Cov kav dej manifold ntau kab siab siv los txuas ob chav ntawm cov khoom siv hydraulic, feem ntau ntawm cov chav faib: kev ua tau zoo thiab kev tswj hwm siv los tswj cov ntu sib ze ntawm cov npog mechanized. Lawv tso cai rau xa cov kev tswj hwm impulses remotely ntawm kev tswj hwm thiab kev ua tiav units.