These spring engaged, air disengaged brakes, are used when load holding is required if air pressure is lost: They they are offered in 6 sizes and have a range of spring pockets that allow torques as high as 9143 inlbs with a release pressure 103 psi. Typically offered with 3 numbers of springs for lower torques and release pressures but others are possible to be tailored to fit your needs. Maximum Operating Speed up to 1800 rpm. Continuous Thermal rating of: 2.23 Hpt @ 1800 rpm. Heat Sink capacity of 125,000 ft-lbs.The tapered bore to accepts QD Bushings for a wide range of bore sizes up to 3.25 in. with standard keyways or 3.50 in. with shallow keyways. The single plate finned friction discs provide high heat dissipation, and high dynamic torque capacity ensures fast load response. The split friction facings allow easy replacement without brake removal or disassembly. These brakes include a flow restrictor valve controls disengagement air to prevent shock load on brake components. Accessories: Torque Pin Bracket to anchor the housing, Brake Safety Guard for protection available. If you do not see exactly what you need as Nexen for a quote.