The power selection plant is a critical stage in the design or modernization of any lifting system. lift-motor Not only does it determine maximum load capacity, but it also determines speed, energy efficiency and safety of the entire machinery, and mistakes in the selection phase can lead to frequent overloads, emergency stops, or even the destruction of the gearbox.
The modern market offers a wide range of solutions, from compact motors for small building winches to powerful traction drives for elevators. You need to consider many factors, including operating mode (S3, S4, S5), insulation class and the way the flange is fastened. Asynchronous motors It is a de facto standard because of its reliability, but forced-cooled engines (Blower) are becoming more popular for tasks with frequent launches.
In this article, we will discuss the technical details of selection, the features of different types of motors and discuss the rules of safe operation. Understanding the physics of processes will help you avoid typical errors and prolong the life of equipment. Don't rely only on data-sheet figures, real-world operating conditions often make their own adjustments.
Engine typology for lifting machinery
The basis of the market of lifting equipment is motor-motorsTheir popularity is due to their simplicity of design, lack of brush-manifold assembly and high reliability, but for lifts, the operating mode is critical, which is different from pumps or fans.
Most specialised winch and lift motors operate in a re-to-short-term mode, which means they are designed to alternate between periods of load operation and periods of rest or idling. The key parameter here is PV (LD), which for lifting equipment is usually 15%, 25% or 40%.
In addition to classical asynchronous models, high-comfort cargo and elevators are increasingly being used for accurate positioning. electromagnetic-brake and frequency-regulatingSuch systems allow smooth acceleration and braking of the load, excluding jerks, which are dangerous to the structure.
Below is a table comparing the main specifications of common types of engines used in lifting equipment:
| Type of engine | Mode of work | Presence of brakes | Application |
|---|---|---|---|
| Asynchronous (conic) | Repeated-short-term | Built-in | Tali, winches. |
| Asynchronous (cylindrical) | Long-term (S1) | Separate | Conveyors, elevators |
| With electromagnetic brakes. | S3, S4 | Integrated | Lifts, gates. |
| Servo motor | Continuous | Built-in | High-precision elevators |
When choosing a type of drive, it is important to consider not only power, but also weight and size specifications. For compact construction lifts, conical rotor motors are often used, where braking occurs due to the axial movement of the rotor when applying voltage.
Power calculation and gear ratio selection
The right power calculation is the foundation of safety: insufficient power will lead to overheating of windings and failure of insulation, and excess power will lead to unjustified increase in cost of the project and difficulties with starting currents.
Formula for calculating power P (in kW) is as follows: P = (Q Γ v) / (102 Γ Ξ·), where Q is the load capacity in kg, v is the lift speed in m/s, and Ξ· is the overall efficiency of the mechanism. The resulting value should be adjusted for the reserve factor, which for lifting mechanisms is usually 1.2-1.3.
The most important element of the gearbox is the gear ratio, which determines how many revolutions the engine shaft must make for the winch drum to make one rotation, and a mistake in the calculations will either lead to the inability to lift the load (there is not enough traction) or to exceed speed, which is dangerous.
Temperature effect on power
When operating in high temperatures (above +40Β°C), the rated power of the engine must be reduced, due to worsening heat transfer conditions and the risk of overheating insulation classes.
When selecting equipment, also consider starting torque. The engine must have sufficient torque to pull the load from the spot, especially if the system does not have compensatory counterweights.
Design features and types of fastening
The dimensions and the way the motor is installed are dictated by the design of the lift itself, the most common models with paws (paw fastening) and flange options, the choice between them often depends on the layout of the gearbox and the available space in the mine or on the frame.
Special attention should be paid to the engines with built-in brakes. In lifting mechanisms, this is a mandatory safety element; the brake must act automatically when the power is turned off, preventing the load from falling; There are models with a handle for forced release, which is necessary for emergency descent of the load.
- π© Flange fastening (B5, B14): Allows you to directly dock the engine with the gearbox, saving space and eliminating the need for couplings.
- π© Paw fastening (B3): A classic variant requiring a separate base and, as a rule, a connecting coupling.
- π© Combined (B35): Universal version, having both paws and flange, which simplifies installation in various conditions.
An important aspect is the hull protection class (IP). For work in the open air or in dusty construction conditions, a level not lower than the level required. IP54 or IP55This will protect the windings from moisture and metal dust, which can cause short circuits.
Use vibration insulation pads when mounting the engine on your paws, this will reduce noise and prevent the destruction of the seats from constant vibration.
Connection schemes and drive control
The electric motor of the lift requires strict adherence to electrical circuits. A phase switching error can cause a rotational reversal, which in systems without end switches can cause an accident. For three-phase induction motors, the most common Star and Triangle circuits.
The Star circuit provides smooth start-up and smaller starting currents, but does not allow full power. The Triangle circuit gives maximum power, but the starting currents can be 5-7 times higher than the nominal. For powerful engines, the Star-Triangle switching method or frequency converters are often used.
Frequency regulation (FR) is becoming the standard for modern lifts, allowing not only smooth speed changes, but also shaft moment control, especially in elevators where passenger comfort depends on smooth acceleration and braking.
When installing power cables, be sure to use cable tips and check for tightening contacts. Weakened contacts warm, oxidize and can cause a fire. Also, install a heat relay that will turn off the engine when overcurrent is required.
Maintenance and diagnostics of malfunctions
Regular maintenance is essential to the long life of the lift, and visual inspection should be performed daily before the shift, paying attention to extraneous noise, vibration and heating of the body, and routine maintenance includes checking the condition of the brushes (if any), bearings and braking system.
Pay special attention electro-brakeThe gap between the brake disc and the pad should be adjusted according to the product passport, too large a gap will lead to delay in braking, and too small will lead to friction and overheating even when unbrakeable.
Periodically, the resistance of windings to megaohmmeter insulation must be measured. A decrease in insulation resistance below normal (usually 0.5 IUM for low-voltage motors) indicates moisture or varnish destruction.
βοΈ Monthly service checklist
Listen to the sound of the engine running. A hum, howl or knock can indicate a bearing malfunction or a rotor skew, and changing the lubricant in bearings in a timely manner significantly prolongs their life.
β οΈ Attention: It is strictly forbidden to operate an engine with a faulty or removed cooling fan. Even short-term work under load without blowing will lead to thermal breakdown of the insulation.
Security and emergency situations
Safety in lifts comes first. The electric motor is a source of increased danger due to high voltage and rotating parts. All maintenance work should be carried out only with fully de-energized equipment and a banning poster posted.
In emergency situations, such as phase breaks or cargo jamming, protective devices come into action; the heat relay must turn off the control circuit; the limit switches must limit the flow of the cargo; ignoring the triggered protection and trying to βstart by any meansβ are unacceptable.
When you fire in a room where the lift is installed, you need to turn off the entire electric drive, using water to extinguish a burning electric motor under voltage is deadly, use only powder or carbon dioxide fire extinguishers.
β οΈ Attention: Never attempt to manually brake the engine shaft or gearshield during operation, resulting in instantaneous injury and destruction of the mechanical part.
Compliance with operating rules and regular monitoring of the condition lift-motor Keep in mind that saving on a quality motor or maintenance can lead to much higher repair costs and simple production.
How often should the lubricant in the engine bearings be changed?
The frequency of the lubrication change depends on the mode of operation and type of bearings. For standard operating conditions and closed bearings, the lubricant is often designed for the entire life of the bearing. However, in severe conditions (high temperature, dust, round-the-clock operation), it is recommended to check and replace the lubricant every 2000-4000 motor hours.
Can a conventional industrial engine be used instead of a specialised one for a winch?
It is possible to use, but with limitations: conventional S1 (long-term) engines are not designed for frequent start and braking. When operating in winch mode (S3/S4), they will quickly overheat, require a powerful independent forced cooling fan and careful monitoring of the body temperature.
What if the engine is humming but not rotating?
This is a sign of "double phase" (one phase break) or mechanical jamming. You need to immediately turn off the power to avoid windings burning out, check the integrity of the fuses, the starter contacts and the absence of mechanical obstacles to the rotation of the shaft.