At a recent Armstrong Siddeley Owners Club area lunch time meeting, one of our members produced this little item pictured below and asked those present if anyone knew what it was.
Picture of front showing scale and indicator.
We are guessing that your first thought, just like ours, was – a tyre depth indicator. We are all in the correct ‘ball park’ as it does have to do with checking tyres, but in this case it is for checking tyre pressures. The text on the face reminds one after reading the meter to return the indicator to zero. Below this the scale is marked in lbs from zero to 50, and the equivalent kps below. This handy little tool dates back prior to the 1920s at a time when bikes, cars, trucks and light aircraft were fitted with ‘balloon’ type tyres. The merit of these tyres was the cushioning effect over uneven surfaces.
Instructions on how to use the gauge are inscribed on the rear face as seen below.
Picture of rear.
Car fitted with Balloon tyres.