Engineering and applications
Kelly Bar Glossary
A practical glossary of terms used when specifying telescopic drilling bars.
Use this guide to connect the bar configuration with the drilling method, equipment limits and service routine that will shape performance on site.
Section and stage
A section is one telescoping steel element; a stage describes its position or movement within the complete bar. Clear section marks help crews assemble, inspect and service the bar in the correct order. The terminology is simple, but consistent naming prevents avoidable confusion in drawings and delivery records.
Drive keys and friction faces
Interlocking bars use mechanical keys or drive surfaces to transfer torque. Friction bars depend on controlled contact between sections. Both designs need clean interfaces and compatible clearances. The exact geometry belongs in the approved drawing rather than being inferred from a general product name.
Stroke, overlap and working depth
Stroke is the useful movement available as a section extends. Overlap is the length remaining engaged between sections. Working depth is the practical drilling depth after the tool, connection and operating clearances are considered. These values should be reviewed together when selecting a configuration.
Guide, weld and connection
Guides keep telescoping sections aligned, welds join or reinforce components, and the connection transfers load to the tool or drive. Inspecting each area as part of the same load path gives a more complete picture than checking one feature in isolation.
For a project-specific discussion, compare this guide with the product range, the sizing checklist and the quotation form. Keeping those three references together helps the team move from an idea to a verified configuration.
Project reference notes
Kelly Bar Glossary | Kelly Bar Systems is intended to be used as a working reference alongside the rig documentation and the approved project drawing. The useful decision is always specific to the machine, tool and ground: check the rotary interface, available torque, crowd behavior, target depth, section overlap and handling space before a final configuration is released. These details also help the field team understand why a particular bar arrangement was selected.
Keep the page available during quotation, commissioning and service review. During installation, confirm the section order and connection fit at low speed. During production, record ground changes, tool changes and any new sound or movement. During demobilization, clean the contact areas, protect the connections and carry the inspection record with the section marks. That small information loop makes the next decision faster and keeps the equipment history useful across projects.
For procurement and site planning, identify the bar by its complete model and section arrangement rather than by a shortened label alone. Confirm how it will be packed, lifted, stored and connected to the selected tool. If the project involves more than one rig, compare the interfaces before standardizing the order. Clear information at this stage reduces field modifications, protects the schedule and gives the service team a reliable starting point when the equipment returns from the job.