MAKISHINKO ALL PRODUCTS GUIDE
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E-19JACKJA Allowable axial direction loadScrew jack, depend on application, must preventeffect of bucking on screw, there is limitation ofapply of the axial direction load.Allowable bucking-load can be calculated by thefollowing formula.W=nf・π2・E・Ⅰ・α(Eulers formula)L2W:permissible bucking Load(N)E:vertical modulus elasticity factor 2.06×105(N/㎜2)Ⅰ:minimum sectional secondary moment of screw shaft(㎜4)Ⅰ=πd464D:screw shaft root diameter(㎜)L:shaft supporting length(㎜)nf:factor by installation methodFixed-freenf=1/4(0.25)Supported-supportednf=1Fixed-supportednf=2α: safety factor0.25Example of calculationJack size JA050From the basic specification, screw shaft rootdiameter d=31.5㎜, minimum sectional secondarymoment of screw shaft is,Ⅰ=π×31.54=48329(㎜4)64Shaft supporting length L=1000(㎜)Installation method: fixed-freenf=1/4Permissible bucking loadW=0.25×3.142×2.06×105×48329×0.2510002≒6135(N)=6.1(kN)In addition, in the case of permissible bucking loadexceeds nominal capacity, the permissible axialdirection load should be limited to nominalcapacity.Shaft supporting length Lshaft end freeJack fixed15001250100075050040030025020015010075502510251100Graph1 fixed-freelySizenf =1/450010000500020001000kNAxial Supporting length(㎜) Axial direction load

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