Tsubaki: The solution for shaft locking devices
Technical Notes SELECTION GUIDE AND PROCEDURE
SL Series
(1) When the required transmissible torque Mt is different from the (Mt) listed in the EL Series Specifications table Calculate the actual locking force Fe, thrust Pax, contact pressure P and P' using the following formulas. C 1 ＝ Mt／〔Mt〕 ( Required transmissible torque ratio） Fe ＝ C 1 ×〔Fe〕 ( Actual locking force） F ＝ Fo＋Fe （Total Force） Pax ＝ C 1 ×〔Pax〕 (Transmissible thrust） P ＝ C 1 ×〔P〕 ( Contact pressure on the shaft） P´ ＝ C 1 ×〔P´〕 ( Contact pressure on the hub） Mt： Required transmissible torque Fo, [Fe], [Mt], [Pax], [P´]: Values are listed in EL Series Specifications table STEP 1 Actual Locking Force, Transmissible Torque and Contact Pressure EL Series 2) When the required actual locking force Fe is different from the (Fe) listed in the EL Series Specifications table Calculate transmissible torque Mt, thrust Pax, contact pressure P and P' using the following formulas. C 2 ＝ Fe／〔Fe〕 (Required actual locking force ratio） Mt ＝ C 2 ×〔Mt〕 (Transmissible torque） Pax ＝ C 2 ×〔Pax〕 (Transmissible thrust） P ＝ C 2 ×〔P〕 (Contact pressure on the shaft） P´ ＝ C 2 ×〔P´〕 (Contact pressure on the hub） Fe： Required actual locking force Note: 0.25≦C 2 ≦2
STEP 1
Shaft and Hub
(1) Material Strength Large contact pressure applies to both the shaft and hub during installation. Select shaft and hub materials that meet the following strength requirements. σ 0.2S ≧ 1.2 × P σ 0.2B ≧ 1.2 × P´
P : Contact pressure on the shaft P ´ : Contact pressure on the hub σ 0.2S : Yield point of shaft material σ 0.2B : Yield point of hub material
(2) Hub Material Strength Torque and contact pressure will combine and produce stress on the hub. Calculate this stress using one of the following four formulas. (a) Stress applied to the hub from a normal direction ( σ w) σ W=−P P: Shaft contact pressure (b) Stress applied to the hub from a tangential direction ( σ t)
P : Contact pressure on the shaft P ´ : Contact pressure on the hub d W : Shaft diameter d : Hub outer diameter (c) Shearing stress applied to the hub by torsional force ( τ B ）
(d) Combined stress applied to the hub （σv）
Make sure σ 0.2B (yield point of the hub material) is greater than σ V . σ V ＜ σ 0.2B
(3) Hollow Shaft Inner Diameter Calculate the inner
(3) Multiple POWER-LOCK Installation Calculate transmissible torque Mtz, thrust Paxz and contact pressure Pz and P'z using the following formulas. (z is the number of EL units installed.)
diameter of a hollow shaft using the following formula.
Mtz ＝ S・Mt 1 Paxz ＝ S・Pax 1 Pz
d B : Hollow shaft inner diameter d W : Hollow shaft outer diameter σ 0.2S : Yield point of shaft material P : Contact pressure between the inner ring and shaft
＝ P 1 （Contact pressure on the shaft） P´z ＝ P´ 1 （Contact pressure on the hub） Mt 1 , Pax 1 , P ´ 1 apply to single unit installation.
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