RK Pipe sells new and used square and pin kelly bushings and replacement parts for your drilling equipment. Please peruse our online inventory and contact our sales department for questions and quotes.
Square drive kelly bushing dimensions, pin drive kelly bushing dimensions, square drive master bushings dimensions, and pin drive master dimensions are shown in Figure 1 and Table 1 (based on API Spec. 7K).
There are two basic designs of kelly drive bushings – single and double-plane rollers.
1. In the first design, the drive rollers are in a single plane. Depending on the manufacturer, the kelly bushing may have a split or solid body casing.
a. In the split body design, the roller pins are supported in the body journals and clamped by top nuts which bolt the body halves together. To replace the roller assemblies, the cover is removed and the rollers are accessible.
b. In a solid cast body, the roller pins are supported by replaceable sleeves. To remove a roller assembly, retain¬ing pins are removed, the roller pin taken out from the side, and the roller removed from the back.
2. The second basic design of kelly drive bushings used two rollers for each driving surface on the kelly. The rollers are stacked one above the other in “cages”. All roller pins and bearings are part of this cage assembly. The cages are removable from the bushing body. The two plane roller bushing for hex kellys is adjustable for kelly and bushing wear. The two plane roller bushing for square kellys is not adjustable.
See Figure 2 for Kelly Bushing Replacement Parts.