Norbar Case Study
Crane Turret Head Bolt Torquing
Accurately Torquing difficult-to-access crane turret assembly bolts.
The Client — Premier Proline
Premier Proline is a leading South Australian manufacturer of truck-mounted crane borers supplied to utility providers and contractors throughout Australia.
Crane Turret Head Bolts
Each truck-mounted crane turret base has 30 socket head cap screws that need to be torqued accurately to 460 Nm in order to function reliably and optimally.
The service technicians were finding it difficult to access these bolts for torquing, with clearance of only 17 mm in between the screw and the turret base. This meant that neither a powered nor manual torque wrench could access the bolts.
In order to torque the 30 bolts, technicians were using a modified extension arm applied directly onto a manual torque wrench.
Safety Risks and Inefficiencies
Manually operating the large wrench and extension arm was physically strenuous, and placed the operator in danger of a repetitive strain injury.
The extension bar flexed heavily under force, making accurate application and measurement of torque nearly impossible.
Engineering the Solution
The Norbar mechanical engineering team developed a fully customised Offset Drive (OSD) with an in-built reaction arm that would fit easily into the low-clearance space adjacent to the bolts.
The weight of the OSD was kept to a minimum by fabricating the casing from aluminium, while the gears are tough, high quality machined steel for a long and reliable life.
The OSD combined with a Norbar PTS 1000–200–1000 Nm Pneumatic Tool accurately and easily achieves the required torque of 460 Nm.
The tool and OSD is well balanced for comfortable use, while a safe reaction can be achieved by the reaction arm, keeping hands clear of moving parts and unsafe forces. The whole operation is simplified, with no more need to manoeuvre an unwieldy extension bar in awkward positions.
- Custom solution — designed for maximum power at a minimum weight, the OSD perfectly fits the crane turrets form.
- Efficient — Rapidly torques all 30 bolts, no more manual torquing.
- Safe — Removes the risk of repetitive strain injury, plus hands are kept clear of the bolts. Supportive of continuous improvement strategies and OH&S requirements.