Mechanical Design

Use this calculator to determine the gear ratio between a driver and driven gear, the output shaft speed (RPM) and the output torque. Enter the number of teeth on each gear and the input speed or torque. Applies to spur, helical and bevel gear pairs following AGMA standards.

Compute gear module m, tooth pitch t, pitch circle diameter D, addendum circle da, root circle df, full tooth depth h and pair centre distance C. Works in three modes: compute module from D and Z, compute diameters from module, or find the centre distance of a meshing pair.

Compute pitch cone angle γ₀, back cone angle α, equivalent tooth count Zc, pitch circle diameter D, tip circle diameter Da, cone distance A, tip/root cone angles for straight bevel gear pairs. Two modes: cone angles only (Table 1) or full dimensions (Tables 1 + 2).

Determine the theoretical minimum number of teeth to avoid undercutting during gear hobbing or shaping, and compute the minimum profile shift coefficient x₀ and required shift amount Lₜ for gears with fewer teeth than the safe limit.

Calculate the rated service life L_h (hours) of a rolling bearing using the simplified Chinese standard method. Enter the basic dynamic load rating C, the applied load W, and the rotational speed n. Optionally enter the reliability factor a₁ and combined factor aᵢₛₒ to compute the ISO 281 modified life Lₙₘ.

Determine the minimum required thread major diameter for bolts subjected to axial tensile loads, combined axial and torsional loads, or shear forces perpendicular to the bolt axis. Results are automatically rounded up to the nearest standard metric size.

Use this calculator to determine the required thread engagement length (screw-in depth or nut height) and verify that the contact surface stress on thread flanks stays within allowable limits. Applicable to metric threads per ISO 261 / GB standards.

Calculate rivet shear capacity, plate tear-out strength, bearing pressure, minimum pitch, and joint efficiency with metric/imperial unit support.

Determine the minimum required diameter for shafts subjected to bending moments. Supports both solid shafts (Formula ①) and hollow shafts (Formula ②) with an inner-to-outer diameter ratio k. For design, use the larger of the two calculated values.

Determine the required shaft diameter when subjected to a torsional moment. Supports solid shafts, hollow shafts with a known diameter ratio, and hollow shafts with a known outer diameter.

Determine the minimum shaft diameter when both bending moment M and torque T act simultaneously. Two methods are used: the equivalent bending moment method and the equivalent torque method. The larger of the two results is taken as the recommended diameter.

Design a power transmission shaft by checking two criteria: torsional rigidity (twist ≤ 1/4° per metre, Formula ①) and shear strength (allowable shear stress, Formulas ②③). The larger of the two results is taken as the recommended diameter.

Based on standard IT grades (IT4~IT11) and fundamental deviation tables, this calculator computes upper/lower deviations and limit sizes for shaft or hole tolerance zones at a given nominal size. Supports shaft/hole switching for fit design and tolerance verification.

Enter the mean coil diameter, wire diameter, number of active coils, applied load, and shear modulus to compute the spring index, Wahl correction factor, torsional stress, deflection, and spring rate (stiffness). Results follow Chinese national standards for helical spring design.

Enter the load, free length, width, thickness, and elastic modulus to compute the bending stress and deflection at the free end of a leaf spring (flat spring). Supports rectangular, trapezoidal, and triangular profiles with the appropriate deflection correction factor. Results follow Chinese mechanical engineering standards (cantilever beam model).

Enter the load, span, leaf width, thickness, elastic modulus, and number of leaves (or allowable stress) to compute the bending stress and deflection of a laminated leaf spring. Supports clamp correction and inter-leaf friction correction. Results follow Chinese mechanical engineering standards.