活板 meaning in English

sfl
trap

Universal screw wrench
活扳手活板手
A meek smile accompanied him as he lifted the counterflap , as he passed in through the sidedoor and along the warm dark stairs and passage , along the now reverberating boards . but will he save the circulation
他掀起柜台的活板，穿过一扇侧门，并沿着暖和而昏暗的楼梯和过道走去，还经过如今正回荡着噪音的一个个车间，一路脸上泛着柔和的微笑。