Knowledge

Technical Guides

Field notes on choosing springs, taking measurements, diagnosing failures and deciding on materials. The engineering behind our catalogue, in plain language.

What this section covers

Replacing a spring is usually easy; understanding which spring is needed and why the old one failed is the hard part. This section collects the questions that have come back most often from the field since 1978: when a spring should be replaced, why it opens out, how to measure it, and which material belongs where.

You will not find fixed service-life figures, lead times or prices in these articles — those depend on the machine, on how hard it is worked, and on the item ordered. What you will find are the measurable signs to look at when making the decision, and the engineering reasoning behind them.

The order we suggest is this: if something is wrong on the machine, start with the diagnostic articles — when a spring should be replaced, why it opens out, why it breaks. If you are having a new part made, the measurement and material articles will do the job. And if you want to know how a spring actually works, the spring types section covers it in more detail.

The glossary below gathers the terms used throughout these articles in one place. When you place an order or ask for a quotation, these six terms are what establish a common language between us.

Articles

3 minWhen Should Baler Springs Be Replaced?How to spot the moment before breakage: loss of free length, legs opening out, tip wear and a drop in bale density.3 minWhy Do Hay Rake Springs Open Out?Why fatigue in a torsion spring appears as opening rather than breakage, why the leg angle widens, and when replacement is due.3 minWhy Springs BreakThe seven causes seen most often in the field: overstress, corrosion, wrong-way fitting, hook radius, resonance, missing heat treatment and surface damage.3 minHow to Measure a Compression SpringThe five dimensions needed to order from the spring in your hand, how to take them, and the mistakes made most often.8 minChoosing Spring SteelThe difference between spring steel, stainless and chrome silicon; the role of coating, and which working conditions call for which.4 minRotary Rake Tine SpringsWhat a gearbox-driven rotary rake is, why its tine springs are torsion form springs, when they should be replaced and which dimensions are needed to order.3 minPre-Season Spring ChecklistA half-hour spring check before harvest starts, for balers, hay rakes, seed drills and combines — what to look at on each group and how to decide.5 minWhy Do Bales Tie Badly?Missed knots, broken twine, loose and misshapen bales — a field guide that works back from the symptom to the group and the spring you should check.6 minRake Spring Types and Their Field NamesRake spring, tine, pickup spring, windrow spring, rake plate — five names for what buyers are looking for. Which name describes what, and which one works on which machine.4 minWhat Is a Lynch Pin? Types and Choosing the SizeLynch pin, R pin, hairpin clip, D pin, square pin and split pin — what each one does, how they actually differ, and which dimension to give when ordering.

Key terms

The terms used in these articles and in quotation correspondence. All of them are quantities the calculator on our home page also works with.

Term	What it means
Spring rate · k	The force needed to compress or extend the spring by one unit of length (N/mm). On a torsion spring the equivalent is the moment rate (N·mm per degree). This is what people mean by the "stiffness" of a spring.
Spring index · C	The ratio of mean diameter to wire diameter (C = Dm/d). It indicates manufacturability: below four the wire is overstrained during coiling, above twelve coiling becomes unstable.
Free length · L₀	The end-to-end length of the spring with no load applied. This is the most honest indicator of fatigue; it shortens before the spring breaks.
Solid length · Ls	The length a compression spring takes when fully compressed; about (n+2)·d on a closed-end spring. If the installation gap falls below it, the spring is permanently crushed.
Initial tension · F₀	The force set into the wire of an extension spring during coiling that presses the turns together. The spring does not begin to extend until it is exceeded.
Tempering	The heat treatment applied after coiling. It relieves the stress left by coiling and makes the elastic property permanent; skip it and the spring loses length on its first loads.

If you already have your dimensions

The spring calculator returns rate, solid length and spring index instantly. For compression springs it also computes stress and the safety factor.

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Cannot find the spring you need?

We produce to your dimensions in the 0.20–40 mm wire range, with no tooling dependency. A sample, a technical drawing, or simply a photograph of the old spring is enough.

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