Commuter locos

[zardoz]

QUOTE: Originally posted by Sterling1

Would electro-pneumatic braking be better than blended braking or is it about ihe same?

I'm not sure. The 'blended brake" worked like this: when an automatic brake application is made, the locomotive air brakes set just like on any locomotive. What also happens when the application is made, the dynamic brakes automatically activate (assuming the throttle is shut off), and as the dynamic amperage builds, the air to the brake cylinders is bled off until there is only about 5psi left on the cylinders, as well as the full dynamic brake, thus the two systems "blend" together to create a smooth, but much stronger braking system.

Also what about the extra diesel engine on some locomotives that's Cummins or whatever what's the horsepower rating and what's the reason for having a separate engine when it could be driven by alternator or inverter?

I do not know that much about the HEP specs, other than that the Cummins operated at 1800rpm, was incredible loud, and sprayed oil all over the inside of the engine compartment. Which not only made quite a mess of your clothes if you had to walk past it to get to or from the cab from the coaches, but the oil got into the electrical cabinet for the controls of the HEP engine (which were mounted unwisely right next to the engine), and caused many operational problems.. The engine itself was mounted perpendicular to the prime mover, and did not allow much space to walk past it, hence the above mentioned problems with turning your work clothes into oil rags.

The F40PH did what you suggested, using the prime mover to supply motive and head-end power. The HEP when activated was regarded as taking about 500HP away from the traction motors.

[daveklepper]

A separate diesel for head-end "hotel" power allows the main diesel to operate economically, with a low idle speed. If the main diesel is also used for "hotel" power, then it may have to be operated at constant speed OR at a range of speeds with the lowest still well above idle. Given the use of only one diesel, the choice of the two (constant speed or some attempt at fuel economy and noise reduction) depends on how much money you want to spend on such things as the generator or alternator, frequency conversion or inverter equipment, batteries, and other such electrical stuff and their automatic electronic controls. So there really are three choices for suburban locomotives.

In the old days, the CB&Q E-7's and E-8's were used interchangeably on long-distance and Chicago suburban passenger trains. But in those days the hotel power for the suburgan trains, including the new Budd gallery cars, was provided by old heavyweight steel coaches converted into generator power cars at the oppposite end of the train from the locomotive. The "Q" started putting head-end power from the traction diesel itself, removing the steam-heat boilers and I guess installing Cummings diesels but I am not sure, and went to push-pull operation with cab cars, about the same time. I rode the "Q" suburban trains regularly in 1952, when steam heat was still used on long-distance trains, and power cars for the suburban trains. There were still a few Pacific stream locos in suburban service, sometimes with gallery cars, but all suburban trains had hotel power cars with head end electric power. Wen I rode regularly 1967-1970, the E units were still running, but were providing the head end power with push-pull operation and all "Q" suburban trains used gallery cars. I think at the time, the few diesels still required for long-distance service were separate from the suburban group.
Also, no B-unnits and no E-5's were used in suburban service during either period in my memory.

[Anonymous]

I have seen some MBTA (Mass. Bay Transportation Authority) F40PH's with metal grates over the winshields. I'm assuming these grates are to protect from vandalism and falling debris.

[Anonymous]

I know the coaches on the West Coast Express (a commuter train here in Vancouver) is equipped with Disc brakes as well as regular air brakes.

[Anonymous]

An engine used for passenger service would need automatic brakes equipped for graduated release, I would think. The cut-out **** would have "Out; Freight, and Pass." settings. A passenger engine wouldn't have to have the blended brake feature; in fact, that's a fairly recent addition. I know they couldn't put blended brakes on the commuter nags fast enough.

[Junctionfan]

From the sounds of it, GO transit in Toronto may decide to get some P-42s. Does anybody have confirmation on this?

[Sterling1]

Would electro-pneumatic braking be better than blended braking or is it about ihe same?

Also what about the extra diesel engine on some locomotives that's Cummins or whatever what's the horsepower rating and what's the reason for having a separate engine when it could be driven by alternator or inverter?

[Anonymous]

Are you refering to any railroad specifically, such as Metrolink or Coaster?

[Glen Ellyn]

Metra, the Chicago & Subarb train authority has alot of stuff.

[zardoz]

The F7 & E8's that the CNW used were (as far as I know) stock units, with the exception of gearing for higher speeds. The only addition I am aware of was the second diesel engine (Cummins originally, later replaced by Detroit brand) in the rear of the carbody to supply electrical power to the coaches (prior to that there was a steam generator in the rear portion. The cabs were somewhat modified with the replacement of the 24RL brake valve with a 26L, and some other control stand modifications.

The F40's were designed for passenger service. And as such there were likely considerations made in the construction (that I am not technically knowledgeable about) to withstand the demands of that type of service. For suburban service, there may have been further modifications that differed from long-haul passenger (Amtrak) service.

A suburban train starts and stops on average (at least on the CNW) about every 3-4 minutes, as some stations are close together (some less than a mile apart). And as a set of suburban equipment might make 80 such stops in a day, this equipment takes quite a pounding.

When the unit is on a train and all functions are enabled, the prime mover runs at a constant full speed (to supply a steady current for the coaches). The trucks have only one brake shoe per wheel, and the unit goes into dynamic braking at every stop (called "blended braking"). There are some electrical modifications in the cab for the head-end power controls. I'm sure there are other, less obvious differences, but someone with more technical knowledge than me will have to enlighten us.

[Anonymous]

The post about train handling and suburban service reminded me of a recent Trains article that talked about hardening locos used for commuter service in Ca. I recall reference made to cracked engine mounts and warped connecting rods. What types of changes are made to locos intended for this service? Traction motors, cooling, braking, etc.??