What should be done if a small truck-mounted crane is “unstable” during work?

Small truck-mounted cranes play a significant role in the construction of new rural areas. Their affordability, combined with the ability to both lift and transport, makes them highly suitable for various construction tasks in these areas. However, a common issue arises when many of the operators of these truck-mounted cranes are not sufficiently professional. As a result, when lifting heavy objects, overturning phenomena may occur, which can lead to damage to the vehicle as well as pose a threat to people and property in the vicinity. The main cause of these problems is often the “instability” of the truck-mounted crane, which is typically due to an unstable foundation. So, what measures can be taken to avoid these potentially disastrous situations? The author will explain in detail.

The road on which the truck-mounted crane travels must be flat, solid, and reliable. A flat road surface provides a stable base for the vehicle to move and operate. Uneven or potholed roads can cause the truck to sway and can have a negative impact on the stability of the crane when it is in operation. Solid and reliable roads ensure that the vehicle can move smoothly without unexpected bumps or jolts that could affect the crane’s balance.

The parking place for the truck-mounted crane must also be flat. A level parking surface is crucial for the proper setup and operation of the crane. When the truck is parked on an uneven surface, the crane may not be able to extend its outriggers evenly, resulting in an unstable foundation. This can increase the risk of the crane tipping over when lifting heavy loads.

For example, in a new rural construction site, if the truck-mounted crane is parked on a sloping or uneven patch of ground, it can be difficult to ensure the stability of the crane when lifting materials for building a house. On the other hand, if the truck is parked on a flat and solid area, the operator can set up the crane with more confidence, knowing that the foundation is stable and less likely to cause problems during the lifting operation.

Truck-mounted cranes are strictly prohibited from working on slopes. Working on a slope can cause the crane to tilt in one direction, making it extremely unstable. The force of gravity acting on the crane and the load being lifted can combine to create a significant imbalance, increasing the risk of overturning.

It is also not allowed for the two crawlers or outrigger staying parts of the crane to be at different heights. Uneven support can lead to an unstable base for the crane. If one side of the crane is higher or lower than the other, the weight distribution will be uneven, and the crane may tip over when lifting even a relatively light load.

Furthermore, the soil where the crane is operating must not be loose and soft in one place. Soft or loose soil can give way under the weight of the crane and its outriggers, causing the crane to sink or tilt. This can be particularly dangerous when lifting heavy objects, as the sudden shift in the crane’s position can cause the load to swing and potentially lead to a catastrophic accident.

For instance, imagine a truck-mounted crane attempting to lift a heavy concrete beam on a slope. The uneven terrain and the force of gravity working against the crane can cause it to lose balance and tip over, potentially causing serious damage to the equipment and surrounding structures. In contrast, if the crane is operating on a flat and stable surface with firm soil, the risk of overturning is significantly reduced.

When lifting components, the sling must be vertical. A vertical sling ensures that the force applied to the load is directly upward, minimizing the risk of the load swinging or tilting. If the sling is dragged obliquely, it can create an uneven distribution of force on the load, increasing the likelihood of it slipping or the wire rope breaking.

Dragging the sling obliquely can also cause the crane to become unbalanced. The off-center force can put stress on the crane’s structure and affect its stability. Moreover, an oblique sling can exceed the slewing radius of the crane, which can lead to overload and instability.

To avoid these problems, when lifting heavy components, a traction rope should be set up. The traction rope helps to control the movement of the load and keep it stable during the lifting process. It can prevent the load from swinging or rotating unpredictably, reducing the risk of accidents.

For example, when lifting a large steel beam with a truck-mounted crane, a vertical sling is used to attach the beam to the crane. A traction rope is then set up to guide the beam as it is lifted and to keep it from swaying. This not only ensures the safety of the operation but also makes it easier for the operator to control the load and position it accurately.

When operating the crane, the boom lifting, lowering, and slewing must be stable. Rapid or jerky movements can cause the crane to sway in the air, increasing the risk of instability. The operator should control the movements of the crane carefully, ensuring that they are smooth and gradual.

At the same time, try to avoid emergency braking or impact vibration and other phenomena. Sudden stops or impacts can cause the load to shift suddenly, putting stress on the crane and potentially leading to instability. Emergency braking can also cause the crane to lurch forward or backward, disrupting its balance.

Without taking reliable technical measures and without approval from relevant departments, the crane is strictly prohibited from overloading and lifting. Overloading can put excessive stress on the crane’s structure and mechanical components, accelerating the wear of parts and increasing the risk of the crane overturning.

For instance, if an operator is lifting a heavy load and suddenly makes a sharp movement with the boom or applies the brakes too hard, the load can swing violently, potentially causing the crane to tip over. On the other hand, if the operator operates the crane smoothly and avoids overloading, the risk of instability is greatly reduced.

Truck-mounted cranes should try to avoid full-load driving. When the vehicle is fully loaded or close to full load, it becomes more difficult to control and is more prone to instability. The weight of the load can affect the handling and braking of the vehicle, increasing the risk of accidents.

When the vehicle is fully loaded or close to full load, it is strictly prohibited to perform two actions of lifting and slewing (lifting and horizontal rotation or lifting and walking) at the same time. Performing these actions simultaneously can cause the truck-mounted crane to become unbalanced due to the combined forces acting on it. Uneven roads or inertia can exacerbate this instability and lead to overturning accidents.

For example, if a truck-mounted crane is driving with a full load and attempts to lift and rotate the boom at the same time, the added stress on the vehicle and crane can cause it to lose balance and tip over. By avoiding these simultaneous actions and being cautious when driving with a full load, the operator can reduce the risk of accidents.

When two truck-mounted cranes perform lifting operations at the same time, there should be a safety distance of more than 5 meters between the components suspended by the hooks of the two machines. This safety distance is necessary to avoid collision accidents. If the hooks or loads of two cranes come into contact with each other, it can cause a sudden shift in the loads and lead to instability of the cranes.

For instance, if two truck-mounted cranes are working in close proximity without maintaining a proper safety distance, a slight movement or gust of wind can cause the loads to collide, potentially causing the cranes to tip over or suffer damage. By keeping a sufficient distance between the cranes, the risk of such accidents is minimized.

When two truck-mounted cranes lift components together, reasonable load distribution should be carried out according to the lifting capacity of the truck-mounted cranes. The lifted weight must not exceed 75% of the total lifting capacity of the two truck-mounted cranes. This ensures that the cranes are not overloaded and can operate safely.

The load on each crane should not exceed 80% of its safe load. This provides a margin of safety and allows for some unexpected variations in the load or operating conditions.

During the operation, under unified command, the movements must be coordinated. The operators of the two cranes need to work together and follow the same instructions to ensure that the lifting and moving are carried out simultaneously and smoothly.

The hooks and pulley blocks of the two truck-mounted cranes should be kept basically vertical. This helps to maintain a balanced distribution of the load and reduces the risk of one crane being overloaded while the other is underloaded.

The drivers of the two cranes should cooperate closely with each other. They need to communicate effectively and be aware of each other’s actions to prevent one crane from losing weight and causing the other truck-mounted crane to be overloaded.

For example, when two truck-mounted cranes are used to lift a large and heavy object, proper load distribution and coordinated movements are essential. If one crane is carrying too much of the load or if the movements are not synchronized, it can lead to instability and potentially cause an accident. By working together and following the proper procedures, the operators can ensure a safe and successful lifting operation.

Summary: By adhering to the above points, the phenomenon of small truck-mounted cranes being “unstable” can be significantly reduced or even eliminated. Ensuring a stable road and parking area, avoiding slopes and uneven ground, using slings and traction ropes properly, operating the crane smoothly, avoiding full-load driving and simultaneous actions, maintaining safety distances between multiple cranes, and coordinating lifting operations with multiple cranes are all crucial steps in ensuring the safety and stability of small truck-mounted cranes during operation. With proper care and attention to these details, operators can minimize the risk of accidents and perform their construction tasks more efficiently and safely.