Authorities say 68-year-old Raymond Mundy, of Ramapo, was killed in what is being called a freak accident.
Mundy's wife, Judy, found him pinned under the wreckage when she got home from work.
Paramedics pronounced him dead at the scene.
The Hudson Valley Humane Society's executive vice president, Ann Marie Gaudio, said the society lost someone who had great empathy for animals and people.
Mundy also was an adjunct professor at Rockland Community College, where he taught philosophy and business ethics. He served as Humane Society president for more than 20 years.