Roller Kelly Bushings can be classed as two types based on different ways of drive, square drive and pin drive. Also they can be classed as three types based on different style, heavy, medium and light-duty. They are used for 17.1/2 to 49.1/2inch rotary tables. They are designed and manufactured according to API Spec 7K.
Model |
Type |
Drive way |
applicable size of kelly(in) |
Square |
Hex |
HDS |
Heavy duty |
Square drive |
21/2-6 |
3-6 |
27-HDP |
Pin drive |
21/2-6 |
3-6 |
20-HDP |
21/2-6 |
3-6 |
RTM4 |
Medium duty |
Square drive |
21/2-51/4 |
3-41/4 |
RTS4 |
Light duty |
21/2-41/4 |
3-41/4 |
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