Hydraulic Steering Gear
Hydraulic steering gear takes hydraulic oil as the working medium, which can make the ship turn the rudder and keep the rudder position. According to the power source of different ways, can be divided into manual, electric, electric hydraulic steering gear. The electro-hydraulic steering gear is reliable, easy to operate, lightweight and durable, economical and convenient to maintain and manage, so it is an ideal steering device for ships.
Large ships almost all use hydraulic steering gear. The electric steering gear is only used on some small ships. Hydraulic steering gear uses the incompressibility of liquid and the controllability of flow and flows directly to achieve the purpose of steering. Rotary vane hydraulic steering gear is a new type of hydraulic steering gear. Compared with other types of steering gear, it has a series of advantages such as small size, lightweight, simple structure, easy manufacturing, convenient maintenance and so on.
The hydraulic steering gear is to uses liquid pressure energy and flow, flow controllability to achieve the purpose of steering. Hydraulic steering gear can be divided into pump control and valve control according to the different pressure elements used in the hydraulic oil flow direction changing method.
Analysis of common faults of hydraulic steering gear
1.The steering gear won’t turn
(1) The remote control system fails and the machine side operation is normal.
For the electrical remote control system, it may be the circuit breaker (fuse burned, contact is welding or poor contact, electrical component damage, etc.), it may also be the mechanical transmission part of the fault (such as guide rod jammed or should be inserted into the bolt is not inserted, etc.). If the control system has a servo-hydraulic cylinder, it may also be the control oil source interruption (auxiliary pump damage, the oil level is too low), the servo-hydraulic cylinder bypass valve is not closed, relief valve opening pressure is too low, or reversing valve can not leave the median.
(2) The main pump can not supply oil.
The fault symptom is that the steering gear cannot rotate. Whether the main pump cannot supply oil causes the steering gear cannot to rotate, which can be verified by changing the spare piano.
If the variable mechanism of the pump is stuck and the two main pumps share a floating lever mechanism, the variable mechanism of the faulty pump must be disengaged before the standby hydraulic pump can be replaced.
If the hydraulic pump unit can not start, it should be found out whether there is a circuit fault. At this time, it should be noted that some devices have chain protection – the main pump can not start before the auxiliary pump is not started, and the method of turning can be used to determine whether the hydraulic pump has mechanical resistance.
If the hydraulic pump can operate but almost no oil pressure, in the exclusion of the main oil roadside pass or leakage possibility, that is, the main pump does not supply oil, on the valve controlled open steering gear hydraulic system, can first check whether the circulating oil tank is short of oil, or suction pipe is blocked; For the pump-controlled steering gear, the variable mechanism of the pump should be checked whether the normal operation can be performed by the method of machine side operation. If the variable mechanism is stuck, the differential piston control oil is interrupted or the oil circuit is blocked, the floating lever mechanism pin is broken or the energy storage spring is too soft, then the beside operation can not make the hydraulic pump leave the middle position. If necessary, the variable mechanism of the pump or the pump itself can be dismantled to identify the damage to the working parts.
(3) Main oil roadside through or serious leakage.
Symptom Suction and discharge oil pressure of the main pump is similar (equivalent to a working pressure of auxiliary pump). The main oil roadside pass is caused by the standby pump locking loosely (reverse), bypass valve opening, safety valve opening pressure is too low or pad up, the valve control system may also be caused by the failure of the reversing valve can not leave the median.
(4) Main oil circuit is blocked or rudder rotation is blocked.
Fault symptoms main pump discharge high oil pressure, noise, safety valve open. The biggest reason for the main oil route blockage may be that the pump valve and cylinder valve are not opened or the liquid control lock valve of the main oil route cannot be opened.
2. Only turn the rudder in one direction
(1) Remote control steering can only be one-way steering, manual steering beside the machine is normal. The reason may be electrical remote control circuit fault (such as solenoid valve coil break) or control with servo-hydraulic cylinder side serious leakage caused.
(2) Variable pump can only one-way oil discharge. The reason may be that the one-way operation of the variable pump mechanism is difficult, such as a one-way jam or blockage of the differential piston control oil hole.
(3) The main oil circuit is blocked or bypassed in one direction. The reason may be that the opening pressure of the relief valve on one side is too low, or one of the main oil lock valves cannot open during oil return.
3.Abnormal noise and vibration of steering gear
(1) Liquid noise. The system produces cavitation, the closed system is not completely deflated or oil supply is insufficient; It may also be that the oil level in the tank is too low, the oil suction filter is blocked or the suction pipe leaks; In addition, when the oil temperature is too low and the oil Hertz is too large, liquid noise may also occur.
(2) Abnormal noise of hydraulic pump unit. It may be that the pump and motor are not aligned properly, or that bearings or other moving parts in the pump are damaged.
(3) Pipes or other components are not firmly fixed.
(4) The plunger packing of the steering hydraulic cylinder is too tight.
(5) Some forms of main oil circuit lock valve are easy to produce knock when the rudder rotates faster under the action of negative torque.
(6) Rudder column bearing wear or poor lubrication.
(7) The bearing of the rudder is damaged by external forces and deformed.
(8) The rudder is inaccurate, that is, the error between the actual rudder Angle and the command rudder Angle exceeds ± 1O when the rudder is stopped, then the steering gear should be readjusted.
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