The 4MT sees its first fire!

I took the new 4MT Standard Class Tank loco to Urmston club on Sunday for its hydraulic and steam test, and to see how it runs.

It passed both tests with no issues at all. A few teething troubles were revealed on running it, but once those are put right under warranty I think it has the potential to be a superb locomotive.

The pictures tell the story. 

On the 'arrival' table at Urmston club. This can be raised or lowered by compressed air to suit the height of one's car load area. 

 The flight deck

 On the prep bay. I'm replacing the two safety valves with one blanking plug and one blanking plug with a connection to 'Boiler' Bob's (standing next to me) calibrated pump and pressure gauge (behind the loco).

I have filled the boiler to the brim with water, and Bob will pressurise it to 1.5 times working pressure (135 psi for a working pressure of 90 psi). If it should fail (which it won't as it has a manufacturer's shell test certificate to twice working pressure) there will be no explosion, water being incompressible.

 With its door open so Bob can check the front of the boiler for hydraulic leaks, here's a look into the smoke box. 

The blast pipe is in the foreground (the exhaust steam from the cylinders exits her to blast up the chimney), below the skirt of the chimney petticoat. The two big copper pipes exiting the sides of the smoke box are the superheated steam feeds to each of the two cylinders from the superheater header.

In the background is the the front tube plate of the boiler showing the boiler flue tubes that run through the water space from the firebox at the back of the boiler.

The partial vacuum formed in the smoke box by the blast pipe is what draws the hot flue gasses through the boiler tubes and draws the fire to almost white heat when the loco is working hard.

The small copper pipe into the side of the blast pipe feeds boiler steam to the blower, controlled from the cab this gives a blast up the chimney to draw the fire when the loco is not on the move.

The steam test followed the hydraulic test. This ensures that the boiler has at least two methods of getting water into it (the 4MT has a live steam injector, a hand pump, and an axle pump) and that with full blower to give a maximum fire the safety valves blow off at or just before working pressure is reached, and can dissipate the steam at a rate that holds the boiler pressure within the limit. 

After I'd driven the loco around the track a few times 'Boiler' Bob has a go, watched by Malc. Loco blowing off healthily through both safety valves!

The 4MT in its element - albeit on the short Urmston track.

Note that the cylinder drain cocks have not fully closed hence the steam from the front end, one of several 'teething' faults to be addressed before we take her out on the main track.

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