Short Cable Jack For Sale – Service – Repair
Short Cable Jacks Save Post Tensioning Crews a Lot of Time in the Field
Short cable jacks are a valuable addition to any post-tensioning crew’s toolkit, as they’re able to tension cables that standard tensioning jacks have trouble with. The clue is in the name. Short cable jacks are the go-to machine when there isn’t enough tensioning cable to work with.
When reinforcement cables are installed, the idea is to leave a tail – at least eight inches in length – of excess cable outside the anchorage zones. This ensures the post tensioning team can quickly and reliably attach the jack to the cable for tensioning purposes. Of course, things don’t always go according to plan at a project site. Whether the cables weren’t sized correctly or installed correctly, it’s common for post tensioning crews to run into cables that don’t extend far enough for standard tensioning jacks to fit.
Short cable jacks, though, can be used to apply force to these short cable lengths, needing only two to three inches of cable to function properly. This prevents interruptions during tensioning and saves the crew from having to fetch a bunch of extra equipment to fix the cable.
What Makes a Short Cable Jack Different Than Other Post-tensioning Jacks?
One of the benefits of post-tension foundations is that they tend to be easier to repair. If parts of the foundation need to be replaced, though, it’s likely that a post-tension jack will be required.
Post-tension jacks are what deliver the pulling force needed to prestress the bars or rods responsible for reinforcement. Once the concrete is poured and the steel laid in place, the foundation is given several days to cure. Following this curing process, tensile force is applied to the steel strands. To do so, a post-tension jack is installed adjacent to one of the anchors holding the steel strand in place. The jack presses against the anchor while pulling at the steel strand at the same time.
This simultaneous pushing and pulling motion places both the concrete and the steel in ideal prestressed modes. The concrete, which handles compression well, is squeezed, while the steel is stretched.
Short Cable Jacks in Operation
During post tensioning, the jack’s nosepiece is inserted inside the wedge cavity and bears against the anchor. On the other end of the jack, a hydraulic pump provides fluid power to a pair of cylinders. These cylinders advance, providing the pulling force that tensions the cable.
To transfer this tensioning force from jack to cable, a set of grippers inside the nosepiece grab onto the cable and pull it through the nosepiece during tensioning. Spring-seating short cable jacks also have a spring inside that controls load bearing as the cylinder pistons retract.
It’s an efficient process that’s similar to how other jacks operate and allows tensioning crews to stress a large number of short cables without losing time.
A Few Features to Consider When Looking for a Short Cable Jack
If you’re looking for a short cable jack to add to your crew’s capabilities, there are a few features to target. They include:
Minimal stroke length for low-clearance applications
Flickinger Machine offers several short cable jack models that vary only in stroke length. This includes stroke lengths from four to 10 inches, so there’s a fit for every short cable situation.
If your post tensioning team frequently works in low clearance situations, though, consider a minimal stroke length to aid in low clearance settings.
Low weight, durable build
Short cable jacks are used to tension many cables in a short period of time, often in challenging, even hazardous field conditions. Choosing a lightweight jack is essential, then, to reduce strain on tensioning crews. Anything under 50 pounds is a good place to start.
However, you can’t sacrifice durability for weight, so stick with reputable manufacturers that build their short cable jacks from steel. Carbon steel is ideal for the housing and cylinder bodies.
Internal hydraulic fluid controls
Internal fluid controls are recommended for post tensioning applications, as they are safer and more efficient during piston advancement.
Simple, maintenance-friendly design
Spring-seated short cable jacks are the preferred choice for most post tensioning teams, as spring-seated jacks are simpler and easier to maintain. Their simplicity also means superior reliability, which is critical for teams tensioning hundreds of cables per project.
We Can Help with Short Cable Jack Maintenance and Replacement
Short cable jacks are designed and built for reliability. There are intense forces involved in post tensioning, though, so your jacks will eventually require maintenance. This maintenance is usually focused on the hydraulic cylinders, as there are potentially multiple failure points involved. Seal failures, leaks and hydraulic oil contamination are all inevitable issues that affect hydraulic cylinders and the short cable jacks they’re used with.
If your short cable jack is having trouble applying consistent pressure, then it’s time for cylinder maintenance or replacement. If that’s the case, the Flickinger Machine team is experienced in both. Our pump and jack experts can inspect your short cable jacks, spot where the failures are coming from, and either repair the jack or source an effective replacement for your crew.