Boatnerd Discussion Forum

This is called a cross compound turbine. Still used in power plants on shore. Great space saving design for boats; shafts are side by side thus leaving more space for cargo, shafts could be longer with additional bearings, just like in a power plant but would use valuable, revenue producing space.

Without going into too much detail the more nozzles and rows of blades the steam passes through as it expands in the turbine the more power is developed
When running in the Ahead direction steam passes through the HP turbine first and then through the LP turbine to the condenser.
When running in the Astern direction the steam is directed another set of nozzles and blades mounted in the LP Turbine casing and allowed to expand very rapidly to the condenser.
The turbine will develop 100% power in the ahead direction but will develop less than 33% power in the astern direction with the same amount of steam

On the Gov. Miller and Wm. A. Irvin, the low pressure turbine was used for going astern.

the smaller casing is the high pressure and the larger casing is the low pressure turbine. Without getting into too much detail, the two turbines act like one, the high pressure steam flows into the high pressure turbine, gives up its energy then crosses over to the low pressure turbine where it uses up most of the energy that is left. It has been a while since I have looked at my old steam notes since I dont sail on steam boats anymore but the high pressure turbine has impulse blades and the low pressure turbine has reaction blades to help efficiently use up the lower pressures. The reason why there are two turbines and not one is because if it was one rotor, the rotor would sag under the weight of itself. Attached to the low pressure side of the low pressure turbine is the reverse turbine, which just windmills when the ahead turbine is in use. In some cases you can arrange the piping to use the low pressure turbine in the case you lose the hp turbine but you can not use the individually, they are connected together through the reduction gear.

Does the Mather have 2 different turbines, one low pressure and one high pressure?
How were they used, together or individually? For what purpose? TIA