Glossary · Mechanism
Safety roller
A disc on the balance staff, notched to work with a guard pin, preventing the pallet fork from moving out of position.
Explanation
The safety roller is the smaller roller in a double-roller lever escapement that works with the guard pin of the pallet fork to prevent the fork from crossing over at the wrong moment ('overbanking'). Single-roller escapements, common in older American watches, lack it and are more prone to setting when jolted.
In the object catalogue
Catalogued objects whose own source record mentions “Safety roller”. The quoted line shows where; it is the seller’s or museum’s wording, not independent verification.
