Reader has more info on old pea vineries
In regard to the post card view of the canning plant in Albion, the peas are not going up the conveyor but are sliding down, probably being helped by people on the ground with pitchforks. The ramp was probably a simple chute instead of an actual conveyor.
A person would sit by one of the small dormer-like structures and pick the pods off the vine. The remains would then be sent down the chute to be sold as cattle feed. I remember there were several “pea vineries” located in northern Genesee County, which were barn-like structures and not part of plants as in Albion.
By the 1950s they were worked by migrant labor and were active during the pea season, surrounded by farm trucks, people, a migrant bus, and vines sliding down the chute. Then they would sit idle the rest of the year. By the late ’60s or early ’70s, they had all collapsed or been torn down.