Cylinders make crane stand tall

Oct. 9, 2012

The Hiab XS 1055 truck-mounted crane, from Cargotec Corp., Helsinki, takes full advantage of the power and controllability of hydraulics. It uses what Hiab calls an E-link system — a type of lever connection from the crane’s column cylinder to the inner boom and inner boom cylinder to the outer boom. It connects the pivot point of both cylinders’ rod ends to mechanical links that improve vertical lifting of loads to high elevations. The links force out the boom cylinders to obtain a long lever arm, which ensures maximum mechanical advantage between the booms and cylinders in all boom positions.

The crane is available with up to ten hydraulic extensions, for a total reach of nearly 24 m, while still providing a lifting capacity of 2.5 tonnes. A dual-capacity, hydraulically operated jib increases outreach to 29 m while maintaining a lifting capacity of 1240 kg.

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Hiab’s E-link feature mounts the rod end of the column cylinder and the inner boom cylinder to a mechanical linkage that improves lifting loads straight up to high positions, such as moving supplies to the top of scaffolding.

The XS 1055 also uses a hexagonal boom profile to provide balance, large bearing surface areas, and low deflection. In fact, hydraulic hoses are routed inside the boom, which protects them from environmental elements and damage from impact with external objects.

Sophisticated electrohydraulic control
Another innovation with the XS 1055 is Hiab’s Valve 91 feature, a closed-center valve system that features pressure-compensation and load sensing to improve both speed and controllability. The result is that the same control lever movement always produces the same crane response, regardless of whether one or multiple functions are in use under light or heavy loading. Regenerative load-holding valves provide fast extension of cylinders.

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Close-up on Hiab's E-link feature, which force out the boom cylinders to obtain a long lever arm.

Another useful feature is pump flow distribution (PFD), which keeps crane operation independent of the oil flow available, so when lifting, hoisting, and other crane functions occur simultaneously, they always run at the same relative speed. The technology also allows consistent fingertip control regardless of how far out the crane boom tip is. This is especially valuable when the crane operates in confined spaces.

In situations when the operator is working at the machine’s performance limits and using multiple functions simultaneously, even the largest pump may not be able to supply enough oil. The result can be unpredictable response. However, PFD routes all oil from the pump in proportion to the operator’s lever movements. When flow demand exceeds the pump’s maximum output, all functions continue to work as expected but at a slower rate. Once the flow demand returns to within maximum ratings (about 100 lpm), the XS 1055 can again operate at full speed.

Automatic speed control provides up to a 10% stepless increase in lifting capacity in one smooth, continuous motion. This feature, unique to Hiab, engages automatically, so the operator does not sense any transition. The function activates upon reaching the machine’s regular capacity limit. The tradeoff for the capacity boost is that the speed of the inner and outer boom is slightly reduced.

For more information on the Hiab XS 1055 crane, visit www.hiabus.com.

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