# What is the difference between total runout and runout?

Total runout is a composite tolerance, that is applied to an entire surface, that restrains geometric variation (so this means it controls variation in straightness circularity, coaxiality, tapers, angularity and profile). To put it another way, runout control the location of a circular feature relative to its axis.
A.

### What is total indicator runout?

Total indicated runout (which before the days of the double arrow GD&T symbol was specified on drawings by writing "T.I.R.") is measured by setting up a part so that it rotates about a particular axis, then a dial indicator is used to measure a surface of interest as the part is rotated.
• #### What does it mean TIR?

Transports Internationaux Routiers
• #### How the straightness is measured?

STRAIGHTNESS MEASUREMENT. The straightness application is measured in two axis, where the laser beam is used as reference. The deviation in distance between the laser beam and the measurement object is measured in two or more positions with the use of a receiver. The program allows for up to 99 points to be measured.
• #### What does circularity mean?

Circular definition. Circular reasoning; also known as circular logic. Circularity (roundness) specification of an object. A circularity ratio as a compactness measure of a shape. An assumption of ANOVAs with repeated-measures.
B.

### What is runout of a shaft?

On rotating machinery, runout is defined as the degree to which a shaft or coupling deviates from true circular rotation. Every shaft or coupling has a center or rotation, or centerline. If runout is severe, it can cause many problems with equipment, such as: Excess vibration.
C.

### What is the symbol for runout?

GD&T Runout Definition. In GD&T, runout tolerance is used to control the location of a circular part feature relative to its axis. This is different than circularity, which controls overall roundness.

Updated: 2nd October 2019