A ruler, sometimes called a rule or line gauge, is an instrument used in geometry, technical drawing, printing as well as engineering and building to measure distances or to rule straight lines. The ruler is a straightedge which may also contain calibrated lines to measure distances.

Read more on Wikipedia

Guides that use

Renewing drum-brake shoes

Check drum brakes at least every six months, 6,000 miles or 10,000 km, or as recommended in the ...

Checking, adjusting and refitting drive belts

Drive belts always stretch a little in use, because of the strains put on them by driving the wa...

Testing an alternator and checking output

Alternators have replaced dynamos as generators on modern cars; they can produce more current. A...

How to overhaul a Stromberg carburettor

The Stromberg carburettor does not have a regular service schedule, but should be cleaned about ...

Adjusting the clutch

To work efficiently, the clutch needs the right amount of play in the linkage between the foot p...

How to replace dampers

Modern telescopic dampers cannot be overhauled at home. The only servicing possible is to replac...

Replacing track-rod-end ball joints

Track-rod-end ball joints are not adjustable on later cars. If they wear, you must replace them....

Replacing steering-rack gaiters

If a check of the rack gaiters reveals that the rubber is starting to crack, split or perish, rep...

Adjusting toe alignment on wheels

Front wheels wrongly aligned cause uneven tyre wear and may seriously affect the car's handling....

Checking and cleaning a fixed-jet carburettor

Fixed-jet carburettors are easily blocked by small dirt particles and chemical residues from fue...

How to remove a cylinder head

Removing the cylinder head is straightforward on pushrod engines, but more complicated on overhea...

Renewing alternator brushes

Unlike dynamo brushes, alternator brushes normally last for several years. Electrical arcing bet...

Adjusting and replacing a power-steering drive belt

The belt that drives a power-steering hydraulic-fluid pump is usually at the front of the engine...

How to align headlights at home

Only a garage with special equipment can align headlamps accurately. However, you may need to do ...

Checking the oil pump

Low oil pressure - indicated on the oil-pressure gauge or dashboard warning light - could provid...

Update your charging system

Alternators are powerful enough to cope with the demand for current made by a modern car's electr...