NorthPennLimited wrote:That engine seems so small to be putting out 4,700hp.
I guess if you add enough smaller cylinders in a 4-stroke it will equal the output of a 2-stroke V12 EMD built locomotive.
I'll hold my opinions on acceleration and wheel adhesion until it goes out for field testing, but my gut and experience is telling me 4,700 hp on a 280,000lb platform is going to get a lot of wheel slip.
Not necessarily; under ideal track conditions (dry rail, fair weather; which southern california has most of the time compared to new jersey and new york), wheel slip is typically more of a function of starting tractive effort vs adhesion weight, and not horsepower vs adhesion weight. The example I'll use is the NJT ALP-46 vs the NJT ALP-45DP. All three locomotives (F125, ALP-46, and ALP-45DP) are rated at 71,000 lbs of starting tractive effort. The ALP-46 weighs around 202,000 lbs and, as such, experiences wheel slippage when starting a train from a dead stop regularly in service. In such cases, depending on the consist and track conditions, slippage usually lasts until ~20-30 mph. The ALP-45DP, on the other hand, weighs 284,000 lbs and, as such, does not have much of a problem applying all 71,000 lbs of effort to the rails at low speed without slippage as the ALP-46 does. Given this example, I expect the F125, with a similar weight and same starting tractive effort as the ALP-45DP, to have perfectly fine adhesion characteristics.
Remember that the speed at which highest continuous tractive effort is achieved is the speed where maximum wheel horsepower is achieved. Below that speed, the locomotive is only putting a fraction of its rated horsepower to the wheel rim, with hp output closer to 0 at VERY low speeds (below 5 mph) and increasing incrementally until rated horsepower is achieved. Also remember that the F125 is never going to put nearly 4700 hp to the wheel rim. After factoring in a 90% (which is optimistically high) electrical transmission efficiency, you are left with about 4200 hp for traction. THEN you have to factor in HEP load to the passenger cars AND on board locomotive auxiliary loads. Metrolink estimates these loads at an average of 50 kW (67 hp) for the locomotive and 72 kW (95 hp) per passenger car (https://web.archive.org/web/20140201230 ... gation.pdf
" onclick="window.open(this.href);return false;). Take those values, do the math, and you discover that, when powering a 6 car train with the F125, you are left with around 3560 hp for traction.
That being said, Metrolink operates significantly shorter consists than NJT does (3-6 cars versus 8-10 cars), so with 71,000 lbs of starting effort, the F125 should be relatively peppy with its trains. I'm not sure if Metrolink has the spare cars to lengthen its trains longer than 6 cars on a regular basis, but who knows... maybe we'll see 8 car trains rolling around the system in cali. That would be treat