Torque Required in Lifting Load with Trapezoidal Threaded Screw Calculator

Torque Formula:

\[ M_{tli} = 0.5 \times d_m \times W \times \left( \frac{(\mu \times \sec(0.2618)) + \tan(\alpha)}{1 - (\mu \times \sec(0.2618) \times \tan(\alpha))} \right) \]

Mean Diameter of Power Screw:

Load on Screw:

Coefficient of Friction:

Helix Angle of Screw:

rad

Torque for Lifting Load: N·m

1. What is Torque Required in Lifting Load?

Definition: This calculator determines the torque needed to lift a load using a trapezoidal threaded screw, accounting for friction and screw geometry.

Purpose: Essential for mechanical engineers designing screw jacks, presses, or other lifting mechanisms with trapezoidal threads.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ M_{tli} = 0.5 \times d_m \times W \times \left( \frac{(\mu \times \sec(0.2618)) + \tan(\alpha)}{1 - (\mu \times \sec(0.2618) \times \tan(\alpha))} \right) \]

Where:

\( M_{tli} \) — Torque for lifting load (N·m)
\( d_m \) — Mean diameter of power screw (m)
\( W \) — Load on screw (N)
\( \mu \) — Coefficient of friction at screw thread (±5%)
\( \alpha \) — Helix angle of screw (radians)
0.2618 — 15° thread angle converted to radians

Explanation: The formula accounts for the screw geometry (15° trapezoidal thread) and friction effects during lifting.

3. Importance of Torque Calculation

Details: Accurate torque calculation ensures proper motor selection, prevents mechanical failure, and optimizes power efficiency in lifting mechanisms.

4. Using the Calculator

Tips: Enter mean diameter, load, friction coefficient (default 0.15±5%), and helix angle in radians. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why is the thread angle fixed at 15° (0.2618 rad)?
A: This calculator is specifically designed for standard trapezoidal threads which typically have a 30° included angle (15° per side).

Q2: What's a typical friction coefficient for screw threads?
A: For steel-on-steel with lubrication, μ ≈ 0.15±5%. Dry conditions may increase this to 0.2-0.3.

Q3: How do I find the helix angle?
A: Helix angle α = arctan(lead/(π×dm)), where lead is axial distance for one screw revolution.

Q4: Does this account for efficiency losses?
A: Yes, the friction coefficient accounts for efficiency losses in the thread interface.

Q5: Can I use this for other thread types?
A: No, this is specifically for 30° trapezoidal threads. Different formulas apply for square or ACME threads.