Product category:
Roads, Bridges and Tunnels
News Release from: Enerpac | Subject: Aluminium jacks
Edited by the Buildingtalk Editorial
Team on 22 October 2003
Lightweight Contender Challenges
Heavyweight
Aluminium jacks offer the most economical long-term solution to pushing, pulling or lifting applications.
The rigger picks up 100 ton jacks and hefts them into place to set a bridge section, thinking about how it used to be The waiting for lifting equipment and help
This article was originally published on Buildingtalk on 23 Jan 2003 at 8.00am (UK)
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The pushing and prying.
What changed? The weight of his jacks went from 60 kg to one-third that, because his new ones are made from high-strength aluminium.
Way back in 1663, Pascal described the transmission of fluid pressure from point to point and its application to the hydraulic jack.
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Ever since, jacks have served to lift and move bridges and structures.
The very simplicity of the device has limited innovations to details such as better seals, surface hardening and variations in size, shape, and accessories.
Generation after generation, one thing remained constant: the plunger and housing were machined from steel.
Steel reigned supreme as the basic material of jack construction until about a decade ago, when aluminium jacks appeared on the scene.
Aluminium jacks offer considerably lighter weight, but had their drawbacks.
The benefits of aluminium's lighter weight were reduced by the lower material strength of common alloys as compared with steel.
The lower material strength meant thicker parts, which offset some of the weight advantage and also made aluminium jacks bulky.
Weight-loss program Jacks have followed the same pattern as beverage cans and cars.
First, aluminium was introduced as a replacement for steel.
After that, attention was devoted to reducing bulk and cutting more weight.
Computerized design, finite element analysis and modern alloys have made quite a difference.
The 7075T-6 alloy provides strength that rivals steel.
The result: aluminium jacks are now available in weights as low as one-third that of their steel counterparts, yet their physical size is virtually the same as for steel.
The lightness of aluminium jacks provides a two-fold benefit: not only are they easier to handle, but the jack size that can be handled manually by one or two workers is doubled.
That is significant in light of the increased safety margins that may be required by Departments of Transportation; a lift-point that requires, for example, a 50-ton capacity may have to be served by a 100-ton jack.
Manually placing a 100-ton aluminium jack is no problem; steel can be another story.
What about corrosion? Properly designed aluminium jacks are corrosion resistant.
In fact, they are selected for use in drydocks because of their resistance to saltwater.
In certain situations, the non-magnetic properties of aluminium are of special interest.
In those cases, the ancillary steel parts can be replaced with aluminium versions to create a non-magnetic jack.
Do the math When considering procurement of hydraulic lifting equipment, life-cycle cost analysis is the key to spending the least money.
Upfront, steel jacks cost considerably less than aluminium jacks, but that's only the first chapter of the story.
Purchasing justification should include a brief explanation of differences in total cost over the life of the equipment.
Here's an example.
A purchase of 150-ton jacks is being considered.
It is estimated that each jack will be placed 1000 times during its lifetime.
If the steel version requires an additional 50 euros of labor compared to the aluminium model each time it is placed; then the lifetime labor usage cost of the steel jacks is 50.000 euros higher than the aluminium version.
Don't agree with the numbers? Use your own.
The savings are almost certain to be dazzling, even when more sophisticated analysis includes factors such as the time value of money.
What to look for Today's aluminium jacks may offer a far more attractive alternative to steel than the limited selection of bulky models available a decade ago.
But there 's more to aluminium hydraulic jacks than the aluminium.
In order to cover your needs without having to use multiple sources, look for a supplier that provides: * Lifting range 3/4 A 20 to 150 ton range covers the realm of manually placed jacks.
* Type selection 3/4 Availability of single- and double-acting, hollow plunger, and lock nut versions assures ability to meet project requirements.
* Stroke range 3/4 Availability of a wide stroke range, such as 50 to 250 millimeters for each capacity and type, covers most requirements.
* Surface hardening 3/4 Plunger and housing should be both hardened and anodized to resist wear and galling.
• Stop rings 3/4 Jacks should be equipped with stop rings to positively prevent over-extension.
* High-strength alloy 3/4 Only jacks made from high-strength alloy deliver the full benefits of aluminium construction.
* Composite bearings 3/4 These prevent metal-to-metal contact, reduce side-load problems and increase life.
* Steel base-plate 3/4 For protection from abrasive surfaces, a replaceable steel base-plate should be supplied with each jack.
* Removable saddle 3/4 A removable, hardened steel saddle handles wear caused by use on concrete and other abrasive surfaces.
* Compliance with ASME B30.1 3/4 This is the design and test specification for jacking cylinders.
(Jacking cylinders are not to be used for production or other "high-cycle" uses.) The bottom line For those willing to make the initial investment, aluminium jacks offer the most economical long-term solution to pushing, pulling or lifting applications.
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