The main operating element that physically changes its position for unloading is cargo-platform (body) moved by a hydraulic drive. When activating the control system hydrocylinder telescopic type creates a force pushing the body upwards around the axis of rotation located at the rear of the frame or on the subframe. This is the nucleus often called tipperIt provides fast unloading of bulk cargo under the influence of gravity without the participation of people or additional equipment.
The lifting process begins with the opening of the shut-off organ hydrodistributorAfter which the working fluid under high pressure enters the cylinder cavity. hydraulic cylinder rod connected to the bottom of the body through finger-point Or the eye, it starts to move, causing the platform to rotate. The angle of lifting can vary from 45 to 60 degrees depending on the design of the articulated frame and the type of side.
It is important to understand that rollover is not just a slope, but a strictly regulated mechanical process that depends on serviceability. hydraulics. Any oil leak, pump suffocation or wear of the rod seals can cause the body to not rise or fall spontaneously, creating an emergency situation. Therefore, knowledge of the structure of this node is critical for operators and mechanics.
Dump truck design and types of bodies
The cargo platform, which is subject to rollover, is made of high-strength steel and has a reinforced bottom. The design of the body directly affects the center of gravity of the car and the efficiency of unloading. There are several main types of bodies, each of which has its own characteristics in the mechanism of lifting and fastening to the frame.
- 🚛 Bucket-type: has the shape of a bucket, which contributes to a better rash of viscous cargo, but is more difficult to manufacture.
- 📦 Rectangular (boxed): the most common form, easy to manufacture, but requiring a greater lifting angle for full unloading.
- 🔄 Round-section: used for transporting bulk materials, does not require a large angle of inclination for rash.
The body is attached to the frame is carried out through pivot Or special brackets with fingers. Some models, especially articulated dump trucks, use a “swing frame” system where the entire front part is overturned relative to the joint. The reliability of these connections is checked at each maintenance, as vibrations when driving off-road can lead to weakening of the fastener.
⚠️ Attention: Operation of the dump truck with cracks in the body spars or worn mounting bushes is prohibited, as this can lead to the destruction of the structure at the time of lifting.
The choice of body type depends on the specifics of the cargo being transported. For rock, reinforced versions with additional protection of the bottom are used, while for coal or sand, standard solutions are suitable. The rollover mechanism shall be designed for maximum loading, taking into account the safety factor.
The principle of operation of the hydraulic lifting system
The heart of the system that provides rollover is hydraulic actuator. It consists of a pump, a hydraulic distributor, a hydraulic cylinder and a tank for the working fluid. A pump powered from the car’s engine through a power take-off box (COM) creates the necessary pressure in the system.
The process is controlled by the driver through a pneumatic or electrical switch that acts on the driver. spreader. When switching to the "Rise" position, the oil is directed into the piston cavity of the cylinder, causing the rod to extend. If it is necessary to hold the platform in an elevated state, the spool covers the drain of the liquid, fixing the rod.
Hydraulics scheme
The hydraulic pump creates pressure -> Oil through the distributor enters the cylinder -> Stock is pushed out and raises the body -> When lowering the oil by gravity or under pressure returns to the tank.
The lift speed depends on the pump performance and cylinder diameter. Modern systems can be equipped with a “smooth lowering” function, which prevents a sharp impact of the body on the frame at the end of the unloading cycle. This is achieved by throttling the flow of oil on the plum.
- 💧 hydropump: gear or axial piston, provides fluid flow.
- ⚙️ Distributor: directs oil flows to the desired cavities of the cylinder.
- 🛢️ Hydrocylinder: converts the energy of the pressure of the liquid into mechanical motion.
The efficiency of the entire system depends on the quality of the hydraulic oil and its temperature. In the cold season, preliminary heating of the liquid is required, since high viscosity can lead to a failure of the pump or damage to seals.
Typical failures of the rollover mechanism
In the process of operation, the mechanism that overturns at the dump truck is subjected to significant loads, which leads to wear and breakage. One of the most frequent problems is lift-outwhen the body is either not raised at all, or rises very slowly even at high engine speeds.
The cause may be wear of the cuff seals of the hydraulic cylinder piston, which leads to internal oil leaks. Also often goes out of order. pressure-restriction-valve (a safety valve) that does not hold the desired pressure in the system. Visually, the malfunction can manifest itself in the form of jerks when lifting or spontaneously lowering the platform.
Another common problem is the distortion of the body during lifting. This occurs when one of the cylinders fails (in two-cylinder circuits) or when it is destroyed. hub-sleeves. Operation of the dump truck with distortion is strictly prohibited, as this can lead to the car tipping over on its side.
| Malfunction | Probable cause | Elimination method |
|---|---|---|
| Body doesn't go up. | Low oil, pump breakdown | Oiling, pumping. |
| Self-incline | Wear of distribution seals | Repair or replacement of the distributor |
| Pulls on lift | Stifling the system | Hydrosystem pumping |
| Platform distortion | Different speed of cylinder extension | Defection of cylinders and spools |
Diagnosis should begin with a visual inspection for leaks and check the level of oil in the tank. The pressure in the system shall then be checked by means of a pressure gauge installed at the control points. This allows you to localize the faulty node: pump, distributor or actuator.
Procedure for safe operation and unloading
To ensure the durability of the unit that overturns, and the safety of others, it is necessary to strictly observe the unloading regulations. Before the start of the lifting of the body, the car must be installed on flat-side. The tips of the ground or the presence of roll can shift the center of gravity and lead to an accident.
The driver must ensure that there are no power lines or other obstacles above the unloading place. Lifting the body should be done only with the engine running at medium speeds to ensure stable operation of the hydraulic pump. A sharp increase in speed can cause a hydrostroke.
☑️ Checking before lifting
After unloading, you must wait for the body to be completely lowered to the point on the frame. Movement with the body raised or not fully lowered is prohibited, as this can lead to contact with the power line or damage to the locking mechanism. The fixers ("dogs") must be securely snapped before starting the movement.
⚠️ Attention: It is strictly forbidden to be under a raised body without installing special stops (insurance racks), even if the hydraulic system is serviceable.
Compliance with these simple rules avoids most emergencies and prolongs the life of expensive equipment. Regular lubrication of hinge joints is also a mandatory procedure.
Diagnostics and maintenance
Regular maintenance of the rollover mechanism includes checking the tightness of the joints, the condition of the hoses and the level of the working fluid. Special attention should be paid hydraulic-cylinder-rods: their working surface must not be bullied, corrosion or sticky dirt that may damage the osteoils.
Hydraulic oil is replaced according to the manufacturer’s regulations, usually every 1-2 years or after a certain number of hours. Old oil loses its properties, wear products and water accumulate in it, which leads to corrosion of internal surfaces and jamming of spools.
Use only those brands of hydraulic oil that are recommended by the manufacturer. Mixing oils of different types can lead to the formation of sediment and failure of the system.
The diagnosis is also checked by the work quick-downIf it is provided by the design. It must operate clearly and ensure a quick but controlled fit of the body. Any extraneous noise during the operation of the hydraulics (hum, whistle) is a signal for immediate cessation of work and diagnostics.
- 🔍 Visual examination: search for leaks, damage to hoses and fasteners.
- 📏 Pressure measurement: check the pump and valves.
- 🧼 Cleaning the rodsRemoval of abrasive particles before each cycle of operation.
Qualified service allows you to identify hidden defects at an early stage. Ignoring minor malfunctions, such as leaking oil from the oil oil oil, can lead to a complete system failure at the most inopportune moment.
Frequent questions about the rollover mechanism
Why is the truck slowly lowering the body?
Slow lowering is most often due to contamination of the distributor channels or low temperature of the hydraulic oil. It is also possible to jam the control spool due to the ingress of mechanical impurities.
Can I lift the body on a working engine?
Yes, lifting the body is possible only with the engine running. The hydraulic pump is driven from a crankshaft, and at idle turns its performance may not be enough to lift the full body.
How often should you lubricate the fingers of the body attachment?
Lubrication of hinge joints and fingers is recommended daily or every 10-12 hours, especially when working in dusty or high humidity conditions.
What to do if the body is jammed in an elevated state?
It is necessary to shut down the engine, carefully put pressure on the system (if the design allows it) and call a repair crew. Independent intervention in the work of hydraulics under pressure is life-threatening.
The main conclusion: The dump truck rollover mechanism is a complex hydro-mechanical assembly that requires regular monitoring of oil levels, lubrication of hinges and checking the tightness of the connections for safe operation.