| Diagram | Fig. 14 — ELECTRICAL EQUIPMENT · ref 40 |
| Subsystem | electrical |
| Listed in parts books | 1968–1970 |
Bulb (50/40W. Vert dip. Pre-focus)
Headlamp bulb, 50/40W with vertical dip and pre-focus base, later superseded by 446L.
This is the headlamp bulb, a 50/40W unit with vertical dip and a pre-focus base, listed in the electrical equipment sections covering the headlamp, wiring harness, switches, and tail lamp. It's the standard main bulb that sits in the headlamp shell, giving you both a high and low beam off the two filaments.
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The pre-focus base means the bulb only seats one way in the reflector, so you don't have to worry about aiming it once it's fitted. Catalog listings for this part run from 1968 to 1970. This number was later superseded by 446L, so if your parts book or an old invoice shows that number, it's the same bulb under Triumph's later numbering.
If you're chasing a headlamp fault, don't overlook the obvious - a bulb going down is far more common than a wiring or switch problem, so check this first before pulling the loom apart.
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