Safety protection devices are essential measures to prevent accidents involving cranes. These include devices that limit travel and working positions, devices to prevent crane overload, devices to prevent crane tipping and slipping, and interlocking protection devices. These devices ensure the safe and normal operation of cranes. Today, we'll introduce the common safety protection devices used on bridge cranes during daily production operations.
1. Lifting height (lowering depth) limiter
When the spreader reaches the limit of lifting (lowering), it can automatically cut off the power source and stop the bridge crane hook. It mainly controls the safe position of the crane hook to prevent the hook from hitting the top and causing the hook to fall and other safety accidents.
2. Running stroke limiter
Cranes and trolleys (except for suspended electric hoist trolleys) must be equipped with travel limiters in each direction of travel. These automatically cut off the forward power supply when the specified limit position is reached. These limiters primarily consist of limit switches and safety-bar-style impact blocks, ensuring the crane trolley or crane remains within its travel limits.
3. Lifting Capacity Limiters
The load limiter maintains the load 100mm to 200mm above the ground and gradually increases the load without impact to 1.05 times the rated load. This device cuts off upward movement, but allows downward movement. Also known as an overload protector, it primarily prevents cranes from exceeding their rated load capacity. Electrical load limiters are common, typically consisting of a load sensor and a secondary instrument. Short-circuiting is strictly prohibited.
4. Anti-collision device
When two or more cranes or trolleys are operating on the same track, or when they are not on the same track and there is a risk of collision, an anti-collision device should be installed to prevent collisions. When the two vehicles approach, an electrical switch is triggered, cutting off the power supply and stopping the cranes. This is because, in complex operating conditions and high speeds, it is difficult for the operator to avoid accidents solely through judgment.
5. Interlocking Protection Devices
Doors for access to and from the lifting machinery, and doors connecting the operator's cab to the bridge, must be equipped with interlocking devices unless the manual specifically states that the doors must be opened and safe operation can be guaranteed. When the doors are open, the power supply cannot be connected. If the machinery is in operation, the power supply must be disconnected and all mechanisms must cease operation when the doors are opened.
6. Other Safety and Protection Devices
Other safety and protection devices primarily include buffers and end stops, wind and anti-skid devices, alarms, emergency stop switches, track sweepers, protective covers, and guardrails.
Safety Reminder
Finally, we remind users of cranes that although cranes are equipped with various safety protection devices at the factory, accidents can still occur if the company's safety management is inadequate and personnel violate regulations, even if the equipment has technical protection measures.
Users of cranes should effectively implement their primary responsibility for safety, establish and effectively implement a safety management system, actively conduct safety education and training, conduct regular maintenance and self-inspections of cranes based on their characteristics and usage, and conduct hazard detection and control according to the hazard detection and control system. This ensures that safety protection devices remain safe and effective, that cranes operate safely, and that the company's production and operations are safe.
