Crusher Vibration Severity Tracker

Per ISO 10816, up to 3.5 mm/s RMS is new-machine condition (zone A) and up to 7.1 mm/s is acceptable for unrestricted long-term operation (zone B). Between 7.1 and 11 mm/s the machine should be scheduled for corrective maintenance (zone C), and above 11 mm/s vibration is severe enough to cause damage (zone D).

Inspect before running at load: tramp events bend pitman/eccentric components, crack welds and dent bearing races. Check toggle/tension rod condition (jaw), countershaft endplay (cone), flywheel keys, and foundation bolts torque. A post-tramp step change that persists is mechanical damage, not 'it just runs rougher now'.

On the main bearing housings (jaw: pitman bearings; cone: countershaft housing) — as close to the bearing as possible, on stiff metal (never on covers or guards). Take horizontal, vertical and axial readings if you can; use the highest for the ISO grade and always re-measure at the same spot, load and speed.

The usual suspects are uncrushable tramp events, worn liners changing the crushing geometry, main/pitman bearing wear, flywheel imbalance and foundation bolt loosening. A frequency spectrum tells them apart: imbalance shows at 1× running speed, misalignment at 2×, bearing defects at non-synchronous frequencies, and looseness as a raised noise floor with harmonics.

Velocity in mm/s RMS, 10–1,000 Hz. ISO 10816 zone tables are defined on broadband RMS velocity because it weights low- and high-frequency faults evenly for general machines. Acceleration (g) suits high-frequency bearing analysis and displacement (µm) suits low-speed machines, but neither maps onto these zone boundaries.