A spring requirement needs both an output and a position. “Strong enough” or “constant force” is a starting description, not a complete specification.
Force and torque describe different outputs
Force describes a linear push or pull. Torque describes a turning effect about a shaft or axis. State where the output is measured: at the strip end, the spring shaft, a cable or a user-operated handle. The surrounding mechanism may change the relationship between these points.
On a reel, the effective winding radius and friction influence the cable pull obtained from shaft torque. Record the drum and cable arrangement instead of treating torque and cable force as interchangeable values.
Define the installed starting point
The free part and the installed spring can have different starting conditions. Show preload, winding direction, initial extension or installation angle. Then define the usable travel from that installed position, with the stops or limits that prevent movement beyond it.
For angular requirements, use a labelled view to establish the direction and zero reference. An angle without a reference can be interpreted in more than one way.
Describe the curve you actually need
List target output at several relevant positions: the start, intermediate points and end of the working range. Add the permitted range at each point where necessary. For a lift, consider both upward and downward operation. For a shelf pusher, include the full row and final item.
Constant force springs aim for approximately steady pull over their working range. Variable force springs address a changing force requirement. The names do not remove the need to agree measurement points and permitted variation.
Separate component output from mechanism behaviour
A spring can provide force or torque while other parts determine friction, locking, speed or position holding. A satisfactory spring measurement is not automatically a full-system acceptance test. For spring energy storage, useful torque over the release range matters alongside winding input and the connected mechanism.
Make a sample check repeatable
- Identify the drawing and sample revision.
- Show the fixture, support and attachment arrangement.
- State the installed preload and measurement direction.
- List force-versus-position or torque-versus-angle targets with units.
- Define the working range, operating conditions and acceptance limits.
We use a force gauge with a reel fixture to check spring output under conditions that represent installation. For your part, we will agree the support, preload, measurement positions and acceptable variation before the sample check.
Prepare a clear inquiry
Combine the output requirement with material, dimensions, installation space and quantities. The spring RFQ checklist helps separate known values from the questions still to be resolved.
Discuss your spring requirement
Send your drawing, sample details or operating requirements through our Contact / RFQ page and tell us what you need the spring to do.