Would anyone please enlighten me on how the scale speed, traction/pull effort of the loco is measured? Keep seeing this on product reviews and don’t have a clue how it is done. Thanks!
Scale speed is pretty straight forward. A scale mile in HO is 60 real feet. It is just simple math to figure out how fast the train is going. So 60 feet per minute is 60 SMPH.
Traction would be measured by coupling the loco to a spring scale on a test bench. Power is slowly applied up to the point of wheel slip. The max. tension on the spring would be the tractive effort available. Several articles have been published in MR about building “Test Benchs”. Check the index.
I have an unorthodox short method but it works for me.
My test distance on a 40 ’ oval, divided by the time , then X 60 .
In my case it’s the 40 feet divided by the 20 seconds it takes for the engine to go around, times 60=120MPH
I test all my few engines this way so I know which ones will double head without a struggle.
10MPH= 1FOOT OF TRAVEL IN 6 SECONDS, 30MPH= 1 FOOT OF TRAVEL IN 2 SECONDS.
One Sunday at the late, lamented Great Train Store in Atlanta, we put a P2K E6 on some flex track and powered it with a MRC powerpack. It would travel 2.5 inches in 20 minutes without ever stopping. That was the best performance I’ve every seen.
Jock Ellis
If you are into bells and whistles, there is a device on the market that will measure the speed and give a digital readout. Lots of fun for the kids at train shows. Kind of boils down to a contest among them about which train is faster. Also quiets those that question if the train is going too slow.
Here’s another short-cut that is “Close Enough!” And EASY!
60 miles an hour = 88 feet per second, HO scale is 87 to 1, ergo 1 foot actual per second = roughly 60 mph. That means 2 seconds to go a foot= 30 mph, 4 seconds to go a foot = 15 mph. 8 seconds to go a foot = 7 1/2 mph. So pick some places on your layout that are about a foot apart, and all you have to do is count seconds then note the throttle setting! Enjoy!
This is a good topic.
On my upcoming layout, I really wi***o run at prototype speeds. Local freights, 45 scale mph. My long distance freights would have a max speed of 65 scale mph, while my SCL and New Haven passenger trains would be at 85 mph max.
Yes, prototype New Havens hauled by EP5s and SCL trains hauled by GG1s in the Northeast hit between 90 and 100 mph, however, when you think about it …this wouldn’t look realistic on a layout as the curves on the end of a layout have to be considered.
Especially with DCC/Sound, I imagine that I’m going to be enjoying watching and hearing a 4 unit locomotive lashup rev up the diesel engines and slowly pull a long freight train like they’re straining with the load.
BTW: I would definetly be interested in the speed indicator device just mentioned on a previous post. Anyone have any details on this?
Cheers!
Maybe this?,http://www.trainspeed.com/products.htm
that’s great slow speed performance.