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JACKE-59Shaft supporting length Lshaft end freeJack fixed30025020015010075502510251100Graph1 fixed-freelySizenf =1/450010000500020001000005010025050075100150200kNAxial direction loadAxial Supporting length(㎜) JTB Allowable axial direction loadScrew jack, depend on application, must preventeffect of buckling on screw, there is limitation ofapply of axial direction load.Allowable buckling-load can be calculated by thefollowing formula.W=nf・π2・E・Ⅰ・α(Eulers formula)L2W:permissible buckling load (N)E:vertical modulus elasticity factor 2.06×105(N/㎜2)Ⅰ:minimum sectional secondary moment ofscrew shaft(㎜4)Ⅰ=πd464d:screw shaft root diameter (㎜)L:shaft supporting length (㎜)nf:factor by installation methodFixed-freelynf= 1/4(0.25)Supported-supportednf=1Fixed-supportednf=2α: safety factor 0.25Example of calculation:Jack size JTB 150From the basic specification, screw shaft rootdiameter d=42(㎜), minimum sectional secondarymoment of screw.Ⅰ=π×424/64=152745(㎜4)The shaft supporting length L=1200(㎜)Installation method: fixed-supported nf=2Permissible buckling load isW=2×3.142×2.06×105×152745×0.2512002≒107800(N)=107.8(kN)In addition, in the case of permissible buckling loadexceeds nominal capacity, the permissible axialdirection load should be limited to nominalcapacity.

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