Enerpac high-tonnage hydraulic cylinders have stood the test of use in many building, resources and infrastructure applications, including demanding prestressed concrete applications, where harsh and dusty conditions are the norm.
The proven capabilities of the cylinders mean they have been chosen for a new 450TT stressing bed at HEB Precast in Mt Maunganui, New Zealand, which manufactures floor and wall panels for commercial and industrial buildings. The cylinders were supplied by Bay Engineers.
“We started using Enerpac cylinders about 10 years ago. They are robust and stand up to the wear and tear of our industry, which is why we chose them for our new flat bed,” said Paul Brewer, operations manager at HEB Precast.
“The hydraulic rams must work successfully in both directions – actuation and retraction. Other rams that we have tried in the past have failed. We want equipment that just keeps on going.”
HEB Precast is a division of civil contracting company HEB Smithbridge, which employs more than 660 staff. The company’s precast and prestressed concrete slabs enable multi-story buildings to be erected efficiently to tight timeframes.
Lightness and strength of prestressed concrete means thinner slabs, easier handling on the job, and lower construction costs. Typical floor sections made by HEB Precast are three metres wide and up to 18 metres in length.
The slabs are craned into place, eliminating scaffolding, boxing work and concrete pouring on construction sites.
“We have used different types of manufacturing techniques for the slabs over the years. Once wires were loaded individually, but now do multi-wire stressing,” Paul Brewer said.
The stressing strands in the new 450TT flat bed are tensioned by four Enerpac CLRG Series 100 tonne double-acting cylinders, which are activated by electric pumps to the required 28 mpa.
“The 450TT flat bed can accommodate up to 20 hi-tensile stressing strands, but we are presently using 6-12 wires. These consist of 12.7mm diameter LHL low relaxation super strand.”
Once the wires have been stressed, HC high-strength concrete is poured into the mould and the concrete is covered with a hot-water thermal blanket to cure overnight. It achieves seven days strength in just 12 hours. The wires are then locked in and the hydraulic cylinders retracted.
The CLRG10012 Enerpac cylinders used in the stressing bed each weigh 70 kilograms; have a stroke of 300mm and a collapsed height of 430mm.
Neville Stuart of Enerpac NZ said: “For the new bed, we specified cylinders fitted with extra bearing surface to ensure long life while operating horizontally under large loads.
“We were able to meet a strict deadline for delivery of these cylinders, ensuring the stressing plant was up and running right on schedule.”
Neville Stuart noted that Enerpac has been working with HEB Smithbridge for some years, satisfying their needs for high tonnage cylinders that perform under all conditions.
Enerpac has supplied the company with CLRG cylinders for bridge lifting and stressing applications, including reconstruction of the Matata rail bridge that collapsed in devastating floods in 2005.
The CLRG Series of double-acting cylinders have a capacity of 50 to 1000 tonnes and are designed for a wide variety of construction and heavy load moving applications.
They offer a new standard in safety and reliability, including an integral stop ring that provides piston blow-out protection, and top or side mounted lifting eye positions for safety and ease of handling.
Base mounting holes are standard, allowing versatility and security in positioning, and plunger wipers on all models help reduce contamination and extend cylinder life.
The special bearing design can withstand side-load forces up to 10 per cent of the cylinders’ rated capacity. All CLRG double-acting cylinders are fitted with a safety valve in the retract side to prevent product damage or personal injury in case of accidental over-pressurisation.
Enerpac hydraulic cylinders address the needs of major areas of industry, including mining and energy, infrastructure construction, commercial and industrial buildings, roading and bridgework, manufacturing, pipelines, mobile machinery, mobile and stationary vehicles, craneage and fixed plant.