Staff at Stockton mine have agreed to work fewer hours and a resulting pay cut as Solid Energy seeks to cut costs, but only as a temporary measure.
Machinery operators at the West Coast mine who belong to the Engineering, Printing and Manufacturing Union (EPMU) have twice rejected Solid Energy's plan to cut shifts from 12 to 10 hours.
Solid Energy has said the cuts were needed to get back to profitability due to a massive cut in the world price of coal, and redundancies were the only other alternative.
Union staff have twice rejected the smaller shifts but agreed in Westport on Thursday to cut the shifts for three months.
The 118-91 vote will result in their pay reduced by 17 percent.
"They didn't really have a choice," EPMU West Coast organiser Garth Elliott told Radio New Zealand.
"There was no other way around it that we could see or the company could see. Hopefully this is only a short-term thing."
Solid Energy spokesman Bryn Somerville said the decision would help both sides trial what was needed to keep the mine afloat financially.
"It gives us and the workforce a chance to look at how it works, and an opportunity to be able to start achieving the savings that we're looking for and talk through what's needed."
Mr Elliott said he hoped the company would reward its staff when the situation improves.
"I just hope that the company remembers what these guys have done to help them out of a tight situation when times are good."
The lower world coal prices led Solid Energy to cut more than 400 jobs around the country last year.