• Sep 09, 2025
• News

Rubber Tired Gantry Crane: Functions, Tires, and Mobility

Learn about the functions, tire design, mobility, and how it can accomplish various lifting tasks of a tire gantry crane. If you are also looking to buy a RTG, I hope this article will be helpful to you.

A rubber-tired gantry (RTG) crane is a large mobile gantry crane on wheels used for container handling in ports and yards. Its portal frame is mounted on heavy-duty rubber tires, allowing the crane to straddle multiple lanes of containers. RTGs can travel on concrete, asphalt or even tracks, giving them flexibility to navigate complex yard layouts. With a powerful hoist and spreader, an RTG can lift and move shipping containers dozens of tons in weight. In operation, RTGs drive into a stack of containers and lift them up (often 1-over-6 high), then transport and place the containers on trucks, rail cars or other stacks.

Key Capabilities of Rubber-Tired Gantry Cranes

Rubber-tired gantry cranes offer mobile container stacking with high efficiency. They are typically designed to span multiple rows of containers: an RTG can straddle four or more container bays plus a roadway. This multi-row design means an RTG can pick up containers from one row and move them to another without repositioning the crane itself. In practice, RTGs allow yard operators to stack and retrieve containers in blocks, speeding up storage and retrieval. For example, by spanning several lanes, an RTG can reduce congestion by moving containers over obstacles, loading them onto waiting trucks or placing them into storage rows. Their rubber-tired mobility also lets RTGs adapt to yard changes – they can be driven to where containers need to be picked up, enabling flexible container movement in the yard.

RTGs are engineered for heavy-duty duty. Many models lift 30–50+ tonnes (or more) per hoist operation. The portal crane carries a spreader that locks onto container corner castings, and a winch or cables hoist the load. Steered by powerful axles, an RTG's wheels are stationary-turning capable, meaning the crane can rotate about its center without moving forward. Rubber-tired gantry cranes combine this maneuverability with precision: modern RTGs have automated steering and guidance systems that allow smooth turns and accurate placement in tight spaces.

Overall, RTGs significantly increase yard throughput. They can simultaneously handle inbound containers (from ships or trucks) and outbound containers (to trucks/rail) by shuttling between stacks. By eliminating the need for forklifts or straddle carriers for large loads, RTGs streamline operations. For example, a single RTG can transport containers from ship to stack and then out to waiting trucks in one coordinated cycle. This makes RTG cranes central to efficient, high-volume container handling in port and terminal environments.

Power and Energy Systems in RTG Cranes

Rubber-tired gantry (RTG) cranes rely on strong and reliable power systems to handle heavy lifting and continuous movement within container yards. Their power configuration directly impacts efficiency, operating costs, and environmental performance. In response to the global quest for sustainable port operations, RTG cranes have changed throughout time from conventional diesel-driven machines to more energy-efficient electric and hybrid variants.

1. Diesel-Powered RTGs

Rubber-tired gantry cranes use robust power systems to lift heavy loads and move themselves. Traditional RTGs are typically powered by onboard diesel generator sets. Each crane usually carries one or more large diesel generators that produce electricity to power all crane functions, including hoisting, trolley movement, gantry travel, and steering. Because RTGs are mobile machines, they do not typically connect to a fixed power grid. Instead, they burn diesel fuel continuously to generate electricity. When a loaded container is lowered, the motors generate excess energy. In diesel RTGs, this regenerative energy has no outlet, so it is dissipated through resistor banks, producing waste heat. This approach leads to high fuel consumption and increased wear on components. Moreover, diesel RTGs release large amounts of exhaust gases, noise, and particulate matter, contributing to local air pollution and global carbon emissions. These drawbacks make traditional diesel RTGs less compatible with modern energy-saving and low-carbon development goals. To solve this problem, energy-saving RTGs are gradually replacing diesel RTGs.

2. Electric RTGs (E-RTGs)

Electric RTGs eliminate onboard diesel use by connecting directly to an external power source. They typically draw electricity from the port's power grid through a cable reel system or conductor rail. By removing the need for a diesel generator, E-RTGs significantly reduce local emissions, lower noise levels, and improve air quality in port environments. A major advantage of E-RTGs is their ability to handle regenerative energy efficiently. When containers are lowered, the motors generate electricity, which can be fed back into the port's power grid rather than wasted as heat. This not only improves energy efficiency but also reduces the overall operational cost. However, E-RTGs require substantial infrastructure investment in power supply systems and may face limited mobility compared to fully diesel-powered units.

3. Hybrid RTGs

Hybrid RTGs represent a middle ground between diesel and electric models. They are equipped with a smaller diesel engine, battery packs, and sometimes supercapacitors. The diesel engine runs at optimal efficiency to charge the batteries or provide additional power during peak demand. When containers are lowered, the regenerative energy is stored in the batteries instead of being wasted. This stored energy can later be used to support hoisting or traveling operations. Hybrid RTGs can reduce fuel consumption by 30–50% compared to conventional diesel units, depending on workload and operating conditions. They also produce fewer emissions and offer lower noise levels, making them a practical solution for ports that want to balance mobility with sustainability without fully committing to fixed electrical infrastructure.

4. Comparison Between Different RTGs

Ports and container yards frequently evaluate various power systems when selecting a rubber tired gantry (RTG) crane in order to strike a balance between operational flexibility, environmental effect, and efficiency. Diesel, electric, and hybrid RTGs each have their own benefits and drawbacks. The size of the yard, the infrastructure that is accessible, and long-term financial objectives typically influence the choice.

• Diesel RTGs provide maximum mobility and independence, as they do not rely on external power connections. They are widely used in ports where infrastructure for electric supply is limited. These cranes can operate across large yards and handle heavy workloads without interruption. However, their operation comes with high fuel consumption, noise, and emissions, which increase running costs and environmental impact.
• Electric RTGs offer a cleaner and more sustainable solution. Powered through external infrastructure, usually cables or conductor rails, they produce no on-site emissions and operate more quietly. They are well suited for modern ports that prioritize green operations and have reliable access to electricity. The main challenge is the need for costly infrastructure investment and limited mobility compared to diesel units. Once installed, however, electric RTGs deliver significant savings in energy and maintenance.
• Hybrid RTGs combine the strengths of both systems. They typically use a smaller diesel generator along with battery storage or a power recovery system. This setup reduces fuel consumption and emissions compared to traditional diesel models while maintaining more mobility than fully electric units. Hybrid RTGs are attractive for ports seeking to lower their carbon footprint without fully overhauling their infrastructure. They also provide greater flexibility, allowing operators to adapt to changing energy costs and environmental regulations.

Although diesel RTGs are flexible and durable, they are noisy, generate pollutants, use more fuel, and require frequent engine maintenance. They operate onboard engines and provide strong, dependable power without relying on shore infrastructure, making them ideal for ports with limited electricity. Although they require shore power and more upfront infrastructure, electric RTGs use the grid to generate power and reduce pollution, noise, and fuel expenses while providing smoother acceleration and regenerative energy recovery. In order to save fuel and cut emissions, hybrid RTGs combine diesel engines with electric drives or batteries to switch between modes. They maintain the flexibility of diesel in situations where grid power is intermittent, but they also increase the complexity and initial cost of batteries and control systems.

RTG Crane Tires: Design, Stability and Durability

RTG tires are specialized for the extreme demands of container yards. Unlike truck or car tires, RTG crane tires must support enormous loads, absorb stress from stationary turns, and minimize heat buildup. Key tire features include:

• Spherical Contact Surface and Easy Turning: RTG wheels often pivot while the crane is stationary. To facilitate this under heavy load, many RTG tires have a slightly curved tread contact surface rather than flat. This design means when the crane steers or turns on the spot, the tires roll on a smooth curve, reducing friction on the actuators. The tread pattern is also optimized for low rolling resistance, enabling easier wheel rotation. Together, these features make container repositioning smoother and put less stress on the crane.
• Low Heat Build-Up: High use rates and weight create heat in RTG tires. Excess heat can quickly wear out a tire. Manufacturers design RTG tires with compounds and structures that minimize heat build-up. Lower heat not only extends tire life but also saves energy: reduced rolling resistance means the crane uses slightly less power to move.
• Bias-Ply Structure for Stability: Many RTG tires are built with bias (cross-ply) construction. Bias-ply RTG tires have multiple plies of fabric at angles, giving extra sidewall support. In practice, a bias RTG tire flexes less under load, reducing swaying of the crane during moves. The stiffer construction also helps handle the side loads when an RTG moves heavy containers.
• Durability and Wear Resistance: RTG tires are engineered for longevity. They use tough rubber compounds and thick treads to resist wear under high loads. According to tire manufacturers, essential features include superb lifting capacity (to carry heavy loads), minimal heat build-up, reduced energy consumption, excellent stability, easy-turn tread pattern, and overall long life.

In short, RTG tires are specifically designed to limit heat, offer stability, and permit rotation under load (spherical tread). Look for these characteristics when selecting tires for an RTG crane because they will result in safer and more effective container movements.

Environmental Impact and Efficiency

Rubber-tired gantry cranes have significant environmental considerations. Diesel RTGs produce emissions of CO₂, NOx, and particulates. Not only does this increase your cost of ownership, but it can also pollute the air in your harbor with long-term use. Although the engine technology of diesel tire gantry cranes has improved, and pollution emissions have improved compared to the previous, but it is still a larger source of pollution. Modern emissions standards and clean engine technologies have helped, but ports still see RTGs as major polluters.

To improve air quality, many terminals adopt electric or hybrid RTGs. Electrifying RTGs eliminates on-site exhaust: an electric RTG running on mains power produces virtually no local emissions. Similarly, hybrid systems (diesel-electric) capture energy and reduce fuel use, dramatically cutting CO₂ and particulate output.

Beyond fuel, RTGs also consume electrical energy. Energy-efficient designs (from generators to tires) help minimize this. In summary, using E-RTGs or hybrid power is the most effective way to reduce an RTG's environmental footprint. It's important for buyers to consider electric vs diesel options early, especially if reducing emissions is a priority.

RTG vs. Rail-Mounted Gantry (RMG) Cranes

When selecting a gantry crane for a container yard, a key decision is RTG (rubber-tired) vs RMG. Each has advantages:

• Mobility: RTGs drive on tires and can roam the yard freely. They are ideal for yards with irregular layouts or frequent reconfiguration. For example, if container stacks are repositioned often, an RTG can be simply driven to a new location. RMGs, by contrast, run on fixed rails and cannot stray from their track. This limits yard flexibility: the layout must be built around the crane paths.
• Lifting Capacity: RMG cranes typically have higher lifting capacity. Their steel rail wheels and rigid frame give them a more stable base. As a result, RMGs can lift significantly heavier loads than similarly sized RTGs. An RTG's lift is limited by tire strength and balance (too heavy a load can risk tipping on soft tires). In practice, RTGs are best for medium-duty lifts, while RMGs handle the heaviest, high-volume lifting.
• Efficiency and Energy: RMGs are usually electric and more energy-efficient. They draw power from overhead lines or busbars and have lower friction (steel-on-steel), giving higher throughput and lower operating costs over time. RTGs running on diesel have higher fuel costs and more maintenance. Some yards mitigate this by using hybrid RTGs, but a fully electric RMG remains more eco-friendly.
• Maintenance: RTGs require more mechanical maintenance (tyres wear out, diesel engines, etc.). RMGs have fewer moving parts and simpler drive systems, so generally less downtime – although any rail fault can stall multiple cranes.

Key considerations when choosing between RTG and RMG include yard layout, stacking density, cost and environmental goals. For an irregular or expanding yard, an RTG (or multiple RTGs) may be best. For a high-capacity, fixed terminal, RMGs often deliver greater throughput. In practice, many large ports use a mix: RTGs for general yard flexibility and RMGs for the hottest, most capacity-critical blocks.

Selecting and Buying an RTG Crane

For buyers looking to purchase an RTG crane, consider these factors:

• Capacity and Size: Choose an RTG sized for your heaviest containers and stacking height. RTGs come in spans from ~4 to 8 container rows wide, lifting up to 50+ tons per lift. Ensure the span covers your container lanes and an adjacent truck lane.
• Power Type: Decide on diesel, electric or hybrid. Diesel RTGs have lower upfront cost and full mobility, but higher emissions and fuel costs. Electric RTGs reduce emissions (if you have power rails or cable), and hybrids offer a compromise. Remember that diesel RTGs need fuel storage (genset fuel tanks) and ventilation.
• Tire Design: As discussed, features like spherical tread and heat-resistant compounds improve uptime. The right tire choice can reduce energy use and maintenance.
• Automation and Safety: Modern RTGs can include automated stacking systems, GPS positioning, and remote operation. Safety features (cameras, collision avoidance) are crucial when moving containers. Buyers should look for cranes with ergonomic cabins and controls, and consider automation to improve yard efficiency.
• Energy Efficiency: Because ports are under pressure to cut emissions, evaluate the RTG's efficiency. Ask about fuel consumption (gallons/hr) and whether the crane can be retrofitted with hybrid kits or drives.
• Deployment: RTGs are mobile, but need space to turn and operate. Plan yard paths and crane lanes in advance. Also, remember that RTGs may require minimal road-grade preparation (paved surfaces) for smooth operation.

All in all, purchasing an RTG is a costly endeavor. Use the above criteria and check manufacturer specs. If possible, request demos or site visits to see RTGs in action. A well-chosen RTG will enhance your yard's flexibility and throughput for years.

Conclusion

Strong, versatile tools that are vital to modern container handling are rubber-tired gantry cranes. RTGs move throughout the yard, lift heavy goods, and span multiple rows of containers to optimize storage and throughput. They are available in diesel, electric, and hybrid varieties that balance emissions, efficiency, and mobility.