The UK buyout firm made a return of more than three times the £14m it paid for the mobility aid manufacturer in 2004.
The mid-market deal comes after a string of big-money acquisitions last week.
Gresham has been in contact with Norwegian mobility giant Handicare for several years, according to a source close to the matter, but a formal bid was only made last week.
Minivator is one of the world’s leading manufacturers of stair-lifts, selling to over 35 countries.
It has distribution operations in the UK and Germany and a production base in China. Since the Gresham buyout, employee numbers at Minivator have increased by 75 per cent to more than 400.
Handicare is one of the leading health companies in Europe. The acquisitive company has operations across the continent, including subsidiaries in Sweden, Denmark and Germany. It is owned by Ferd Private Equity.
Gresham confirmed a deal was imminent but declined to comment on the value.
However, industry sources said the deal was likely to be worth up to £44m.
Last week US buyout company KKR paid Bridgepoint a staggering £955m for Pets at Home, Advent International bought Xafinity from Duke Street for £190m, ICG acquired CPA Global for £440 and Warburg Pincus picked up
Survitec Group for £280m.