Alignment control coupler issues are addressed on the BNSF Railway in the following manner; they can be placed in through-freight trains. I'll post this without the accompanying pictures, just as its easier for me right now.

Alignment Control Coupler Comparison

 


Figure 1. Coupler without alignment control

Figure 2. Coupler with alignment control



Couplers without the alignment control feature provide a greater range of coupler movement while negotiating tight curves in yards and industrial spurs. Couplers without alignment control permit a drawbar angle as large as +/- 34 degrees.

The alignment control feature on the coupler restricts the lateral movement of the drawbar when longitudinal in-train forces are in compression, or buff. Alignment control couplers, under buff conditions, can limit the drawbar angle to +/- 17 degrees. A lower drawbar angle reduces the lateral forces placed on the track at the wheel-rail interface and consequently lowers the possibility of derailment from rail rollover.

The locomotive manufacturer (EMD in this instance) recommends that bolster stops be installed when locomotives without alignment control features operate in consists with units capable of generating high dynamic effort.

For further reference and application
of this information on BNSF Railway,
refer to AB&TH Rule 101.18

Illustration credit: Transportation Safety Board of Canada, 2005- Report No. R05C0082

Revised, Oct. 2010


Note that AB&TH Rule 101.18 refers to train placement as DIT and close to rear end of train.