Dead Ender Jack
Jack used to seat wedges on the dead end of a post-tension tendon.
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Dead Ender Jacks Provide the Power for Dead Ending Applications
Every piece of reinforced concrete gets an anchor on both ends. The dead end is the anchorage set installed at the concrete plant and is tensioned well before it reaches the field. Placing this dead end requires the reliable application of linear force.
That’s what dead ender jacks are designed to do – take the fluid power introduced by a hydraulic pump and convert it into many tons’ worth of pushing or pulling force. Dead ender jacks are designed to safely apply this force hundreds or thousands of times a day. The jack you choose for your crew should offer that level of reliability.
What Dead Ender Jack Models are Preferred by Dead Ending Crews?
Although there are several jack models that dead ender crews target, they all share several traits. For example, dead ender jacks tend to be:
Single-acting – Hydraulic cylinders are either single-acting or double-acting in design. A single-acting cylinder is one that only has a single port for hydraulic oil. During operation, the oil is pushed into this port and advances the piston for loading. Once loading is complete, the oil is returned to the reservoir and the piston retracts using loading forces (typically gravity) or a spring.
Single-acting jacks are the choice for dead ending purposes because loading is simple and safe during dead ending. A complicated cylinder design is unnecessary for this purpose, and single-acting cylinders are less complex than double-acting models. A simple cylinder is a reliable cylinder, and reliability is paramount for dead ending, given the frequency of force application.
Designed with spring return – Some single-acting cylinders retract using loading forces, and this is a popular feature for jacks relied on for lifting purposes.
In dead ending, though, gravity doesn’t have a role to play. That’s why dead end jacks are designed with spring return functionality. Cylinders with spring return use a spring to maintain loading as hydraulic oil is returned to the reservoir. This allows for steady, controlled ram retraction. With a spring, the load is also maintained should power be immediately cut to the jack. Springs are also reliable and easy to maintain if the cylinder experiences operating issues.
In the lower part of the tonnage range – Dead ending doesn’t require extremely high capacity cylinders for the job. In fact, dead ending can be handled by cylinders with rated capacities at 25 tons or below. These cylinders weigh less and operate quickly, which is perfect for mobile dead ending crews that don’t have time to waste.
Choosing the Right Model for Your Dead Ending Application
What’s the difference between those models? The clue is in the name. The first two numbers refer to the cylinder’s capacity, in tonnage. So, for example, the C254C comes with a 25-ton capacity, noted by the “25” inside the model name. The number that follows is the stroke length, which in this case is 4” for the C254C.
A cylinder’s stroke is the length, in inches, that the ram piston inside the cylinder can travel during operation. Stroke length varies slightly among dead ender jacks, and the best option for your dead ending applications will depend on field conditions.
As with all load bearing applications, it’s recommended that you select a dead ender jack that exceeds your needed load bearing capacity by at least 20 percent. Although side-loading isn’t a significant concern in dead ending, it’s also recommended that you select a stroke length that well exceeds the job’s requirements.
What are Some Features to Look for in a Dead Ender Jack?
Dead ending is characterized by rapid repetition, so the ideal jack is built for durability, reliability, and ease of use. To support that, here are some of the features to target:
Solid steel construction
Some jacks are manufactured with aluminum, and while aluminum is lightweight, it is also not as durable as steel. Pick a jack made with a solid steel body so that it will hold up under repeated tensioning.
Wear and corrosion-resistant components
Dead ender jacks are exposed to high-wear processes and high-corrosion environments, so look for components that can withstand those stresses. High quality jacks will come with larger springs that offer improved durability and retraction speed. They’ll also come with rods that are plated with corrosion-resistant materials.
Lightweight and mobile
Dead ender jacks are constantly on the move, so mobility is a priority for tensioning crews. The C254C, C256C, C258C and C154C all weigh between 15 and 25 pounds, so they’re easy to carry. Handles can also be attached to the jack’s body for added mobility.
Extensive customizability
Hydraulic cylinders are designed to go just about anywhere, which is why the most popular models are compatible with a range of mounting accessories. Also look for collar threads, as they make fixturing easier to manage.
The Flickinger Machine Team Supplies Dead Ender Jacks, and Maintains Them
Dead ender jacks are built for durability, so they’re built to last. As long as the manufacturer’s guidelines are followed, a well-made jack will provide years of reliable performance. When a dead ender jack does have issues, our team can identify and, in most cases, correct them. Whether it’s an unexplained sound or an unexplained leak, we can help.
And if you’re looking for the right dead ender jack for your crew, we can help you select the safest, most cost-efficient option for your application.
Frequently Asked Questions
Seating the wedges on the dead end of a post-tension tendon. Every piece of reinforced concrete gets an anchor at both ends, and the dead end is the one set at the concrete plant before the piece ever reaches the field. The dead ender jack is what applies the force to seat that anchor properly.
Because the job does not need anything more complicated. A single-acting cylinder has one port for hydraulic oil and returns by spring or gravity rather than by a second oil circuit. For dead ending, loading is straightforward and a simpler cylinder is both safer and easier to maintain. Complexity buys nothing here.
Different end of the tendon and a different job. A stressing jack pulls the live end to tension the strand. A dead ender seats the wedges on the anchor at the opposite end, usually in a plant rather than in the field. They are not interchangeable.
When it stops holding pressure or the seating gets inconsistent. That usually points at the cylinder, and cylinders develop seal wear and leaks with cycles. Inconsistent pressure on a wedge-seating tool is worth acting on early, because a poorly seated anchor is not something you want to discover later.
Yes. We carry the cylinders and the wear components for the post-tension jacks we sell, and we service them here in South Houston. Call 832-671-0978 with the model and we will tell you what is on the shelf.
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Push-on dead-end anchorage component for post-tension tendons.
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Nose cones and nose bodies for power-seating jacks and stressing equipment.
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Manual tool for seating wedges in post-tension anchors.
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Grippers and gripper blocks for holding cable during stressing.