Dynamic brake useage.

[BaltACD]

Can the dynamic brake 'power' be regulated? For example, an engine brake in a semi has typically 3 settings...1-low, 2-med, 3-high.

Also...say...if a non-DB equipped engine was leading 3 other DB equipped units does the non-equipped unit have a provision for DB control...?

Dynamic Braking has 8 settings....the 8 notches of the throttle.  On the controlling locomotive the selector switch gets set to power or braking, you cannot have both at the same time.  Once the switch is set to braking, the engineer notches out to the level of dynamic braking he requires.  1st notch is a limited level of dynamic braking, the 8th notch is the maximum level of dynamic braking.  The position can be varied as needed by the terrain and the actions of the train.  When power is required, the throttle is notched back to idle and the selector switch set back to power and then the locomotives can be used to pull again.

If the lead engine is not DB equipped, there will be no DB on that engine consist, even if all trailing unit are equipped. 

[Modelcar]

.....Comparing braking force in a truck to a locomotive using DB and what it might effect to wear faster.

Many years ago when we were doing {automotive testing}, in the Pennsylvania mountains with trucks and automatic transmissions, which included a hydraulic retarder.  Of course using the retarder on all downgrades, loaded the pinion and ring gear sets in the trucks differental as opposed some of the time using the air brakes, etc....

Over in the locomotive...{and I'm not the expert on that}, but I would think using DB exclusively would put more wear thru the gearing between the traction motor and the axle.  Each side of the gears too, because all engines are run in both directions.

[METRO]

I've always wondered how much dynamic breaks used to cost? I've not seen any newer engines without it, but I know several roads (CNW, CRI&P, NKP ECT) didn't equip certain road engines with it. However if a line saves on maintainance, couldn't that offset the initial cost of dynamics?

[Gambi80]

Can the dynamic brake 'power' be regulated? For example, an engine brake in a semi has typically 3 settings...1-low, 2-med, 3-high.

Also...say...if a non-DB equipped engine was leading 3 other DB equipped units does the non-equipped unit have a provision for DB control...?

[Murphy Siding]

     Thinking of this as like a truck, downshifting to save the brakes.....does using dynamic brakes a lot, cause undue wear on the locomotive?  Perhaps wearing out the electrical equipment faster in a mountainous area, verses a flat area?

[jeffhergert]

Yes it can be limited but not proportionately.  I believe there is an electrical switch in the cab that lets the engineer turn off the DB in a particular engine.  That is how IC limits the axles with DB and I assume all railroads do. 

Correct.  Most of our newer DB equipped units have a switch that has a cut in, cut out for DB Axle restrictions, or cut out defective options.  

We also have restrictions in how much DB force to use going through turnouts and curves to reduce in-train forces.

Jeff    

[ndbprr]

Yes it can be limited but not proportionately.  I believe there is an electrical switch in the cab that lets the engineer turn off the DB in a particular engine.  That is how IC limits the axles with DB and I assume all railroads do. 

[daveklepper]

The disadvantage of dynamic braking is that only the locomotive is exerting the braking force.   Thus, if all the locomotive power is at the front of the train, and the  train is long, the rear of the train wishes to keep moving and with too much brake effort a buckle will occur, with cars in the middle derailing.   So, limiting the amount of dynamic braking in design only solves the problem if only one unit is used, or possibly two.  Of course, some of this problem still exists with air brakes, since it takes time for the drop in air pressure in the train line to pass to the rear of the train, activating the brakes there.   Being a locomotive engineer is a profession of skill, not for amatures, that is for sure!    On mountain railroads, there are varous measures to mitigate the problems, including distributed power.

[zardoz]

....That was my question too....Can Dynamic braking be varied from locomotive to locomotive and or not used on one of the {3}, that might be at the head end of the train....?

Dynamics cannot be varied between locomotives that are connected via the 27-point jumper--they will all work at whatever level they would work at if they were single units responding to similar throttle positions..

DP units can be operated independently of the lead units (one can even work power on the DP unit while at the same time working dynamics on the lead units-a great way to keep the train bunched).

[csxengineer98]

A little known fact is that with dynamic braking you can have too much braking.  IC limits dynamic braking to 16 axles on a train for that reason.

What happens if you have too much braking?  Skid marks?   Also, is are the dynamics an all-or-nothing type affair?  For example, if a train is being pulled by 3 locomotives, do the dynamic brakes of all 3 work in unison?

you can slow the head end down to fast and buckle the train and derail... and if the DB is cut in on all the units and the units are all equpiped with DB..then yes..they all work in unison just like the throttle dose...

css engineer 

[Modelcar]

....That was my question too....Can Dynamic braking be varied from locomotive to locomotive and or not used on one of the {3}, that might be at the head end of the train....?

[Murphy Siding]

A little known fact is that with dynamic braking you can have too much braking.  IC limits dynamic braking to 16 axles on a train for that reason.

What happens if you have too much braking?  Skid marks?   Also, is are the dynamics an all-or-nothing type affair?  For example, if a train is being pulled by 3 locomotives, do the dynamic brakes of all 3 work in unison?

[ndbprr]

A little known fact is that with dynamic braking you can have too much braking.  IC limits dynamic braking to 16 axles on a train for that reason.

[mackb4]

 All mentioned.

 The NS-1 states that the use of the dynamic brake is first priority in slowing down a train.

 I'm sure most railroads ask that of their Engineer's.

 

[Saxman]

Yes dynamic braking is used on "flat Land".  It is an effective braking system especially the extended range high capacity braking of the new locomotives. I prefer it over the air especially during cold weather and with long trains.

[CShaveRR]

Besides the reduction in maintenance, the use of dynamic brakes saves the time and energy required to release the brakes when you wish to move or increase speed again.

[Ted Marshall]

     Are dynamic brakes used for braking on reletively flat tracks, or  garden variety hills, or just on the *big* hills?

 Here in "flat" Florida, dynamics are used regularly to slow trains. The use of dynamics vs. friction brakes results in reduced brake wear/maintenance which save the railroad money which is the bottom line.  In hilly or mountainous terrain, dynamics compliment friction brakes by preventing them from overheating on downgrades as well as helping the engineer control slack.

[Murphy Siding]

     Are dynamic brakes used for braking on reletively flat tracks, or  garden variety hills, or just on the *big* hills?