🔍 Key Concepts

• Difference between single mode and tandem/union purchase mode when using paired pedestal cranes • How the rated capacity (30 tons) of each crane is applied — is it per crane or for the pair together? • Why manufacturer's safe working load (SWL) limits cannot be exceeded even if two cranes are installed side‑by‑side

💭 Think About

• Look closely at the illustration: how many separate crane jibs and hooks are shown, and what does that tell you about how the 30‑ton rating is applied? • If you are using only one crane (one hook) instead of both together, should the safe working load be multiplied, divided, or left unchanged? Why? • In cargo handling, what does the term single mode usually mean compared with combined or twin‑lift operations?

✅ Before You Answer

• Confirm whether the 30‑ton rating refers to each individual crane or the combined system. • Make sure you are thinking about one hook in use when you read “single mode.” • Eliminate any choices that would require exceeding the 30‑ton SWL of one crane when operating it by itself.