A Hiab XS 288 HiPro crane with a variable-displacement pump consumes 32% less diesel oil than a fixed-displacement pump, says Hiab. A variable pump on an 800 HiPro save 40%. Less fuel used means less carbon dioxide released into the atmosphere.
A variable pump costs EUR1,000–2,000 as an option on a new crane, or as a retrofit. But Hiab argues that the extra investment would pay for itself in about a year, with annual savings carrying on from there.
Also, the variable pump keeps oil temperatures lower, so the crane does not need an oil cooler.
Much of the oil in a hydraulic circuit is wasted when circulated with a fixed-displacement pump, the company says.
For example, if a customer chooses a fixed pump for a 166 HiPro crane, Hiab recommends a flow of 70–90L of oil per minute. The truck engine uses three litres of oil per hour to produce this flow rate. However, often the crane is turned only 90°—from the loading dock to the truck’s bed and back—and with 60% speed.
“This function uses only 25L of oil per minute, so at least 50L of oil is circulating in the system in vain. The excess energy converts to heat in the control system, and since the oil temperature must be kept below 70°, an oil cooler is needed,” says structural R&D manager Lars Andersson.
