Giants broadcaster Mike Krukow revealed Thursday that he will cut his schedule to 120 games this season, with former relievers Jeremy Affeldt and just-retired Javier Lopez taking his place on the others.

Krukow said by phone he plans to broadcast all of the Giants’ 81 home games and National League West road games, but “nothing east of Denver until the playoffs.”

Affeldt and Lopez will team with Duane Kuiper and sometimes Dave Flemming in place of Krukow, who has worked about 156 games a year.

Krukow’s mobility is hampered by a progressive but non-life-threatening disease. He revealed his reduced schedule Thursday morning on KNBR, saying it was “not by the Giants’ design. It’s all I can do.”

Later, speaking to The Chronicle, he said, “The problem with me was just being able to maintain strength getting up and down stairs, getting out of the plane. I have to respect it.”

However, the 64-year-old former pitcher said he has no plans to retire, saying, “Hopefully I can do this many more years. I want to.”

In fact, Krukow originally planned to call just 100 games in 2017 but upped it to 120 because of how well he has felt this winter.

“The Giants are unbelievable,” he said. “Larry (Baer) said, ‘You give me what you can give me.’ That’s where I am right now.”

Krukow has broadcast Giants games on TV for 26 seasons. He and Kuiper are considered one of the best teams in baseball. In November, Krukow was named a finalist for the Hall of Fame’s Ford C. Frick Award, which the late Bill King won.

Affeldt retired after the 2015 season and served as an analyst for Comcast Sports Net Bay Area, also doing some color work on game broadcasts. Lopez announced his retirement Tuesday.

Neither the Giants nor KNBR have announced the broadcast changes formally.

Henry Schulman is a San Francisco Chronicle staff writer. Email: hschulman@sfchronicle.com Twitter: @hankschulman