Quote:
Originally Posted by drolston
I get why you are stuck on this. With mechanical brakes, when the pedal goes down, all shoes move at the same time.
Thought experiment: If you were blowing on two straws, one in water and one in molasses, where would the bubbles come out? The fluid (air in this case) would all come up in the water, none in the molasses. It would follow the path of least resistance.
As the pedal is pushed down the pressure in the whole system will go up. The resulting flow will follow the path of least resistance. When the pressure gets high enough to over come friction within the shoe with least friction, that shoe will move. It will continue to move until it hits something that offers resistance, like a brake drum. The the pressure within the system will then rise until it overcomes the shoe with the next weakest friction; then that shoe will move until it hits resistance (the drum). In short order, all shoes are pushing against the drums and friction within the wheel cylinders is not a factor. With the drums off you could easily push the lowest friction wheel cylinder piston completely out of its cylinder before another shoe moves. But that is completely not an issue with the drums on and all shoes meet the drum after very little brake fluid has moved.
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drolston ......Great example (water/molasses), and an even better explanation about the shoe(s) movement/friction! DD
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