Bygging's double-acting hydraulic tank jacks come in three models: 2510-35D (12 metric tons), 2510-40D (18 metric tons) and 2510-50D (25 metric tons), with test loads of 18, 27 and 37.5 tons. The piston is hydraulically controlled in both directions, so a tank can be lifted 2.5 metres in about 40 minutes, compared with 3–4 hours using single-acting jacks. Each stroke climbs 10 cm, giving smooth, controlled lifting for storage tank erection.