What do you know about Strand Jacks and how does it work
by Pooja Late so cutStrand jacks are specially configured hydraulic jacks, which can give continuous pulling or lifting
movement. A combination of a number of strand jacks can lift very heavy loads
of thousands of tons, whereas the jack itself weighs very less and occupies
only a very small footprint.
Hydraulic jacks are small devices that can do a large work using
hydraulic pressure. Strand jacks use
a combination of gripping and lifting to produce a continuous linear movement
that can lift very heavy loads to great heights. These are especially very
useful in lifting heavy loads in restricted areas. They are also simple to
install and operate.
How does it work?
A number of strands - steel wires - arranged circumferentially
passes through a hydraulic cylinder jack with anchors at both ends of the jack.
The anchors have grips which alternatively grip and release the strands. The
strand jack is positioned on a support beam vertically on top of the location
to where the load has to be lifted. The load is connected to the strands by a
suitable block. To start with the upper anchor grips the strands, and the
hydraulic cylinder forces the anchor upwards together with the strand and the
load connected to it. Once it reaches the stroke length, the lower grip, grips
the strands preventing it from going down. The upper grip is released and the
hydraulic cylinder strokes down to the bottom position. The upper grip then
grips the strands and the lower grip is released. The cycle repeats itself
creating a continuous linear movement, lifting the load.
How is it more
effective than using a crane?
For lifting a large load of say 200 Tons a 350 Ton
crane is required. A 350 Ton crane with all its accessories can weigh around
250 Tons. Mobilizing and de-mobilizing the crane, assembling the booms, having
trained operators all are logistic headaches. Added to this, positioning the
crane in restricted areas can also lead to very great difficulties. On the
other hand the jack itself is much smaller equipment weighing only around 4
tons. It operates on the normal electric supply system. Even one operator can
control the entire operation. The existing structures can be used to support
the jack, or in other cases a temporary support system can be used. All these
weigh considerably less than the crane. This makes the installation and use of
the Strand Jack much easier.
·
As the radial
distance between the crane and the load point increases, it considerably
reduces the lifting capacity of the crane. The jack applies the lifting force
exactly in-line with the point of load, capacity is fully utilized.
·
A number of jacks
can be operated simultaneously by computers or hydraulic controllers to lift
very large loads of thousands of tons. Even the tandem use of two cranes is
very difficult operation.
·
A crane normally
uses a single strand hoist with pulley sheaves to lift the load. Whereas each
strand jack uses multiple strands to lift the load. This adds to the redundancy
and safety.
·
In restricted
areas where cranes do not have access, strand
jacks are the best bet.
Author’s Bio
John Trump in this piece enlightens his readers on
what hydraulic jacks are. He went
further to explain that strand jacks
uses a combination of gripping.
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Created on Jan 19th 2018 03:43. Viewed 218 times.