5.8　Hydraulic Lifting Equipment

5.8.1　Medium Bore Jack

5.8.1.1　Medium bore jack shall be used with appropriate power unit in accordance with the manufacturer′s technical documents.

5.8.1.2　Medium bore jack shall be firmly supported，and shall be capable of carrying applied load.

5.8.1.3　The number of steel strands reeving through a medium bore jack shall be determined depending on the lifting load.After all steel strands are reeved through the medium bore jack，they shall be adjusted one by one to ensure that an even force is carried through each steel strand between the upper and lower anchorage.

5.8.1.4　To ensure that steel strands can be vertically pulled out of the medium bore jack，a proper support shall be provided to hold the steel strands.Additionally，the weight of the steel strand pulled out shall not be applied on the plunger rod of the medium bore jack.

5.8.1.5　Where medium bore jack is used to lift a workpiece，the slip path of the steel strands pulled out of the medium bore jack should be of a rolling friction type track.

5.8.1.6　If medium bore jacks experience local slackness in the steel strands during service，they shall be stopped for cause analysis and subsequent adjustment.

5.8.1.7　Medium bore jacks whose steel strands have been properly reeved should not be lowered under empty load.

5.8.1.8　Before and after operation of medium bore jack，all clips on the anchorage shall be cleaned and checked for any damage，and those with 20% of effective tooth loss shall be replaced with new ones.

5.8.1.9　Medium bore jack，when in service，shall have an included angle of not larger than 2°between the steel strands and the axis of the jack.

5.8.1.10　Steel strands that are bent，oil contaminated and pitted shall not be used.

5.8.1.11　When the oil piping and control line of a medium bore jack are connected，commissioned and accepted，the following items shall be inspected:

a）All rods，pins and release plates for free rotation；

b）Clamping jaw of the upper and lower anchorage for cleanliness and good lubrication；

c）Oil cylinder of main jack and micro jack for oil tightness；

d）Oil piping and quick connector for oil tightness.

5.8.1.12　Where several groups of medium bore jacks are used，an equalizing device shall be provided between every two medium bore jacks，and between every two medium bore jack groups.

5.8.2　Clamping Jack

5.8.2.1　Clamping jack shall be used with appropriate power unit in accordance with the manufacturer′s technical documents.Before clamping jack is put into service，the teeth of the steel clamp wedge shall be checked for cleanliness without any foreign matters，and the formed or hardened layer of the sharp tooth surface shall be free of any damage.

5.8.2.2　Clamping jack shall be installed according to the moving direction of the workpiece.

5.8.2.3　For clamping jack，the dimension error of the square steel cross section deviated from the centerline shall not exceed±0.5mm，the straightness error of each square steel shall not exceed 1/1000 of its length and shall not be greater than 5mm，and the stagger deviation of the square steel joints shall not be greater than 1mm.

5.8.2.4　Clamping jack and square steel shall be securely supported，and shall be capable of carrying applied load.

5.8.2.5　The square steel surface being clamped shall be free of any paint，oil，scale and dirt.

5.8.2.6　When the oil piping and control line of a clamping jack are connected and commissioned，the following items shall be inspected:

a）All rods and pins for free rotation；

b）Pistons and glands for oil tightness；

c）Clamping jaw of the upper and lower anchorage for cleanliness and good lubrication；

d）Oil piping and quick connector for oil tightness；

e）Power unit and control system for proper operation.