ALCO HiAD trucks on the Burlington Northern

[David914]

Reading my copy of the Burlington Northern 1976-77 Annual, I came across the statement that the ALCO C636 locomotive were unpopular because of their hi-ad trucks. I would have thought that high adhesion would have been better for pulling long and/or heavy trains. Would it be that the trucks on EMD's SDP40F units had the same problems?

 

[bnsf971]

The issue was with the trucks, not the hi adhesion part.
On some railroads, they would do their best to fling themselves off the rails.

 

[Robert Gift]

The issue was with the trucks, not the hi adhesion part.
On some railroads, they would do their best to fling themselves off the rails.

Interesting! What made them fling themselves off the rails?

 

[bnsf971]

Interesting! What made them fling themselves off the rails?

It appears to be a harmonic between the 39' jointed rails, the axle and truck spacing on the 636s, low speeds (10-15mph), and the equipment layout of the engine. They were worse when low on fuel.