The left hand side of the cab shows: (1) The valve towards the top is the vacuum ejector duplex valve (2) Below the running plate is the cylinder drain cock actuating valve. This valve has a drain which is attached to the large pipe behind it, this large pipe being for water delivery from the injector under the fireman's side of the cab to the clack valve on the front ring of the boiler. 18 July, 2015, P GIBBS.