Atomic Systems

As some may be aware I am putting together a simple spreadsheet for data that can be used for ENGine and WAGon files within MSTS.

So far I have not been able to build-up any significant published data on Maximum Tractive Effort values for these units, and hence would welcome any values, hints, pointers, comments, etc. on this area?

I use these to arrive at suitable values for Maximum and Continuous Force in the ENGine file for the MSTS driving units.

If not, is anyone aware of a suitable means of estimating Maximum Tractive Effort? Is it a simple case of Mass times the coefficient of friction - typicallly 0.8 for steel on steel?

Ruf

PS Whilst this is to some extent a Physics based topic, I have posted here because I am initially looking for "real" values!

I have seen anything published for EMUs, or DMUs for that matter. But I would be interested to see if anyone has anything. Otherwise probably your best bet would be to look at the traction motor characteristics, and work out the torque produced at various voltage/speeds. From this you could get total tractive effort curve for the MU. Probably would help to know how the control system worked too.

I think wheel-on-rail friction is normally taken as approx 0.25 rather in 0.8, in the real world at any rate.

regards
Ed

Thanks for the response. The 0.8 figure was purely a tabulated value for steel-on-steel!

I shall consider your suggestion, and post if and when I get some sort of answer.

Ruf

Thinking back to my DEMU data I recall that the EE507 traction motors were used in the Classes 201 to 207, with the electrical current coming from the diesel engines. Several sources referred to a maximum tractive effort of 12500lbf, which I adopted for those units.

In the absence of any specific data I will initially adopt this value to allow me to develope the ENGine file data, and I can then update as further information comes to light/hand.

Ruf

That is useful information thanks, and I see it is quoted widely.

However to me it seems a high value. When you consider that there are 4 traction motors used per motorcar, and motorcars typically weigh between 40- 50 tons, then total TE would be 50,000 lbf. This gives a factor of adhesion of around 2, whereas normally 4 would be used as a design value. This comes from the 0.25 rail adhesion I mentioned before. This suggests to me that the real TE available would be half of what is quoted, at the point of starting to move. It may be that the control system is designed to allow the motors to develop their maximum tractive effort at say 15 mph. Then TE would begin to decline with speed as normal, with electrical resistance progressively switched out until full line voltage is applied to the traction motors.

I'm not sure how that all relates to the MSTS .ENG context though!

regards
Ed.

Following further research I have still been unable to locate any written data for EMU tractive effort, and therefore I intend to estimate the maximum force and maximum continuous force values for the ENGine files in MSTS by using the spreadsheet called ENG_FILE_ASSISTV2 (UKTS 10163). This uses the quoted horsepower to arrive at a maximum power value, from which I have estimated the maximum force value - similarly for the maximum continuous force.

Ruf