An endless-rope system in which the rope runs over the tubs or cars in the center of the rails. This system is generally adopted on undulating roads, where the tension in a heavily loaded rope would cause the rope to lift in swilleys and derail tubs. It is also generally adopted in highly inclined roads, as the lashing chain, often adopted with this method of haulage, obtains a good positive grip on the rope and is easier to detach than a clip. The rope is kept from rubbing on roof supports by holding-down pulleys: six or eight small pulleys are mounted in circular cheeks, allowing chains or clips to be accommodated in the spaces between the pulleys; or large diameter pulleys may be used, of the hat or mushroom shape, often starred to provide recesses for chains and clips. Similar large pulleys direct the rope around curves. Compare: undertub system.