﻿GET_GEVOMechL2_01_01_01_19 - ANIMATION Screen
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Tightening large bolts requires very high tensioning torques that can be difficult to achieve.

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You can overcome this problem by using a hydraulic torque wrench.

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Hydraulic tensioning devices are commonly used for bolts over 20 mm in diameter.

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The tension method uses a small hydraulic ram, which fits over the nut.

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The threaded portion of the bolt or stud protrudes well past the nut, and a threaded puller is attached.

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Hydraulic oil from a small pump acts on the hydraulic ram, which in turn acts on the puller.

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The puller stretches the bolt or stud.

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The nut can then be rotated by hand with an integral socket aided by a bar or pin.

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Control of the hydraulic pressure effectively controls the preload in the bolt.

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However, a small amount of preload reduction occurs when the pressure is removed as the nut elastically deforms under the load.

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It can also be difficult to remove nuts corroded to bolts with this method.

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The tensioning method solves most of the problems with torque control and bolt elongation measurement tools.

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In addition, hydraulic tensioning devices eliminate the problem of thread galling and allow all the bolts or studs on that part of the assembly to be tightened with identical amounts of force, all at the same time.

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This eliminates the danger of uneven pressure distribution on parts and gaskets.
