In 1998, we cooperate with Baoji Petroleum Machinery company(BOMCO)and Dagang Oilfield, the double circuit hydraulic disc brake device was firstequipped on 3 rig drawworks of 4000 meters in China. In 1999, the disc brakedevice of 5 rig drawworks in Daqing Oilfield was successful once. Since then,improvement, upgrading and promotion, the disc brake device of rig drawworkshas been mature, recognized and popularized in China.

Characteristics of disc brake device：

1.The number of working tongs and safety tongs is equal (9000 metersand 12000 meters are the same). The braking torque of the working tongs andsafety tongs meet the maximum braking torque requirements of the drilling rig(higher than the requirements of the national standard for working brakingtorque). The combined torque of emergency braking is larger, which avoids thesmall number of safety tongs (parking tongs). The brake lag of the workingtongs is relatively small during emergency braking However, the brake torque ofthe safety gear is smalland the accidents of stumbling and slipping occurfrequently.

2.Learn from foreign advanced experience, the loop control ofelectronic brake handle using electronic control air valve-air valve to controlthe hydraulic directional valve for realize the control of brake caliper workthat it will avoiding the accident caused by the large electromagnetic power ofhydraulic directional valve, large heat, easy to make the valve stuck.

3.Double safety design is adopted in the control circuit of safetygear. The hydraulic directional valve is set as one open and one close, thatis, one for use and one for standby. It works at the same time when braking, soas to avoid accidents caused by heating or particles in oil blocking the valve.

4.The hydraulic station is equipped with a hand pumpwhich can ensurethat the disc brake can work normally at any time under the condition of powerfailure and gas failure.

5.The hydraulic station is equipped with oil filling and selfcirculating filtering deviceswhich can prevent the oil pollution of thehydraulic system and minimize the occurrence of faults and accidents.