NOV TDS-4S top drive
What it does
The TDS-4S is an older 750-ton top drive, and it is DC. A GE 752 motor rated 1,100 horsepower turns a two-speed gearbox: 7.95:1 in low and 5.08:1 in high. Continuous torque is 45,500 ft-lb in low gear. Low gear stops at 130 rpm. High gear stops at 205 rpm.
Which rig it fits
It fits a 750-ton derrick that still has DC power, or a rig that has added a conversion package to feed a DC motor. It will not connect to the AC VFD bus of a TDS-11 rig and run. Published weight is 32,000 pounds and working height is 20.8 feet. The pipe handler is a PH-85.
How to tell it apart
A TDS-8SA is the AC replacement in the same 750-ton class, with one 1,150 horsepower motor and 62,250 ft-lb. The 4S is the DC machine with the two-speed gear. If the listing says “750-ton top drive” and does not say AC or DC, ask before you price the installation.
What to check before you buy
Confirm the motor is the DC 752, and confirm the rig can supply it. Check which gear the seller is quoting torque in. The 45,500 ft-lb figure is low gear. Also confirm washpipe pressure, because NOV offers 5,000 or 7,500 psi on this model.
Sellers list what they have, so this exact model is not always up. Top Drives is where that kind of equipment is listed.
Ratings that matter
| Hoisting | 750 ton |
|---|---|
| Motor | 1,100 hp, GE 752 Hi-Torque DC |
| Gears | Low 7.95:1 (130 rpm); high 5.08:1 (205 rpm) |
| Continuous torque | 45,500 ft-lb in low gear |
| Makeup / breakout | 85,000 / 85,000 ft-lb |
| Pipe handler | PH-85; IBOP 15,000 psi |
| Weight / height | 32,000 lb; 20.8 ft working height |
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Sources
Catalog ratings are for the published configuration. A used machine can differ by year, upgrade, and nameplate. 9LINE does not inspect equipment or take part in the sale.