Reinforced, primarily intended for motors with a power output above approx. 5–6 hk, but also works for lower power outputs starting at approx. 1 hk
Technical data:
Free length: 27.6 mm (unloaded length)
Outer diameter: Ø=9.4 mm
Wire diameter: Ø=1.2 mm
Number of coils: 8
Number of springs: 6