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Post-tensioning portable hydraulic pumps

Supplier News
article image Eddie Shay and his team with the ZU4.

QUEENSLAND-based construction company StrongForce has boosted the speed, efficiency and safety of its post-tensioning operations by introducing energy-saving hydraulic pumps engineered to run cooler than conventional designs with greater durability.

StrongForce - headquartered in Brisbane and applying its technology in Australia, Asia and the UK - teamed up with high force tool specialists Enerpac to develop a post-tensioning model of Enerpac's new ZU4 series portable hydraulic pumps.

The joint development after the pumps' introduction as part of a worldwide launch, represented the first international in-service trials of a ZU4 model engineered specifically for the type of work undertaken by StrongForce on civil, commercial, industrial, infrastructure, and retail sites.

The pumps - which offer lower operating costs and simpler service - feature a 1.25kW universal motor coupled with a new pump element design that reduces oil flow turbulence, producing an industrial workhorse with fewer moving parts, and less friction.

StrongForce post tensioning manager Eddie Shay said the pump was quieter, lighter and more solid for the type of work.

"We also like the better cooling it offers, because conventional pumps really get hot when you are applying pressure as we do, at up to 20 tons per square inch.

"Not only can excessive heat impair the hydraulic efficiency of the cylinders we use, but also it is very uncomfortable for the guys who have to move the equipment up and down in hot conditions."

Introduction of an NV251 shut-off valve to the ZU4 enhanced its suitability for slow release of tension required in StrongForce's work.

The pumps' increased flow rates, reduced heat generation, and decreased power needs also translated into higher productivity and reliability.

"Because the pump body is made of moulded composites, it wears better than metal types and it is a lot lighter and easier to handle when you're up and down building sites," Mr Shay said.

"And because the motor draws less power, we found it wasn't overloading power sources such as power boards. Often this can be a problem when you have a lot of electrical equipment drawing current from the same source - if they all go on together, you can get problems."

Typically weighing 26-33kg with reservoir capacities from 4-40 litres, the 700 bar ZU4 pumps are suitable for use with powerful and compact single-acting and double-acting high-pressure hydraulic cylinders and hydraulic tools.

The ergonomic heavy duty composite shroud of the ZU4 protects the electric motor and key electrical components from environmental contamination, rain and debris and provides a non-conductive handle for operators.

An ergonomic and durable low-voltage (15 volt) pendant with sealed switches facilitates safe remote operation.

Reliability is enhanced by brushes designed to last four times longer than conventional designs. They feature "auto-stop shunt" to prevent commutator damage from normal brush wear. An easily accessible brush cavity allows rapid brush replacement in the field.

The ZU4 series is best suited to medium-to-large cylinders or hydraulic tools - or for use wherever high-speed, intermittent duty cycle is needed. The pumps are available with backlit LCD and multiple valve configurations for remote or manual control of advance, retract and hold combinations.

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