Overhead Crane Setup in Heavy Machinery Plant Design: Parameters and Layout

In large machinery factories, cranes are essential material handling equipment. Common types include overhead cranes, gantry cranes, semi-gantry cranes, suspension cranes, og wall-mounted cranes. In final assembly workshops, where workpieces are large and heavy, cranes may have lifting capacities exceeding 100t and runway heights over ten meters. Once rated load, runway height, and span are defined, they directly impact production capacity and construction cost. Therefore, proper crane setup is critical for meeting production needs, supporting future product strategies, controlling plant costs, and ensuring safety. This article discusses how to set up cranes reasonably in large machinery plant design.

Determining Basic Parameters of a Crane

The basic parameters of a crane include rated lifting capacity, runway height (lifting height), span, and duty class.

Rated Lifting Capacity

This refers to the maximum total weight a crane is allowed to lift, including any detachable lifting devices (or attachments). When designing a factory, it is essential to understand the heaviest product or component to be lifted and consider possible future increases in product size due to industry trends. Since the crane’s capacity limits the plant’s maximum product size, a margin should be allowed for potential growth. It’s also crucial not to overlook the weight of the lifting device itself. For safety, the total lifted weight must not exceed the crane’s rated capacity.

Kranspenn

The span is the horizontal distance between the centers of the runway rails along which the crane travels. It is determined by the workshop’s width, which in turn depends on the size of the products, the space needed for operation, and maneuvering. In large machinery workshops, spans of 30 m or 36 m are common. The crane’s span is typically the workshop width minus 1.5 m. For double-layer crane setups, the upper-level crane span must align with the building’s structural design.

Runway Height (Track Height)

Runway height relates to the maximum hook height required, which depends on how high the load must be lifted. This is calculated based on operational needs. When designing, the size of the largest product must be considered, and the crane runway height determined through elevation drawings. For large items, the height of the lifting device itself must also be included in the calculation.

• H1 represents the net lifting height of the workpiece.
• H2 is the height of the workpiece.
• B denotes the width of the workpiece.
• H3 is the height of the lifting beam or spreader.
• H4 is the minimum vertical distance between the lifting hook and the lifting beam, determined by the wire rope’s slant angle.
• H5 is the maximum height the crane hook can reach.
• H is the maximum crane runway elevation.

The net lifting height (H1) should account for the height required to move the workpiece onto the test platform or for loading onto a vehicle. The workpiece has a height of H2 and a width of B. To ensure safety, the angle between the wire ropes and the horizontal should generally be no less than 60°, which determines the minimum wire rope height between the hook and lifting device (H4). The crane rail height limit (H) can be calculated as: H = H1 + H2 + H3 + H4 + H5. The designed crane rail height of the workshop should exceed this limit.

If a double-layer crane system is used, the upper crane’s rail height is also restricted by the lower crane’s rail height and girder dimensions, and a safe clearance must be maintained between the girders of the two cranes. In large machining workshops, where equipment is tall, the clearance between the bottom of the crane girder and the top of the equipment must also be considered when determining the crane rail height.

Determining the Work Duty of Cranes

The work duty of cranes is a key concept that reflects their operating characteristics and serves as an important basis for ensuring crane safety. The classification of a crane’s work duty is based on two factors over its entire design life: the frequency of use and the load spectrum. According to these criteria, cranes are classified into eight duty classes, from A1 to A8. In general, overhead cranes used in machining workshops and assembly shops of mechanical factories fall under work duty class A5.

Reasonable Crane Configuration and Layout

In large machining and assembly workshops, the facilities are typically spacious, and workpiece lifting is frequent. Especially in assembly workshops, cranes may be occupied for extended periods due to continuous hoisting operations. Therefore, the design often involves multiple cranes. A well-thought-out crane configuration plays a critical role in improving production efficiency, reducing operating costs, and ensuring operational safety.

During final assembly in large-scale machinery manufacturing, most components are small to medium-sized parts, accounting for approximately 70%–80% of all components. These parts typically weigh from several hundred kilograms to several tons or even dozens of tons. Since lifting operations are frequent and time-consuming, such workshops commonly adopt double-layer crane systems. Small and medium parts are primarily handled by the lower-level cranes, while large parts or entire machines are hoisted by the upper-level cranes.

Lower-level cranes generally have a lifting capacity no greater than 50 tons, with most being 32 tons or less. The number of cranes is typically set at one crane per 50–60 meters of workshop length. However, if the cranes are frequently occupied or the hoisting frequency is high, more small cranes (10 tons or less) may be installed in specific areas. Various types of small cranes are available, such as single girder cranes, semi gantry cranes, wall travelling jib cranes, og frittstående svingkraner. Among them, wall travelling jib cranes are especially popular in large machinery workshops due to their flexibility, lack of floor obstructions, and no interference with upper-level cranes.

However, too many cranes on the same track may interfere with each other and reduce operational efficiency, making it crucial to reasonably determine the number of cranes.

For upper-level cranes, typically one large-capacity crane is installed, capable of lifting over 100 tons or even several hundred tons, along with one smaller crane with a capacity 1 to 2 levels below. Since these large-capacity cranes are expensive and have high operating costs, their quantity should be strictly controlled.

In actual production, lower-level cranes should be prioritized whenever possible, and smaller cranes should be used instead of large-capacity ones whenever feasible.

Crane Setup for Flipping Large Workpieces

In large machinery workshops, flipping heavy and large workpieces is often required. To avoid sudden impact during the process, which could affect the crane and the building, a crane with two trolleys can be used. This means one crane is equipped with two trolleys that have the same lifting capacity, while the total lifting capacity of the crane remains unchanged.

During operation, the two trolleys lift the workpiece together to a certain height. Then, Trolley 1 lowers slowly until the workpiece becomes vertical. Trolley 2 then turns the workpiece 180 degrees in the air. After that, Trolley 1 lifts the workpiece back to a horizontal position. Finally, both trolleys lower the workpiece slowly to complete the flipping.

Konklusjon

In large machinery factories, final assembly workshops are costly due to high-tonnage cranes and tall buildings. The crane’s tonnage and rail height largely determine both the workshop cost and the maximum product size the factory can handle.

A well-designed crane setup ensures smooth production and safe operation. Therefore, workshop design must align with product development plans, define the largest workpiece size, and use careful calculations to choose a suitable crane configuration.

Cindy

Hva skjer: +86-19137386654

E-post: cindywang@hndfcrane.com

Jeg er Cindy, med 10 års arbeidserfaring i kranindustrien og samlet et vell av faglig kunnskap. Jeg har valgt de tilfredsstillende kranene for 500+ kunder. Hvis du har behov eller spørsmål om kraner, ta gjerne kontakt med meg, jeg vil bruke min ekspertise og praktiske erfaring til å hjelpe deg med å løse problemet!