We know that every motion control system needs a reliable transmission. That’s why you must understand the cycloidal gearbox beyond its specifications. So in this blog, we explain its design and components, working mechanism, and how it differs from traditional and planetary gearboxes.
What is a Cycloidal Gearbox?
This is a specialized compact mechanical transmission system that utilizes cycloidal discs and rollers instead of traditional gear teeth to achieve high reduction ratios and torque output.
Structure of Cycloidal Gears
Input Shaft
This is one of the main parts where the cycling begins. Connected to the motor, the input shaft transfers rotational energy from the electric motor to the gearbox.
Eccentric Bearing
Rather than allowing the cycloidal disc to rotate like a conventional gear, it guides the disc through an orbital motion as the input shaft turns. This continuous motion enables the disc to engage with the ring pins in a controlled way while the gearbox gradually reduces speed and increases torque.
Cycloidal Disc
A cycloidal disc doesn’t look like a regular gear. They usually feature precise lobes that engage with the fixed pins inside the housing. Because the number of lobes is always fewer than the ring pins, the disc rotates slightly in the opposite direction during every input revolution.
Many high-performance gearboxes use two cycloidal discs arranged 180 degrees apart. This way, the gearbox can carry heavy loads, and vibration is reduced.
Ring Pins
These are hard steel pins that are organized in a circular row and revolve around the cycloidal disc. These pins remain static while the disc rolls against them. Compared to conventional gears where only a few teeth carry the load at a time, several pins maintain contact with the disc simultaneously.
Output Pins
They pass through some holes within the cycloidal disc, and their motion transmits rotational force to the output shaft.
Output Shaft
The output pins deliver the motion to this component when the disc moves. At this stage, higher torque and less speed are generated, and this causes a smooth rotation that can move equipment like robotic arms, CNC machines, conveyors, etc.
Housing
It keeps internal components aligned and protects them from dust, contamination, vibration, and mechanical damage.
Key Features of Cycloidal Gearbox Design
Excellent Torque Density
When heavy loads are involved in your application, you don’t automatically need a larger gearbox. We often recommend cycloidal gearboxes to our customers who need high torque without redesigning the whole system. Because multiple pins and discs share the transmitted force, the gearbox can deliver more torque output.
Compact Design
Not every machine has plenty of space. This gearbox can fit into installations like robotic joints because the main bearings carry both radial and axial loads without the need for external supports.
Minimal to Zero Backlash
To maintain precision, there mustn’t be any unwanted movement. Think about a robot installing tiny electronic connectors. If the end effector stops slightly outside its actual position, alignment problems can occur. By keeping backlash to a minimum, the robot repeats the same movement with accuracy.
High Reduction Ratios
If you require high torque without many gear stages, a cycloidal gearbox suits this. Depending on the design, you can get a reduction ratio of 30:1 to 300:1.
Shock Resistance
Several industrial equipment operate in unstable conditions. Unexpected load, emergency stops, and redirection create shock that can damage conventional gear systems. Because several contact points share the load, cycloidal gearboxes absorb impact better without any tooth damage.
How does a Cycloidal Gearbox Work?
To explain how it operates, we’ll follow how power flows from the input to the output.
- Rotation begins at the motor and passes through the input shaft to the eccentric bearing.
- The bearing causes the cycloidal disc to move in a distinct orbital path instead of spinning like a regular gear.
- Around the disc are fixed ring pins that guide its movement. As the disc moves, its lobes continuously press against the pins lining the inner wall of the housing.
- Because the disc has fewer lobes compared to the housing pins, it rotates in the opposite direction of the input shaft.
- Next, the output pins receive the controlled motion and send it to the output shaft.
- By the time power leaves the gearboxes, speed reduces and torque increases.
How Much Torque Can It Actually Deliver?
When it comes to the amount of torque it can deliver, this varies because output depends on size, materials, bearings, reduction ratios, and working conditions. Small gearboxes used in collaborative robots may produce 20 to 100 Nm, while industrial ones deliver 200 to 1000Nm and heavy-duty ones may exceed 5000Nm.
A good example can be seen in automated welding cells. A robot that lifts a 50 kg welding fixture in a 12-hour shift needs a gearbox that can withstand consistent loads without losing accuracy. That’s why we look at operating speed, shock load, application requirements, and service life when making a selection.
Cycloidal vs Planetary Gearbox
When making recommendations for our customers, we don’t just consider the torque or reduction ratio and specification alone. Rather, we look at how the equipment will operate.
So when high speed is needed, we select planetary gearboxes, but in critical applications where low backlash, shock resistance, rigidity, and high torque are needed, cycloidal is the best choice.
Conclusion
Cycloidal gearbox design delivers high reduction ratios and excellent torque density and many other benefits within a small compact area, which many traditional ones cannot offer.
RobotCNCParts specializes in producing high-quality and durable robotic components, including gearboxes that meet industrial standards. We deliver globally and offer no minimum order quantity. Get in touch with us today for a seamless collaboration.
See the machined robot gearbox components.
