P = T·2πn/60; P = Fv
SI: P watts, T N·m, n RPM, F newtons, v m/s. Mechanical power at the same shaft/load point.
Tập 1, Chapter 2, printed pp. 16–20; independently derived work/time relationship. Existing ValiCalc power expressions retained.
VALICALC / MECHANICAL ENGINEERING SUITE / DS02
Motor Load & Duty Design Sheet
Build the required motor speed, shaft power and torque from the actual load. Separate continuous, acceleration and peak demand before reviewing a physical motor's torque-speed and duty data.
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
kg·m²
kg·m²
Duty cases
02 / CALCULATE → SELECT → RECALCULATE
Calculation & checks
Peak mechanical power at load
5.29082 kWTransmission efficiency (entered)
90 %Required peak shaft power
5.87869 kWTotal mechanical peak demand (includes rotor acceleration)
5.92804 kWRequired peak motor torque
37.73905 N·mDuty RMS torque · mathematical summary
34.77101 N·mRequired maximum motor speed
1,500 rpmReflected load inertia (ideal kinematics)
0.01111 kg·m²| Case | Output RPM start → end | Duration (s) | Motor torque (N·m) | Motor RPM | Motor total peak demand (W) | Load peak power (W) | Model |
|---|---|---|---|---|---|---|---|
| 1 | 0 → 500 | 5 | 37.739047 | 1,500 | 5,928.035679 | 5,290.818892 | Motoring |
| 2 | 500 → 500 | 20 | 37.037037 | 1,500 | 5,817.764173 | 5,235.987756 | Motoring |
| 3 | 500 → 500 | 5 | 18.518519 | 1,500 | 2,908.882087 | 2,617.993878 | Motoring |
Criterion-specific verification
- PASSED · Motoring load-case model
Every case stays within the positive load-torque model.
- UNKNOWN · Physical motor performance
Check the actual torque-speed envelope, starts, cooling, supply, duty and ambient conditions. No model has been selected.
Method and calculation trace
P = Tω; motor/output speed ratio i is positive. Transmission η is motoring mechanical efficiency, not electrical motor efficiency.
Tmotor = (Tload + Jload·αout)/(iη) + Jmotor·i·αout. This constant-η model applies only while load-side torque is nonnegative.
J reflected = Jload/i² (ideal kinematic inertia); motoring loss is accounted separately in load acceleration torque.
Duty rows use constant torque and constant angular acceleration. Case peak power considers both speed endpoints. Delivered shaft power excludes motor rotor acceleration; total mechanical demand includes it.
Assumptions & scope
Constant resisting torque and constant acceleration within each case. RMS torque is a duty summary, not thermal approval; dwell cooling and speed-dependent motor losses need manufacturer review.
Regenerating/braking load cases need a separate reverse-loss and drive/brake model; they are explicitly blocked.
No automatic catalog model recommendation or starting/thermal approval.
Worked example
100 N·m at 500 RPM needs 5.236 kW at the load. At 3:1 and 90% motoring efficiency the steady motor requirement is 5.818 kW, 1500 RPM and 37.037 N·m.
Calculation methods and sources
J reflected = J load / i²; T acceleration = J·α
Rotational inertia in kg·m²; angular acceleration rad/s². Motoring transmission efficiency is separately applied to output-side torque.
T RMS = √(Σ Tj²·tj / Σtj)
Constant torque per case including modeled acceleration. RMS is a mathematical summary, not an automatic thermal or motor selection approval.
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.