Guthrie Rolling Bridge - Running The Bridge In

Running The Bridge In

To raise the bridge a initial lift to the inner end of the bridge is required. This raises the inner wheels back up the inclines of the granite slabs. At the same time the outer ends are pulled from the lip of the granite slab, the wheels rolling down the sprung metal guides. When the inner wheels are pulled up onto the metal trays the weight of the lifting arms assists the raising of the bridge to a point where the centre of gravity of the arms is over the pivot of the upper support stays. From here on the pull necessary to raise the centre wheels is negligible. Once the lifting arms are in the fully retracted position the centre wheels are on top of the metal trays and the axles disengage from the cups. The bridge now sits on its inner two axles. From here it is necessary to pull the bridge in until the outer two wheels arrive at the trays. The bridge is then pulled within the gates on all six wheels.