technical data Power-Lock Selection and Procedure

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SL Series Selection

1. Check the maximum torque and thrust load

The maximum torque and thrust load are calculated by Service factor in the transmission capacity.

*When connecting a servo motor or stepping motor, use the maximum torque (peak torque) of each as the maximum generated torque (Tmax).

SI units

Tmax = 9550 × H n ・f

Tmax = Maximum torque (N・m)

  • H: Transmission capacity (kW)
  • n: Power-Lock mounting shaft rotation speed (min-1)
  • f: Service factor
Gravity Units

Tmax = 974 × H n ・f

Tmax = Maximum torque (kgf・m)

  • H: Transmission capacity (kW)
  • n: Power-Lock mounting shaft rotation speed (min-1)
  • f: Service factor

Pmax = Pax・f

  • Pmax: Maximum thrust load kN{kgf}
  • Pax: Thrust load kN{kgf}
  • f: Service factor

f: Service factor

Load Condition Service factor
Smooth load without shock Small inertia 1.5～2.5
Light shock load Medium inertia 2.0～4.0
High impact loads Large inertia 3.0～5.0

When only torque is applied

Compare the Tmax obtained above with the catalog transmission torque Mt.​

Mt ≧ Tmax → Can be used.

​Mt < Tmax → Consider increasing the model number.

When torque and thrust load are applied simultaneously

The combined load M R is calculated and compared with the transmitted torque M t.

MR = Tmax2 + (Pmax × d 2 )2

  • Tmax: Maximum torque N・m{kgf・m}
  • Pmax: Maximum thrust load N{kgf}
  • d: shaft diameter m

Compare the M R calculated above with the catalog transmission torque Mt.​

M t ≧ M R → Can be used.

M t < M R → Consider increasing the model number.

*This series cannot be used in multiple units.

2. Consideration of the axis and boss

(1) Consideration of material strength

A large surface pressure acts on the shaft and boss when fastened. For this reason, the shaft and boss should be made of a material with a strength that satisfies the following formula.

σ0.2S≧ 1.2 × P       σ0.2B≧ 1.2 × P'

  • P: Shaft side pressure MPa{kgf/mm2}
  • P': Boss side pressure MPa{kgf/mm2}
  • σ 0.2S: Yield stress of shaft material used MPa{kgf/mm2}
  • σ 0.2B: Yield stress of the boss material used MPa {kgf/mm2}

Please refer to the steel material strength table, which shows the yield point values of representative steel materials.

(2) Boss strength considerations

The boss will generate a combined stress due to the applied torque and surface pressure. Calculate this combined stress using the following formula.

  • (a) Normal stress (σ w) generated in the boss

    σW = - P MPa{kgf/mm2}

    P: Shaft side pressure MPa{kgf/mm 2}

  • (b) Tangential stress (σ t) generated in the boss

    σt = P(1 + Q2) - 2 × P' 1 - Q2 MPa{kgf/mm2}

    Q = dW d

    P: Shaft side pressure MPa{kgf/mm 2}

    P': Pressure on outer hub diameter MPa{kgf/mm 2}

    d W: Shaft diameter mm d: outer hub diameter mm

  • (c) Shear stress due to torsion of the boss (τB)

    τB = 1600 × Tmax・d π(d4 - dW4) MPa{kgf/mm2}

Ensure that the yield stress (σ 0.2B) of the boss material you use is σv < σ0.2B.

(3) Consideration of the inner diameter of the hollow shaft

When using a hollow shaft, calculate the hollow shaft inner diameter using the following formula.

中空軸内径の検討

dB ≦ dW σ0.2S - 1.6 × P σ0.2S

  • d B: Maximum allowable hollow shaft inner diameter mm
  • d: shaft diameter mm
  • σ0.2S: Yield point of shaft material MPa{kgf/mm 2}
  • P: Shaft side pressure MPa{kgf/mm 2}