Loco faults
Here’s a fault I had to repair recently on an A3, the boiler thermal cut out had failed and needed replacing. This is not a very regular fault but crops up from time to time.
This device is used to protect the tender from overheating or if you forget to switch off the loco after the water has run out. It is set to cut out at 145C.
I’ve found these devices can fail in two ways; they fail totally and the controller alarms after about 10 seconds from being switched on, or they fail at random temperatures during steaming. You can test if it has completely failed with a continuity test across the two tender chassis plates. If it is failing at random temperatures then it’s possible to listen for a soft ‘click’ when it resets as the tender cools down, then you know that it is faulty.
It is connected in series with the tender cartridge heater and to replace it the tender needs to be dismantled as seen in the pictures below. It is housed inside a plastic moulding which is screwed to the underside of the boiler. A spare unit is supplied with an eyelet crimped onto one wire, the conductor is bared on the other wire for soldering which needs to be insulated afterwards.
The device and assembly method is the same for both the A3s and the A4s.
Hello Eric, Excellent advice to loco problems with pictures 5 STAR*. A BIG problem I came across was on the timing fine adjustment screw in the forward direction. Noticed that when screwed inwards to improve running speed the screw contact on the pin was to high. IE:- the gear driving peg. To eliminate the problem I used a 1.2mm threaded nut to give larger area contact for more positive response. With spares very limited found that SUPER HEATER ELEMENT was unavailable. Would you know the wattage of this element as to try to track down the equivalent replacement CHEEERRRRRRRRSSSSSSSSS!!!!!!!!!!!!!! steve.