Cylindrical telescopic kelly-bar apparatus
US5263899A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1990 |
| Grant date | Nov 23, 1993 |
| Priority date | — |
| Expiry date | Jun 7, 2010 |
Classification
- Technology area (CPC F)Mechanical Engineering; Lighting; Heating
- CPC primaryF16D3/185
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A kelly-bar apparatus includes, for example, an inner kelly-bar, a second kelly-bar and an outer kelly-bar. These kelly-bars are relatively telescopically operable and torque is transmitted from outside to inside. When the second and outer kelly-bar are in a contracted position, they are supported by a spring on a spring support fixed to the inner kelly-bar. The bottom end of a torque transmitting projection of the inner kelly-bar is fitted into and welded to the spring support. The spring support is fixed onto an engagement member formed integrally with the inner kelly-bar. In addition, a stop member for preventing the second kelly-bar from coming away from the outer kelly-bar projects from the inner periphery of the outer kelly-bar at a location above the torque transmitting portion.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.