headbolt

noun

1. A bolt that is used to secure the head of something (such as the cylinder head of an internal combustion engine).

   “The headbolt heater consists of a hollow steel bolt containing an electric heating element. This device is designed to heat the water jacket and is applied to the engine head by replacing a headbolt.”

   “A second type replaces a headbolt or freeze plug depending on manufacturer's recommendations included with the unit.”

   “These systems consisted of a panic-bar-activated headbolt, footbolt, and mortised deadbolt. The headbolt and footbolt are 5/8-inch stainless steel bolts with a -inch projection (throw) at the top and bottom encased in stainless steel channels.”