Whether it is a home lift, scissor lift, cargo lift, the lift must know when to stop at the correct position. This is where a limit switch becomes important.
What Does a Limit Switch Do?
A limit switch works like a sensor that sends a signal to the control system.
When the lift cabin or platform reaches a predetermined position, the limit switch is activated and sends a signal to the controller. The controller (PLC or relay-based control system) then processes the signal and starts or stops the motor accordingly.
In lift applications, limit switches are commonly used to:
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Define upper and lower travel limits
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Prevent over-travel
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Improve operational safety
Two Common Wiring Methods
Limit switches are typically wired in one of two ways:
Normally Open (NO)
Under normal conditions, the circuit remains open.
When the limit switch is activated, the circuit closes and sends a signal to the control system. The PLC or relay then performs the programmed action, such as stopping the lift or changing its direction.
Normally Closed (NC)
In a normally closed configuration, the circuit remains closed during normal operation.
When the limit switch is activated, the circuit opens and sends an interruption signal to the controller.
Both wiring methods are widely used depending on the design requirements of the control system.
For a practical wiring demonstration, you may refer to this video:
The Mechanical Limit Switch We Use
For most of our lift products, we use the Chint YBLX-ME/8101 mechanical limit switch.
One advantage of this model is its adjustable actuator arm, allowing installers to fine-tune the trigger position during installation and commissioning.
A demonstration of arm adjustment can be seen here:
Magnetic Strip Position Sensors
In recent years, magnetic strip positioning systems have become increasingly popular in some lift applications.
The basic principle is simple:
When the magnetic sensor mounted on the cabin approaches a magnetic strip installed in the shaft, a signal is generated and transmitted to the control system, which then stops the lift at the target floor.
Some advantages include:
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Quiet operation
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No mechanical clicking sound
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Reduced mechanical wear
However, several factors should still be considered:
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Long-term durability data may vary depending on the installation environment.
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Positioning accuracy can depend on sensor quality, installation precision, and control logic.
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Long-term performance of magnetic components may differ between applications and environmental conditions.
Why We Continue to Use Mechanical Limit Switches
Mechanical limit switches have been used in lift systems for decades.
Their operating principle is straightforward, installation is simple, replacement parts are widely available, and their long-term reliability has been proven through years of practical use.
While new sensing technologies continue to develop, we currently continue to use mechanical limit switches in many of our lift products because they provide a proven, dependable, and cost-effective solution.
For us, reliability always comes first.
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