This number is often most eye-catching when we see a heavy-duty gimbal with a nominal “100kg class” rating. Many people only focus on the weight when selecting a model, thinking that as long as the total weight of the equipment does not exceed the standard, everything will be fine once it is hung up. However, in actual engineering applications, 100kg is at best just a “entry threshold”, far from being enough to be directly decided. It can only indicate that, under specific installation posture and center of gravity conditions, this device can “carry” this weight. As for whether it can rotate and brake after being hung, or even whether it can work stably for many years, it depends on a series of more core hard indicators in the future.
Why can't you choose a model based solely on “being able to carry multiple loads”? Because of the same weight, different placement and installation methods, the suffering caused to the rotating shaft is completely different. The rated load given by the manufacturer is usually calculated based on some “ideal operating conditions” ——such as top load installation, and the center of gravity is close to the pitch axis. Once you switch to side suspension, or the center of gravity of the device deviates from the axis of rotation, the actual load-bearing capacity of the gimbal will be greatly reduced. So, before you are impressed by the number “100kg”, you have to find out what installation method and center of gravity conditions the manufacturer measured this data under.
To determine whether a gimbal can handle a certain moving load, three physical quantities really play a decisive role: torque, center of gravity position and moment of inertia.
Let's talk about torque first. In layman's terms, torque is the weight of the load multiplied by the distance from the center of gravity to the axis of rotation. For equipment weighing the same 100 kg, if the center of gravity is close to the pitch axis, the torque generated will be very small; but if the center of gravity is pushed out a few dozen centimeters, the torque will be multiplied and turned upward. When selecting a type, you must take the actual torque calculated from the “load weight × distance from the center of gravity to the rotating shaft” and work hard against the allowable torque of each shaft and bearing. You must not only focus on the total weight.
The center of gravity is also crucial. The mass distribution of the equipment determines where the center of gravity falls, and the center of gravity is directly related to the stress state under top load or side load. To calculate this clearly, you need to list all the parts that rotate with the horizontal axis and pitch axis, write down their weight, size, installation position and fixing method one by one, and finally calculate the total mass and the true distance from the center of gravity to each axis.
As for moment of inertia, it is a blind spot that many people are prone to stepping on. Just knowing the total weight, you can't tell how much force the motor needs to accelerate and brake. Also 100 kg, the mass is concentrated near the axis and dispersed around the periphery of the equipment. Its moment of inertia varies greatly, which has a great impact on the acceleration, deceleration and positioning performance of the motor. If your project requires frequent start-stop, back-and-forth scanning, or long-term continuous operation, then you must additionally calculate the operating system, continuous heat capacity, and permissible load inertia of the transmission mechanism.
Once the equipment is turned around, there are even more troubles. Normally, you can't expect the gimbal to run at the set maximum speed when fully loaded. How fast the gimbal can run and how long it can accelerate to the target value when fully loaded are completely different from when it is unloaded or lightly loaded. The target speed, acceleration time, movement frequency, and external interference are all combined to determine the exact load torque and acceleration torque you need. When selecting a model, be sure to leave a sufficient safety factor according to the manufacturer's calculation specifications.
If used outdoors or in a vehicle environment, wind load, platform motion, impact, and vibration must all be taken into account. Never treat these as ordinary static loads. Especially for behemoths in the 100kg category, the windward area is huge, and the additional torque brought by the wind load when the wind blows is quite terrifying.
As installation methods change, the permissible load often changes accordingly. The spatial geometry of top load and side load is completely different from that of pitch axis. For the same set of equipment, the load-bearing capacity under these two installation methods must not be equated. After confirming whether it is installed on the wall, laid flat on the top surface, hung on a vertical pole or some other structure, the working environment must be carefully checked: temperature, protection level, humidity, whether it will condense, wind load, salt spray corrosion, sand and dust, ultraviolet radiation, etc. If a gimbal with even the strongest paper parameters is thrown into a high-temperature, high-humidity or highly corrosive environment, its actual combat effectiveness will be discounted.
Once you understand the above instructions, go back and look at the so-called “15kg gimbal”“25kg gimbal” and “100kg gimbal” on the market, and your thinking will become much clearer. To put it bluntly, these names are simply load levels assigned to cater to user habits and should never be used as a conclusion for finalizing the model. Also called a 15kg gimbal, the allowable top load torque, center of gravity range and speed range of different manufacturers may not be at all in line; and a 25kg gimbal is by no means as simple as making a 15kg model more compact. Its internal transmission, bearings and motor may have adopted a completely face-changing design.When comparing goods with 3, remember to control variables: comparison must be made under the same installation method, the same center of gravity and torque conditions, and the same speed and acceleration conditions. The selection can only be based on the allowable torque, center of gravity limit, moment of inertia, and the matching relationship between load-speed-acceleration indicated in black and white in the manufacturer's specification. If the manufacturer does not provide these detailed parameters, you must not pat your head on your feelings and rely on the so-called "weight allowance" to shape it hastily. The correct approach is to list these as items to be confirmed and ask the manufacturer for a written reply.
If your project requires infinite continuous rotation in the horizontal direction, the situation is even more complicated. For limited angle rotation, as long as the cable allowance is left and the mechanical limit is confirmed. However, to achieve infinite continuous rotation, not only the rotating structure needs to be able to bear it, but also the electrical connection of the rotating interface must keep up with it. When the load cable passes through the rotary joint, it usually has to rely on conductive slip rings or similar rotation transmission scheme to transmit power and signals. It is not enough to write "360 degrees" in the specification, which does not prove that it can rotate in infinite circles. You have to carefully check whether there is a clear description of "continuous rotation" and whether the equipment supports the cable transmission scheme you need.
In the final analysis, any selection conclusion can not stay on paper forever. In the final acceptance stage, the real load must be hung, and the full stroke operation, forward and reverse switching, continuous operation and positioning test must be run 1 in the expected working environment with the actual bracket, cable and control system. Only when all these actual combat checkpoints pass smoothly can the so-called "100kg heavy-duty pan-tilt" really fall into place, from a nominal value on the color page of the product to an absolutely reliable conclusion in engineering application.
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