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Rotary Ball Spline SPB



The NB ROTARY BALL SPLINE SPB type combines a spline nut and a set of angular contact bearings in a compact, high accurate, and high-speed rotation-capable assembly, providing both linear and rotational motion at the same time.

Structure of SPB type

Structure of SPB


Preload and clearance

The amount of clearance and preload for the spline nut is expressed in terms of the clearance in the rotational direction. Three levels of preload are available: standard, light( T1), and medium( T2).
The preload is properly adjusted by the spacer for the angular contact bearings.

Table 1 Preload and Clearance in Rotational Direction( Linear Motion) unit/μm
part number standard light(T1) medium(T2)
SPB16 -3~+1 -8~-3 -13~-8
SPB20 -4~+2 -12~-4 -20~-12
Table 2 Operating Conditions and Preload
preload symbol operating conditions
standard blank minute vibration is applied. a precise motion is required. a torque is applied in a given direction.
light T1 slight vibration is applied. slight torsional load is applied. cyclic torque is applied.
medium T2 shock/vibration is applied. over-hang load is applied. torsional load is applied.

The spacer is adjusted to give a proper spacing for the best preload condition. Please do not adjust the spacer.



The NB ROTARY BALL SPLINE is measured for accuracy at the points shown in Figure 2.

Figure 2 Accuracy Measurement Points


Table 3: Tolerance of Spline Shaft Groove Torsion(Max.)
accuracy grade
precision( P)

The groove torsion is indicated per 100mm, arbitrarily set as the effective length of the spline shaft section.

Table 4: Tolerance Relative to Spline Support Area(Max.) unit/μm
part number ①radial runout of part attachment area ②perpendicularity of the end of the spline shaft section
(when grinding is requested on the drawing)
③perpendicularity of the flange
high-grade precision-grade(P) high-grade precision-grade(P) high-grade precision-grade(P)
SPB16 19 12 11 8 18 13
SPB25 22 13 13 9 21 16
Table 5: Radial Runout of Outer Surface of Rotary Spline Nut Relative to Spline Shaft Area(Max.) unit/μm
part number ④lateral runout of flange mounting side ⑤radial runout of outer ring
high-grade precision-grade(P) high-grade precision-grade(P)
SPB16 18 13 21 16
SPB25 21 16
Table 6: Radial Runout of Spline Nut Relative to Spline Support Area(Max.) unit/μm
spline shaft total
part number
SPB16 SPB20・25
greater than or less high-grade precision-grade(P) high-grade precision-grade(P)
200 34 18 32 18
200 315 45 25 39 21
315 400 53 31 44 25
400 500 62 38 50 29
500 630 75 46 57 34
630 800 92 58 68 42
800 1,000 115 75 83 52
1,000 1,250 153 97 102 65
1,250 1,600 195★ 127★ 130 85
1,600 2,000 171 116

★SPB16 shaft maximum length : 1,500mm

Part number structure

Part numbering


↓It expands by click.



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