The fan motors used until about 1972 were a pair of huge diesel engines. These were two of the earliest type of diesel with tall exhaust stacks high above the fan house. The diesels were connected by a drive shaft to large spoked flywheels. These in turn shared the drive shaft with the squirrel cage fans. The fans forced air through the roof of the tunnel which had a false wooden ceiling to direct air into the tunnel. Each tower housed a separate fan motor. One of the fan motors suffered a bearing failure and fire which destroyed both the fan motor and part of the tower housing it. These diesel cylinders were photographed lying outside and a short distance away from the building in 1972. More modern diesels were added about this time using the original flywheels and squirrel cage fans.