How Does a Gantry Crane Work?

If you’re considering using a gantry crane in your operations, understanding how it works will help you fully understand the equipment and ensure you choose the right equipment for the job. So, how does a gantry crane work? Let’s explore the working principle of gantry cranes below.

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The Main Working Mechanism of Gantry Crane

To understand the gantry crane working principle, it’s important to first understand its main working mechanism. This mechanism consists of a hoist and trolley system, a bridge, and the supporting legs.

Bridge: Spanning Large Working Area

The bridge is the horizontal beam that extends across the space, supported by the vertical legs. It houses the hoist and trolley system and moves along the rails on the legs. This allows the crane to cover a wide area, offering high mobility within its operational range.

Hoist System: Lifting and Lowering the Loads

The hoist system, typically located on the bridge, includes the motorized mechanism that lifts and lowers loads. It features a drum or winch that pulls a cable or chain connected to a hook or lifting device. The hoist can be controlled to lift heavy items vertically, allowing for precise positioning.

Trolley: Enabling Horizontal Load Movement Along the Bridge

A trolley runs along the bridge and holds the hoist system. It allows the hoist to move horizontally across the span of the bridge, enabling it to pick up and place loads anywhere within the crane’s operational area. This makes gantry cranes ideal for tasks that require lifting and transporting heavy objects across long distances.

Legs: Supporting and Stabilizing the Crane

The supporting legs of the gantry crane are crucial for stabilizing and supporting the structure. They are mounted on wheels or rails that allow them to move along the ground or tracks, giving the crane the ability to travel within the working area. Some gantry cranes are designed to be rail mounted, while others, such as rubber tired gantry cranes, are designed for mobility.

Control System: Operating the Crane with Precision

Gantry cranes are typically equipped with a control system, which can be operated from a control room, ground-level panel, or via remote control. Operators can control the hoist system, trolley movement, and even the movement of the crane itself. Some gantry cranes are often equipped with advanced technology, such as automated controls, to increase precision and safety.

How Do Gantry Cranes Work: General Process

Now that we know the main components, let’s explore how a gantry crane works in action.

Positioning the Crane:The gantry crane is first positioned within the area where it will be operating. The crane’s legs are placed on tracks or on the ground, depending on whether it is a rail-mounted or rubber tired gantry crane. Once in position, the operator checks the area to ensure there are no obstructions.

Lifting the Load:Once the crane is in place, the operator will use the control system to activate the hoist mechanism. The hoist will raise the hook or lifting device and attach it to the load. With the load secured, the operator can begin lifting.

Transporting the Load:After the load is lifted, the trolley will move horizontally along the bridge. The gantry crane’s ability to move the load across a wide span is one of its key advantages. The operator can move the load to the desired location within the working area.

Placing the Load:After transporting the load, the operator uses the hoist to lower it into place. The precision of the gantry crane allows for controlled placement, whether it’s positioning large steel beams in construction or unloading containers at a port.

The working of a gantry crane differs from other lifting equipment, like overhead cranes, due to its high maneuverability, especially in the case of rubber tyred gantry cranes. These mobile gantry cranes have legs mounted on rubber tires, allowing them to move on the ground flexibly. This mobility is crucial in applications where the crane needs to cover a large area, such as in shipping yards or large construction sites.

How a Gantry Crane Works in Different Applications

The gantry crane’s design allows it to operate in different environments and applications, providing flexibility and reliability. Here’s a breakdown of how a gantry crane works in several common applications:

• Gantry Crane Working in Railway And Ports
• Gantry Crane Working in Construction

Gantry Crane Working in Railway And Ports

In railway and ports, rail mounted gantry cranes (RMG) and rubber tyred gantry cranes (RTG) are commonly used to move shipping containers.

• Rail Mounted Gantry Cranes (RMG): These cranes are mounted on fixed rails that run along the container yard. The RMG crane moves horizontally along the tracks to position itself over the containers that need to be lifted. The fixed rail system provides stability and precise control.
• Rubber Tyred Gantry Cranes (RTG): Unlike RMGs, RTGs are mounted on rubber tyres, making them highly mobile. They can move freely across the yard and navigate between stacks of containers, allowing them to position themselves anywhere within the container storage area.

How It Works When Handling Container:

• Lifting the Containers: The crane’s hoist is equipped with a spreader, which is a device used to grip the corners of the container. Once the crane is positioned over the container, the hoist mechanism lifts the spreader and the container together.
• Horizontal Movement of the Containers: Once the container is lifted, the crane can move horizontally, either along the tracks (in the case of RMG) or by driving on the tyres (in the case of RTG). The crane can shift containers from railcars and the ship’s deck to the yard or vice versa, or between different stacks in the storage area.
• Stacking and Placement of Containers: The crane uses its precise control system to position the container in a designated storage spot. This could involve stacking containers several layers high or placing them on a truck or rail car for transportation. RTGs can stack containers in multiple rows, maximizing space in the yard, while RMGs can be used for more structured, fixed layouts.
• Remote or Automated Control: Both RMGs and RTGs can be controlled by operators using control panels located in the crane cabin or via a central control room. In modern ports, these container gantry cranes may also be part of automated systems that enhance operational efficiency and reduce human error.

Gantry Crane Working in Construction

In construction, particularly in projects involving large-scale infrastructure, handling precast concrete beams is a crucial task. Gantry cranes, especially our straddle carrier gantry cranes, are widely used for this purpose, as they offer an efficient and safe method for lifting, moving, and placing precast concrete beams into position.

How It Works When Handling Precast Concrete Beam:

• Positioning the Straddle Crane: The straddle carrier crane is set up at the construction site, typically near the area where the precast concrete beams will be offloaded, transported, and placed.
• Loading the Precast Concrete Beam: Precast concrete beams are typically lifted off trucks or other transport vehicles by the crane. The crane’s hoist system, which includes a specific lifting device such as spreader clamp, is used to attach to the lifting points on the beam. The spreader clamp is commonly used for large beams to distribute the lifting force evenly, reducing the risk of damage during handling.
• Lifting the Beam: Once the crane’s spreader clamp is securely attached to the beam, the crane’s hoist mechanism is activated. This system, which may be electric or hydraulic, gradually lifts the beam from the transport vehicle.
• Horizontal Movement Across the Construction Site: After the beam is lifted, the gantry crane’s bridge moves horizontally. This horizontal movement allows the crane to transport the beam across the construction site to the designated placement area. The crane operator controls the movement using a wireless remote control system or cabin control, ensuring the beam is transported safely without obstruction.
• Placing the Beam: The final step in handling precast concrete beams involves placing them accurately into their designated position. Our straddle carrier cranes are highly precise, allowing the operator to lower the beam gently into position, whether it’s on top of columns, in a foundation, or onto a support structure.

Conclusion: The Importance of Knowing How a Gantry Crane Works

Understanding how a gantry crane works is essential for ensuring safe, efficient, and precise lifting operations. Knowledge of the gantry crane components, lifting mechanisms, and working principle helps operators optimize their workflow, minimize downtime, and enhance overall safety.

If you’re looking to learn more about gantry cranes, don’t hesitate to contact Aicrane. Our team is ready to provide guidance, answer your questions, and offer customized lifting solutions to meet your lifting needs.

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Those are gantries, and they are part of the next big thing at the PA Turnpike – Open Road Tolling. 

Turnpike Senior Project Manager Steve Brousse is leading the teams that are designing and constructing the gantries, where tolls will soon be read as traffic passes underneath at highways speeds rather than slowing down at the old toll plazas. He explains how it all works and gives us a peek behind the scenes in this video: 

Open Road Tolling gantry design explained (vbrick.com) 

Open Road Tolling is an immense project, covering all 564 miles of the Turnpike, so it had to be broken down into several phases with several contractors performing the design and construction work. It started with four engineering firms designing the gantries and adjacent buildings that house the electronic equipment east of the Reading Interchange and along the Northeast Extension. 

Those sites will be going live with Open Road Tolling in January , shortly followed by the demolition of the old toll plazas in that section of the Turnpike, creating safer interchanges with less congestion. 

It’s not only more convenient for travelers, but it also gives the Turnpike greater flexibility in building new interchanges across the system.

Pictured above is PA Turnpike Senior Project Manager Steve Brousse. He is leading the teams that are designing and constructing the gantries that are a part of Open Road Tolling.

“We’re going to be able to grow as an organization as the community grows around us,” Brousse said. “Open Road Tolling will allow us to add interchanges more efficiently.” 

Open Road Tolling is expected to go live on the rest of the Turnpike in January , and the wheels are already turning on the four contracts to construct 19 gantries there. Turnpike Commissioners approved the first contract with a bid price of $17.8 million earlier this month. A second contract is pending approval and the remaining two will be going out to bid soon.

“Fingers crossed, if everything goes well, we’ll be knee deep in construction this summer,” Brousse said.    

Being a part of such a large project is exciting for Brousse, not just as an engineer, but also as a part of the Turnpike’s 80-plus-year history.

“Being the project manager on such an important aspect of our system is great,” Brousse said. “I alone can’t do it. I do rely heavily on all of our liaisons and construction folks, but it’s been great to be a part of a project that I’ll see for the next 40 years.”

If you want to learn more, please visit our website Road Gantry.