Technical Data Locking Device Sizing and procedure
To view selection procedures and precautions, please proceed to the following.
Click here to narrow down the product series or to make a tentative selection.
If you have specific conditions of use and wish to make a detailed selection, please click here.
Selection of ML series
1. Maximum Torque and Maximum Thrust
Calculate maximum torque and thrust based on transmissible capacity and safety factor f.
※For servo motor and stepping motor locking, use the maximum torque (peak torque) of each as the maximum torque to be generated (Tmax).
| SI Unit |
|---|
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Tmax = 9550 × H n ・f Tmax = Max. Generated Torque (N・m)
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| Gravity unit |
|---|
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Tmax = 974 × H n ・f Tmax = Max. Generated Torque (kgf・m)
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Pmax = Pax・f
- Pmax：Max. Thrust Load kN{kgf}
- Pax：Thrust load kN{kgf}
- f：Service factor
f：Service factor
| Load conditions | Service factor | |
|---|---|---|
| Load without shock | Low inertia | 1.5～2.5 |
| Load with minor shock | Medium inertia | 2.0～4.0 |
| Load with major shock | High inertia | 3.0～5.0 |
If only torque is applied
Compare the Tmax obtained from the above calculation with the catalog rated transmissible torque Mt.
Mt ≥ Tmax → Acceptable
Mt < Tmax → Use larger size or multiple units.
If torque and thrust are applied simultaneously
Calculate the total load MR, and compare it with transmissible torque Mt.
MR = Tmax2 + (Pmax × d 2 )2
- Tmax：Max. Generated Torque N・m{kgf・m}
- Pmax：Max. Thrust Load N{kgf}
- d：Shaft diameter m
Compare the MR obtained from the above calculation with the catalog rated transmissible torque Mt.
Mt ≥ MR → Acceptable
Mt < MR → Use larger size or multiple units.
*Installing multiple units is possible for this series. When installing more than one unit, multiply the Mt value with the multiplying ratio given below.
| Quantity | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Amplification | 1 | 1.2 | Inapplicable | Inapplicable |
2. Shaft and Hub
(1) Material Strength
Select shaft and hub materials that meet the following strength requirements.
σ0.2S ≧ 1.4 × P
σ0.2B ≧ 1.4 × P'(When B ≥ ℓ )
σ0.2B ≧ 1.4 × P'K(When B < ℓ )
When B < ℓcalculate PK using the following formula.
P'K = P'・ ℓ B
- P ：Shaft-side contact pressure MPa{kgf/mm2}
- P'、P'k：Hub-side contact pressure MPa{kgf/mm2}
- σ 0.2S：Yield point of shaft material MPa{kgf/mm2}
- σ 0.2B：Yield point of hub material MPa{kgf/mm2}
Please refer to the strength table for iron and steel materials, which shows the yield point values of typical steel materials.
(2) Hub Outer Diameter
After determining the product size, hub material, and contact pressure between the outer ring and hub, find the required minimum outer hub diameter DN in the Hub Diameters table for ML Series shaft-hub locking devices.
DN ≦ Outer hub diameter
If you are calculating the outer hub diameter use one of the following formulas.
DN ≧ D σ0.2B + K3・P' σ0.2B - K3・P' (When B ≥ ℓ )
DN ≧ D σ0.2B + K3・P'K σ0.2B - K3・P'K (When B < ℓ )
- DN：Hub outer diameter mm
- D ：Inner Hub Diameter mm
- σ 0.2B：Yield point of hub material MPa {kgf/mm2}
- P'、P'K：Hub-side contact pressure MPa{kgf/mm2}
- K3：Hub configuration coefficient (See illustration below. )
(3) Hollow Shaft Inner Diameter
Calculate the hollow shaft inner diameter using the following formula.
dB ≦ d σ0.2S - 2 × P σ0.2S
- dB：Maximum hollow shaft inner diameter mm
- d：Shaft diameter mm
- σ0.2S：Shaft material yield point MPa{kgf/mm2}
- P：Shaft-side contact pressure MPa{kgf/mm2}
3. Radial load
If a large load acts to the Power-lock ML as a radial load Pr, as in belt drive applications, calculate the contact pressure on the shaft Prad and the contact pressure on the hub P'rad (P'krad). Then, it is acceptable if Prad, P'rad (P'krad) are 25% or less of P and P', respectively.
Prad = 1.3 × Pr d × ℓ ≦ 1 4 × P
P'rad = 1.3 × Pr D × ℓ ≦ 1 4 × P' (When B ≥ L1 )
P'krad = 1.3 × Pr D × ℓ ≦ 1 4 × P'k (When B < L1 )
- Pr：Radial load N{kgf}
- ℓ：Width of hub and outer ring contact surface mm
- B：Hub width mm
- d：Shaft diameter mm
- D：Inner Hub Diameter mm
- P：Shaft-side contact pressure MPa{kgf/mm2}
- P'、P'k：Hub-side contact pressure MPa{kgf/mm2}
If a radial load applies, calculate the required hub outer diameter Dn and inner hollow shaft diameter dB by adding Prad and P'rad to P and P' (P'k) respectively.
