How Nobles delivered a challenging crane hook refurbishment

Friday, 16 November 2018

In June 2017, a tier 1 mining customer approached Nobles to undertake the assessment and refurbishment of four insulated hook blocks from a crane that was originally commissioned in 1987 (MRC 20t), and later uprated in 2000 (to MRC 22t).  The scope of work was to strip and assess, inspect (NDT) each block, replace or repair parts as necessary then rebuild and proof load accordingly.  In this, the aim was to ready the blocks for continued service whilst preserving their key attributes. 

This presented some particular challenges because the integrity of the original electrical insulation design had to be preserved, the blocks had to remain compatible with their payloads, and the effective dimensions of the blocks had to be maintained.

During inspection, defects were noted in the hooks, guards and axles and they needed replacing as a result.  The natural recourse at this point would be to find matching replacements, however there was a problem.  It was at this point that discrepancies in the design details provided were noticed.  At some point the original hooks had been replaced and the hooks as fitted did not meet requirements for the duty class for the crane.  Further, it was impossible to revert back to the original specification due to the earlier increase to the WLL and difficulties in supply.

Nobles Engineering team worked closely with the customer to investigate alternatives to meet both the application and design criteria of C9 M8 class crane.  It is no simple matter to just change a hook and Nobles had to model the interface with the payload, making sure the new hook would fit and build new side-plates which maintained the blocks’ working dimensions.

Once the appropriate hook was selected and sourced from an approved supplier, Nobles’ engineering team began the full block and hook re-engineering and design process to current Australian Standards, including modifications to enable the fitment of the new replacement hook and cross-head.  The customer was presented with the revised design drawing to seek their approval prior to commencing all other refurbishment works.

Remarkably, the finished refurbished blocks look quite similar to the original, yet are greatly improved in terms of performance and safer as a result.

Recieved unit

Refurbished unit

The blocks were surface treated to the customer’s paint specification and proof loaded in accordance with AS2089.  Wherever lifting gear is in need of repair or overhaul, it is important that this is undertaken in a competent manner.  With specialised below the hook devices such as crane hook blocks, experience and expertise in design and manufacture of these is vital to maintaining safety and function that complies with the relevant standards.

With engineering personnel on Australian Standards Committees for both Cranes and Lifting Tackle, Nobles have been designing, manufacturing and repairing sheave blocks for many years and offer a complete service for all lifting device redesign, repair and refurbishment work.

For more information about our engineering design and refurbishment capabilities please call our engineering team on 1300 711 559 or send them an email at