National 80B Drawworks

National Oilwell 80B Drawworks – Specifications

Manufacturer: National Oilwell
Model: 80B
Type: Mechanical Drawworks
Application: Workover & light drilling rigs

General Description

The National 80B Drawworks is a compact, rugged mechanical drawworks designed for light to medium duty hoisting. It is well known for its simple design, reliability, and ease of maintenance, making it popular on workover rigs, shallow drilling rigs, and service rigs.

Mechanical Specifications

• Drum Diameter: ~24 in

• Drum Length: ~36 in

• Drum Type: Single drum, grooved

• Main Shaft Diameter: ~6 in

• Frame: Cast steel construction

Power & Drive

• Rated Input Power:

  • 300–400 HP (varies by gearing and brake configuration)

• Drive Type:

  • Chain drive or compound drive

• Clutches:

  • Air-operated friction clutches

Hoisting Capacity

• Fast Line Pull: ~30,000 – 40,000 lb

• Maximum Hook Load: ~150,000 – 200,000 lb (depending on line size & reeving)

• Drilling Line Size:

  • ⅞ in – 1 in wire rope (typical)

Braking System

• Primary Brake: Mechanical band brake

• Auxiliary Brake:

  • Hydromatic brake (optional / common upgrade)

• Emergency Brake: Manual band brake

Gearbox & Speeds

• Number of Speeds: 3–4 forward speeds + reverse

• Gear Type: Spur / helical gears

• Lubrication: Splash lubrication