (similar to that shown in Figure 61) converts the rotary action of the ship’s wheel to the push-pull action on the cable.
Mechanical steering arrangements may use rigid rod and lever mechanisms, in place of cables.
Direct (Hand-Operated) Hydraulic System
Direct Hydraulic Steering
Force, leverage, and movement of the direct system can be altered by changing the sizes of rams, gears, ratios, and linkages
In this arrangement, the movement of the wheel is transmitted to the rudder stock by the flow of fluid through hydraulic lines.
Explanation of the Direct System
The manual effort used to move the wheel, produces the hydraulic pressure needed to move the cylinder driving the rudder shaft.
A more detailed explanation of this system is shown in Figure 61.
Power Assisted System
A power-assisted system (similar to that used with road transport) can be used with marine steering (see Figure 62).
Power Assisted Steering
The power assist pump is controlled by signals through the control line from the manual system.
Hydraulic pressure assists the operator. If the power assist should fail, manual steering is maintained, but extra effort is needed.
Clearance is needed all round the rams for the sweep of the tiller, and for the resulting sweep of the ram.
Single Ram Arrangement
Ram linkages must provide sufficient flexibility to allow for this movement.
Dual cylinder installations may be used to increase the steering torque on the rudder.
Dual Cylinder Arrangement for Extra Thrust
Dual cylinder arrangement to cancel side force on rudder post
On most installations, a large hydraulic side-force can be exerted on the rudder-post, especially at the extremes of the rudder stroke (see Figure 63).
This side-force can be cancelled using two double-acting rams - one pushing, the other pulling, both from the same side (see Figure 65) .
A typical hydraulic system may have the following components:
A Tank or Reservoir to hold a reserve of oil. The reservoir also helps in cooling, and settling and filtering out contaminants
A Pump supplies oil flow to the actuators
Relief Valves or Regulators to reduce the pump pressure to a safe level
Stainless or Synthetic Gauze Mesh Filters remove larger contaminants from the oil. A ‘filter condition indicator’ may be provided to give an indication of the state of the filter
Direction Valves to control the fluid path.
cause an action.
They may consist of two parts; a transmitter (pump) and a receiver (ram). Actuators may
- Linear Actuators (rams) which move things in a straight line.
- Rotary Actuators which rotate things
- Semi-Rotary Actuators