TA/TB Fuel Switch

by Jeff Redman

Description of the bits:

‘A’ … the main body – chromed – with the small fine-threaded retaining screw shown below the main body
‘B’… the diversion valve with cork ‘seal’ ( 1/8” hole drilled down cork centre, cork cut at same angle as diagonal flat, then pushed into place along square section of brass shaft. Cork trimmed to approx. shape with sharp modelling knife and chucked and filed using a crisp new 2nd-cut file, finished to tight fit inside ‘A’ with 320 grade paper. Ensure sufficient square shaft exposed to engage C,D, E and F
‘C’… grooved brass retaining collar, circular centre hole fits loosely on square section of ‘B’, held in place by that fine screw under ‘A’ body.
‘D’… fibre washer (to help seal valve), followed by thin plate ‘E’ which limits rotary movement of valve by abutting protrusion on body of ‘A’.
‘F’… chrome barrel engages square brass end of ‘B’, and is retained by circular threaded nut ‘G’.
The shaft ‘N’, which is connected to the cockpit control is then threaded with chrome end ‘M’, steel washer ‘L’ (which fits inside M), the fine compression spring ‘K’, and finally the eared toggle ‘J’ and washer ‘I’ . Both ‘J’ and ‘I’ have a slot which engages the flat end tongue on the rod ‘N’, and are retained by fine split-pin ‘H’.

Final assembly: The rod and its assembly with the ‘ears’ of ‘J’ engaging the slotted section of ‘F’… the chromed end nut ‘M’ securing the rod in place by screwing onto ‘F’. I’ve made it sound worse than it really is! It’s fiddly but quite simple when laid out on the bench. Don’t know about soaking the cork seal in oil… open to suggestions by those more qualified.