Pneumatic high/low beam

[Guest Ken G]

Now this one is probably obscure! My 1925 Rover has mechanically dipping headlights. (At present they dip to the left, but I am planning to rotate the reflectors so they dip to the right). Each reflector pivots so that it can point straight ahead or be deflected downwards via a little piston and cylinder operated pneumatically; there is a light over-centered spring to provide a toggle action. Very narrow-bore copper piping goes to the dash, where there is a master piston and cylinder. You pull the handle to dip, push it for high beam. All the pistons and cylinders seem to operate properly, with leather washers in good order, and if I connect the master cylinder to either of the slaves with short pipes, they work vigorously. The piping has no leaks (we checked with a water manometer). However, when I join everything up as intended, the extra volume of air in the piping apparently prevents the pressure from rising and falling sufficiently relative to atmospheric for the slaves to work, or at least, they try but do not toggle. I am beginning to wonder whether the system ever worked properly; it is not mentioned in the instruction book, but must have been a recognized accessory because the reflectors had to be ?official?. I am pretty sure that the piping is original (i.e. not a larger bore).

Has anyone experience of such a system, and if so, does it work?

Ken G, 1925 Rover 16/50 (San Francisco)

[Guest Ken G]

For anyone who might be interested, I played with the more sluggish of the slave cylinders, adding larger metal washers to encourage the leather piston washers to press against the walls of the cylinder, and perhaps more importantly I experimented with the several ways in which the over-centered toggle spring would fit. To my surprise the system now works.

Now I have to tackle changing the dipping from left to right, without spoiling the beautiful newly silvered reflectors (it's amazing how much more light the modest bulbs give with decent reflectors!).

Ken G, 1925 Rover 16/50 (San Francisco)