An excavator operator is lifting a heavy object. The lift chart specifies a maximum capacity of 5,000 kg at a 4-metre load radius. The operator has properly assessed the load to be 4,500 kg. During the lift, the operator notices the excavator's tracks start to lift slightly off the ground. What is the most probable cause?

Question: An excavator operator is lifting a heavy object. The lift chart specifies a maximum capacity of 5,000 kg at a 4-metre load radius. The operator has properly assessed the load to be 4,500 kg. During the lift, the operator notices the excavator's tracks start to lift slightly off the ground. What is the most probable cause?

Answer options:

• The engine RPM was too low for the lift. ✅ The load radius has subtly increased beyond 4 metres during the lift.
• The hydraulic system is malfunctioning.
• The operator neglected to engage the travel lock.

Correct answer: The load radius has subtly increased beyond 4 metres during the lift.

Explanation: If the tracks are lifting, it indicates that the excavator is becoming unstable, and the load is approaching or exceeding the machine's tipping capacity. Although the measured load is within the stated capacity at 4 metres, a subtle increase in load radius, perhaps due to slight boom creep or inaccurate initial measurement, can quickly reduce the effective lifting capacity. The other options are less likely to directly cause track lift related to stability during a lift within stated capacity.