Exam Question
(a) Describe Hydraulic Jack for large nut tightening used onboard; Draw diagrammatic Sketch of the jack descibing each part. (8)
(b) Describe procedure for tightening and unscrewing the nut with Hydraulic Jacks. (8)
Class 4 (4th Engineer)
MEP
📅 Jan 2023
Reference Answer
### (a) Hydraulic Jack for Large Nut Tightening
#### Principle of Operation
A hydraulic jack, more accurately termed a **hydraulic bolt tensioner**, operates on the principle of axial elongation. Instead of applying a large and often inaccurate torque to a nut, the tensioner directly stretches the stud or bolt along its axis with a precise hydraulic force. While the stud is held in this elongated state, the nut is turned down with minimal effort until it is seated firmly against the joint face. When the hydraulic pressure is released, the stud attempts to contract to its original length, creating a highly accurate and uniform clamping force on the joint. This method eliminates inaccuracies caused by friction between threads and the nut face, which can consume up to 90% of the energy applied during traditional torque tightening.
#### Construction and Parts
#### Principle of Operation
A hydraulic jack, more accurately termed a **hydraulic bolt tensioner**, operates on the principle of axial elongation. Instead of applying a large and often inaccurate torque to a nut, the tensioner directly stretches the stud or bolt along its axis with a precise hydraulic force. While the stud is held in this elongated state, the nut is turned down with minimal effort until it is seated firmly against the joint face. When the hydraulic pressure is released, the stud attempts to contract to its original length, creating a highly accurate and uniform clamping force on the joint. This method eliminates inaccuracies caused by friction between threads and the nut face, which can consume up to 90% of the energy applied during traditional torque tightening.
#### Construction and Parts
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