In the world of lifting technology, there are many specific terms that can confuse an untrained person. One of the key elements that determines the capabilities of a crane operator is jib. This is not just a metal beam, but a complex engineering solution that allows you to significantly expand the working area of the machine without the need to move the chassis.
The main task of this device is to increase the length of the main boom. When the standard length is not enough to perform operations at height or when large horizontal distances need to be covered, operators use this additional element. Gusek is mounted on the head of the main boom, continuing its line, which allows you to deliver cargo to hard-to-reach places where a regular boom cannot physically reach.
Understanding the operating principle of this unit is critical for the safe operation of special equipment. Incorrect calculation of loads or ignoring certified data when working with an extended boom can lead to fatal consequences. In this article we will analyze in detail the design features, types and operating rules of this important component.
Design features and device
Structurally jib is a lattice or tubular truss that is attached to the top of the main boom. Depending on the model of the truck crane, the connection can be hinged or rigid. The lattice structure is most often used in heavy machines, as it provides high strength with minimal dead weight. Tubular options are typical for medium-duty telescopic cranes.
The key element of the device is the fastening system, which must withstand enormous dynamic loads. Typically, several fixation points are used: the lower support rests on special boom stops, and the upper part is hinged to its head. To control the angle of inclination, hydraulic cylinders or mechanical stretchers are often used, allowing the reach to be changed during operation.
Manufacturing materials
What are the jibs made of?: The jibs are made of high-strength low-alloy steels, such as 09G2S or imported analogues. This provides the necessary elasticity and tear resistance. The surface is coated with special anti-corrosion compounds that are resistant to aggressive environments and temperature changes.
It is important to note that the weight of the extension device itself significantly affects the overall lifting capacity of the machine. During installation goose part of the carrying capacity is “eaten up” by the weight of the additional section itself. That is why the crane’s passport always contains separate tables of lifting capacity for working with an extended boom, which cannot be neglected.
The jib is a removable element that increases the length of the boom, but reduces the maximum lifting weight due to its own weight and increased lever arm.
Types of jib and installation methods
There are several classifications of extension devices, and the choice of a specific type depends on the tasks facing the truck crane. The most common division is by type of design and method of changing the reach. Understanding the difference between them is necessary for the correct selection of equipment for a specific object.
The first type is rigid jibs that are fixed at a certain angle and cannot be changed during operation without dismantling. The second type is telescopic or articulated options, which allow you to change the angle of inclination relative to the main boom. This gives the operator flexibility in handling the load while avoiding obstacles.
Installation of a device is a separate technological operation that requires adherence to a strict sequence of actions. Typically the process looks like this:
- 🏗️ Site preparation and installation of the crane on outriggers with horizontal control.
- 🔩 Transporting the jib to the crane and carefully laying it on special supports or the ground within the reach of the main boom.
- 🔗 Raising the head of the main boom and docking with the lower eye of the jib, fixing with fingers.
- ⚙️ Lifting the structure and attaching the upper part of the jib to the boom head, installing guy wires or turning on hydraulic cylinders.
It is worth remembering that there are models where jib stored in transport position along the side of the vehicle. This speeds up the process of preparing for work, since there is no need for additional transport to transport the extension section. However, such designs are more difficult to maintain and require more frequent lubrication of the hinge joints.
Effect on load capacity and reach
The use of an extension section radically changes the characteristics of the truck crane. The main law of physics states: the farther the load is from the center of rotation, the less weight the machine can lift. Installation goose increases this radius, which inevitably leads to a decrease in rated load capacity.
When operating a reach boom, the operator must refer to the specific lifting capacity charts. They take into account not only the reach, but also the angle of inclination of the boom itself. It often happens that at minimum reach a crane can lift 50 tons, but with full jib and maximum reach - only 2-3 tons.
⚠️ Attention: Exceeding the lifting capacity when working with a jib leads to the crane tipping over. The center of gravity shifts, and the stability of the car drops sharply. Never rely on intuition, use only data from the load table.
It is also worth considering wind load. The tall and long structure formed by the boom and jib works like a sail. Even with a load that does not exceed the limits, a strong gust of wind can create a critical heel moment. In such cases, work must be suspended.
For clarity, let’s look at how the lifting capacity changes depending on the reach (average data for a crane with a lifting capacity of 25 tons):
| Configuration type | Reach (m) | Load capacity (t) | Lifting height (m) |
|---|---|---|---|
| Main boom | 4.5 | 25.0 | 10.5 |
| Main boom | 18.0 | 5.2 | 28.0 |
| Boom + Jib | 24.0 | 2.1 | 36.5 |
| Boom + Jib | 30.0 | 0.9 | 41.0 |
As can be seen from the table, jib allows you to reach a significant height, but the price for this is a sharp drop in carrying capacity at long reach. This requires the crane operator to master the technique and accurately plan operations.
Reach Boom Safety Precautions
Operating a truck crane with a jib installed is considered high-risk work. This is where many additional restrictions come into play that are not present when working on the main boom. The first step is to make sure that the load limiters (LOL) are in good working order.
Modern systems UCP must be reprogrammed or switched to jib mode. If the sensors think that a short boom is working, they may not work at a critical moment, since the load parameters for them will be calculated incorrectly. An error in setting up a security system is unacceptable.
☑️ Check before lifting the load
Particular attention should be paid to the work area. The radius of the danger zone around a crane with an extended boom is much larger. The signalman must be within the operator's field of vision and have reliable communication. Any sudden movements of the boom are prohibited, since the long truss has great inertia and the swinging of the load can become uncontrollable.
⚠️ Attention: It is prohibited to install or dismantle the jib near power lines without obtaining a permit. The length of the boom assembly may accidentally come close to live parts, which can be fatal.
In addition, it is necessary to monitor the condition of the soil. The pressure on the supports when working with a long lever increases unevenly. If the ground begins to sag under one of the supports, the crane may become unstable faster than the operator has time to react. The use of special supports for supports is a mandatory requirement.
Maintenance and troubleshooting
Regular Maintenance goose - the key to long service life of the equipment. The metal structure is subjected to constant cyclic loads, which can lead to metal fatigue. The main focus of the inspection is on the welds, especially in the areas where the lugs and hinge joints are attached.
Cracks in metal can be microscopic in the early stages, so visual inspection is often complemented by ultrasonic flaw detection or magnetic particle testing. Particular attention is paid to areas of stress concentration. Any detected crack requires immediate repair or replacement of the element.
Lubricate jib pivot joints only when the boom is lowered or in a position that allows safe access. An attempt to lubricate the upper hinge while hanging without insurance is a direct violation of safety regulations.
Rope-locking systems, if they are designed to change the jib angle, also require inspection. Wear of the blocks, the appearance of fistulas on the ropes or a violation of the geometry of the pulley grooves can lead to breakage. Stretch marks must be checked for deformation and corrosion.
Storing goose also has its own characteristics. If the device is removed, it must be placed on flat wooden pads, excluding contact with wet ground. Transport fixation must prevent beating and friction against the sides of the vehicle, which can damage the paintwork and accelerate corrosion.
Economic feasibility of use
The use of a jib boom truck crane is often dictated by economic benefits. Instead of ordering a heavier and more expensive crane, which may not fit into the site or not reach the work site due to weak soil, it is more rational to use existing equipment with an extension. This allows you to optimize the construction budget.
However, it is worth considering the time spent on installing and dismantling the device. If there are many short operations to be performed on a site, the time it takes to retool a crane can wipe out the savings. In such cases, it is more profitable to rent a crane with a higher lifting capacity and a long main boom.
Also jib allows you to perform unique operations that are not available to other methods. For example, supplying cargo inside existing buildings through the roof or installing structures behind obstacles. In such situations, the cost of renting single-file equipment is justified by the uniqueness of the problem being solved.
For equipment owners, the presence of a removable jib expands the range of services. The crane becomes a more versatile tool, capable of taking on jobs that would otherwise have to be abandoned due to lack of height or reach. This increases the company’s competitiveness in the special equipment rental market.
Is it possible to make a jib for a truck crane yourself?
Absolutely not. Homemade extension devices do not undergo strength calculations and do not have certification or passports. Their use is a violation of industrial safety rules and in the event of an accident will entail criminal liability. The jib is a certified attachment that requires changes to the crane passport.
How is the jib angle calculated?
The angle of inclination depends on the design. For rigid jib it is fixed (usually 0 or 30 degrees). For steerable jib, the angle is set by the operator via hydraulics within the limits specified in the passport (for example, from -10 to +80 degrees). The choice of angle affects lift height and reach.
Does the jib affect the speed at which the load is lifted?
Yes, it does. When using a reach boom, it is often necessary to operate at slower lifting and swing speeds to prevent the load from swinging too much. A long lever increases inertial forces, so smooth movement becomes a priority over speed.
Is it necessary to re-register the tap with the supervisory authorities when installing a jib?
No, if the jib is a standard removable equipment provided by the manufacturer for this crane model and included in the passport. In this case, an entry in the logbook is sufficient. If the jib is non-standard or the crane has been modified, an industrial safety examination and changes to the passport are required.