06.01 – Engine maintenance: The Boiler

A steam locomotive requires specific attention and technical knowledge. Regularly on pre-scheduled times the loco needs inspection and examining regarding all taken measurements to meet the highest standards to gain safe and high speed driving in the best economical and less expensive way. Throughout all the years the steam lcomotive was in service. Engineers always redesign and recalculates the best way to perform better, using cheaper materials and methods to make an engine cost effective. Though this chapter is not directly needed for TS2015 but reveals in a short overview what it takes to repair an engine. For a complete and enhanced technical overview, visit a workshop from a club or society otherwise try to make a holiday with a visit to RAW Meiningen in Germany.

RAW Meiningen is the last remaining workshop to restore steam locomotives. The workshop now is receiving orders from all over the world. The boiler for newly build Tornado is manufactured here.

The Boiler

The most important power source of a steam locomotive is the boiler. A boiler is continuously pressurized at about 220 PSI / 16 Bar. It is therefore rather important to inspect the boiler closely, and investigate on metal fatigue. The tremendous forces a boiler endures could result in an explosion if the boiler is not treated well. In chapter 3 a boiler explosion is mentioned.

The boiler is a sophisticated piece of engineering. It is not only the material that is used to manufacture a boiler, but all effort that is needed to build a boiler.

Stainless steal is used here for the new boiler for the Tornado 60163 in RAW Meiningen

The stays of the boiler holds the inner surface of the fire box and outer surface of the boiler steady in place. The water and pressure is captured In between both surfaces. The diagram shows three different stays. The stays are all hollow to avoid total refracting on certain pressure changes. 

The boiler in preparation. The super heater elements are installed and the steam transportation tubes needs to be installed now. The spark arrestor installed in the smoke box in front of the super heater header catching the coal sparks before they disappear out of the chimney.

The steam dome

On top of the boiler the dome is present. The dome is to prevent water priming. The valve inside the dome is installed with the steam inlet upwards. in the valve that is regulated by the regulator contains a series of valves that opens up one after each other. The first valve has the smallest steam inlet and the last valve has the widest steam inlet.

These series of valves are operated one after each other. The reason why this is installed has to do with the amount of steam that suddenly is revealed into the steam pipe. The steam released into the pipe is saturated steam that now is led to the super heaters if installed.

The open dome with the steam valve that is regulated by the regulator itself. From this point saturated steam flows to the super heater elements in the header that is installed in the top of the smoke box.

Periodical wash-out

During a blow down not all sediment comes loose out of the boiler and some lime sediment will still settle in the bottom of the boiler. At strategically points the boiler contains special oval shaped hatched that can be removed when de boiler is depressurized and dewatered.

When the boiler is empty the wash-out plugs can be removed.

The wash-out plugs removed. Mention the oval shape model the plug has. These plugs need to be unplugged from inside out. The bolt that is welded on top of the plug contains a nuts and a bore hole. Through the bore hole a string is placed that attaches the hand of the employee to avoid the plug to drop down in between the tubes and pipes inside the boiler.

The wash-out takes about 1 hour to take place completely depending the size of the boiler. After unplugging the wash-out plugs from the boiler, water now is sprayed into the boiler at high pressure by a spray lance will flush all the lime scaling from the bottom, tubes and pipes. 

The sediment feels like mud (also called “slush”) and contain clogs of lime, some hardened out to a stone like shaped bricks that scratches the hands of the worker busy at the wash-out. The wash-out of the boiler is finished when the water that comes out of the wash-out gap is crystal clear.

The wash out normally takes place by the use of a large industrial spray lance.

The spray lance is inserted into the wash-out plug pointed by the red arrow when unplugged at this Live-steam miniature railway engine Original engines have an oval plug installed. 

The blower and exhaust pipes installed. The blower is the brass ring that surrounds the exhaust pipes. opening the blower valve wil spray the steam out of tine holes in the pipe towards the chimney.

The working of the blower is clearly visible.

When the smoke door should be closed here. A vacuum is produced due to the working of the blower pulling all air through the fire grate, boiler pipes and tubes through the chimney together with the hot gasses and coal sparks.

The Boiler studs

The boiler studs supports the boiler that carries the weight of the boiler onto the rigid frame. This point is fixed to the frame the other side of the boiler is carried by slider bars the carries the weight of the boiler but the boiler is able to move parallel to the frame by these slider bearers. The slider bearers are attached at the side of the fire box. These sliders are mounted to the frame.

The fixed rigid studs that supports the smoke box and the boiler. Boiler slider bearers that carries the weight of the boiler but gives the possibility the move along the sliders bearers.

The middle support bearers are flexible steal plates that carries the weight of the boiler in the middle. The plate moves with the lenght of the boiler when it expands by heating up

A boiler slider attached to the fire box

The boiler now rest on top of the frame that is supported by these studs and slider bearers. The weight of the boiler is divided over the different support bearers.