A narrow V-belt is a power transmission belt with a greater depth-to-width ratio than a classical V-belt. The narrow profile places more of the sheave directly under the reinforcing cord, so loads are transferred more directly to the sheave sides with minimum load shedding. For a given width, narrow V-belts therefore have power ratings up to 3 times higher than conventional V-belts — or the same horsepower can be transmitted in one-third to one-half the drive space.
Raydafon narrow V-belts are manufactured to DIN 7753 and ISO 4184 standards in DIN sections SPZ, SPA, SPB, SPC, and to RMA/MPTA standards in sections 3V, 5V, 8V. All sections have a 40° wedge angle. Maximum recommended belt speed is 40 m/s. Available lengths range from 508 mm to 16,500 mm.
The construction uses an oil and heat-resistant neoprene rubber compound with high-strength polyester, nylon or aramid tensile cords. Wrapped, raw-edge and cogged configurations are available for different pulley diameter and speed requirements.
Narrow V-belt — SPZ / SPA / SPB / SPC / 3V / 5V / 8V — ISO 4184 / DIN 7753 compliant
The narrow V-belt cross-section determines the power range and pulley compatibility. Use the dimensions below to verify fitment with your existing sheaves. All sections have a 40° wedge angle.
Values in the table are nominal. For raw-edge cogged belts, the recommended minimum pulley diameter may be smaller. Send your pulley dimensions for a fitment check.
The cross-section diagram shows the trapezoidal profile and dimensional references for the narrow V-belt. The dimensions D (datum width), H (height) and the 40° wedge angle define the belt's engagement with the sheave groove.
Cross-section diagram — trapezoidal profile, 40° wedge angle, datum width and height references
Narrow V-belt product view — wrapped construction with oil and heat-resistant neoprene compound
The performance of a narrow V-belt depends on two critical components: the rubber compound that grips the pulley, and the tensile cords that carry the load.
Narrow V-belts are specified wherever high power must be transmitted in a compact drive space. The 3x power advantage over classical V-belts makes them particularly suitable for space-constrained and high-reduction drives.
The table below shows typical datum length ranges for each narrow V-belt section. Custom lengths are available on request. All dimensions in millimetres.
| Cross-Section | Standard | Datum Length Range (mm) | Typical Applications |
|---|---|---|---|
| SPZ / 3V | DIN 7753 / RMA | 508 – 3,556 | Small motors, light-duty compressors |
| SPA | DIN 7753 / ISO 4184 | 508 – 4,318 | Pumps, machine tools, HVAC |
| SPB / 5V | DIN 7753 / RMA | 1,120 – 6,300 | Medium motors, compressors, agricultural machinery |
| SPC / 8V | DIN 7753 / RMA | 2,000 – 12,500 | Heavy-duty motors, large compressors, mining |
For lengths outside these ranges or for custom sections, contact our engineering team. Values shown are typical reference values; actual availability may vary by cord material and construction.
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