NOV 1625 Drawworks – Jackshaft Assembly Spec

1. Identification 

• OEM: National Oilwell (NOV / IDECO)
• Equipment: Drawworks – Model 1625
• Component: Jackshaft Assembly
• Part Number: S41134-A
• Classification: Major Rig Equipment – Drawworks

2. Function

The jackshaft is an intermediate power transmission shaft in the drawworks drivetrain:

• Transfers torque from:
  • Drive motors / input shaft → gear train → drum shaft
• Used to:
  • Split or combine motor inputs
  • Adjust speed/torque via gearing
• Critical for:
  • Smooth torque delivery
  • Load balancing across drivetrain

3. System Context (1625 Drawworks)

• Rated Power: ~1,625 HP class
• Typical Line Pull: ~300,000–400,000 lbs
• Torque Range: ~25,000–35,000 lb-ft (system level)

👉 Jackshaft carries a large percentage of system torque, but not always full drum torque depending on gearing stage.

4. Mechanical Characteristics

Shaft Type

• Stepped cylindrical shaft
• Multi-journal configuration

Material (Typical)

• Forged alloy steel:
  • AISI 4140 / 4145H / 4340 equivalent
• Heat treated:
  • Quenched & tempered
  • Surface hardened at wear areas