The PEI Patented design known as SURE-SPRING® represent the most advanced level of technical innovation in the field of roll-up covers.

sure spring

  • Suitable for HIGH SPEED operation
  • The multiple springs remain COAXIAL
  • The springs NEVER INTERSECT
  • REDUCED overall diameters
  • EXCELLENT reliability
  • Advancement speeds of up to 150 m/min
  • Acceleration of up to 2 g
  • 2,000,000 movements guaranteed
  • SECURE attachment of the band to the tube, because NO adhesive products are used
  • PRACTICAL maintenance, since the band can be replaced quickly and easily
  • Also suitable for use in work environments where STRONGLY AGGRESSIVE chemicals are used
  • HEALTHY for the environment.

SURE-SPRING® Technical Specifications


sure spring app01

The rotary movement of the tube in relation to the fixed central shaft is transmitted by a sliding spline.
This system compensates for the elongation of the multiple springs by moving the spring mounting point axially along a threaded shaft.


sure spring app02

This new system allows the multiple springs to work according to an ideal geometry, keeping their coils properly spaced.


sure spring app03

This is the most reliable system for insuring a secure attachment between the band to the tube.


1) Traditional system
2) PEI SURE-SPRING® system

This illustration clearly highlights the different behavior of the spring mechanisms during operation:

  • In Mechanism 1 (traditional system) the springs are rigidly attached to the fixed caps at the ends of the shaft.
    In this system the springs helically twist and snake while winding or unwinding, causing obvious problems of friction and wear between the coils as well as between the coils and the central shaft.
  • In Mechanism 2 (SURE-SPRING® system) the springs are attached to a special moving cap, which slides lengthwise while winding and unwinding, keeping the spring coils packed and concentric at all times.
    This spring configuration avoids most of the wear mentioned above, allowing better performance and a much longer operating life-span for the spring mechanism.

Recommended dimensions


The SURE-SPRING HP winding mechanism is the answer to the elevated power required to wind up large size protectivecovers.
An optimal dimensioning of the springs guarantees the tensile force required for moving “J”-series apron covers.

Sure Spring