When it comes to lifting heavy loads safely and efficiently, overhead gantry cranes with dual hoists offer flexibility and strength. But with that capability comes the need for careful control — and that’s where load summation plays a critical role.
At Granada Cranes, we recently completed a project in Worcester involving a 34 tonne + 34 tonne double girder overhead gantry crane, fitted with two SWF hoists. The system was designed with load summation technology, ensuring the crane could only lift a maximum total of 34 tonnes, even when both hoists are in use. This blog explains why that feature is so important.
🔍 What Is Load Summation?
Load summation is a control system used in cranes with more than one hoist. It monitors the combined weight being lifted and ensures the total safe working load (SWL) is not exceeded, no matter how the hoists are used.
In a dual-hoist setup like our Worcester installation, each hoist is capable of lifting up to 34 tonnes. Without load summation, an operator might unknowingly lift more than the crane’s design limit by using both hoists simultaneously — potentially compromising structural integrity and operator safety.
With load summation, the crane control system constantly calculates the combined load between the two hoists. If the total approaches the 34-tonne threshold, the system will automatically prevent further lifting — protecting both people and equipment.
✅ Why Is Load Summation So Important?
1. Safety First
Preventing overloading is crucial in any lifting operation. Load summation eliminates the risk of an operator unknowingly exceeding the crane’s maximum capacity.
2. Protects Equipment
By keeping lifting loads within safe limits, you reduce wear and tear on hoists, motors, and structural components — extending the life of your overhead gantry crane.
3. Supports Complex Lifts
In our Worcester project, the crane was fitted with Cattron radio control, allowing the hoists to operate independently for tasks like turning or rotating heavy items. Load summation made it possible to carry out these manoeuvres with full confidence.
🔧 Load Summation in Action: Our Worcester Crane Installation
In this installation, we delivered a double girder crane with:
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2 x 34T hoists
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Full load summation
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Independent joystick control for each hoist
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A custom paint scheme to match incoming machinery
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Full catwalk and interlock safety platform
Even with both hoists active, the crane is hard-limited to a combined 34T lift — ensuring the crane’s structural and mechanical limits are never breached.
This smart integration of control and safety features helps our customer lift with precision and peace of mind, all while preparing for future expansion of their production line.
Check out our case study on this project: Evtec / JVM Double Girder Crane Installation
🏗️ Final Thoughts
As lifting technology advances, so do the expectations for safety, control, and performance. Load summation may not be visible at first glance, but it’s one of the most important safety systems in today’s overhead gantry cranes — especially for high-capacity or dual-hoist installations.
If you’re planning a crane system where multiple hoists will work in tandem, load summation isn’t a nice-to-have — it’s essential.
