The crown blocks complies with API Spec 4F, and conforms to the
SY/T5527 standard. The crown block consists of crown basement,
fast-line sheave, dead-line sheave, main sheave, sand-line sheave,
drilling line protector and sheaves for hydraulic and air winch,
bumper wood for the Crown-O-Matic and guardrail. It’s designed with
closed type and open type. The traveling system is divided into
7×6, 6×5, 5×4, and 4×3, which fit to 7/8”～1 1/2” drilling lines.
The sheave groove conforms to the requirements of API RP 9B. The
sheave groove surface is processed with a quenching treatment. The
bearing adopts centralized lubrication for convenient operation.