The efficiency and safety of navigation on a small vessel are directly dependent on the serviceability of the outboard motor. boat-engineIt's this system that allows the wearer to change the angle of inclination of the lower unit relative to the transom, which is critical when going into planing, driving through shallow water or mooring on shore, and understanding the principles of operation of this unit helps to avoid costly repairs and extend the life of the entire unit.
In modern models, whether they are powerful four-stroke giants or lightweight two-strokes, the design may differ, but the essence remains the same. Hydraulic cylinder Or mechanical stress takes on the enormous loads that come with impacts on underwater obstacles, and ignoring the state of the rod, seals or fasteners often leads to spontaneous lowering of the motor or, conversely, to jamming in the upper position, let's take a detailed look at how this system works and what to look for in service.
Principle of operation and purpose of the system
The main function of the lifting system is to change differential By adjusting the tilt of the engine, the boatmaster optimizes the driving performance of the vessel. When the lower unit is properly positioned, the boat moves faster, reduces fuel consumption and reduces the risk of cavitation. The mechanism allows the propeller to be raised above water level, which is necessary for the passage of shallow areas or storage of the vessel.
The structurally complex system is a complex unit that combines the power element and the control system. hydraulicThe pump creates pressure that is transferred to the piston inside the cylinder, causing the rod to extend and lift the motor. The upper position is often fixed by mechanical stops or water locks.
⚠️ Warning: Operation of the engine with a faulty lifting mechanism can lead to a sharp change in the trim at high speed, which is fraught with the overturning of the boat or the ejection of the passenger overboard.
It is important to understand the difference between the system tilt (rise/lower) and trim The first is used primarily in parking or low speed to overcome obstacles, the second is used to adjust the course during movement. Although actuators are often combined, the control circuits may differ in pressure settings and response speed.
Design features of hydraulics
The heart of the system is a hydraulic pump, which is driven by a DC motor. When you signal from the control panel, the pump starts pumping fluid from the tank into the cylinder. The pressure in the system can reach significant values, which requires high strength of all connections. Hydraulic fluid It performs not only a transmitting function, but also lubricates rubbing vapors, preventing corrosion of internal surfaces.
The safety key is the return valve, which holds the liquid in the cylinder when the pump is off, preventing the motor from going down under its own weight, and if the valve is contaminated or worn, there is a creeping-down effect of the lower unit. pass-valve, which releases excess pressure, protecting hoses and seals from rupture when reaching the maximum angle of lift.
Technical nuances of hydraulic fluid
Use only specific liquids recommended by the manufacturer (usually ATF or special hydraulic oils). Mixing different types of liquids can cause the rubber seals to swell and the system to lose leakage.
The liquid tank is often designed as an expansion tank, integrated into the pump body or located separately, the level of liquid in it should always be within acceptable limits. Falling below the minimum level will lead to air entering the system, which will cause suffocation and loss of lifting efficiency. The air in the hydraulics is compressed, unlike the liquid, so the rod will move in jerks.
Mechanical components and fastenings
In addition to hydraulics, mechanical elements play an important role. brackets The bolting loads are constantly being applied to the cylinder, the bolting rods are weakened, the rods can be distorted and the cuffs wear out quickly, and regular checks of the tightening moment of the bolts are a mandatory maintenance procedure.
The hinged joints of the rod with the lower unit and the transom plate must be free-flowing, but without backlashes. lithium-greaseLack of lubrication leads to creaking, jamming and corrosion of the fingers of the hinges, which can eventually block the mechanism.
When lubricating the hinge joints of the lifting mechanism, use a syringe oil to supply the lubricant under pressure to displace water and dirt from the gaps.
Many models have a mechanical lift stopper, a metal pin or bar that physically limits the angle of deflection of the motor backwards, and its function is to prevent the motor from tipping too far, which could damage the hydraulic cylinder or lead to water intake through the exhaust hole at start-up. Adjustment or replacement of the stopper is rarely required, but its integrity needs to be checked.
Typical malfunctions and diagnosis
The most common problem is leakage of hydraulic fluid, which can be oily spots on the surface of the cylinder or around the pump. If you notice a drop in the level in the tank, you should immediately examine all the connections. Leakage is often caused by wear and tear. sludge Or damage to high-pressure hoses, and ignoring the problem will cause the system to fail completely.
The second common malfunction is the failure of the pump motor, which can be due to oxidation of the contacts, moisture entering the electrical part, or wear of the engine brushes. If you press the lift button you hear a click of the relay, but the motor is not humming, the problem is most likely electrical. If the motor is humming but the rod is not moving, perhaps a jam pump or a critically low fluid level.
There's also the problem of spontaneously lowering the motor in an elevated state, which is a direct sign of malfunction. hydraulic valve In some cases, the cause is deformation of the cylinder rod, which leads to loose fit of seals, diagnostics requires removal of the cylinder and defective internal surfaces.
Procedure for maintenance and replacement of liquid
To keep the machine running, you need to change the hydraulic fluid periodically, and the process starts by lowering the motor to the bottom position so that the rod is completely drained into the cylinder. Then the tank plug is unscrewed, and the old liquid is drained. It is recommended that you pump the system several times, pressing the up and down button to remove the remnants of the old oil from hard-to-reach places.
After the old liquid is drained, the system is filled with new fluid, so it's important to avoid getting dust and dirt inside the tank. MAXAfter that, you need to perform the procedure of removing air: several times fully raise and lower the engine. If the rod moves smoothly and without jerking, and the fluid level does not fall, the service can be considered complete.
☑️ Checklist of maintenance of the lifting mechanism
Special attention should be paid to the purity of the rod hydraulic cylinder. Every time the engine rises, the rod leaves the cylinder and is exposed to salt water and dirt. Before lowering the rod must be wiped with rags. The accumulation of abrasive particles on the chrome surface of the rod when retracted inward acts like sandpaper, destroying the cuffs and the cylinder mirror.
Table of parameters and specifications
To better understand the differences in lifting systems between different engine classes, a comparative table of basic specifications can vary depending on the model and year of production.
| Parameter | Low-power engines (up to 15 hp) | Middle class (15-90 hp) | Powerful motors (100+ hp) |
|---|---|---|---|
| Type of drive | manual or simple electric | Hydraulic (PTT) | Hydraulic reinforced |
| System pressure. | Low (up to 50 bar) | Average (50-100 bar) | High (100+ bar) |
| Time for full lift | 10-15 seconds | 5-8 seconds | 3-5 seconds |
| The presence of a trim regulator | Often absent | Optionally. | Standard |
As can be seen from the table, with the increase in engine power, the requirements for reliability and speed of the mechanism grow exponentially. Hydraulic systems High-powered motors operate at significantly higher pressures, requiring better materials and seals, and maintenance errors are more expensive than those on small motors.
The selection of spare parts must be strictly in accordance with the catalog number, the use of analogues of questionable quality can lead to rapid failure of the entire unit, especially rubber products and electrical components of the pump.
Extension advice
To keep the lifting mechanism of the outboard motor lasting, it is important to follow simple rules of operation. After each trip in salt water, the mechanism must be washed with fresh water. The salt, drying, crializes and corrodes the metal, and also accelerates the wear of moving parts. Pay special attention to the area of the rod exiting the cylinder.
Regular fresh water washing and grease of the rod are the most effective ways to prevent corrosion and jamming of the lifting mechanism.
Frequent up and down cycles should not be abused unnecessarily. A hydraulic pump is not designed to operate continuously in start-stop mode. Prolonged hold of a button after reaching the extreme position is also harmful: although valves relieve pressure, the pump continues to operate in overload mode, which reduces the life of its brushes and bearings.
When storing the boat in the off-season, it is recommended to lubricate the hydraulic cylinder rod with conservation grease and set the mechanism in motion several times to distribute fresh liquid throughout the system, which will prevent cuffs from sticking to the cylinder mirror during idle time.
What to do if the motor stops moving?
First of all, check the electrical connections: battery terminals, circuit fuse and contacts at the pump itself. If the electrician is fine, check the hydraulic fluid level. If the level is normal, there may have been an air shutter or valve failure, in which case a professional hydraulic cylinder defect is required.
Can I use the engine if the lifting mechanism is not working?
You can operate the boat, but there are limitations. You can't lift the screw above the water when you moor or pass shallow water. You can't adjust the trim for optimal running. However, if the motor is securely fixed in the operating position and has no backlashes, you can move. Be sure to carry a spare transom stop or wedges to fix the lower unit by hand.
How often should I change the hydraulic fluid?
Manufacturers recommend changing the liquid every 3 years or 300 hours, but with intensive operation in an aggressive environment (salt water, dust), the interval is better to reduce to 1-2 years.