They are skilled and practised hands, gnarled and calloused through decades of working spanners, milling and welding, forging and drilling.

The hands of Ken Houlahan, Colin Ogilvie and Ian Stewart are wise and clever in the ways of the past.

They were trained in the days when problem-solving was part of the job, tuning an engine was art not science, when grease remained imbedded under the fingernails and almost every single mechanism worked on tension, vacuum, pressure, or a combination of all three.

What troubles the conservators at the National Museum of Australia is that these three men, all long retired but back in semi-active service, won't always be around and there's precious few new hands with the skills, knowledge and commitment to take up the task.

Important elements of the national collection are wholly mechanical in function. Their internals have clutches and gears, lubrication and cooling systems, pumps and floats, valves and pistons, springs and gaskets, some dating back 100 years or even more.

Mr Ogilvie, who has been working in the museum's machine shop the longest, has had a couple of health issues and is close to retiring for a second time, this time for good.

The museum needs a succession plan but doesn't quite know what that looks like.

"The multiple skills that these men bring to the museum are just not being taught now, things like carburettor jetting, float setting and tuning," conservator Nathan Pharoah said.

"They know how to study a problem, take something apart, then if needed make a replacement from scratch.

"They have a deep knowledge and understanding of how mechanical things work that is, sadly, very rare today."

At 82 years old, Ken Houlahan is the elder statesman of the trio. Colin Ogilvie turned 80 recently, and the pair refer to 74-year-old Ian Stewart as the "pup".

All three were once very familiar names in and around the Canberra automotive trade.

Trained mechanics, they owned and operated their own successful businesses in Canberra when cars and their constituent parts were repaired, not replaced, components were made to go the distance and almost anything on two or four wheels could be mobilised with a bit of mechanical ingenuity.

Back in 1958, Ken Houlahan was Canberra's first accredited Mercedes-Benz mechanic, he worked out of an Esso garage behind the now Canberra Hyatt hotel, servicing the sizeable fleet of Mercedes 190 sedans which curiously all belonged to the Indonesian embassy.

Oil and petrol was the lifeblood of the Houlahan business back when all service stations had busy workshops attached.

Years before modern-day trendy Braddon became liberally infused with man-buns, manicured beards and soy lattes, he operated several service stations in the area, introduced the first independent petrol discounter Solo to Canberra and then ran Precision Automotive in Mitchell.

Canberra's northern industrial suburb provides the common link between the three men.

A self-confessed "old school" mechanic, Colin Ogilvie ran his business Ogilvie Automotive from the same suburb.

He has a wealth of knowledge about almost anything mechanical which combusts and reciprocates.

Ian Stewart's Berco Engineering, then the largest specialist re-engineering and engine reconditioning operation in the region, was just up the road.

"We used to get together after work now and again and swap yarns," Ian Stewart said.

"Canberra was small enough in those days that everyone in the local [automotive] game knew everybody else.

"We could all work on anything but we each had our specialities.

"Ken [Houlahan] knows electrics, carburettors and early injection systems, Colin [Ogilvie] is also great with carbies, brakes and all types of engine tuning and I'm a jack of all trades, really, because my business rebuilt and reconditioned every type of engine."

Colin Ogilvie's connection to the museum goes right back to its formative years, well before the National Museum was constructed at its current Acton Peninsula site and when the first of the exhibits were being set aside.

Back in 1987 some of the museum's very first machinery exhibits needed delicately lifting off a semi-trailer and Mr Ogilvie, whose workshop was just down the road, was called in to provide some practical assistance. Over the years, he has provided that and much more.

"Then some of the vehicles in the collection had been sitting around for a while and were pretty stubborn to get started. So one of the conservators asked if I could help get them going," Mr Ogilvie said.

As the museum's collection has grown so too, has the need for diverse knowledge and more skilled hands. That's when Ian Stewart and Ken Houlahan came on as contractors.

Australia's unique motoring heritage, from a massive Fowler steam-powered road locomotive which hauled the formative building materials of the national capital into place, to a tiny home-engineered potato-farming tractor, are protected gems of the museum's collection but rarely fall under the public gaze.

Tucked away in the Mitchell warehouse, coddled in plastic cocoons under positive air pressure to keep out the dust, are some significant nuggets from our automotive past.

There's the first Holden 48-415 ever sold to a member of an eager Australian public and purchased by the head of BHP, Essington Lewis; the infamous Bean "Sundowner" driven across inhospitable parts of the world by the indefatigable Frances Birtles, and; Sir Jack Brabham's 1967 Repco-Brabham prototype racing car with "made in Australia" proudly stamped on its V8 engine block.

Proof that Australia's fascination for electric vehicles and solar power has a long history is a machine called The Quiet Achiever.

This oddball craft, which looks just like a bathtub topped with a reflective garage door, crossed the continent from Perth to Sydney, a distance of over 4000 kilometres, under solar power in 20 days way back in 1982.

Another remarkable part of the collection is the rusty Bedford truck which delivered letters and supplies to stockman Vincent Lingiari and the 200 brave Aboriginal stockmen who walked off Wave Hill cattle station in 1966, striking for better pay and working conditions.

The tough old truck made the slow 1200km round trip into Darwin and back on terrible dirt roads many times to provide vital support to the indigenous activists.

The Wave Hill land rights battle against the rich and powerful Vestey cattle barons culminated in the famous victory for the Gurindji people and for Aboriginal land rights, with the soil of the land poured by Gough Whitlam into Lingiari's open palm.

Cars and motorcycles are wonderful mobile exhibits much-loved by the public but problematic for conservation.

Every vehicle in the museum collection has its own maintenance schedule. Each must be extracted from the collection according to that schedule, put on a hoist, the lubricants, coolant, tyres and underbody components carefully checked, and the fuel then added before start-up.

If petrol stays in the vehicles' tanks too long, it loses its volatility and won't easily combust. Over a longer time, it also can degrade other components.

Earlier this year in Canberra, internationally renown car collector and judge Dr Aldolfo Orsi, whose family remains forever connected with the famous Maserati nameplate, added his supporting voice to those who love to see old cars driven and preserved, with the patina of time giving them their unique character.

"Cars are dynamic things; they were created to be this way," the knowledgeable Dr Orsi said. "They need to move; they desire to be driven."

However, all mechanical devices are subject to wear and tear. And when something old wears out, the replacement parts are hard to find or simply don't exist.

Inside the museum's hangar-sized facility is a small but well-equipped workshop where Canberra's three wise men of the museum re-make that which can longer be bought or found.

The museum's giant precision machining mill, trucked up from the former Ansett Airways machine shed at Victoria's Moorabbin airport, is many decades old but performs just as faultlessly now as it did when keeping Sir Reg Ansett's aircraft airborne back in the 1960s.

There's a toolmaker's lathe, several sizes of drill press, a dedicated welding area, and a bench spread with with well-worn mallets, hand-drawn sketch designs and various sized taps and dies used to cut threads in steel.

"Over the years we've argued and chewed over a lot of design and re-work problems at this bench," Ian Stewart said with a smile.

"We can't cast anything here but other than that there's not much in the way of parts we can't make.

"The big issue is that very often the original plans and designs of the machines we are working on are long gone.

"If that's the case, then we put our heads together and reverse engineer it."

That's the exact problem being tackled now with the luxurious four-tonne 1949 Daimler laundette sedan, imported to Australia for Royal tours including the young monarch's first back in 1954 when 115 vehicles were shuffled around the country with military precision to support the then-young Queen's busy itinerary.

The Daimler's imposing coachwork body, with its rich leather and mahogany interior, was custom-built by a British specialist company which no longer exists, so reverse-engineering, or carefully taking it apart to determine how it was put together in the the first place, is the only solution.

For Ken Houlahan, it's these mental challenges he most relishes, although his ageing body creaks with complaint.

"Once we finish the Daimler, because that's a project I've been pretty closely involved with, then that might be time for me to leave the museum," he said.

"It's just getting too physically tough for me.

"I've loved coming here one or two days a week because it keeps me thinking and active and problem solving when blokes I know my age have retired, sat on the couch and then fallen off the twig.

"But I'm finding now I just can't do do all the things I used to do. So I'm happy to hand over the reins . . . if we can find someone who will take them."

For the first time, many unseen vehicles from the museum collection will be driven and on show at Goulburn's Wakefield Park Raceway on Saturday August 17. Visit www.nma.gov.au/wakefield.