Henley skates were the first skate with adjustable tension via a screw, the ancestor of the kingbolt mechanism on modern quad skates.
Kaynak: Quad skates

Henley skates were the first skate with adjustable tension via a screw, the ancestor of the kingbolt mechanism on modern quad skates.
Kaynak: Roller skating

prevent the carriage from tipping; it consists of two parts rotating on each other about the kingbolt above the fore axle and beneath the body.
Kaynak: Carriage