|
|
|
Gearbox for rotary drives in drilling rigs. 313 SERIES
November 2007
|
|
Drilling rigs have to deliver amazingly high performance. In particular, a wide range of tool rotation speeds is required. This is partly to match the wide range of tools now available for different drilling operations, and partly to improve drilling capacity on the various types of terrain on which the rigs have to operate.
As an alternative to single speed gearboxes, which permit tool speed to be varied only by varying the speed of the hydraulic drive, and mechanical drives which have two separate gearboxes and a hydraulic motor offering one slow drilling speed and one fast speed for withdrawing the tool from the ground (spin off), we have now developed a 3-speed gearbox in which the different speeds can be selected via hydraulically operated clutches.
This system offers two mechanical ratios for low speed drilling as well as a high speed for tool spin-off.
Compared to conventional systems
|
|
these new gearboxes offer the following benefits:
- A choice of two drilling speeds
- A single gearbox design, eliminating the need for a second gearbox and motor for spin-off
- Gear selection clutches, with no mechanical engagement, for totally reliable speed selection.
The new gearbox incorporates three planetary reduction stages. The first two stages are equipped with hydraulically operated multi-plate clutches.
All three speeds can be selected by engaging and disengaging these clutches in different combinations.
The gearbox has a hollow splined output shaft for direct coupling to the final reduction gear of the rotary table.Lubrication is ensured by an external pump that delivers oil from the rotary table casing to the top of the gearbox.
Incoming oil cascades over the gearbox internals (gears and clutches) by gravity feed, cooling them in the process, before returning to the rotary table which functions as the system sump. |
|
