Commonly unseen, the inner workings of our G class Garratt have recently been on display during the engines 'D' exam. This is the most thorough of the 4 locomotive examinations, which range from 'A' to 'D', and for G42 occurs every 18,000 miles. Above, the boiler cradle is lifted from the engine units, and below, is carefully lowered onto the purpose built supports which will hold it while work is carried out.
The later Garratt designs had a self-adjusting lower pivot housing, which utilised a sprung piece to take up any slack as the 2 halves of the joint wear. G42 isn't fitted with this technology, so the wear must be measured during the exam, and wear liners replaced if outside condemning limits.