Concrete Pour with a Rated Capacity Gap
You are operating a 12 m telehandler with a maximum lift capacity of 4,000 kg at 2 m and a load chart that shows 1,800 kg at 7 m reach with the boom fully retracted and the machine on level ground. The site engineer asks you to lift a concrete skip with a declared gross mass of 1,650 kg from a stockpile to a first-floor slab edge 6.8 m from the front tyres. The ground is compacted hardcore, but you notice a soft patch about 3 m in front of the machine where a recent water main repair was backfilled. The tyres are inflated to the correct pressure and the machine is fitted with a 1.2 m³ general-purpose bucket, not forks, and the skip has lifting eyes suitable for a shackle. The site supervisor is pressing you to complete the pour before the concrete truck leaves at 15:00.
1. Assess whether the planned lift is within the machine's capacity and identify the two most significant variables that could change your answer.
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The declared load of 1,650 kg is below the 1,800 kg chart figure at 7 m, but the margin is only 150 kg (about 8%). That margin is not a safety factor you can spend. Two variables dominate:
- Attachment and rigging mass. The chart figure is for the machine as configured. Swapping the bucket for forks, adding a shackle and slings, and the skip's own tare all add mass at the load centre. Even 100–150 kg of attachment and rigging eats the entire margin. You must confirm the chart applies to the exact attachment fitted and add the mass of slings, shackles and any lifting frame.
- Ground bearing and machine level. The soft patch 3 m ahead is within the zone where the front axle loads up during a lift. A wheel dropping into a void tilts the machine, increases the effective reach and can transfer load outside the stability envelope. The chart assumes level, firm ground.
You should not proceed on the supervisor's timetable. Re-position so the front tyres are on verified firm ground, confirm the actual gross mass (not the declared figure) by weighbridge or lift plan, and re-read the chart for the true reach and attachment. If the true load plus rigging exceeds the charted capacity at the actual reach, the lift needs a larger machine or a reduced load.
2. The supervisor says the concrete truck leaves at 15:00 and asks you to 'just do it quickly'. Describe how you respond and what you record.
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A schedule pressure argument does not change the load chart. You should decline clearly and explain the specific reason - the margin is too small for the rigging mass and the ground is unverified - rather than simply saying no. Offer a workable alternative: reposition onto firm ground, verify the load mass, or split the skip into two smaller lifts. If none of those can meet 15:00, the pour slips.
Record the decision: the time, the load, the reach, the chart figure used, the ground condition, the supervisor's instruction and your refusal with reasons. This protects you if there is later pressure to explain the delay, and it creates the paper trail that a formal lift plan should have produced in the first place. If the supervisor insists, escalate to the site manager or the appointed person for lifting operations.