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Re: BART's new cars: Why hydraulic brakes instead of air brakes?
Author: Max Wyss
Date: 05-01-2016 - 15:17
Under "railroad applications", I understand anything somehow rolling on rails, from mainline to transit, and certainly not limited to the north American continent.
The example with hydraulic parking brake were/are the Be4/6 1600 series of the VBZ (from 1966 zo 1969), where only 2 units are left in Zürich; the others either left for Vinnizya or the scrapyard. In this case, the hydraulic pressure was built up manually by turning the parking brake wheel in the cab, and released by pressing a pedal. I have not read or heard of any serious issues, that the parking brake developed undetected leaks.
OK, it could be that spring-loaded parking brakes are more an European thing… They are used in mainline vehicles, as well as in transit. In transit, they are very often electromechanically released (in an all-electric vehicle…). Note that modern European light rail vehicles are mainly all-electric, eliminating the need of a pneumatic subsystem (with its maintenance requirements).
Ah, yeah, the "last glory" of the traditional Swiss locomotive building industry, the Lok 2000 (Re460 / Re465 / NSB El18 etc.) has a permanent magnet parking brake (acting on the rails). Once set, you can't get it moved anymore…
Brake shoes? what's that? Where you have spring-loaded parking brakes, you essentially have disk brakes, or, if you have brake shoes, they rarely wear out… remember, parking brakes…
FWIW, the first use of spring-loaded brakes in railroad applications what with cog railroad vehicles … for understandable reasons.
The example with hydraulic parking brake were/are the Be4/6 1600 series of the VBZ (from 1966 zo 1969), where only 2 units are left in Zürich; the others either left for Vinnizya or the scrapyard. In this case, the hydraulic pressure was built up manually by turning the parking brake wheel in the cab, and released by pressing a pedal. I have not read or heard of any serious issues, that the parking brake developed undetected leaks.
OK, it could be that spring-loaded parking brakes are more an European thing… They are used in mainline vehicles, as well as in transit. In transit, they are very often electromechanically released (in an all-electric vehicle…). Note that modern European light rail vehicles are mainly all-electric, eliminating the need of a pneumatic subsystem (with its maintenance requirements).
Ah, yeah, the "last glory" of the traditional Swiss locomotive building industry, the Lok 2000 (Re460 / Re465 / NSB El18 etc.) has a permanent magnet parking brake (acting on the rails). Once set, you can't get it moved anymore…
Brake shoes? what's that? Where you have spring-loaded parking brakes, you essentially have disk brakes, or, if you have brake shoes, they rarely wear out… remember, parking brakes…
FWIW, the first use of spring-loaded brakes in railroad applications what with cog railroad vehicles … for understandable reasons.
