It holds a panel wherever it is placed, by internal friction.

Hinge and brake are the same component.

No stay, strut or catch is needed.

The panel is positionable anywhere rather than at fixed stops.

Display screens, covers and instrument panels use them widely.

Removing the second component entirely is much of the appeal.

From the panel's weight and the distance to its centre of gravity.

Weight alone is not enough.

A panel cantilevering further needs more torque for the same mass.

Two identical-weight panels can need quite different hinges.

Manufacturers publish selection calculations.

Guessing produces a panel that either drifts or is stiff to move.

Adjustable where the torque may need retuning; fixed where it will not.

Friction hinges lose torque as they wear.

An adjustable hinge can be corrected when it slackens.

A fixed one cannot be corrected at all.

Fixed hinges are simpler and cheaper.

Where a panel is opened constantly, adjustability usually repays itself.

A rated number of open-and-close cycles at stated torque.

It separates a good hinge from a disappointing one.

A hinge used far beyond it holds progressively less.

The panel then begins to drift.

Where a cover is opened many times a day, that figure matters most.

It frequently matters more than the initial torque rating does.

Yes - the torque of each adds together.

Torque per hinge is the total required divided by the number fitted.

Fitting an extra hinge to a drifting panel is a legitimate remedy.

Hinges should be matched rather than mixed.

Uneven torque between hinges twists the panel.

Wider panels benefit from more hinges regardless of the torque calculation.

Some designs more than others, and it is worth checking.

Friction media can stiffen in cold conditions.

They can also soften when warm.

A hinge set correctly indoors may behave differently outdoors.

Manufacturers publish operating temperature ranges.

Where the equipment sees a wide range, that specification deserves the same scrutiny as the torque figure.

Adjustable types can, and doing so is part of commissioning.

Adjustment should be made with the panel fully assembled.

Adding a heavier front afterwards changes the requirement.

Small equal adjustments across all hinges keep the panel square.

Over-tightening makes the panel hard to move and accelerates wear.

A hinge that will no longer hold at maximum adjustment has reached the end of its life.