Bungador's Tony Roberts pioneered a differential locking system coined the "Roberts Diff-Lock" in 1984 to help four-wheel drives get out of tricky situations, like getting bogged.

Australian four-wheel drive accessory brand ARB bought the product three years later, and listed on the ASX soon after.

The locking system has been in Australian and overseas vehicles ever since.

But nearly four decades later Mr Roberts has made another breakthrough and has developed a second part, coined a "double diff-lock", he believes will reduce occasional failures.

"I had an idea," he said. "We can bypass that area of failure."

Federal government grants worth about $300,000 in the past year have given confidence to the engineering, including $99,550 in April from the manufacturing modernisation fund.

The grants have helped the Roberts family business Altair Aviation increase production to more than 100 models and test the part in Toyota's Hilux and Landcruiser.

"We will probably end up covering the entire range of four-wheel drives that are available in Australia," Mr Roberts said.

The equipment is quickly outgrowing the workshop and the business has early plans for a Camperdown factory, where the workforce could increase beyond the family.

Mr Roberts said he was as young as 12 when he came to love cars and engineering.

"'It's something I messed around with since I was very young," he said.

He and wife Patricia later owned the biggest pilot ground training school in Australia in the 1970s and early 80s at the Moorabbin Airport.

At the time Mr Roberts had the highest pass rate for student pilots in Australia.

But it was exploring rough terrain in Victoria's high country as a pastime on family holidays that led to Mr Roberts' design.

The family would go on four-wheel drive holidays for a week or two, but daughter Sarah recalled their car would get bogged.

"If you went in there you might not be able to get out until the mud dried off or you needed a winch," Ms Roberts said.

She said her father, with no formal engineering training, invented a locking mechanism.

"I think they got sick and tired of getting stuck in the bush and the mud with little kids," Ms Roberts said.

"The idea is that you can actually get in the car and flick a switch and you don't have to get out of your car in the mud."

She said the part was also more contained than any other, allowing many people to install it themselves at home.

Around the same time the part sold to ARB the family also moved to Bungador in the south-west. They took to beef farming and manufacturing parts for dairy platforms from a machine shop at the farm.

"My parents loved the area. My grandparents moved here in the early 80s and they spent some time here and liked the area," Ms Roberts said.

For the past four years Mr Roberts and son David have worked to improve on the successful locking device.

"We had an idea over the years, I have seen failures in locking differentials and it is pretty commonly a failure of the bevel gear teeth." Mr Roberts said.

"What we have here is a way of bypassing the bevel gear teeth when the differential is locked, we can bypass that area of failure."

The new part will initially sell as a four-wheel drive after-market part and the Roberts expect it will sell mostly in Australia, the United States and the Middle East, but also in Asia and Europe.

Mr Roberts said the new product would help the business diversify alongside manufacturing products for the dairy industry.

"It's important to try and not have all your eggs in one basket. My son is working with me and we have worked to perfect the design of this," he said.

David described his father's flair for innovation as "brilliant" and said he was proud the south-west was manufacturing a global car part.

"A lot of our competitors they will have a lot of their components made all over the world. Some have them made in Thailand, China or all over the place and they bring it in and assemble it and sell it," David said.

"But we like to keep things Australian and keep things here, we do as much as of it as we possibly can."

He said it was also working in the south-west that he appreciated after he was schooled in Camperdown but later studied and worked in Melbourne.

"I will be talking to people we deal with in Melbourne and one day for instance I was looking out the window and a great big tiger snake dropped off the roof onto the ground, in that way it's nice to work where I grew up," David said.

The federal grant has helped the farm workshop gain new machinery that completes more work in-house.

But Sarah Roberts says the farm site is now quickly "running out of room".

"It's a workshop with fairly advanced machinery, they have the ability to prototype almost anything," she said.

Ms Roberts said there was now a move on the cards to Camperdown, where the business will find or build a factory site.

"Our goal is to move into Camperdown and we think by the end of the year we will be hiring staff," she said.

"In the short-term we may hire three-to-four people. In the long-term it will depend."

Mr Roberts said the grants would likely see the business grow. "These grants are allowing companies like ours to increase our productivity and it's great for the regions, in that it should increase employment ," he said.

"I just hope it's successful and it will keep running for another 30 or more years as the last product did."

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