• Mar 04, 2025
• News

What is an end truck on a crane?

An end truck is a wheeled assembly at either end of a crane's bridge girder. It supports the hoisting mechanism and moves the load along the crane's runway.

The smooth running of an overhead crane along a track relies on more than just the wheels; it also relies on the crane end trucks. They are like the legs and feet of the overhead crane, which make the crane move along the track. This article focuses on the crane end trucks, an important part of an overhead crane.

Introduction to Crane End Trucks

Decoding Crane End Trucks: The Wheeled Foundation of Crane Travel In simple terms, crane end trucks are the wheeled assemblies located at each end of an overhead crane's bridge girder, comprising a frame, wheels, and a motorized mechanism. Their primary job is to support the bridge, trolley, hoist, and the load, and to allow the entire crane structure to travel horizontally along the runway system. You might also hear them called crane truck assemblies, bridge trucks, or simply end carriages. But whatever the name, their role is the same: to provide reliable and controlled mobility for the overhead crane.

Key Components of Crane End Trucks

Crane end trucks, while appearing as relatively simple assemblies, are actually composed of several key components that work together to ensure reliable and safe crane travel. Understanding these crane end truck components is essential for proper specification, maintenance, and troubleshooting.

Essential Components:

• Wheels (Crane Wheels or End Truck Wheels): Crane end truck wheels are the most fundamental component, providing the rolling contact with the runway rails that enables crane movement. Crane wheels are typically made of hardened steel or cast iron and are precisely machined to match the crane rail profile. Flanged crane wheels are most common for runway guidance. The crane wheel diameter, tread width, and material are critical design parameters.
• Axles (Crane Axles or Wheel Axles): Crane axles are the shafts that support the crane wheels and transmit the crane load to the wheel bearings. Crane axles are typically made of high-strength steel and are precisely machined to ensure accurate wheel alignment and smooth rotation. Heavy duty crane axles are designed for demanding loads and long service life.
• Bearings (Crane Wheel Bearings or End Truck Bearings): Crane wheel bearings are essential for enabling smooth, low-friction rotation of the crane wheels under heavy loads. Crane wheel bearing types commonly used include ball bearings, roller bearings, and tapered roller bearings, selected based on load capacity, speed, and duty cycle requirements. Proper crane wheel bearing lubrication is crucial for longevity.
• Drive Motors and Gearboxes (for Motorized End Trucks): Motorized crane end trucks incorporate electric drive motors and gearboxes to power the bridge travel motion. Crane drive motors are typically AC induction motors or geared motors, selected for their torque, speed control, and reliability. Crane drive gearboxes reduce motor speed and increase torque to drive the wheels effectively.
• Brakes (Crane Bridge Brakes or End Truck Brakes): Crane end truck brakes are essential safety components that provide braking force to stop and hold the crane bridge in position. Crane bridge brake types commonly used include shoe brakes, disc brakes, and motor brakes, often with fail-safe designs that engage automatically in case of power loss. Crane safety brakes are critical for preventing uncontrolled crane movement.
• Bumpers (End Truck Bumpers or Crane Bumpers): Crane end truck bumpers are cushioning devices mounted on the ends of the end trucks to absorb impact energy and prevent damage in case of accidental collisions with runway stops or other cranes. Crane bumpers can be made of rubber, polyurethane, or spring-loaded mechanisms.
• Collector Shoes (Current Collectors or Power Collectors): If the crane uses a conductor bar system for power, collector shoes or current collectors are mounted on the end trucks to draw electrical power from the runway conductor bars. Crane power collectors ensure continuous power supply to the moving crane.
• Frame and Structure (End Truck Frame or Carriage): The crane end truck frame is the structural steel framework that supports all the end truck components – wheels, axles, bearings, motors, brakes, and bumpers. The end truck frame is engineered for strength, rigidity, and proper alignment of all components. Robust crane end truck frames are essential for heavy-duty applications.

These components are carefully designed, manufactured, and assembled to create a functional and reliable crane end truck assembly that ensures smooth, safe, and efficient crane travel.

The Essential Function of Crane End Trucks

The main functions of the crane end trucks are mainly as follows:

1. Supporting Vertical Load: First and foremost, crane end trucks must bear the substantial vertical load of the crane bridge, trolley, hoist, and the lifted load itself. They transfer this weight to the runway rails and ultimately to the building structure. The crane end truck design is engineered to distribute this load evenly across the wheels and minimize stress concentrations.

2. Providing Horizontal Mobility: Crane end trucks are equipped with wheels and drive mechanisms that enable the entire crane bridge to travel horizontally along the runway system. This horizontal movement is essential for covering the work area and positioning the hoist and load precisely where needed. Crane end truck wheels are the key to this mobility.

3. Ensuring Stability and Guidance: Crane end trucks play a critical role in maintaining the stability of the crane bridge and ensuring smooth, controlled travel along the runway. Flanged wheels, guide rollers, and other features are incorporated into the crane end truck design to prevent derailment, minimize sway, and ensure accurate tracking along the rails.

4. Accommodating Drive Systems: Crane end trucks often house the drive motors, gearboxes, and braking systems that power the crane's bridge travel motion. The crane end truck assembly provides a mounting platform and protection for these critical drive components.

In essence, the purpose of crane end trucks is to provide a robust, mobile, and stable base for the overhead crane, enabling it to move heavy loads safely and efficiently throughout the workspace. Without properly functioning crane end trucks, the entire crane system would be immobile and unable to perform its essential lifting and material handling tasks.

Types of Crane End Trucks

Different crane types, load capacities, and operating environments call for different end truck designs. The primary classification of crane end truck types is based on their structural construction:

Box-Type End Trucks: The Heavy-Duty Standard

Box-type end trucks are generally considered the most robust and heavy-duty design, favored for large industrial cranes, high-capacity applications, and demanding operating environments. As the name suggests, box-type crane end trucks feature a fully enclosed, box-shaped structural design.

• Maximum Strength and Rigidity: The closed box section provides exceptional torsional stiffness and resistance to bending and twisting forces. Box-type crane end trucks are engineered to withstand very heavy loads and demanding duty cycles.
• Superior Load Distribution: The box construction distributes loads evenly across the entire end truck structure, minimizing stress concentrations and ensuring long-term durability.
• Protection of Components: The enclosed box design offers some protection to internal components, such as drive motors, gearboxes, and wiring, from dust, debris, and accidental impacts.
• Ideal for Heavy Industrial Cranes: Box-type end trucks are typically used on large double-girder cranes, heavy-duty gantry cranes, steel mill cranes, and other applications where maximum strength, reliability, and longevity are paramount. Heavy duty crane end trucks are almost always box-type.

However, box-type end trucks can be more complex and costly to manufacture compared to fabricated end trucks.

Fabricated Plate End Trucks

Fabricated plate end trucks, also known as welded plate end trucks or simply plate end trucks, are a more versatile and cost-effective alternative to box-type designs. Fabricated crane end trucks are constructed by welding together steel plates to form the required structural shape, typically an open or partially enclosed design.

• Cost-Effective Manufacturing: Fabricated end trucks are generally less expensive to manufacture than box-type end trucks, especially for lighter to medium-duty applications. The fabrication process is more straightforward, often involving less machining and welding complexity.
• Good Strength for Many Applications: While not as torsionally rigid as box-type end trucks, fabricated end trucks provide ample strength and durability for a wide range of common overhead crane applications, handling medium to heavy loads effectively.
• Versatile Design Options: Fabricated end trucks can be readily customized in terms of plate thickness, web height, and overall dimensions to optimize the design for specific load and span requirements.
• Suitable for Light to Heavy Duty Cranes: Fabricated end trucks are used on a broad spectrum of overhead cranes, including single-girder cranes, double-girder cranes, and gantry cranes in manufacturing facilities, warehouses, fabrication shops, and general industrial settings. Standard crane end trucks are often fabricated plate designs.

Specialized End Truck Designs

Beyond box-type and fabricated plate end trucks, there are also specialized designs tailored to specific crane types or operating conditions:

• Under-Running End Trucks: Under-running crane end trucks, also known as underhung end trucks, are designed for cranes where the bridge girder is supported beneath the runway rails, rather than on top. Under-running end trucks are typically more compact vertically, minimizing headroom requirements. They are commonly used with underhung cranes and monorail systems.
• Low Headroom End Trucks: Low headroom crane end trucks are specifically designed to minimize the vertical space occupied by the end truck assembly, maximizing lifting height in buildings with limited headroom. They often incorporate compact drive systems and optimized structural designs to reduce overall height. Low headroom crane end trucks are essential for maximizing space utilization in facilities with low ceilings.
• Gantry Crane End Trucks: Gantry crane end trucks are designed for gantry cranes, which are floor-running cranes supported by legs. Gantry end trucks are typically larger and more robust than overhead crane end trucks, as they must support the entire crane structure and load from floor level. Heavy duty gantry crane end trucks are engineered for demanding outdoor and industrial applications.
• Motorized and Non-Motorized End Trucks: Motorized crane end trucks incorporate drive motors, gearboxes, and wheels to provide powered bridge travel. Non-motorized end trucks (also called idler end trucks) are used on the non-drive end of the crane bridge and simply support and guide the bridge without providing driving force. Most overhead cranes utilize a combination of motorized and non-motorized end trucks.

Conclusion

The crane end trucks is an important part of the bridge crane that supports the crane as well as the load and ensures the safe and smooth operation of the equipment on the track. It is an important part of the crane equipment.