The Anglepoise Lamp: How a Spring-Balanced Arm Works

The Anglepoise lamp is a piece of engineering before it is a piece of design. Its jointed arm can be pushed into almost any position and simply stays there, without clamps or friction knobs to tighten. That apparently effortless behaviour comes from a carefully balanced arrangement of springs, devised in the early 1930s by a British engineer who specialised in vehicle suspension. The result became one of the most recognisable task lights ever made and the ancestor of countless balanced-arm lamps.

This article covers the lamp’s design history, explains how the spring mechanism works in plain mechanical terms, and draws out what it still teaches about task lighting. It is a design-history read, not a buying guide.

George Carwardine and the 1932 patent

George Carwardine (1887–1947) was an automotive engineer whose work focused on suspension systems — the springs and linkages that keep a vehicle stable over uneven ground. Working on the problem of a constant-tension spring and a mechanism that could hold a limb in balance, he arrived at an arm that could be moved freely in three dimensions and would stay where it was put.

He applied for a patent on the mechanism in July 1932. A lamp was a natural application: a light source that could be positioned precisely over a workbench, drawing board or desk, and then left in place. Early production of a four-spring model, known as the 1208, was aimed at workplaces such as factories and offices.

Herbert Terry & Sons and the 1227

Carwardine’s springs were supplied by Herbert Terry & Sons, a long-established spring manufacturer in Redditch, England. In 1934 he licensed the design to the company, giving it exclusive rights to manufacture the lamp. The partnership joined an inventor’s mechanism with a firm that understood the material at its heart.

The design was then adapted for the home. A three-spring version, the Anglepoise 1227, went into production in 1935. With its stepped base, slender arm and domed metal shade, it established the silhouette most people still associate with the name. It was more refined than the industrial model and suited the domestic study, bedside and drawing table.

Over the following decades the lamp was produced in large numbers, used in homes, offices and drawing offices, and its arrangement was licensed and imitated around the world. The phrase balanced-arm lamp now describes a whole category of task lights that all owe something to Carwardine’s principle.

How the Anglepoise lamp mechanism works

Any arm that holds a weight at its end tends to fall under gravity. The usual ways to stop that are friction, which needs tightening and wears, or a counterweight, which is heavy and bulky. Carwardine used springs instead, arranged so that the force they exert balances the turning effect of the arm and shade at every angle.

The key ideas are straightforward:

Parallel linkages. Each section of the arm is a parallelogram of rods. As the arm moves, the parallelogram keeps the shade at a consistent attitude relative to the arm and transmits forces in a predictable way.
Springs sized to the load. The springs are anchored near the base and attached to the arm at points chosen so that, as the arm drops and the turning effect of gravity changes, the spring stretches and its pull changes in step.
Balance, not grip. When the spring moment and the gravitational moment are nearly equal across the range of movement, the arm is in balance everywhere. A light push moves it; letting go leaves it in place. A small amount of joint friction absorbs the remaining imbalance.

For an engineer, it is a neat example of designing a mechanism around a load path: the weight of the shade is carried through the linkage into the springs and down into the base, which must in turn be heavy or wide enough not to tip. Change the shade weight significantly and the balance is lost, which is why the lamp’s components are tuned to each other. Our explainer on load paths describes the same idea at the scale of a building.

Why it works as a task light

A task light has a simple job: put a well-defined pool of light exactly where the eyes and hands are working, without shining into the user’s eyes. The Anglepoise lamp does this through two features. The deep shade concentrates light into a directed beam and shields the source from the user’s line of sight. And the balanced arm allows that beam to be positioned close to the work and angled precisely, so the light falls from the side opposite the writing hand and casts no shadow across the page.

Bringing the source closer to the work is also efficient. Illuminance falls off quickly with distance, so a small lamp near the page can provide far more light on the task than a much more powerful fitting in the ceiling. That is why good practice combines modest ambient light with local task light at desks and workbenches, rather than flooding a whole room to task levels. Our guide to lux levels sets out typical targets for reading and desk work.

A design classic and its lessons

The Anglepoise lamp belongs to a lineage of objects whose form follows almost entirely from how they work. Nothing about its silhouette is decorative: the springs are exposed, the linkages are visible, and the base is as heavy as it needs to be. It is close in spirit to the design-classic lamps of the same period that solved a lighting problem from first principles — compare it with Poul Henningsen’s PH lamp, which tackled glare through the geometry of reflecting shades.

For anyone planning a workspace, the lessons remain practical. Provide adjustable task light at every desk; position it on the side away from the writing hand; choose a shade that hides the source; and prefer a fitting that can be moved close to the work. Our guides to home office design and study room design apply these principles to whole rooms.

Caring for a balanced-arm lamp

Because the lamp depends on balance, a few things affect how it behaves over time. Springs can lose tension after decades of use, and joints can loosen or stiffen; when an older lamp starts to droop, the cause is usually one of these rather than a fault in the design. Fitting a much heavier or lighter shade or light source can also upset the balance. Older lamps with original wiring should be checked before use, and a lamp that plugs into a socket does not need an electrician, but new fixed outlets or wall-mounted versions connected to the fixed installation in Singapore must be installed by an EMA-licensed electrical worker.

Frequently asked questions

Who invented the Anglepoise lamp?

George Carwardine, a British automotive engineer who specialised in suspension systems. He applied for a patent on the spring-balanced mechanism in July 1932.

How does an Anglepoise lamp stay in position?

Springs anchored near the base pull on the jointed arm with a force that balances the weight of the arm and shade at every angle. Because the arm is in balance, it stays wherever it is left without needing to be clamped.

What is the Anglepoise 1227?

The three-spring domestic version of the lamp, produced from 1935 by Herbert Terry & Sons, the Redditch spring makers to whom Carwardine licensed his design in 1934.

Why is an Anglepoise lamp good for desk work?

Its deep shade directs light onto the task and hides the source from the eyes, and its balanced arm lets you bring the light close and angle it precisely, avoiding shadows from your hand.

Why does an old Anglepoise lamp droop?

Usually because the springs have lost tension or a joint has loosened, or because a shade or light source of a different weight has been fitted. Restoring the original balance generally cures it.

Planning a workspace or interior where structure and services need careful coordination? Talk to our consultancy or get in touch.