Post-tensioning Systems

If your operations are focused on tensioning concrete, then the following hydraulic components should be part of your essential toolkit:

• Post-tensioning jacks – Post-tensioning jacks are responsible for interfacing with the anchorage pocket and doing the actual tensioning. They’re available in single and double-acting models, but double-acting (power seating) jacks are the preferred option for post-tensioning applications. That’s because power seating jacks provide superior tensioning precision and can be used to apply exact amounts of tension. Further, power seating jacks are able to maintain loading forces on the strand up to the point of anchoring. That means minimal seating losses as the anchorage system slides into the pocket.
  
  
  

   

  Power seating jacks also provide maximum efficiency and safety, as they’re lighter than single-acting models and can be used to tension many strands at once, providing a major boost in efficiency.

  Durability is a must-have in your post-tensioning jacks, as they’re expected to operate in rugged environments where impact and contamination are constant threats. To mitigate these threats, look for a post-tensioning jack that’s built with solid steel construction and designed with interior fluid conduits.

   

• Short cable and low clearance jacks – Many foundation repair and installation crews also keep short cable and low clearance jacks on hand for challenging work environments. Specifically, short cable jacks are necessary when the post-tensioning strand is damaged or too short to access for some reason. Short cable jacks are designed to fit onto these shortened strands and tension them like normal.
  
  

  Low clearance jacks fill a similar role – expanding the post-tensioning crew’s capabilities to manage challenging work conditions. Specifically, low clearance jacks are deployed when it’s impossible for a standard post-tensioning jack to fully stroke. Low clearance jacks are designed to fit into these smaller spaces and provide the same tensioning force. You’ll most often see low clearance jacks used in applications where existing foundation slabs are present and there is less room to work with.

   

• Hydraulic cylinders – Hydraulic cylinders are designed into every post-tensioning jack and are responsible for applying tensioning force to the strand. Standard tonnage for post-tensioning jacks is 20 or 30 tons, depending on the strand’s diameter.
  

  
  When selecting hydraulic cylinders for post-tensioning applications, durability is what’s important. Durability features to target include solid steel construction, aluminum bronze bearings (to reduce wear from off-center loads) and corrosion-resistant rod components.

   

• Hydraulic pumps – You’ll need a hydraulic pump to drive your post-tensioning jacks, and you’ll need reliability from your hydraulic pump to ensure your operations aren’t interrupted. Power Team’s hydraulic pumps are a frontline option for post-tensioning crews, as it’s backed by the brand’s well-respected manufacturing quality.
  

   

  When selecting a hydraulic pump for your post-tensioning operations, look for a pump that offers an excellent mix of performance and weight (specifically, a lighter weight model). Post-tensioning is often done at elevation, so minimizing equipment weight is about safety, as well as comfort. Further, select a hydraulic pump with a true unloading valve, as this will ensure your pump can output higher flows even under maximum pressure.

   

• Post-tensioning jack components – In addition to hydraulic pumps, post-tensioning jacks and the right hydraulic cylinders, it’s recommended that contractors maintain an inventory of post-tensioning accessories and components like nose pieces, wedge setters, wedges, grippers and more. With an expanded inventory of post-tensioning parts, your crews will have a replacement on hand if one is needed in the field.