U.S. TSUBAKI POWER-LOCK ®
Technical Notes SELECTION GUIDE AND PROCEDURE
STEP 2
Shaft and Hub
(b) Bolts Fastened to the Shaft Section
EL Series POWER-LOCKs do not have a self-centering function. A hub must be pre-centered, using the guide portion provided between the shaft and hub. A guide portion length above d/2 is generally preferred. Also, select guide tolerance based on the degree of accuracy you desire. (1) Material Strength Select shaft and hub materials that meet the following strength requirements. σ 0.2S ≧1.4×P σ 0.2B ≧1.4×P´ σ 0.2S 、 σ 0.2B ： Yield point of shaft and hub material P, P´： Contact pressure on the shaft and hub bore (2) Required Hub Outer Diameter D N and Allowable Hollow Shaft Bore Diameter d B Hubs must have a D N that is greater than the value obtained from the following formula.
P, P´ : Contact pressure on the shaft and hub.
STEP 3 Selecting Locking Bolts
(1) Bolt Strength Classes and Mechanical Properties In general, 10.9 and 12.9 class bolts should be used. These bolts are less affected by vibration and do not loosen as easily as others. (2) Bolt Head Bearing Surface Pressure When using 10.9 or 12.9 bolts, check the pressure at their bearing surfaces. If this pressure exceeds the maximum values provided below, the bearing surfaces will eventually deform, causing the bolts to loosen from decreased axial force. When the bearing pressure rises above the maximum values, reduce by increasing the strength of pressure flange (either change the material or treat with heat) or by lowering the tightening torque in order to prevent the bearing surfaces from deforming.
If using a hollow shaft, its bore must be equivalent to or less than the d B obtained from the appropriate formula below.
(a) Bolts Fastened to the Hub Section
D ：Bolt head diameter mm da max ：Nominal diameter mm
Bearing surface pressure Ps＝Fv／As
F V ：Tightening torque
72
More information at www.ustsubaki.com
Made with FlippingBook Digital Proposal Creator