About six months ahead of expiration of the current labor contract between the Philadelphia Orchestra Association and its players, the two sides have reached an agreement on a pact that keeps the peace for the next four years.

The new deal includes further restoration of positions to the ensemble after its size was cut with the orchestra’s bankruptcy several years ago, and it provides modest raises for players over the term of the contract.

It also contains a significant enhancement for the listening public. Changes in work rules will increase the ability of the orchestra to schedule Sunday afternoon concerts, which are popular with audiences, to 18 per season from the current 12.

That the Philadelphia Orchestra is able to ratify a new labor contract now is notable given the fact that one of its peer ensembles, the Chicago Symphony Orchestra, is on strike.

After a bankruptcy filing by the Philadelphia Orchestra Association in 2011 shook public confidence and a brief strike on opening night in 2016, the organization was determined in this negotiating season to send a positive message to both donors and ticket buyers. Talks in February and March wrapped up about a week ago, and Tuesday a tentative agreement was brought to a vote by players.

The new, early contract agreement represents a significant win for Matias Tarnopolsky, who took over as the orchestra’s new president and CEO in August. It gives him an attractive calling card with donors, who look for continuity and organizational unity when considering where to direct their donations.

The new deal is expected to increase by 2 to 3 percent each year the amount the association must bring in through a combination of earned revenue and donations, said Tarnopolsky, who said the orchestra’s fund-raising prospects were now brightened.

“We want to inspire both the donors of today and of the future with an exciting vision, and this agreement powerfully sets that stage.”

Players are betting that Tarnopolsky can “fill our hall and raise a lot of money,” said violinist William Polk, chair of the musicians’ negotiating committee, who declined to release the contact vote count. The first year of the contract gives players a raise that is below the cost-of-living increase, he said, “and I view that as giving him a little room to maneuver.”

A four-year deal, he said, signals stability. “It would be great to tell the Philadelphia community that we have our act together here and that at one of their flagship cultural organizations we are getting along with each other,” Polk said.

The new agreement calls for the orchestra’s complement (the size of the full-time ensemble) to increase by two positions, with one added back in 2020-21 and another in 2022-23, from the current 97 players and two librarians to 99 players and two librarians.

“Whenever we have an opening our artistic committee and [music director] Yannick [Nézet-Séguin] will decide which position will be filled,” said Polk. The number of players was cut to 95 and two librarians with the bankruptcy, and full complement according to the contract would be 105 musicians and two librarians.

Base salaries will increase over the term of the contract by 2 percent in the first year, 2.5 percent in the second, 2.5 percent in the third, and 3 percent in the last year. Base salary in the current contract is $137,800 per year, though titled players and others earn significantly more.

The pact also includes additional income for players if the organization achieves certain surplus benchmarks.

Also among the work-rule changes is an article that increases by four the number of weeks in which the orchestra can have two double-rehearsal days, and only on weeks when Nézet-Séguin is conducting, to accommodate his conducting schedule at the Metropolitan Opera.

There were no changes in pension or health care, Polk said.

The Philadelphia Orchestra’s new contract runs from Sept. 16, 2019, through Sept. 10, 2023.