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Re: I think the engineer was trying to make up time
Author: Dr Zarkoff
Date: 10-13-2020 - 20:29
A few clarifications:
> All that was left was the old "Subs". They were cast iron shoes used right to the end.
The "Subs", which we used to call "80-footers", had been converted to composition shoes by 1969. By this time all the Harriman coaches had been retired.
> Not much of that type weather on the Peninsula Commutes,
The SP didn't use E-brakes on the Peninsula; the PCS has been using them since 1985 (26-E).
> The old heads on the commutes used to know just how much air to give both type of cars. They would use the main brake valve
I presume you mean the "automatic brake valve" for the train brakes.
> to "Pop" the air in order to get a harder set but the train didn't go into emergency.
If by "pop" you mean "grabbing a small amount of the big hole", you can't do this with the 26-L brake valve the 3197-3199 and 3200s had. You can do this with the DS-24 brake valve used by the geeps, SD9s, and F-Ms to bypass delays arising from equalizing piston operation so the brakes applied sooner, but it's extremely tricky (not to mention frowned upon by the SP). Some of WABCo's brake systems were actually designed to do this, but not 24-RL nor 26-L. A "harder set"? no, because the amount of brake application is dependent on the amount of brake pipe reduction, no matter what you did to make it nor how quickly you obtained it.
At high speeds (above 60 mph) composition shoes produce more retarding effort than cast iron can. However, since their friction/speed curve is flat, you don't experience the rise in retardation rate as speed drops inherent with cast iron shoes. This gives the impression that they "aren't as good" (and using them on swtich engines, yech!). In the end it becomes a question of getting used to the difference and governing your brake applications accordingly.
> These guys were artist in operating the commutes. Some signals would be red but clear to yellow just before you got to them.
"Riding the yellows" is another tricky business. These sorts of abilities come from running the trains day in and day out for years. With the advent of PTC, this sort of grandstanding is no longer possible, particularly anywhere on Unlimited Parking.
> Again, the passages I listed mentioned Winter Snow & Ice Conditions as being a major reason for the electro - pneumatic brake system's problems.
"Weather conditions" is the typical catch-all phrase when they can't definitely find anything else and the weather was bad. It isn't anything unique to E-braking systems; see the Colorado Midland's placement of it's angle cocks and brake hoses on its freight cars. In at least one of these "weather condition" related brake failure accidents, it was not snow and ice but the inability of the electronic brake valve on the engine to regulate brake pressure properly after the brakes had been applied, and there were no E-brakes on the cars in the train.
> All that was left was the old "Subs". They were cast iron shoes used right to the end.
The "Subs", which we used to call "80-footers", had been converted to composition shoes by 1969. By this time all the Harriman coaches had been retired.
> Not much of that type weather on the Peninsula Commutes,
The SP didn't use E-brakes on the Peninsula; the PCS has been using them since 1985 (26-E).
> The old heads on the commutes used to know just how much air to give both type of cars. They would use the main brake valve
I presume you mean the "automatic brake valve" for the train brakes.
> to "Pop" the air in order to get a harder set but the train didn't go into emergency.
If by "pop" you mean "grabbing a small amount of the big hole", you can't do this with the 26-L brake valve the 3197-3199 and 3200s had. You can do this with the DS-24 brake valve used by the geeps, SD9s, and F-Ms to bypass delays arising from equalizing piston operation so the brakes applied sooner, but it's extremely tricky (not to mention frowned upon by the SP). Some of WABCo's brake systems were actually designed to do this, but not 24-RL nor 26-L. A "harder set"? no, because the amount of brake application is dependent on the amount of brake pipe reduction, no matter what you did to make it nor how quickly you obtained it.
At high speeds (above 60 mph) composition shoes produce more retarding effort than cast iron can. However, since their friction/speed curve is flat, you don't experience the rise in retardation rate as speed drops inherent with cast iron shoes. This gives the impression that they "aren't as good" (and using them on swtich engines, yech!). In the end it becomes a question of getting used to the difference and governing your brake applications accordingly.
> These guys were artist in operating the commutes. Some signals would be red but clear to yellow just before you got to them.
"Riding the yellows" is another tricky business. These sorts of abilities come from running the trains day in and day out for years. With the advent of PTC, this sort of grandstanding is no longer possible, particularly anywhere on Unlimited Parking.
> Again, the passages I listed mentioned Winter Snow & Ice Conditions as being a major reason for the electro - pneumatic brake system's problems.
"Weather conditions" is the typical catch-all phrase when they can't definitely find anything else and the weather was bad. It isn't anything unique to E-braking systems; see the Colorado Midland's placement of it's angle cocks and brake hoses on its freight cars. In at least one of these "weather condition" related brake failure accidents, it was not snow and ice but the inability of the electronic brake valve on the engine to regulate brake pressure properly after the brakes had been applied, and there were no E-brakes on the cars in the train.
