VALICALC / MECHANICAL ENGINEERING SUITE / DS07

Poly-V Belt Drive Design Sheet

Evaluate a ribbed drive using product-appropriate pitch/datum dimensions. Recalculate when actual dimensions change; examine equal rib sharing without borrowing V-belt rating coefficients.

Verified mathematical models with explicit assumptions. Component capacity and applicability are shown as separate checks.

Labeled example inputs • SI calculations • Project revision 0 • No account or cloud upload

01 / ENGINEERING INPUTS

Define the operating point

Physical geometry

Actual driver datum diameter

Actual driven datum diameter

Preliminary center distance

Driver RPM

rpm

Transmitted mechanical power

Operating slack tension per belt/rib

Actual operating span tension; not installation pretension.

Mass per length per belt/rib

kg/m

Actual number of ribs

Equal sharing is assumed; this does not determine a rated count.

Entered speed loss

Percent; a user assumption, not a predicted slip value.

Required minimum small-pulley wrap

deg

0 = not specified; use applicable manufacturer requirements.

02 / CALCULATE → SELECT → RECALCULATE

Calculation & checks

Actual center distance

500 mm

Actual pitch/datum length

1,476.24308 mm

Theoretical length at preliminary center

1,476.24308 mm

Center adjustment

0 mm

Actual reduction ratio

Driven RPM

750 rpm

Belt speed

7.85398 m/s

Small-pulley wrap

168.52166 deg

Effective pull · total

190.98593 N

Tight tension · per belt/rib

131.83099 N

Slack tension · per belt/rib

100 N

Estimated span load on each shaft

1,384.1453 N

Centrifugal tension · per belt/rib

6.1685 N

Schematic authored for this worksheet; not a manufacturing drawing. Numerical pitch/datum dimensions and checks control the calculation.

Intermediate values and comparisons - SI units
State	Center (m)	Exact length (m)	Legacy approximate length (m)	Small wrap (rad)
Preliminary	0.5	1.476243	1.476239	2.941258
Actual / recalculated	0.5	1.476243	1.476239	2.941258

Criterion-specific verification

PASSED · Pitch/datum circle geometry
Positive, non-overlapping pitch/datum circles. Outside diameters, take-up and installation clearances remain unverified.
PASSED · Selected-length recalculation
Exact pitch-line residual 0.00e+0 m.
BLOCKED · Rated belt/rib count
No current applicable product rating dataset. Operating load calculations do not establish allowable capacity.
UNKNOWN · Entered minimum wrap criterion
No applicable minimum wrap supplied.

Method and calculation trace

Actual dimensions control all downstream results. Ratio uses consistent datum/pitch diameters.

Exact tangent geometry solves length and center; the established approximate ValiCalc kernel is retained in the comparison table.

P/v gives total effective pull. 6 equal load-sharing belt/rib path(s); operating slack tension is entered rather than inferred from installation pretension.

Entered speed loss 0% affects driven RPM only; tension uses driver pitch-line speed.

Span-force vector estimate excludes weight and transient loads. No overall safety/capacity approval.

Assumptions & scope

Open two-pulley drive with no idler. Enter consistent actual datum/pitch diameters and lengths. Outside diameters, alignment and take-up travel still need checking.

Tensions are operating values; equal sharing across entered belts/ribs is an assumption. Shaft span-force estimate excludes pulley weight, bearing reactions and transient loading.

Capacity, fatigue, installation pretension and allowable speed require current product-specific evidence. No catalog dimensions or ratings are inferred.

Required rib count and allowable rib load are BLOCKED until current profile-specific catalog ratings, wrap corrections and installation guidance are available. V-belt wedge factors are not transferable.

Worked example

Six equally sharing ribs transmit 1.5 kW at 7.854 m/s with 31.831 N effective pull per rib. This is a load requirement, not a six-rib capacity approval.

Calculation methods and sources

L ≈ 2C + π(D+d)/2 + (D−d)²/(4C); small wrap = π−2 asin(|D−d|/(2C))

Open two-pulley drive, consistent pitch/datum diameters in metres. No crossed belt or idler. Existing approximate length/wrap kernels are reused.

Tập 1, Chapter 4; SDP/SI technical section 22

L = 2√(C²−δ²) + π(D+d)/2 + 2δ asin(δ/C); δ=|D−d|/2

Exact ideal tangent pitch-line geometry. A bounded bisection solves selected pitch length → physical center distance. No tooth deformation or installation tension correction.

Independent tangent geometry; SDP/SI equation 22-11

ΔT = P/v; T tight = T slack + ΔT; R = √((Tt+Ts)²cos²α + (Tt−Ts)²sin²α)

α = asin(|D−d|/(2C)). Steady span-force estimate using entered slack tension or operating tension ratio. Equal belt/rib sharing is an explicit assumption; no rated belt count is inferred.

Gates Heavy Duty V-Belt Drive Design Manual, tension ratio D18; independent vector sum

Textbook references identify the method context. Historical numerical catalog, material and service-factor tables have not been copied or treated as current product ratings.

Related calculators and references

Existing component-selection Jobs → · All mechanical worksheets →

Common questions

Does this approve a real component?

No. The worksheet separates mathematical results from criterion-specific checks. Actual motor, belt, sprocket and chain capacity need applicable current manufacturer data and installation review.

What changes after choosing a physical size?

The worksheet recalculates the outputs and geometry from the entered actual dimensions or discrete tooth/link count. Dependent checks are reevaluated; previously saved results are not restored as approvals.