1. The requirement for brakes with manual release devices is not mandatory but depends on the specific application scenario.
Industrial applications:
In working conditions where a gearbox is paired with a brake motor, a manual release device is not universally mandatory. However, in certain specific scenarios-such as when operation or movement is required under power-off conditions (for example during maintenance or vehicle repositioning)-a manual release device becomes necessary. This requirement generally belongs to the manufacturer's design standard for particular applications rather than a universal mandatory regulation.
Passenger vehicle applications:
On July 7, 2025, the Standardization Administration of China released the mandatory national standard "Technical Requirements and Test Methods for Passenger Vehicle Braking Systems." The standard will take effect on January 1, 2026.
The regulation specifies that when regenerative braking deceleration exceeds 1.3 m/s², the vehicle must automatically illuminate the brake lights. In addition, all new passenger vehicles must be equipped with an ABS anti-lock braking system as standard. Regarding the single-pedal driving mode, the new regulation changes it to an optional feature: drivers must manually enable it, the system returns to the default mode after each power cycle, and a continuous visible optical signal must be displayed in the vehicle while the mode is active.
However, this standard does not mention any mandatory requirement for a manual brake release mechanism.
In summary, the requirement for a brake with a manual release device is not universally mandatory but determined by specific application scenarios and relevant standards. In industrial applications, whether to equip a manual release device depends on operational requirements of the working condition; in passenger vehicles, current mandatory standards do not include such a requirement. National or industry standards are typically revised in accordance with industrial development stages in order to better adapt to the needs of different industries.
2. Electromagnetic brakes used in AGV drive wheels are generally of the power-off braking type.
At present, most electromagnetic brakes used in AGV drive wheels adopt a spring-applied, power-released design. In some designs, the brake can optionally be equipped with a manual release handle, while in others the brake is designed from the beginning without any manual release mechanism.
When an AGV experiences a fault and cannot move by itself, the brake can be forcibly released so that the drive wheel is no longer locked. This allows operators to manually move the AGV to a safe area or maintenance zone.
Mechanical approaches to manually releasing electromagnetic brakes
As illustrated in the example where the brake is mounted on the side of the drive wheel, several mechanical approaches can be considered when attempting to release the brake using a manual handle:
Linkage locking mechanism – using a mechanical linkage to push and hold the brake handle in the released position.
Brake cable locking mechanism – using a cable system to pull and hold the brake handle.
Spacer blocking method – manually pulling the brake handle and inserting a V-shaped or M-shaped plastic block between the brake mounting surface and the handle to keep it released.
The first two methods involve complex mechanical structures, lower operational efficiency, and higher implementation difficulty. The third method is simpler and more efficient, but its applicability is limited.
Even when the brake is designed to face outward, in real scenarios the brake side may not always be accessible during maintenance. Moreover, many AGV drive wheels are installed in the middle of the vehicle chassis, making the brake handle difficult or impossible to reach. In some drive wheel designs, the brake is integrated inside the motor, leaving no external mechanical access point at all.
4. Electrical methods for forcing the release of electromagnetic brakes
Since the drive wheel is an electromechanical integrated system, releasing the brake electrically is often the most practical method.
If the AGV's power system is still functional and the brake can be electrically released, the intermediate relay controlling the brake can be selected with a test button function. By pressing the test button, the brake coil can be energized, forcing the brake to release and allowing the AGV to be moved manually.
Another method is to use a small auxiliary battery or portable power source to energize the brake and release it. This solution is particularly suitable for systems that do not rely on onboard batteries, such as systems powered by AC-to-DC converters or directly supplied with AC power for the motor drive.
5. Lifting the drive wheel off the ground through auxiliary mechanical structures
Another solution is to design an auxiliary lifting mechanism on the drive wheel suspension system. By applying lever, linkage, or lead-screw principles, the drive wheel can be lifted slightly off the ground.
This approach is especially suitable for AGVs equipped with small drive wheel units, as it enables quick and convenient handling. The method is purely mechanical and independent of the electrical control system.
6. Third-party rescue solutions for manual vehicle transfer
A practical alternative is to use a short manual pallet jack or forklift. During the AGV chassis design stage, appropriate lifting points can be reserved so that the vehicle can be lifted and transferred when manual relocation is required.
This method requires no modification to the electrical control system and avoids introducing additional complex internal mechanical structures, relying instead on existing handling equipment.
Conclusion
When an AGV fails and cannot move autonomously, relying solely on the brake's manual handle to release the drive wheel lock is often difficult due to the structure of the drive wheel and its installation position within the vehicle. The design can be complex, implementation challenging, and efficiency relatively low.
This article discusses several practical internal and external solutions based on AGV structural characteristics to facilitate manual relocation when necessary. In real engineering work, each problem should be analyzed case by case rather than applying any single method blindly.
Stay tuned as we continue exploring various technical details of AGV systems. ��
Excerpts from Customer Communication Regarding Brake Release and Manual Vehicle Transfer
1. Why is the brake voltage 42V when the motor voltage is 48V?
This is an industry practice. Even when the battery cannot provide sufficient voltage to drive the motor, it can still supply enough voltage to release the brake.
2. Will a fully charged battery voltage of 57V damage a brake labeled as 42V?
First, 42V refers to the minimum voltage required for brake engagement, not the rated voltage. Second, the brake power supply is designed with wide voltage tolerance.
3. Is the brake engagement delay and voltage-reduction function necessary?
When battery energy density was relatively low in the past, this function was an effective energy-saving measure. With modern high-energy-density batteries, it is generally no longer necessary.
4. If customers require a brake handle, how should we respond if our brake does not have one?
Customers may be raising this requirement based on traditional design thinking. Instead of simply following that logic, we should focus on the actual problem they want to solve: how to move the AGV quickly and safely when it cannot operate normally. The solutions discussed earlier can effectively address this requirement.
If we compare the drive wheel to a leg, then the brake handle is like hair on the leg. If the handle cannot be seen or reached within the AGV structure, does it really matter whether it exists?
5. What if a customer insists that a brake handle is mandatory?
This again comes down to communication. The customer's real need is convenient AGV relocation during faults. Their requirement may come from standards in other industries or equipment types. Explaining the structural characteristics of AGVs and proposing alternative solutions is often sufficient.
Twenty years ago, few people imagined that high-speed rail would become a primary travel mode. Today, with such a fast and comfortable option available, how many people still choose long-distance travel by conventional trains or buses?
Similarly, on many highways, one of the three lanes is reserved as an emergency lane. On the surface, it may appear to be a waste of resources, but in reality it ensures safety and smooth traffic flow. During peak traffic, emergency lanes are sometimes temporarily opened to relieve congestion.
With the development and popularization of autonomous driving, perhaps in 20 years highways may even eliminate dedicated emergency lanes and convert all lanes into regular traffic lanes.
Engineering design evolves with technology-and so should our thinking.
