[dforrest]

steamer_ctn, on 26 February 2016 - 01:30 AM, said:

OR currently does not model wheelslip and adhesion fr steam locomotives. This is on a TO DO list.

I was not aware of this. Is there a blueprint or whatever is needed for it?

David

[Sandy River Tom]

OR doesn't model wheelslip for Steam Locos? I thought it did.

I have one steamer that I can't start WITHOUT Wheelslip.
Just cracking the throttle 1% - 2% puts the loco into violent wheelslip.
(They wheels don't actually spin, but I get the message)

[longiron]

I believe the discussion was about helpers, not player loco

[Hobo]

If it's only 1 of your steamers acting up I'd sure be looking at it's engine file very carefully . I run almost 50 different models in OR and haven't had any problems as long as the values of weights , adhesion , friction and weight on drivers are good .
Just a thought !

[Sandy River Tom]

If it's only 1 of your steamers acting up I'd sure be looking at it's engine file very carefully .

Yes, it's only one Loco
I have been going over the .eng file line-by-line.
Changing weight-on-drivers, adhesion, etc.
So far, nothing has helped or even changed the performance.

Thinking it might be 'animation frames' related.
This ONE Loco has 16 animation frames; all the other have 8 animation frames.

[steamer_ctn]

To be clear, the current OR adhesion model is designed for diesel and electric locomotives which have a constant force applied during a full wheel revolution.

The steam locomotive, due to the cranking arrangements of the gears, has different forces applied to it during a full wheel revolution, and therefore will slip under different conditions to a diesel or electric locomotive.

An experimental feature to monitor slip and provide an indication is in place for the steam locomotive (see the bottom of the expanded HUD), but this has not been "linked" into the general adhesion coding (ie slippage will not happen when the monitor indicates that it should).

[steamer_ctn]

A test patch to link the steam locomotive "adhesion" model into the OR model so that it will indicate wheel slips, and show over speed on the wheel rotations, etc. In addition the sander will now use sand, and air from the Main Air Reservoir.

The patch, and a sample ENG file for the test locomotive is attached. The test locomotive is located here.

If you trial this patch, make sure that "Large address aware binaries" is NOT selected. You will also need to select "Advanced adhesion model"

This patch will only apply to "normal" steam locomotives with cranking gear, geared steam locomotives will still use the "standard" diesel adhesion model.

Typically steam locomotives were designed with Factors of Adhesion between 4 and 5 to reduce the risk of them slipping. Locomotives with FoA < 3.0 often established a reputation for slipping.

The FoA is indicated in the extended HUD for the steam locomotive.

Typically under normal dry rail operating conditions, for appropriately designed locomotive, the wheel has enough adhesion to resist slipping. In wet, oily or icy conditions this adhesion is significantly reduced, so applying a large starting force may exceed it and cause wheel slip.

To test this patch set up a heavy consist (within the load capacity of the locomotive) and try starting with full throttle and reverser settings under wet and dry conditions.

The locomotive will perform more realistically if it the ENG file has been aligned to OR parameters.

Attached File(s)

•  OR_program_slip_v1.zip (3.78MB)
  Number of downloads: 222
•  ctn_test_atlantic.zip (6.82K)
  Number of downloads: 201

[copperpen]

steamer_ctn, on 08 March 2016 - 09:49 PM, said:

A test patch to link the steam locomotive "adhesion" model into the OR model so that it will indicate wheel slips, and show over speed on the wheel rotations, etc. In addition the sander will now use sand, and air from the Main Air Reservoir.

What about vac fitted engines?. They do not have an air reservoir and use steam instead.

[steamer_ctn]

copperpen, on 09 March 2016 - 01:07 AM, said:

What about vac fitted engines?. They do not have an air reservoir and use steam instead.

Do you have any info on steam consumption rates, sand consumption, etc?

Would the brake system type be the way to differentiate between an air or steam operated system?

[copperpen]

Far as I am aware there is no such data available. Steam consumption would not have been very high because it was used to blow the sand out of the delivery pipe and under the wheels. Too much steam would have defeated the object by blowing the sand too fast. I suppose the brake system could be used as a marker to decide on air or steam.

I have recently watched a video of Clan Line on a rail tour where sanding was used to counter wheelslip. The steam from the sanding pipes was quite light and whispy, so not a lot of pressure used.