The counterweight is a solid steel block (or concrete block on cranes) mounted at the rear of the superstructure that counteracts the tipping moment of the lifted load. Without a counterweight, every excavator would tip forward as soon as the filled bucket is raised. The mass of the counterweight is precisely calibrated to match the maximum lifting capacity of the machine.
On hydraulic excavators in the 20-ton class, the counterweight typically weighs 4,000–5,000 kg and is permanently bolted to the superstructure. On mobile cranes, the counterweight is modular (in plates of 2–10 tons) and is mounted according to the hoisting configuration: more counterweight = higher lifting capacity, but also increased axle load during road transport.
Short-tail and zero-tail excavators feature optimized counterweights with compact geometry to ensure the rear overhang does not extend beyond the track width. Some models such as the Liebherr R 918 Compact use tungsten granulate instead of steel—significantly heavier for the same size, providing greater stability with a smaller rear radius.