simond
Western Thunderer
Well, Jon, I do have a “mechanical mind”, and some hypothetically relevant experience, in that I worked as a design engineer for Lucas Girling Railway Brake Division some 37 years ago, but... I do not recall having seen such an arrangement before.
So hypothesising...
The shoes appear to be attached to some form of scissors arrangement which appears to provide the actuation (radial force pushing shoes onto wheels) and drag (tangential force opposing wheel rotation) through a single link per shoe. I’m struggling a bit with that, and I wonder if there isn’t a pivot or link hidden up under the solebar, attaching the tops of the shoes to a fixed point.
But it’s not clear how pushing the brake lever down actuates the mechanism. It looks like the end of the shaft is squared, so the shaft rotates and transmits torque to, presumably, a cam or short lever, but it’s not visible. The “scissors” suggest some form of equalisation.
If my surmise that’s there is a hidden fixed pivot on each shoe is correct, then a link attached to the short lever and pushing downwards on the centre of the “scissors” would push the shoes apart and thus against the wheels.
Lifting the lever would allow the shoes to fall away by gravity.
Does this help? I’d be interested if my suggestion could be confirmed or corrected.
Atb
Simon
So hypothesising...
The shoes appear to be attached to some form of scissors arrangement which appears to provide the actuation (radial force pushing shoes onto wheels) and drag (tangential force opposing wheel rotation) through a single link per shoe. I’m struggling a bit with that, and I wonder if there isn’t a pivot or link hidden up under the solebar, attaching the tops of the shoes to a fixed point.
But it’s not clear how pushing the brake lever down actuates the mechanism. It looks like the end of the shaft is squared, so the shaft rotates and transmits torque to, presumably, a cam or short lever, but it’s not visible. The “scissors” suggest some form of equalisation.
If my surmise that’s there is a hidden fixed pivot on each shoe is correct, then a link attached to the short lever and pushing downwards on the centre of the “scissors” would push the shoes apart and thus against the wheels.
Lifting the lever would allow the shoes to fall away by gravity.
Does this help? I’d be interested if my suggestion could be confirmed or corrected.
Atb
Simon