Understanding Russell traction force
Russell traction uses hanging masses, pulleys, and a sling to create a controlled pull on the limb. In a simple physics model, each hanging mass creates rope tension equal to mass times gravitational acceleration. Real rigs lose some force because pulleys, rope bends, and contact surfaces add friction. This calculator lets you include those losses, so the result is closer to a practical classroom estimate.
Why angles matter
The sling force rarely acts in a perfectly horizontal line. It usually has a vertical component and a horizontal component. The horizontal part adds to axial traction. The vertical part can lift the limb and reduce support pressure. A small change in angle can strongly change the balance between pull and lift. That is why angle input is important.
Advanced rig checks
The calculator also includes limb mass, femur axis angle, pulley efficiency, and countertraction. Axial force is resolved along the selected femur line. Perpendicular force shows whether the setup tends to lift or press the limb. Countertraction is estimated from body mass, bed tilt, and friction. This helps show whether the traction pull could overcome resistance and cause sliding in a pure mechanics model.
Interpreting the result
The output shows tension in each rope system, horizontal traction, vertical lift, resultant force, axial force, and safety margin. Values are also shown in newtons and pounds-force. These outputs are useful for physics homework, biomechanics demonstrations, training notes, or checking spreadsheet results. They are not treatment instructions.
Practical use
Start with measured masses and angles. Enter the pulley efficiency if known. Use a lower efficiency when the pulley is worn or the rope path is rough. Check the example table for realistic entry style. After calculating, export the result as CSV or PDF. Keep the assumptions with the result, because the answer depends on every input.
Important note
Clinical traction requires professional judgment, patient monitoring, and local protocol. This page only calculates forces from a simplified static model. It should not replace medical orders, device instructions, or bedside assessment.
Model limits
The model assumes static equilibrium and straight rope segments. It ignores patient movement, skin contact changes, knot slip, and frame bending. Review real equipment before applying any classroom number.