Which instrument is commonly used to determine crankshaft rotation in degrees?

Which instrument is commonly used to determine crankshaft rotation in degrees?

• A. Dial indicator
• B. Timing disk
• C. Vibrometer
• D. Caliper

Answer: (B)

Crankshaft rotation in degrees is read with a degree wheel, commonly called a timing disk. This is a circular plate with degree marks around its edge that attaches to the crankshaft (or to a suitable crankshaft pulley/damper) and is read against a fixed pointer. As you turn the engine, you can see exactly how many degrees have elapsed from a reference position like Top Dead Center, which is essential for setting or verifying valve timing and other timing-related events. A dial indicator measures a linear movement, not angular position, so it doesn’t directly tell you crank rotation in degrees on its own. A vibrometer measures vibrations, not crank angle. A caliper measures linear dimensions, not rotation angle. So the degree wheel provides the clear, direct readout of crankshaft rotation in degrees, making it the standard instrument for this purpose.

Crankshaft rotation in degrees is read with a degree wheel, commonly called a timing disk. This is a circular plate with degree marks around its edge that attaches to the crankshaft (or to a suitable crankshaft pulley/damper) and is read against a fixed pointer. As you turn the engine, you can see exactly how many degrees have elapsed from a reference position like Top Dead Center, which is essential for setting or verifying valve timing and other timing-related events.

A dial indicator measures a linear movement, not angular position, so it doesn’t directly tell you crank rotation in degrees on its own. A vibrometer measures vibrations, not crank angle. A caliper measures linear dimensions, not rotation angle. So the degree wheel provides the clear, direct readout of crankshaft rotation in degrees, making it the standard instrument for this purpose.