Actually I found out that now the more popular system for this kind of door there doesn't even use counterweights or springs, but an endless screw inside a rail or a linear gear.
https://ppa-rp.com.br/item/motor-de-portao-basculante-ppa-ho... max door weight = 250kg
https://ppa-rp.com.br/item/motor-de-portao-basculante-ppa-bv... max door weight = 500kg
For reference: 5.0 R$ ~= 1.0 USD 250 kg ~= 550 lbs
Actually I found out that now the more popular system for this kind of door there doesn't even use counterweights or springs, but an endless screw inside a rail or a linear gear.
https://ppa-rp.com.br/item/motor-de-portao-basculante-ppa-ho... max door weight = 250kg
https://ppa-rp.com.br/item/motor-de-portao-basculante-ppa-bv... max door weight = 500kg
For reference: 5.0 R$ ~= 1.0 USD 250 kg ~= 550 lbs